{"id":346,"date":"2019-11-04T23:54:44","date_gmt":"2019-11-04T23:54:44","guid":{"rendered":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/chapter\/7-5-antiemetic\/"},"modified":"2021-12-07T11:21:00","modified_gmt":"2021-12-07T11:21:00","slug":"7-5-antiemetic","status":"publish","type":"chapter","link":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/chapter\/7-5-antiemetic\/","title":{"raw":"7.5 Antiemetics","rendered":"7.5 Antiemetics"},"content":{"raw":"<div class=\"1.5-nausea-and-vomiting:-antiemetic-&amp;-antinausea-drugs\">\n\nNausea and vomiting are common conditions. Nausea is the unpleasant sensation of having the urge to vomit, and vomiting(emesis) is the forceful expulsion of gastric contents.<sup>[footnote]Bashashati, M. &amp; McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. <em>European Journal of Pharmacology, 772<\/em>, p 79.[\/footnote]<\/sup> There are many potential causes of nausea and vomiting, such as:\n<ul>\n \t<li>Morning sickness during pregnancy<\/li>\n \t<li><strong>[pb_glossary id=\"2257\"]Gastroenteritis[\/pb_glossary] <\/strong>and other infections<\/li>\n \t<li>Migraines<\/li>\n \t<li>Motion sickness<\/li>\n \t<li>Food poisoning<\/li>\n \t<li>Side effects of medicines, including those for cancer chemotherapy<\/li>\n \t<li>GERD\u00a0and ulcers<\/li>\n \t<li>Intestinal obstruction<\/li>\n \t<li>Poisoning or exposure to a toxic substance<\/li>\n \t<li>Diseases of other organs (cardiac, renal, or liver)<\/li>\n<\/ul>\nNausea and vomiting are common and are usually not serious. However, the health care provider should be contacted immediately if the following conditions occur:\n<ul>\n \t<li>Vomiting for longer than 24 hours<\/li>\n \t<li>Blood in the vomit (also called <strong>[pb_glossary id=\"1293\"]hematemesis[\/pb_glossary]<\/strong>)<\/li>\n \t<li>Severe abdominal pain<\/li>\n \t<li>Severe headache and stiff neck<\/li>\n \t<li>Signs of dehydration, such as dry mouth, infrequent urination, or dark urine<\/li>\n<\/ul>\nTreatment of nausea and vomiting should be tailored to the cause. There are several medications that work on different neuroreceptors that when used can treat nausea and vomiting. For severe cases of vomiting, intravenous fluids may also be needed to treat the accompanying dehydration. <sup>[footnote]MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2019 October 23]. <em>Nausea and vomiting;<\/em> [updated 2019 February 7; reviewed 2016 March 17; cited 2019 October 27]. <a href=\"https:\/\/medlineplus.gov\/nauseaandvomiting.html\" target=\"_blank\" rel=\"noopener noreferrer\">https:\/\/medlineplus.gov\/nauseaandvomiting.html<\/a>.[\/footnote],[footnote]Bashashati, M. &amp; McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. <em>European Journal of Pharmacology, 772<\/em>, p 79.[\/footnote]<\/sup>\n<h2>Pathophysiology<\/h2>\nThe vomiting center can be activated directly by irritants or indirectly following input from four principal areas: gastrointestinal tract, cerebral cortex and thalamus, vestibular region, and chemoreceptor trigger zone (CRTZ). See Figure 7.14 for an illustration of the pathophysiology of nausea and vomiting.<sup>[footnote]Becker D. E. (2010). Nausea, vomiting, and hiccups: a review of mechanisms and treatment. Anesthesia progress, 57(4), 150\u2013157. doi:10.2344\/0003-3006-57.4.150[\/footnote]<\/sup>\n\n[caption id=\"\" align=\"aligncenter\" width=\"407\"]<img title=\"Becker D. E. (2010). Nausea, vomiting, and hiccups: a review of mechanisms and treatment. Anesthesia progress, 57(4), 150\u2013157. doi:10.2344\/0003-3006-57.4.150\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2019\/11\/image1-2.png\" alt=\"Chart showing pathophysiology of nausea and vomiting\" width=\"407\" height=\"332\"> Figure 7.14 Pathophysiology of nausea and vomiting[\/caption]\n\nAn important part of the emesis circuit is the <strong>[pb_glossary id=\"1288\"]chemoreceptor trigger zone (CTZ)[\/pb_glossary]<\/strong>, located in the <strong>[pb_glossary id=\"2270\"]area postrema[\/pb_glossary] <\/strong>in the brain. The CTZ is not restricted by the blood\u2013brain barrier, which allows it to respond directly to toxins in the bloodstream such as anesthesia and opioids. The CTZ also receives stimuli from several other locations in the body including the vestibular center; visceral organs such as the GI tract, kidneys, and liver; the thalamus; and the cerebral cortex.\n\nThe vestibular center and cerebral cortex can stimulate the vomiting center directly or indirectly through the CTZ. The <strong>[pb_glossary id=\"1289\"]vestibular system [\/pb_glossary]<\/strong> is located within the inner ear and gives a sense of balance and spatial orientation for the purpose of coordinating movement with balance. The feeling of nausea associated with motion sickness often arises from stimuli from the vestibular center. The gastrointestinal tract sends stimuli to the CTZ via cranial nerves IX and X related to obstruction, distension, inflammation, and infection. The cerebral cortex and other parts of the brain can also stimulate a sense of nausea related to odors, tastes, and images and send these stimuli to the CTZ. The CTZ forwards these signals to the vomiting center in the brain. Pain can also directly stimulate the vomiting center.\n\nThe <strong>[pb_glossary id=\"1290\"] vomiting center[\/pb_glossary]<\/strong> (VC) is located in the medulla in the brain. In response to these stimuli, the vomiting center initiates vomiting by inhibiting peristalsis and producing retro-peristaltic contractions beginning in the small bowel and ascending into the stomach. It also produces simultaneous contractions in the abdominal muscles and diaphragm that generate high pressures to propel the stomach contents upwards. Additionally, autonomic stimulation of the heart, airways, salivary glands, and skin cause other symptoms associated with vomiting such as salivation, palor, sweating, and tachycardia. Several neurotransmitters are involved in the nausea and vomiting process, and antiemetic medications are targeted to specific neuroreceptors.<sup>[footnote]Becker D. E. (2010). Nausea, vomiting, and hiccups: a review of mechanisms and treatment. <em>Anesthesia progress, 57<\/em>(4), 150\u2013157. <a href=\"https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3006663\/\" target=\"_blank\" rel=\"noopener noreferrer\">https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3006663\/<\/a>[\/footnote]<\/sup>\n\nTable 7.5a compares the neurotransmitters involved in the nausea and vomiting process, classes of antiemetic medication targeting these neurotrasmitters, prototype antiemetic medications, and associated mechanisms of action.<sup>[footnote]Bashashati, M. and McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. <em>European Journal of Pharmacology, 772<\/em>, p 79.[\/footnote]<\/sup> Each medication class is also discussed in more detail later in this section.\n\nTable 7.5a Neurotransmitters and Associated Medications Used to Treat Nausea and Vomiting\n<table class=\"grid\">\n<tbody>\n<tr>\n<th style=\"background-color: #a4c2f4\" scope=\"col\">Neurotransmitter<\/th>\n<th style=\"background-color: #a4c2f4\" scope=\"col\">Medication Class<\/th>\n<th style=\"background-color: #a4c2f4\" scope=\"col\">Antiemetic Drug<\/th>\n<th style=\"background-color: #a4c2f4\" scope=\"col\">Mechanism of Action<\/th>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Acetylcholine (M1)<\/th>\n<td>Anticholinergics<\/td>\n<td>scopolamine<\/td>\n<td>Blocks ACh receptors in vestibular system<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Histamine (H1)<\/th>\n<td>Antihistamines<\/td>\n<td>meclizine<\/td>\n<td>Blocks H1 receptors and thus blocks ACh in vestibular system<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Dopamine (DA2)<\/th>\n<td>Dopamine antagonists<\/td>\n<td>prochlorperazine<\/td>\n<td>Blocks dopamine in CTZ and may block ACh<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Dopamine and ACh (DA2 and M1)<\/th>\n<td>Prokinetics<\/td>\n<td>metoclopramide<\/td>\n<td>Blocks dopamine in CTZ and stimulates ACh in GI tract<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Serotonin (5HT)<\/th>\n<td>Serotonin antagonists<\/td>\n<td>ondansetron<\/td>\n<td>Blocks serotonin in GI tract, CTZ, and VC<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Substance P (NK1)<\/th>\n<td>Neurokinin antagonists<\/td>\n<td>aprepitant<\/td>\n<td>Inhibits substance P neurokinin receptors<\/td>\n<\/tr>\n<tr class=\"a-R\">\n<th style=\"background-color: #c9daf8\" scope=\"row\">Cannabinoid (CB1)<\/th>\n<td>Tetrahydrocannabinols (THC)<\/td>\n<td>dronabinol or medical marijuana<\/td>\n<td>Activated CB1 receptor leading to inhibitory effects on cerebral cortex<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Nursing Considerations<\/h2>\n<h3><strong>Assessment<\/strong><\/h3>\nWhen administering antiemetics, identify factors contributing to the symptoms of nausea and vomiting so that treatment can correctly target the cause. Document the frequency and amount of emesis and effects on the patient's appetite and fluid intake. Assess for symptoms of dehydration, such as decreased blood pressure associated with tachycardia, decreased skin turgor, and decreased urine output or dark concentrated urine. If lab tests are ordered, monitor hemoglobin, hematocrit, and serum sodium levels for additional signs of dehydration.\n<h3><strong>Implementation<\/strong><\/h3>\nAdvocate for the most effective route of administration if the patient is vomiting. Consider timing of administration of antiemetics in advance of meals when appetite is affected. Follow drug label administration information and monitor the patient closely for potential side effects associated with that category of medication. For example, when administering anticholinergics and antihistamines, monitor for anticholinergic side effects, especially in elderly patients.\n<h3><strong>Evaluation<\/strong><\/h3>\nMonitor for improvement of nausea and vomiting and notify the provider if expected improvement does not occur so that other treatment can be initiated. Continue to monitor for dehydration. Teach the patient nonpharmacological interventions for nausea such as:\n<ul>\n \t<li>Drink enough fluids to avoid dehydration. If you are having trouble keeping liquids down, drink sips of clear liquids every few minutes.<\/li>\n \t<li>Eat bland foods; stay away from spicy, fatty, or salty foods.<\/li>\n \t<li>Eat smaller meals more often.<\/li>\n \t<li>Avoid strong smells because they can sometimes trigger nausea and vomiting.<\/li>\n \t<li>If you are pregnant and have morning sickness, eat crackers before you get out of bed in the morning.<sup>[footnote]MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2019 October 23]. <em>Nausea and vomiting<\/em>; [updated 2019 February 7; reviewed 2016 March 17; cited 2019 October 27]. <a href=\"https:\/\/medlineplus.gov\/nauseaandvomiting.html\" target=\"_blank\" rel=\"noopener noreferrer\">https:\/\/medlineplus.gov\/nauseaandvomiting.html<\/a>.[\/footnote]<\/sup><\/li>\n<\/ul>\n<h2>Antiemetic Medication Classes<\/h2>\n<h3>Anticholinergics<\/h3>\nScopolamine is an example of an anticholinergic medication that is often used to treat motion sickness or nausea and vomiting associated with surgical recovery from anesthesia and\/or opiate analgesia.\n\n<strong>Mechanism of Action<\/strong>\n\nAnticholinergics block ACh receptors in the vestibular center and within the brain to prevent nausea-inducing stimuli to the Chemoreceptor Trigger Zone (CTZ) and the Vomiting Center (VC). They also dry GI secretions and reduce smooth muscle spasms.\n\n<strong>Specific Administration Considerations<\/strong>\n\nThe scopolamine transdermal patch (see Figure 7.15)<sup>[footnote]\"<a href=\"https:\/\/www.flickr.com\/photos\/andreasnilsson1976\/2551446785\" target=\"_blank\" rel=\"noopener noreferrer\">Scopoderm 278:365<\/a>\" by <a href=\"https:\/\/www.flickr.com\/photos\/andreasnilsson1976\/\" target=\"_blank\" rel=\"noopener noreferrer\">Andreas Nilsson<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC BY-NC-ND 2.0<\/a>[\/footnote]<\/sup>\u00a0is designed for continuous release of scopolamine following application to an area of intact skin on the head, behind the ear. The system is formulated to deliver approximately 1 mg of scopolamine to the systemic circulation over 3 days. It is contraindicated in patients with glaucoma. It has been reported to exacerbate psychosis, induce seizures, and cause drowsiness, confusion, and sedation. Due to its anticholinergic properties, scopolamine can decrease gastrointestinal motility and cause urinary retention. Nurses should perform more frequent monitoring during treatment with Transderm Sc\u014dp and discontinue Transderm Sc\u014dp in patients who develop difficulty in urination. Transderm Sc\u014dp contains an aluminized membrane; skin burns have been reported at the application site in patients wearing an aluminized transdermal system during an MRI scan. Remove Transderm Sc\u014dp before undergoing an MRI.\n\n[caption id=\"\" align=\"aligncenter\" width=\"347\"]<img title=\"&quot;Scopoderm 278:365&quot; by Andreas Nilsson is licensed under CC BY-NC-ND 2.0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image2-2-1.png\" alt=\"Photo of male with transdermal patch behind right ear\" width=\"347\" height=\"521\"> Figure 7.15 Scopolamine Transdermal Patch[\/caption]\n\nApplication instructions:\n<ul>\n \t<li>Only wear one transdermal system at any time.<\/li>\n \t<li>Do not cut the transdermal system.<\/li>\n \t<li>Apply the transdermal system to the skin in the postauricular area (hairless area behind one ear).<\/li>\n \t<li>After the transdermal system is applied on the dry skin behind the ear, wash hands thoroughly with soap and water and dry hands.<\/li>\n \t<li>If the transdermal system becomes displaced, discard the transdermal system, and apply a new transdermal system on the hairless area behind the other ear.<\/li>\n \t<li>For surgeries other than cesarean section, apply one Transderm Sc\u014dp transdermal system the evening before scheduled surgery. Remove the transdermal system 24 hours following surgery.<\/li>\n<\/ul>\n<strong>Patient Teaching &amp; Education<\/strong>\n\nTransderm Sc\u014dp may impair the mental and\/or physical abilities required for the performance of hazardous tasks such as driving a motor vehicle, operating machinery, or participating in underwater sports. Concomitant use of other drugs (e.g., alcohol, sedatives, hypnotics, opiates, and anxiolytics) that cause central nervous system (CNS) adverse reactions, or that have anticholinergic properties, may increase this impairment. Inform patients not to operate motor vehicles or other dangerous machinery or participate in underwater sports until they are reasonably certain that Transderm Sc\u014dp does not affect them adversely. Scopolamine can cause temporary dilation of the pupils resulting in blurred vision if it comes in contact with the eyes. Advise patients to wash their hands thoroughly with soap and water and dry their hands immediately after handling the transdermal system. Upon removal, fold the used transdermal system in half with the sticky side together, and discard in household trash in a manner that prevents accidental contact or ingestion by children, pets, or others.<sup>[footnote]This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>. [\/footnote]<\/sup>\n<h3>Antihistamines<\/h3>\nMeclizine is an example of an antihistamine that is often used to treat motion sickness.\n\n<strong>Mechanism of Action<\/strong>\n\nAntihistamines block H1 receptors in the vestibular center and may also block acetylcholine (ACh).\n\n<strong>Specific Administration Considerations<\/strong>\n\nAntihistamines are contraindicated in patients with glaucoma or an enlarged prostate gland. Dosage should be started one hour before travel begins.\n\n<strong>Patient Teaching &amp; Education<\/strong>\n<ul>\n \t<li>Do not exceed recommended dosage.<\/li>\n \t<li>Be advised that drowsiness may occur.<\/li>\n \t<li>Avoid alcohol, sedatives, and tranquilizers, which may increase drowsiness.<\/li>\n \t<li>Avoid alcoholic drinks.<\/li>\n \t<li>Be careful when driving a motor vehicle or operating machinery.<sup>[footnote]This work is a derivative of <a style=\"text-align: initial\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a><span style=\"text-align: initial\"> by <\/span><a style=\"text-align: initial\" href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a><span style=\"text-align: initial\"> in the <\/span><a style=\"text-align: initial\" href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a><span style=\"text-align: initial\">. [\/footnote]<\/span><\/sup><\/li>\n<\/ul>\n<h3>Dopamine Antagonists<\/h3>\nProchlorperazine is an example of a dopamine antagonist used to treat nausea and vomiting. It can also be used as an antipsychotic medication.\n\n<strong>Mechanism of Action<\/strong>\n\nProchlorperazine blocks dopamine in the Chemoreceptor Trigger Zone (CTZ). It also calms the central nervous system and may also block acetylcholine.\n\n<strong>Specific Administration Considerations<\/strong>\n\nProchlorperazine can be administered orally, intramuscularly, rectally or intravenously. It is contraindicated in children under age 2 or under 20 pounds. Severe side effects have occurred when used to treat psychosis.\n\n<strong>Patient Teaching &amp; Education<\/strong>\n\nPatients should be instructed to take medications as prescribed.\u00a0 They should avoid alcohol and other CNS depressants.\u00a0 Patients may experience increased photosensitivity and extreme temperatures should be avoided.\u00a0 Patients should be advised that urine may turn pinkish to reddish-brown.<sup>[footnote]uCentral from Unbound Medicine. <a href=\"https:\/\/www.unboundmedicine.com\/ucentral\" target=\"_blank\" rel=\"noopener noreferrer\">https:\/\/www.unboundmedicine.com\/ucentral<\/a>[\/footnote]<\/sup>\n<h3>Prokinetics<\/h3>\nMetoclopramide is an example of a prokinetic medication (see Figure 7.16).<sup>[footnote]\"<a href=\"https:\/\/www.flickr.com\/photos\/104346167@N06\/36640425216\" target=\"_blank\" rel=\"noopener noreferrer\">Metoclopramide<\/a>\" by <a href=\"https:\/\/www.flickr.com\/photos\/104346167@N06\/\" target=\"_blank\" rel=\"noopener noreferrer\">John Campbell<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC0<\/a>[\/footnote]<\/sup>\n\n[caption id=\"\" align=\"aligncenter\" width=\"601\"]<img title=\"&quot;Metoclopramide&quot; by John Campbell is licensed under CC0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image4-2-1.png\" alt=\"Photo of metoclopramide vials, a prokinetic\" width=\"601\" height=\"401\"> Figure 7.16 Prokinetics[\/caption]\n\n<strong>Mechanism of Action<\/strong>\n\nMetoclopramide blocks dopamine and may also sensitize tissues to acetylcholine. It is used to promote peristalsis to empty the gastrointestinal tract and thus reduce nausea.\n\n<strong>Specific Administration Considerations<\/strong>\n\nMetoclopramide can be administered orally, intramuscularly, and intravenously. The onset of pharmacological action of metoclopramide is 1 to 3 minutes following an intravenous dose, 10 to 15 minutes following intramuscular administration, and 30 to 60 minutes following an oral dose. Pharmacological effects persist for 1 to 2 hours.\n\nMetoclopramide should not be used whenever stimulation of gastrointestinal motility might be dangerous (e.g., in the presence of gastrointestinal hemorrhage, mechanical obstruction, or perforation). Metoclopramide is contraindicated in patients with pheochromocytoma because the drug may cause a hypertensive crisis. Metoclopramide should not be used in epileptics or patients receiving other drugs that are likely to cause extrapyramidal reactions because the frequency and severity of seizures or extrapyramidal reactions may be increased. Rare reports of neuromalignant syndrome have occured.\n\n<strong>Patient Teaching &amp; Education<\/strong>\n\nTeach patients to immediately inform the healthcare provider if they experience new feelings of depression or abnormal muscle movements they cannot control such as:\n<ul>\n \t<li>lip smacking, chewing, or puckering of the mouth<\/li>\n \t<li>frowning or scowling<\/li>\n \t<li>sticking out the tongue<\/li>\n \t<li>blinking and moving the eyes<\/li>\n \t<li>shaking of the arms and legs<sup>[footnote]This work is a derivative of <a style=\"text-align: initial\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a><span style=\"text-align: initial\"> by <\/span><a style=\"text-align: initial\" href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a><span style=\"text-align: initial\"> in the <\/span><a style=\"text-align: initial\" href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a><span style=\"text-align: initial\">. [\/footnote]<\/span><\/sup><\/li>\n<\/ul>\n<h3>Serotonin Antagonists<\/h3>\nOndansetron\u00a0is an example of a serotonin (5HT) antagonist often used to treat severe nausea and vomiting associated with chemotherapy, postoperative nausea and vomiting, and hyperemesis during pregnancy. (See Figure 7.17 for an image of odansetron blocking the 5-HT<sub>3<\/sub> receptor.<sup>[footnote]\"<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Eichelbaum2.jpg\" target=\"_blank\" rel=\"noopener noreferrer\">Eichelbaum2.jpg<\/a>\" by Michel Eichelbaum is licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/de\/deed.en\" target=\"_blank\" rel=\"noopener noreferrer\">CC BY-SA 3.0 DE<\/a>[\/footnote]<\/sup>)\n\n[caption id=\"\" align=\"aligncenter\" width=\"557\"]<img title=\"&quot;Eichelbaum2.jpg&quot; by Michel Eichelbaum is licensed under CC BY-SA 3.0 DE\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image5.jpg\" alt=\"Illustration of Ondansetron blocking serotonin receptors.\" width=\"557\" height=\"414\"> Figure 7.17 Ondansetron blocking the 5-HT<sub>3<\/sub> receptor[\/caption]\n\n<strong>Mechanism of Action<\/strong>\n\nOndansetron blocks serotonin receptors in the GI tract, the chemoreceptor trigger zone (CTZ), and the vomiting center (VC). See Figures 7.18 and 7.19 for images of the injectable and oral formulations of ondansetron.<sup>[footnote]\"<a href=\"https:\/\/en.wikipedia.org\/wiki\/File:000817lg_Zofran_8_MG_Oral_Tablet.jpg\" target=\"_blank\" rel=\"noopener noreferrer\">000817lg Zofran 8 MG Oral Tablet.jpg<\/a>\" by NLM is licensed under <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC0<\/a>[\/footnote]<span style=\"font-size: 16px\">,<\/span><\/sup><sup>[footnote]\"<a href=\"http:\/\/flickr.com\/photos\/intropin\/4499127380\" target=\"_blank\" rel=\"noopener noreferrer\">Ondansetron (1<\/a>)\" by <a href=\"https:\/\/www.flickr.com\/photos\/intropin\/\" target=\"_blank\" rel=\"noopener noreferrer\">M<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC BY-NC 2.0<\/a>[\/footnote]<\/sup>\n\n[caption id=\"\" align=\"aligncenter\" width=\"313\"]<img title=\"&quot;Ondansetron (1)&quot; by M is licensed under CC BY-NC 2.0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image6-2-1.png\" alt=\"Photo of bottle of Zofran injectable.\" width=\"313\" height=\"418\"> Figure 7.18 Ondansetron in injectable form[\/caption]\n\n[caption id=\"\" align=\"aligncenter\" width=\"436\"]<img style=\"color: #373d3f;font-weight: bold;font-size: 1.125em\" title=\"&quot;000817lg Zofran 8 MG Oral Tablet.jpg&quot; by NLM is licensed under CC0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image7-2-1.png\" alt=\"Photo of Zofran tablets\" width=\"436\" height=\"311\"> Figure 7.19 Ondansetron in tablet form[\/caption]\n\n<strong>Specific Administration Considerations<\/strong>\n\nOndansetron is available as an orally disintegrating tablet and as an injectable for those patients too nauseated to tolerate oral medication. It is contraindicated with apomorphine. <strong>[pb_glossary id=\"1903\"]Serotonin syndrome[\/pb_glossary]<\/strong> can occur if administered concurrently with other serotonin antagonists or selective serotonin reuptake inhibitors. Ondansetron can cause headaches, drowsiness, constipation, fever, and diarrhea. A rare but serious adverse effect of ondansetron is QT prolongation that can cause an abnormal cardiac rhythm.\n\n<strong>Patient Teaching &amp; Education<\/strong>\n\nTeach patients to immediately inform their healthcare provider if they experience a change in heart rate, lightheadedness, or feel faint or have any signs and symptoms of hypersensitivity reactions such as fever, chills, rash, or breathing problems.<sup>[footnote]This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>. [\/footnote]<\/sup>\n<h3>Neurokinin Receptor Antagonists<\/h3>\nAprepitant is an example of a neurokinin antagonist used to prevent nausea and vomiting associated with chemotherapy and surgery.\n\n<strong>Mechanism of Action<\/strong>\n\nAprepitant inhibits substance-P neurokinin receptors in the brainstem.\n\n<strong>Nursing Considerations<\/strong>\n\nAprepitant is usually administered concurrently with dexamethasone (a corticosteroid) and ondansetron. It can be administered orally or intravenously. It has clinically significant CYP3A4 drug interactions with medications such as pimozide, diltiazem, and rifampin, and can decrease INR levels when taken concurrently with warfarin. It can also reduce the effectiveness of oral contraceptives.\n\n<strong>Patient Teaching &amp; Education<\/strong>\n\nTeach patients taking warfarin that they will need to monitor their INR levels more closely, which may require adjustment of the warfarin dosage, while taking aprepitant. Teach patients using an oral contraceptive to use backup birth control.<sup>[footnote]This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>. \u00a0[\/footnote]<\/sup>\n<h3>Tetrahydrocannabinoids (THC)<\/h3>\nDronabinol or medical marijuana is an example of a <strong>[pb_glossary id=\"2306\"]THC[\/pb_glossary]<\/strong> medication used to treat nausea in patients with cancer or AIDS (see Figures 7.20 and 7.21).<sup>[footnote]\"<a href=\"https:\/\/www.flickr.com\/photos\/115645852@N04\/32335066121\" target=\"_blank\" rel=\"noopener noreferrer\">Marinol - Dronabinol<\/a>\" by <a href=\"https:\/\/www.flickr.com\/photos\/115645852@N04\/\" target=\"_blank\" rel=\"noopener noreferrer\">Steffen Geyer<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC BY-NC 2.0<\/a> &amp; 7.21\"<a href=\"https:\/\/www.publicdomainpictures.net\/en\/view-image.php?image=246405&amp;picture=medical-marijuana\" target=\"_blank\" rel=\"noopener noreferrer\">Medical Marijuana<\/a>\" by <a href=\"https:\/\/www.publicdomainpictures.net\/en\/browse-author.php?a=81846\" target=\"_blank\" rel=\"noopener noreferrer\">Circe Denyer<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC0<\/a>[\/footnote]<\/sup>\n\n[caption id=\"\" align=\"aligncenter\" width=\"345\"]<img title=\"&quot;Marinol - Dronabinol&quot; by Steffen Geyer is licensed under CC BY-NC 2.0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image8-1-1.png\" alt=\"Photo of Marinol capules bottle.\" width=\"345\" height=\"517\"> Figure 7.20 Dronabinol, a THC medication[\/caption]\n\n&nbsp;\n\n[caption id=\"\" align=\"aligncenter\" width=\"610\"]<img title=\"&quot;Medical Marijuana&quot; by Circe Denyer is licensed under CC0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image9-1.png\" alt=\"Photo of medical marijuana in prescription bottle\" width=\"610\" height=\"457\"> Figure 7.21 Medical Marijuana[\/caption]\n\n<strong>Mechanism of Action<\/strong>\n\nTHC has inhibitory effects in the cerebral cortex causing an alteration in mood and the body's perception of its surroundings, which may relieve nausea and vomiting, as well as stimulate the appetite.\n\n<strong>Specific Administration Considerations<\/strong>\n\nTHC will cause a dose-related \"high\" (easy laughing, elation, and heightened awareness). It is abusable and, thus, is a controlled substance and scheduled medication. THC should be used cautiously in elderly patients because they may be more sensitive to the neurological, psychoactive, and postural hypotensive effects of the drug. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range.\n\n<strong>Patient Teaching &amp; Education<\/strong>\n\nTeach patients to not drive, operate machinery, or engage in any hazardous activity when using THC. Keep out of reach of children and pets.<sup>[footnote]This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>. \u00a0[\/footnote]<\/sup>\n<h3>Herbal and Vitamin Supplements<\/h3>\nGinger has been used in traditional Indian and Chinese medicine as an antiemetic. Although its mechanism of action is not completely understood, ginger is thought to antagonize the 5HT and cholinergic receptors and may have direct activity on the gastrointestinal tract. Although ginger can cause reflux and heartburn and may potentially cause bleeding because of its anticoagulant effects, dosages of up to 2 g per day in divided doses of 250 mg are considered safe even in pregnant women. Pyridoxine (vitamin B6) has also been recommended for treating nausea and vomiting in pregnancy. Typical dosages of pyridoxine 10 to 25 mg every eight hours cause minimal adverse effects. <sup>[footnote]Flake, Z., Linn, B., &amp; Hornecker, J. (2015). Practical selection of antiemetics in the ambulatory setting. <em>American Family Physician, 91<\/em>(5): pp 293-296.[\/footnote]<\/sup>\n<h2>Antiemetics Medication Grid<\/h2>\nNow let's take a closer look at the medication grid comparing medications used to treat nausea. See Table 7.5b.<sup>[footnote]This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>. [\/footnote]<\/sup>\n\nMedication grids are intended to assist students to learn key points about each medication.\u00a0 Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication. Basic information related to each class of medication is outlined below.\u00a0 Detailed information on a specific medication can be found for free at <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/index.cfm\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a>. On the home page, enter the drug name in the search bar to read more about the medication.\u00a0 Prototype\/generic medications listed in the grids below are also hyperlinked directly to a Daily Med page.\n\n<span style=\"text-align: initial;font-size: 1em\">Table 7.5b Medication Grid Comparing Antiemetics<\/span>\n<table class=\"grid\">\n<tbody>\n<tr>\n<th style=\"width: 120.391px\" scope=\"col\"><strong>Class<\/strong><\/th>\n<th style=\"width: 134.557px\" scope=\"col\"><strong>Prototype\/<\/strong>\n\n<strong>Generic<\/strong><\/th>\n<th style=\"width: 238.724px\" scope=\"col\"><strong>Administration <\/strong><strong>Considerations<\/strong><\/th>\n<th style=\"width: 127.891px\" scope=\"col\"><strong>Therapeutic Effects<\/strong><\/th>\n<th style=\"width: 363.724px\" scope=\"col\"><strong>Adverse\/Side Effects<\/strong><\/th>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Anticholinergic<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId19\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=b877a694-a1d0-4280-937a-a06820b12a88\" target=\"_blank\" rel=\"noopener noreferrer\">scopolamine<\/a><\/td>\n<td style=\"width: 238.724px\">Apply patch to hairless skin behind ear for 3 days or apply the night before surgery and remove 24 hours later\n\nDo not cut patch\n\nAfter application, thoroughly wash and dry hands\n\nRemove before an MRI\n\nContraindicated in patients with glaucoma<\/td>\n<td style=\"width: 127.891px\">Prevent or reduce nausea and vomiting associated with motion sickness or surgery<\/td>\n<td style=\"width: 363.724px\">Monitor for anticholinergic effects such as decreased GI motility and urinary retention\n\nDiscontinue if it exacerbates psychosis or causes seizures or cognitive impairment<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Antihistamine<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId20\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=8b3c9283-b618-4d57-9f15-7cf73e8737f5\" target=\"_blank\" rel=\"noopener noreferrer\">meclizine<\/a><\/td>\n<td style=\"width: 238.724px\">Contraindicated in patients with glaucoma or an enlarged prostate gland\n\nDosage should be started one hour before travel begins<\/td>\n<td style=\"width: 127.891px\">Prevent or reduce nausea and vomiting associated with motion sickness<\/td>\n<td style=\"width: 363.724px\">May cause drowsiness<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Dopamine antagonist<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId21\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=5e771ba7-983f-49b4-a1f2-0f335b637433\" target=\"_blank\" rel=\"noopener noreferrer\">prochlorperazine<\/a><\/td>\n<td style=\"width: 238.724px\">Can be administered PO, IM, PR, or IV<\/td>\n<td style=\"width: 127.891px\">To control nausea and vomiting associated with surgery<\/td>\n<td style=\"width: 363.724px\">Drowsiness, dizziness, amenorrhea, blurred vision, skin reactions, and hypotension may occur<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Prokinetic<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId22\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=50a3cf38-66dc-4fa5-8a45-adf959c987ab\" target=\"_blank\" rel=\"noopener noreferrer\">metoclopramide<\/a><\/td>\n<td style=\"width: 238.724px\">Can be administered PO, IM, and IV\n\nOnset of action is 1 to 3 minutes following an IV dose, 10 to 15 minutes following IM administration, and 30 to 60 minutes following an oral dose\n\nPharmacological effects persist for 1 to 2 hours<\/td>\n<td style=\"width: 127.891px\">To prevent or treat nausea and vomiting associated with surgery or chemotherapy<\/td>\n<td style=\"width: 363.724px\">Restlessness, drowsiness, fatigue, depression, and suicide ideation\n\nShould be immediately discontinued if symptoms of tardive dyskinesia (abnormal muscle movements) or neuromalignant syndrome occur (hyperthermia, muscle rigidity, altered consciousness, irregular pulse or blood pressure, tachycardia, diaphoresis, and cardiac arrhythmias)<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Serotonin antagonist<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId23\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=e0050959-c14c-41b6-9a92-fadc5f6feff3\" target=\"_blank\" rel=\"noopener noreferrer\">ondansetron<\/a><\/td>\n<td style=\"width: 238.724px\">Can be administered as oral disintegrating tablet, PO, or IV<\/td>\n<td style=\"width: 127.891px\">Prevention or treatment of severe nausea and vomiting associated with surgery, chemotherapy, or hyperemesis in pregnancy<\/td>\n<td style=\"width: 363.724px\">Hypersensitivity reactions, including fever, chills, rash, or breathing problems\n\nHeadache, drowsiness, constipation, fever, and diarrhea\n\nMay cause QT prolongation\n\nCan cause serotonin syndrome if given concurrently with other serotonin antagonists or SSRIs<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Neurokinin receptor antagonist<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId24\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=d72e0e10-4557-41b0-b65d-d395468cad19\" target=\"_blank\" rel=\"noopener noreferrer\">aprepitant<\/a><\/td>\n<td style=\"width: 238.724px\">Can be administered PO or IV<\/td>\n<td style=\"width: 127.891px\">Prevention of nausea and vomiting associated with chemotherapy and surgery<\/td>\n<td style=\"width: 363.724px\">Hypersensitivity reaction, such as hives, rash. and itching; skin peeling or sores; or difficulty in breathing or swallowing\n\nIf taking warfarin, increase monitoring of INR levels\n\nIf taking oral contraceptives, use a backup method of birth control<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">THC<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId25\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=1f1af798-17d5-47d0-b129-21d4aa1eb125\" target=\"_blank\" rel=\"noopener noreferrer\">dronabinol<\/a> or medical marijuana<\/td>\n<td style=\"width: 238.724px\">Administered PO\n\nMost patients respond to 5 mg three or four times daily\n\nDosage may be escalated during a chemotherapy cycle or at subsequent cycles, based on initial results<\/td>\n<td style=\"width: 127.891px\">For treatment of nausea and vomiting associated with cancer chemotherapy when other treatment fails<\/td>\n<td style=\"width: 363.724px\">Use cautiously in elderly patients because they may be more sensitive to the neurological, psychoactive, and postural hypotensive effects of the drug. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\n<h2>Critical Thinking Activity 7.5\n<img class=\"alignright wp-image-197\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2019\/12\/ORN-Icons_lightbulb-300x300-1.png\" alt=\"Image of lightbulb in a circle\" width=\"200\" height=\"200\"><\/h2>\n<\/header>\n<div class=\"textbox__content\">\n\nA nurse is caring for a patient who underwent surgery earlier today and is experiencing nausea and vomiting. The original post-op orders included prochlorperazine, but the patient continues to experience vomiting despite receiving this medication. The nurse calls the provider and receives a new order for ondansetron orally dissolving tablets 8 mg three times daily as needed.\n<ol>\n \t<li>How will the nurse assess for symptoms of dehydration?<\/li>\n \t<li>When administering the medication, the patient states, \"This tastes terrible! Why can't I have a normal pill to swallow?\"\u00a0 \u00a0What is the nurse's best response?<\/li>\n \t<li>What other measures should the nurse teach the patient to reduce feelings of nausea and avoid dehydration?<\/li>\n<\/ol>\nNote: Answers to the Critical Thinking activities can be found in the \"Answer Key\" sections at the end of the book.\n\n<\/div>\n<\/div>\n<\/div>","rendered":"<div class=\"1.5-nausea-and-vomiting:-antiemetic-&amp;-antinausea-drugs\">\n<p>Nausea and vomiting are common conditions. Nausea is the unpleasant sensation of having the urge to vomit, and vomiting(emesis) is the forceful expulsion of gastric contents.<sup><a class=\"footnote\" title=\"Bashashati, M. &amp; McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. European Journal of Pharmacology, 772, p 79.\" id=\"return-footnote-346-1\" href=\"#footnote-346-1\" aria-label=\"Footnote 1\"><sup class=\"footnote\">[1]<\/sup><\/a><\/sup> There are many potential causes of nausea and vomiting, such as:<\/p>\n<ul>\n<li>Morning sickness during pregnancy<\/li>\n<li><strong>Gastroenteritis <\/strong>and other infections<\/li>\n<li>Migraines<\/li>\n<li>Motion sickness<\/li>\n<li>Food poisoning<\/li>\n<li>Side effects of medicines, including those for cancer chemotherapy<\/li>\n<li>GERD\u00a0and ulcers<\/li>\n<li>Intestinal obstruction<\/li>\n<li>Poisoning or exposure to a toxic substance<\/li>\n<li>Diseases of other organs (cardiac, renal, or liver)<\/li>\n<\/ul>\n<p>Nausea and vomiting are common and are usually not serious. However, the health care provider should be contacted immediately if the following conditions occur:<\/p>\n<ul>\n<li>Vomiting for longer than 24 hours<\/li>\n<li>Blood in the vomit (also called <strong>hematemesis<\/strong>)<\/li>\n<li>Severe abdominal pain<\/li>\n<li>Severe headache and stiff neck<\/li>\n<li>Signs of dehydration, such as dry mouth, infrequent urination, or dark urine<\/li>\n<\/ul>\n<p>Treatment of nausea and vomiting should be tailored to the cause. There are several medications that work on different neuroreceptors that when used can treat nausea and vomiting. For severe cases of vomiting, intravenous fluids may also be needed to treat the accompanying dehydration. <sup><a class=\"footnote\" title=\"MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2019 October 23]. Nausea and vomiting; [updated 2019 February 7; reviewed 2016 March 17; cited 2019 October 27]. https:\/\/medlineplus.gov\/nauseaandvomiting.html.\" id=\"return-footnote-346-2\" href=\"#footnote-346-2\" aria-label=\"Footnote 2\"><sup class=\"footnote\">[2]<\/sup><\/a>,<a class=\"footnote\" title=\"Bashashati, M. &amp; McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. European Journal of Pharmacology, 772, p 79.\" id=\"return-footnote-346-3\" href=\"#footnote-346-3\" aria-label=\"Footnote 3\"><sup class=\"footnote\">[3]<\/sup><\/a><\/sup><\/p>\n<h2>Pathophysiology<\/h2>\n<p>The vomiting center can be activated directly by irritants or indirectly following input from four principal areas: gastrointestinal tract, cerebral cortex and thalamus, vestibular region, and chemoreceptor trigger zone (CRTZ). See Figure 7.14 for an illustration of the pathophysiology of nausea and vomiting.<sup><a class=\"footnote\" title=\"Becker D. E. (2010). Nausea, vomiting, and hiccups: a review of mechanisms and treatment. Anesthesia progress, 57(4), 150\u2013157. doi:10.2344\/0003-3006-57.4.150\" id=\"return-footnote-346-4\" href=\"#footnote-346-4\" aria-label=\"Footnote 4\"><sup class=\"footnote\">[4]<\/sup><\/a><\/sup><\/p>\n<figure style=\"width: 407px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" title=\"Becker D. E. (2010). Nausea, vomiting, and hiccups: a review of mechanisms and treatment. Anesthesia progress, 57(4), 150\u2013157. doi:10.2344\/0003-3006-57.4.150\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2019\/11\/image1-2.png\" alt=\"Chart showing pathophysiology of nausea and vomiting\" width=\"407\" height=\"332\" \/><figcaption class=\"wp-caption-text\">Figure 7.14 Pathophysiology of nausea and vomiting<\/figcaption><\/figure>\n<p>An important part of the emesis circuit is the <strong>chemoreceptor trigger zone (CTZ)<\/strong>, located in the <strong>area postrema <\/strong>in the brain. The CTZ is not restricted by the blood\u2013brain barrier, which allows it to respond directly to toxins in the bloodstream such as anesthesia and opioids. The CTZ also receives stimuli from several other locations in the body including the vestibular center; visceral organs such as the GI tract, kidneys, and liver; the thalamus; and the cerebral cortex.<\/p>\n<p>The vestibular center and cerebral cortex can stimulate the vomiting center directly or indirectly through the CTZ. The <strong>vestibular system <\/strong> is located within the inner ear and gives a sense of balance and spatial orientation for the purpose of coordinating movement with balance. The feeling of nausea associated with motion sickness often arises from stimuli from the vestibular center. The gastrointestinal tract sends stimuli to the CTZ via cranial nerves IX and X related to obstruction, distension, inflammation, and infection. The cerebral cortex and other parts of the brain can also stimulate a sense of nausea related to odors, tastes, and images and send these stimuli to the CTZ. The CTZ forwards these signals to the vomiting center in the brain. Pain can also directly stimulate the vomiting center.<\/p>\n<p>The <strong> vomiting center<\/strong> (VC) is located in the medulla in the brain. In response to these stimuli, the vomiting center initiates vomiting by inhibiting peristalsis and producing retro-peristaltic contractions beginning in the small bowel and ascending into the stomach. It also produces simultaneous contractions in the abdominal muscles and diaphragm that generate high pressures to propel the stomach contents upwards. Additionally, autonomic stimulation of the heart, airways, salivary glands, and skin cause other symptoms associated with vomiting such as salivation, palor, sweating, and tachycardia. Several neurotransmitters are involved in the nausea and vomiting process, and antiemetic medications are targeted to specific neuroreceptors.<sup><a class=\"footnote\" title=\"Becker D. E. (2010). Nausea, vomiting, and hiccups: a review of mechanisms and treatment. Anesthesia progress, 57(4), 150\u2013157. https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3006663\/\" id=\"return-footnote-346-5\" href=\"#footnote-346-5\" aria-label=\"Footnote 5\"><sup class=\"footnote\">[5]<\/sup><\/a><\/sup><\/p>\n<p>Table 7.5a compares the neurotransmitters involved in the nausea and vomiting process, classes of antiemetic medication targeting these neurotrasmitters, prototype antiemetic medications, and associated mechanisms of action.<sup><a class=\"footnote\" title=\"Bashashati, M. and McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. European Journal of Pharmacology, 772, p 79.\" id=\"return-footnote-346-6\" href=\"#footnote-346-6\" aria-label=\"Footnote 6\"><sup class=\"footnote\">[6]<\/sup><\/a><\/sup> Each medication class is also discussed in more detail later in this section.<\/p>\n<p>Table 7.5a Neurotransmitters and Associated Medications Used to Treat Nausea and Vomiting<\/p>\n<table class=\"grid\">\n<tbody>\n<tr>\n<th style=\"background-color: #a4c2f4\" scope=\"col\">Neurotransmitter<\/th>\n<th style=\"background-color: #a4c2f4\" scope=\"col\">Medication Class<\/th>\n<th style=\"background-color: #a4c2f4\" scope=\"col\">Antiemetic Drug<\/th>\n<th style=\"background-color: #a4c2f4\" scope=\"col\">Mechanism of Action<\/th>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Acetylcholine (M1)<\/th>\n<td>Anticholinergics<\/td>\n<td>scopolamine<\/td>\n<td>Blocks ACh receptors in vestibular system<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Histamine (H1)<\/th>\n<td>Antihistamines<\/td>\n<td>meclizine<\/td>\n<td>Blocks H1 receptors and thus blocks ACh in vestibular system<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Dopamine (DA2)<\/th>\n<td>Dopamine antagonists<\/td>\n<td>prochlorperazine<\/td>\n<td>Blocks dopamine in CTZ and may block ACh<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Dopamine and ACh (DA2 and M1)<\/th>\n<td>Prokinetics<\/td>\n<td>metoclopramide<\/td>\n<td>Blocks dopamine in CTZ and stimulates ACh in GI tract<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Serotonin (5HT)<\/th>\n<td>Serotonin antagonists<\/td>\n<td>ondansetron<\/td>\n<td>Blocks serotonin in GI tract, CTZ, and VC<\/td>\n<\/tr>\n<tr>\n<th style=\"background-color: #c9daf8\" scope=\"row\">Substance P (NK1)<\/th>\n<td>Neurokinin antagonists<\/td>\n<td>aprepitant<\/td>\n<td>Inhibits substance P neurokinin receptors<\/td>\n<\/tr>\n<tr class=\"a-R\">\n<th style=\"background-color: #c9daf8\" scope=\"row\">Cannabinoid (CB1)<\/th>\n<td>Tetrahydrocannabinols (THC)<\/td>\n<td>dronabinol or medical marijuana<\/td>\n<td>Activated CB1 receptor leading to inhibitory effects on cerebral cortex<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Nursing Considerations<\/h2>\n<h3><strong>Assessment<\/strong><\/h3>\n<p>When administering antiemetics, identify factors contributing to the symptoms of nausea and vomiting so that treatment can correctly target the cause. Document the frequency and amount of emesis and effects on the patient&#8217;s appetite and fluid intake. Assess for symptoms of dehydration, such as decreased blood pressure associated with tachycardia, decreased skin turgor, and decreased urine output or dark concentrated urine. If lab tests are ordered, monitor hemoglobin, hematocrit, and serum sodium levels for additional signs of dehydration.<\/p>\n<h3><strong>Implementation<\/strong><\/h3>\n<p>Advocate for the most effective route of administration if the patient is vomiting. Consider timing of administration of antiemetics in advance of meals when appetite is affected. Follow drug label administration information and monitor the patient closely for potential side effects associated with that category of medication. For example, when administering anticholinergics and antihistamines, monitor for anticholinergic side effects, especially in elderly patients.<\/p>\n<h3><strong>Evaluation<\/strong><\/h3>\n<p>Monitor for improvement of nausea and vomiting and notify the provider if expected improvement does not occur so that other treatment can be initiated. Continue to monitor for dehydration. Teach the patient nonpharmacological interventions for nausea such as:<\/p>\n<ul>\n<li>Drink enough fluids to avoid dehydration. If you are having trouble keeping liquids down, drink sips of clear liquids every few minutes.<\/li>\n<li>Eat bland foods; stay away from spicy, fatty, or salty foods.<\/li>\n<li>Eat smaller meals more often.<\/li>\n<li>Avoid strong smells because they can sometimes trigger nausea and vomiting.<\/li>\n<li>If you are pregnant and have morning sickness, eat crackers before you get out of bed in the morning.<sup><a class=\"footnote\" title=\"MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2019 October 23]. Nausea and vomiting; [updated 2019 February 7; reviewed 2016 March 17; cited 2019 October 27]. https:\/\/medlineplus.gov\/nauseaandvomiting.html.\" id=\"return-footnote-346-7\" href=\"#footnote-346-7\" aria-label=\"Footnote 7\"><sup class=\"footnote\">[7]<\/sup><\/a><\/sup><\/li>\n<\/ul>\n<h2>Antiemetic Medication Classes<\/h2>\n<h3>Anticholinergics<\/h3>\n<p>Scopolamine is an example of an anticholinergic medication that is often used to treat motion sickness or nausea and vomiting associated with surgical recovery from anesthesia and\/or opiate analgesia.<\/p>\n<p><strong>Mechanism of Action<\/strong><\/p>\n<p>Anticholinergics block ACh receptors in the vestibular center and within the brain to prevent nausea-inducing stimuli to the Chemoreceptor Trigger Zone (CTZ) and the Vomiting Center (VC). They also dry GI secretions and reduce smooth muscle spasms.<\/p>\n<p><strong>Specific Administration Considerations<\/strong><\/p>\n<p>The scopolamine transdermal patch (see Figure 7.15)<sup><a class=\"footnote\" title=\"&quot;Scopoderm 278:365&quot; by Andreas Nilsson is licensed under CC BY-NC-ND 2.0\" id=\"return-footnote-346-8\" href=\"#footnote-346-8\" aria-label=\"Footnote 8\"><sup class=\"footnote\">[8]<\/sup><\/a><\/sup>\u00a0is designed for continuous release of scopolamine following application to an area of intact skin on the head, behind the ear. The system is formulated to deliver approximately 1 mg of scopolamine to the systemic circulation over 3 days. It is contraindicated in patients with glaucoma. It has been reported to exacerbate psychosis, induce seizures, and cause drowsiness, confusion, and sedation. Due to its anticholinergic properties, scopolamine can decrease gastrointestinal motility and cause urinary retention. Nurses should perform more frequent monitoring during treatment with Transderm Sc\u014dp and discontinue Transderm Sc\u014dp in patients who develop difficulty in urination. Transderm Sc\u014dp contains an aluminized membrane; skin burns have been reported at the application site in patients wearing an aluminized transdermal system during an MRI scan. Remove Transderm Sc\u014dp before undergoing an MRI.<\/p>\n<figure style=\"width: 347px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" title=\"&quot;Scopoderm 278:365&quot; by Andreas Nilsson is licensed under CC BY-NC-ND 2.0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image2-2-1.png\" alt=\"Photo of male with transdermal patch behind right ear\" width=\"347\" height=\"521\" \/><figcaption class=\"wp-caption-text\">Figure 7.15 Scopolamine Transdermal Patch<\/figcaption><\/figure>\n<p>Application instructions:<\/p>\n<ul>\n<li>Only wear one transdermal system at any time.<\/li>\n<li>Do not cut the transdermal system.<\/li>\n<li>Apply the transdermal system to the skin in the postauricular area (hairless area behind one ear).<\/li>\n<li>After the transdermal system is applied on the dry skin behind the ear, wash hands thoroughly with soap and water and dry hands.<\/li>\n<li>If the transdermal system becomes displaced, discard the transdermal system, and apply a new transdermal system on the hairless area behind the other ear.<\/li>\n<li>For surgeries other than cesarean section, apply one Transderm Sc\u014dp transdermal system the evening before scheduled surgery. Remove the transdermal system 24 hours following surgery.<\/li>\n<\/ul>\n<p><strong>Patient Teaching &amp; Education<\/strong><\/p>\n<p>Transderm Sc\u014dp may impair the mental and\/or physical abilities required for the performance of hazardous tasks such as driving a motor vehicle, operating machinery, or participating in underwater sports. Concomitant use of other drugs (e.g., alcohol, sedatives, hypnotics, opiates, and anxiolytics) that cause central nervous system (CNS) adverse reactions, or that have anticholinergic properties, may increase this impairment. Inform patients not to operate motor vehicles or other dangerous machinery or participate in underwater sports until they are reasonably certain that Transderm Sc\u014dp does not affect them adversely. Scopolamine can cause temporary dilation of the pupils resulting in blurred vision if it comes in contact with the eyes. Advise patients to wash their hands thoroughly with soap and water and dry their hands immediately after handling the transdermal system. Upon removal, fold the used transdermal system in half with the sticky side together, and discard in household trash in a manner that prevents accidental contact or ingestion by children, pets, or others.<sup><a class=\"footnote\" title=\"This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.\" id=\"return-footnote-346-9\" href=\"#footnote-346-9\" aria-label=\"Footnote 9\"><sup class=\"footnote\">[9]<\/sup><\/a><\/sup><\/p>\n<h3>Antihistamines<\/h3>\n<p>Meclizine is an example of an antihistamine that is often used to treat motion sickness.<\/p>\n<p><strong>Mechanism of Action<\/strong><\/p>\n<p>Antihistamines block H1 receptors in the vestibular center and may also block acetylcholine (ACh).<\/p>\n<p><strong>Specific Administration Considerations<\/strong><\/p>\n<p>Antihistamines are contraindicated in patients with glaucoma or an enlarged prostate gland. Dosage should be started one hour before travel begins.<\/p>\n<p><strong>Patient Teaching &amp; Education<\/strong><\/p>\n<ul>\n<li>Do not exceed recommended dosage.<\/li>\n<li>Be advised that drowsiness may occur.<\/li>\n<li>Avoid alcohol, sedatives, and tranquilizers, which may increase drowsiness.<\/li>\n<li>Avoid alcoholic drinks.<\/li>\n<li>Be careful when driving a motor vehicle or operating machinery.<sup><a class=\"footnote\" title=\"This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.\" id=\"return-footnote-346-10\" href=\"#footnote-346-10\" aria-label=\"Footnote 10\"><sup class=\"footnote\">[10]<\/sup><\/a><\/span><\/sup><\/li>\n<\/ul>\n<h3>Dopamine Antagonists<\/h3>\n<p>Prochlorperazine is an example of a dopamine antagonist used to treat nausea and vomiting. It can also be used as an antipsychotic medication.<\/p>\n<p><strong>Mechanism of Action<\/strong><\/p>\n<p>Prochlorperazine blocks dopamine in the Chemoreceptor Trigger Zone (CTZ). It also calms the central nervous system and may also block acetylcholine.<\/p>\n<p><strong>Specific Administration Considerations<\/strong><\/p>\n<p>Prochlorperazine can be administered orally, intramuscularly, rectally or intravenously. It is contraindicated in children under age 2 or under 20 pounds. Severe side effects have occurred when used to treat psychosis.<\/p>\n<p><strong>Patient Teaching &amp; Education<\/strong><\/p>\n<p>Patients should be instructed to take medications as prescribed.\u00a0 They should avoid alcohol and other CNS depressants.\u00a0 Patients may experience increased photosensitivity and extreme temperatures should be avoided.\u00a0 Patients should be advised that urine may turn pinkish to reddish-brown.<sup><a class=\"footnote\" title=\"uCentral from Unbound Medicine. https:\/\/www.unboundmedicine.com\/ucentral\" id=\"return-footnote-346-11\" href=\"#footnote-346-11\" aria-label=\"Footnote 11\"><sup class=\"footnote\">[11]<\/sup><\/a><\/sup><\/p>\n<h3>Prokinetics<\/h3>\n<p>Metoclopramide is an example of a prokinetic medication (see Figure 7.16).<sup><a class=\"footnote\" title=\"&quot;Metoclopramide&quot; by John Campbell is licensed under CC0\" id=\"return-footnote-346-12\" href=\"#footnote-346-12\" aria-label=\"Footnote 12\"><sup class=\"footnote\">[12]<\/sup><\/a><\/sup><\/p>\n<figure style=\"width: 601px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" title=\"&quot;Metoclopramide&quot; by John Campbell is licensed under CC0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image4-2-1.png\" alt=\"Photo of metoclopramide vials, a prokinetic\" width=\"601\" height=\"401\" \/><figcaption class=\"wp-caption-text\">Figure 7.16 Prokinetics<\/figcaption><\/figure>\n<p><strong>Mechanism of Action<\/strong><\/p>\n<p>Metoclopramide blocks dopamine and may also sensitize tissues to acetylcholine. It is used to promote peristalsis to empty the gastrointestinal tract and thus reduce nausea.<\/p>\n<p><strong>Specific Administration Considerations<\/strong><\/p>\n<p>Metoclopramide can be administered orally, intramuscularly, and intravenously. The onset of pharmacological action of metoclopramide is 1 to 3 minutes following an intravenous dose, 10 to 15 minutes following intramuscular administration, and 30 to 60 minutes following an oral dose. Pharmacological effects persist for 1 to 2 hours.<\/p>\n<p>Metoclopramide should not be used whenever stimulation of gastrointestinal motility might be dangerous (e.g., in the presence of gastrointestinal hemorrhage, mechanical obstruction, or perforation). Metoclopramide is contraindicated in patients with pheochromocytoma because the drug may cause a hypertensive crisis. Metoclopramide should not be used in epileptics or patients receiving other drugs that are likely to cause extrapyramidal reactions because the frequency and severity of seizures or extrapyramidal reactions may be increased. Rare reports of neuromalignant syndrome have occured.<\/p>\n<p><strong>Patient Teaching &amp; Education<\/strong><\/p>\n<p>Teach patients to immediately inform the healthcare provider if they experience new feelings of depression or abnormal muscle movements they cannot control such as:<\/p>\n<ul>\n<li>lip smacking, chewing, or puckering of the mouth<\/li>\n<li>frowning or scowling<\/li>\n<li>sticking out the tongue<\/li>\n<li>blinking and moving the eyes<\/li>\n<li>shaking of the arms and legs<sup><a class=\"footnote\" title=\"This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.\" id=\"return-footnote-346-13\" href=\"#footnote-346-13\" aria-label=\"Footnote 13\"><sup class=\"footnote\">[13]<\/sup><\/a><\/span><\/sup><\/li>\n<\/ul>\n<h3>Serotonin Antagonists<\/h3>\n<p>Ondansetron\u00a0is an example of a serotonin (5HT) antagonist often used to treat severe nausea and vomiting associated with chemotherapy, postoperative nausea and vomiting, and hyperemesis during pregnancy. (See Figure 7.17 for an image of odansetron blocking the 5-HT<sub>3<\/sub> receptor.<sup><a class=\"footnote\" title=\"&quot;Eichelbaum2.jpg&quot; by Michel Eichelbaum is licensed under CC BY-SA 3.0 DE\" id=\"return-footnote-346-14\" href=\"#footnote-346-14\" aria-label=\"Footnote 14\"><sup class=\"footnote\">[14]<\/sup><\/a><\/sup>)<\/p>\n<figure style=\"width: 557px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" title=\"&quot;Eichelbaum2.jpg&quot; by Michel Eichelbaum is licensed under CC BY-SA 3.0 DE\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image5.jpg\" alt=\"Illustration of Ondansetron blocking serotonin receptors.\" width=\"557\" height=\"414\" \/><figcaption class=\"wp-caption-text\">Figure 7.17 Ondansetron blocking the 5-HT<sub>3<\/sub> receptor<\/figcaption><\/figure>\n<p><strong>Mechanism of Action<\/strong><\/p>\n<p>Ondansetron blocks serotonin receptors in the GI tract, the chemoreceptor trigger zone (CTZ), and the vomiting center (VC). See Figures 7.18 and 7.19 for images of the injectable and oral formulations of ondansetron.<sup><a class=\"footnote\" title=\"&quot;000817lg Zofran 8 MG Oral Tablet.jpg&quot; by NLM is licensed under CC0\" id=\"return-footnote-346-15\" href=\"#footnote-346-15\" aria-label=\"Footnote 15\"><sup class=\"footnote\">[15]<\/sup><\/a><span style=\"font-size: 16px\">,<\/span><\/sup><sup><a class=\"footnote\" title=\"&quot;Ondansetron (1)&quot; by M is licensed under CC BY-NC 2.0\" id=\"return-footnote-346-16\" href=\"#footnote-346-16\" aria-label=\"Footnote 16\"><sup class=\"footnote\">[16]<\/sup><\/a><\/sup><\/p>\n<figure style=\"width: 313px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" title=\"&quot;Ondansetron (1)&quot; by M is licensed under CC BY-NC 2.0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image6-2-1.png\" alt=\"Photo of bottle of Zofran injectable.\" width=\"313\" height=\"418\" \/><figcaption class=\"wp-caption-text\">Figure 7.18 Ondansetron in injectable form<\/figcaption><\/figure>\n<figure style=\"width: 436px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" style=\"color: #373d3f;font-weight: bold;font-size: 1.125em\" title=\"&quot;000817lg Zofran 8 MG Oral Tablet.jpg&quot; by NLM is licensed under CC0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image7-2-1.png\" alt=\"Photo of Zofran tablets\" width=\"436\" height=\"311\" \/><figcaption class=\"wp-caption-text\">Figure 7.19 Ondansetron in tablet form<\/figcaption><\/figure>\n<p><strong>Specific Administration Considerations<\/strong><\/p>\n<p>Ondansetron is available as an orally disintegrating tablet and as an injectable for those patients too nauseated to tolerate oral medication. It is contraindicated with apomorphine. <strong>Serotonin syndrome<\/strong> can occur if administered concurrently with other serotonin antagonists or selective serotonin reuptake inhibitors. Ondansetron can cause headaches, drowsiness, constipation, fever, and diarrhea. A rare but serious adverse effect of ondansetron is QT prolongation that can cause an abnormal cardiac rhythm.<\/p>\n<p><strong>Patient Teaching &amp; Education<\/strong><\/p>\n<p>Teach patients to immediately inform their healthcare provider if they experience a change in heart rate, lightheadedness, or feel faint or have any signs and symptoms of hypersensitivity reactions such as fever, chills, rash, or breathing problems.<sup><a class=\"footnote\" title=\"This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.\" id=\"return-footnote-346-17\" href=\"#footnote-346-17\" aria-label=\"Footnote 17\"><sup class=\"footnote\">[17]<\/sup><\/a><\/sup><\/p>\n<h3>Neurokinin Receptor Antagonists<\/h3>\n<p>Aprepitant is an example of a neurokinin antagonist used to prevent nausea and vomiting associated with chemotherapy and surgery.<\/p>\n<p><strong>Mechanism of Action<\/strong><\/p>\n<p>Aprepitant inhibits substance-P neurokinin receptors in the brainstem.<\/p>\n<p><strong>Nursing Considerations<\/strong><\/p>\n<p>Aprepitant is usually administered concurrently with dexamethasone (a corticosteroid) and ondansetron. It can be administered orally or intravenously. It has clinically significant CYP3A4 drug interactions with medications such as pimozide, diltiazem, and rifampin, and can decrease INR levels when taken concurrently with warfarin. It can also reduce the effectiveness of oral contraceptives.<\/p>\n<p><strong>Patient Teaching &amp; Education<\/strong><\/p>\n<p>Teach patients taking warfarin that they will need to monitor their INR levels more closely, which may require adjustment of the warfarin dosage, while taking aprepitant. Teach patients using an oral contraceptive to use backup birth control.<sup><a class=\"footnote\" title=\"This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. \u00a0\" id=\"return-footnote-346-18\" href=\"#footnote-346-18\" aria-label=\"Footnote 18\"><sup class=\"footnote\">[18]<\/sup><\/a><\/sup><\/p>\n<h3>Tetrahydrocannabinoids (THC)<\/h3>\n<p>Dronabinol or medical marijuana is an example of a <strong>THC<\/strong> medication used to treat nausea in patients with cancer or AIDS (see Figures 7.20 and 7.21).<sup><a class=\"footnote\" title=\"&quot;Marinol - Dronabinol&quot; by Steffen Geyer is licensed under CC BY-NC 2.0 &amp; 7.21&quot;Medical Marijuana&quot; by Circe Denyer is licensed under CC0\" id=\"return-footnote-346-19\" href=\"#footnote-346-19\" aria-label=\"Footnote 19\"><sup class=\"footnote\">[19]<\/sup><\/a><\/sup><\/p>\n<figure style=\"width: 345px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" title=\"&quot;Marinol - Dronabinol&quot; by Steffen Geyer is licensed under CC BY-NC 2.0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image8-1-1.png\" alt=\"Photo of Marinol capules bottle.\" width=\"345\" height=\"517\" \/><figcaption class=\"wp-caption-text\">Figure 7.20 Dronabinol, a THC medication<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure style=\"width: 610px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" title=\"&quot;Medical Marijuana&quot; by Circe Denyer is licensed under CC0\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/image9-1.png\" alt=\"Photo of medical marijuana in prescription bottle\" width=\"610\" height=\"457\" \/><figcaption class=\"wp-caption-text\">Figure 7.21 Medical Marijuana<\/figcaption><\/figure>\n<p><strong>Mechanism of Action<\/strong><\/p>\n<p>THC has inhibitory effects in the cerebral cortex causing an alteration in mood and the body&#8217;s perception of its surroundings, which may relieve nausea and vomiting, as well as stimulate the appetite.<\/p>\n<p><strong>Specific Administration Considerations<\/strong><\/p>\n<p>THC will cause a dose-related &#8220;high&#8221; (easy laughing, elation, and heightened awareness). It is abusable and, thus, is a controlled substance and scheduled medication. THC should be used cautiously in elderly patients because they may be more sensitive to the neurological, psychoactive, and postural hypotensive effects of the drug. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range.<\/p>\n<p><strong>Patient Teaching &amp; Education<\/strong><\/p>\n<p>Teach patients to not drive, operate machinery, or engage in any hazardous activity when using THC. Keep out of reach of children and pets.<sup><a class=\"footnote\" title=\"This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. \u00a0\" id=\"return-footnote-346-20\" href=\"#footnote-346-20\" aria-label=\"Footnote 20\"><sup class=\"footnote\">[20]<\/sup><\/a><\/sup><\/p>\n<h3>Herbal and Vitamin Supplements<\/h3>\n<p>Ginger has been used in traditional Indian and Chinese medicine as an antiemetic. Although its mechanism of action is not completely understood, ginger is thought to antagonize the 5HT and cholinergic receptors and may have direct activity on the gastrointestinal tract. Although ginger can cause reflux and heartburn and may potentially cause bleeding because of its anticoagulant effects, dosages of up to 2 g per day in divided doses of 250 mg are considered safe even in pregnant women. Pyridoxine (vitamin B6) has also been recommended for treating nausea and vomiting in pregnancy. Typical dosages of pyridoxine 10 to 25 mg every eight hours cause minimal adverse effects. <sup><a class=\"footnote\" title=\"Flake, Z., Linn, B., &amp; Hornecker, J. (2015). Practical selection of antiemetics in the ambulatory setting. American Family Physician, 91(5): pp 293-296.\" id=\"return-footnote-346-21\" href=\"#footnote-346-21\" aria-label=\"Footnote 21\"><sup class=\"footnote\">[21]<\/sup><\/a><\/sup><\/p>\n<h2>Antiemetics Medication Grid<\/h2>\n<p>Now let&#8217;s take a closer look at the medication grid comparing medications used to treat nausea. See Table 7.5b.<sup><a class=\"footnote\" title=\"This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.\" id=\"return-footnote-346-22\" href=\"#footnote-346-22\" aria-label=\"Footnote 22\"><sup class=\"footnote\">[22]<\/sup><\/a><\/sup><\/p>\n<p>Medication grids are intended to assist students to learn key points about each medication.\u00a0 Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication. Basic information related to each class of medication is outlined below.\u00a0 Detailed information on a specific medication can be found for free at <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/index.cfm\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a>. On the home page, enter the drug name in the search bar to read more about the medication.\u00a0 Prototype\/generic medications listed in the grids below are also hyperlinked directly to a Daily Med page.<\/p>\n<p><span style=\"text-align: initial;font-size: 1em\">Table 7.5b Medication Grid Comparing Antiemetics<\/span><\/p>\n<table class=\"grid\">\n<tbody>\n<tr>\n<th style=\"width: 120.391px\" scope=\"col\"><strong>Class<\/strong><\/th>\n<th style=\"width: 134.557px\" scope=\"col\"><strong>Prototype\/<\/strong><\/p>\n<p><strong>Generic<\/strong><\/th>\n<th style=\"width: 238.724px\" scope=\"col\"><strong>Administration <\/strong><strong>Considerations<\/strong><\/th>\n<th style=\"width: 127.891px\" scope=\"col\"><strong>Therapeutic Effects<\/strong><\/th>\n<th style=\"width: 363.724px\" scope=\"col\"><strong>Adverse\/Side Effects<\/strong><\/th>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Anticholinergic<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId19\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=b877a694-a1d0-4280-937a-a06820b12a88\" target=\"_blank\" rel=\"noopener noreferrer\">scopolamine<\/a><\/td>\n<td style=\"width: 238.724px\">Apply patch to hairless skin behind ear for 3 days or apply the night before surgery and remove 24 hours later<\/p>\n<p>Do not cut patch<\/p>\n<p>After application, thoroughly wash and dry hands<\/p>\n<p>Remove before an MRI<\/p>\n<p>Contraindicated in patients with glaucoma<\/td>\n<td style=\"width: 127.891px\">Prevent or reduce nausea and vomiting associated with motion sickness or surgery<\/td>\n<td style=\"width: 363.724px\">Monitor for anticholinergic effects such as decreased GI motility and urinary retention<\/p>\n<p>Discontinue if it exacerbates psychosis or causes seizures or cognitive impairment<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Antihistamine<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId20\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=8b3c9283-b618-4d57-9f15-7cf73e8737f5\" target=\"_blank\" rel=\"noopener noreferrer\">meclizine<\/a><\/td>\n<td style=\"width: 238.724px\">Contraindicated in patients with glaucoma or an enlarged prostate gland<\/p>\n<p>Dosage should be started one hour before travel begins<\/td>\n<td style=\"width: 127.891px\">Prevent or reduce nausea and vomiting associated with motion sickness<\/td>\n<td style=\"width: 363.724px\">May cause drowsiness<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Dopamine antagonist<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId21\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=5e771ba7-983f-49b4-a1f2-0f335b637433\" target=\"_blank\" rel=\"noopener noreferrer\">prochlorperazine<\/a><\/td>\n<td style=\"width: 238.724px\">Can be administered PO, IM, PR, or IV<\/td>\n<td style=\"width: 127.891px\">To control nausea and vomiting associated with surgery<\/td>\n<td style=\"width: 363.724px\">Drowsiness, dizziness, amenorrhea, blurred vision, skin reactions, and hypotension may occur<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Prokinetic<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId22\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=50a3cf38-66dc-4fa5-8a45-adf959c987ab\" target=\"_blank\" rel=\"noopener noreferrer\">metoclopramide<\/a><\/td>\n<td style=\"width: 238.724px\">Can be administered PO, IM, and IV<\/p>\n<p>Onset of action is 1 to 3 minutes following an IV dose, 10 to 15 minutes following IM administration, and 30 to 60 minutes following an oral dose<\/p>\n<p>Pharmacological effects persist for 1 to 2 hours<\/td>\n<td style=\"width: 127.891px\">To prevent or treat nausea and vomiting associated with surgery or chemotherapy<\/td>\n<td style=\"width: 363.724px\">Restlessness, drowsiness, fatigue, depression, and suicide ideation<\/p>\n<p>Should be immediately discontinued if symptoms of tardive dyskinesia (abnormal muscle movements) or neuromalignant syndrome occur (hyperthermia, muscle rigidity, altered consciousness, irregular pulse or blood pressure, tachycardia, diaphoresis, and cardiac arrhythmias)<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Serotonin antagonist<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId23\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=e0050959-c14c-41b6-9a92-fadc5f6feff3\" target=\"_blank\" rel=\"noopener noreferrer\">ondansetron<\/a><\/td>\n<td style=\"width: 238.724px\">Can be administered as oral disintegrating tablet, PO, or IV<\/td>\n<td style=\"width: 127.891px\">Prevention or treatment of severe nausea and vomiting associated with surgery, chemotherapy, or hyperemesis in pregnancy<\/td>\n<td style=\"width: 363.724px\">Hypersensitivity reactions, including fever, chills, rash, or breathing problems<\/p>\n<p>Headache, drowsiness, constipation, fever, and diarrhea<\/p>\n<p>May cause QT prolongation<\/p>\n<p>Can cause serotonin syndrome if given concurrently with other serotonin antagonists or SSRIs<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">Neurokinin receptor antagonist<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId24\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=d72e0e10-4557-41b0-b65d-d395468cad19\" target=\"_blank\" rel=\"noopener noreferrer\">aprepitant<\/a><\/td>\n<td style=\"width: 238.724px\">Can be administered PO or IV<\/td>\n<td style=\"width: 127.891px\">Prevention of nausea and vomiting associated with chemotherapy and surgery<\/td>\n<td style=\"width: 363.724px\">Hypersensitivity reaction, such as hives, rash. and itching; skin peeling or sores; or difficulty in breathing or swallowing<\/p>\n<p>If taking warfarin, increase monitoring of INR levels<\/p>\n<p>If taking oral contraceptives, use a backup method of birth control<\/td>\n<\/tr>\n<tr>\n<th style=\"width: 120.391px\" scope=\"row\">THC<\/th>\n<td style=\"width: 134.557px\"><a class=\"rId25\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/drugInfo.cfm?setid=1f1af798-17d5-47d0-b129-21d4aa1eb125\" target=\"_blank\" rel=\"noopener noreferrer\">dronabinol<\/a> or medical marijuana<\/td>\n<td style=\"width: 238.724px\">Administered PO<\/p>\n<p>Most patients respond to 5 mg three or four times daily<\/p>\n<p>Dosage may be escalated during a chemotherapy cycle or at subsequent cycles, based on initial results<\/td>\n<td style=\"width: 127.891px\">For treatment of nausea and vomiting associated with cancer chemotherapy when other treatment fails<\/td>\n<td style=\"width: 363.724px\">Use cautiously in elderly patients because they may be more sensitive to the neurological, psychoactive, and postural hypotensive effects of the drug. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h2>Critical Thinking Activity 7.5<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignright wp-image-197\" src=\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2019\/12\/ORN-Icons_lightbulb-300x300-1.png\" alt=\"Image of lightbulb in a circle\" width=\"200\" height=\"200\" \/><\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<p>A nurse is caring for a patient who underwent surgery earlier today and is experiencing nausea and vomiting. The original post-op orders included prochlorperazine, but the patient continues to experience vomiting despite receiving this medication. The nurse calls the provider and receives a new order for ondansetron orally dissolving tablets 8 mg three times daily as needed.<\/p>\n<ol>\n<li>How will the nurse assess for symptoms of dehydration?<\/li>\n<li>When administering the medication, the patient states, &#8220;This tastes terrible! Why can&#8217;t I have a normal pill to swallow?&#8221;\u00a0 \u00a0What is the nurse&#8217;s best response?<\/li>\n<li>What other measures should the nurse teach the patient to reduce feelings of nausea and avoid dehydration?<\/li>\n<\/ol>\n<p>Note: Answers to the Critical Thinking activities can be found in the &#8220;Answer Key&#8221; sections at the end of the book.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<hr class=\"before-footnotes clear\" \/><div class=\"footnotes\"><ol><li id=\"footnote-346-1\">Bashashati, M. &amp; McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. <em>European Journal of Pharmacology, 772<\/em>, p 79. <a href=\"#return-footnote-346-1\" class=\"return-footnote\" aria-label=\"Return to footnote 1\">&crarr;<\/a><\/li><li id=\"footnote-346-2\">MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2019 October 23]. <em>Nausea and vomiting;<\/em> [updated 2019 February 7; reviewed 2016 March 17; cited 2019 October 27]. <a href=\"https:\/\/medlineplus.gov\/nauseaandvomiting.html\" target=\"_blank\" rel=\"noopener noreferrer\">https:\/\/medlineplus.gov\/nauseaandvomiting.html<\/a>. <a href=\"#return-footnote-346-2\" class=\"return-footnote\" aria-label=\"Return to footnote 2\">&crarr;<\/a><\/li><li id=\"footnote-346-3\">Bashashati, M. &amp; McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. <em>European Journal of Pharmacology, 772<\/em>, p 79. <a href=\"#return-footnote-346-3\" class=\"return-footnote\" aria-label=\"Return to footnote 3\">&crarr;<\/a><\/li><li id=\"footnote-346-4\">Becker D. E. (2010). Nausea, vomiting, and hiccups: a review of mechanisms and treatment. Anesthesia progress, 57(4), 150\u2013157. doi:10.2344\/0003-3006-57.4.150 <a href=\"#return-footnote-346-4\" class=\"return-footnote\" aria-label=\"Return to footnote 4\">&crarr;<\/a><\/li><li id=\"footnote-346-5\">Becker D. E. (2010). Nausea, vomiting, and hiccups: a review of mechanisms and treatment. <em>Anesthesia progress, 57<\/em>(4), 150\u2013157. <a href=\"https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3006663\/\" target=\"_blank\" rel=\"noopener noreferrer\">https:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC3006663\/<\/a> <a href=\"#return-footnote-346-5\" class=\"return-footnote\" aria-label=\"Return to footnote 5\">&crarr;<\/a><\/li><li id=\"footnote-346-6\">Bashashati, M. and McCallum, R. (2014). Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders. <em>European Journal of Pharmacology, 772<\/em>, p 79. <a href=\"#return-footnote-346-6\" class=\"return-footnote\" aria-label=\"Return to footnote 6\">&crarr;<\/a><\/li><li id=\"footnote-346-7\">MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2019 October 23]. <em>Nausea and vomiting<\/em>; [updated 2019 February 7; reviewed 2016 March 17; cited 2019 October 27]. <a href=\"https:\/\/medlineplus.gov\/nauseaandvomiting.html\" target=\"_blank\" rel=\"noopener noreferrer\">https:\/\/medlineplus.gov\/nauseaandvomiting.html<\/a>. <a href=\"#return-footnote-346-7\" class=\"return-footnote\" aria-label=\"Return to footnote 7\">&crarr;<\/a><\/li><li id=\"footnote-346-8\">\"<a href=\"https:\/\/www.flickr.com\/photos\/andreasnilsson1976\/2551446785\" target=\"_blank\" rel=\"noopener noreferrer\">Scopoderm 278:365<\/a>\" by <a href=\"https:\/\/www.flickr.com\/photos\/andreasnilsson1976\/\" target=\"_blank\" rel=\"noopener noreferrer\">Andreas Nilsson<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC BY-NC-ND 2.0<\/a> <a href=\"#return-footnote-346-8\" class=\"return-footnote\" aria-label=\"Return to footnote 8\">&crarr;<\/a><\/li><li id=\"footnote-346-9\">This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>.  <a href=\"#return-footnote-346-9\" class=\"return-footnote\" aria-label=\"Return to footnote 9\">&crarr;<\/a><\/li><li id=\"footnote-346-10\">This work is a derivative of <a style=\"text-align: initial\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a><span style=\"text-align: initial\"> by <\/span><a style=\"text-align: initial\" href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a><span style=\"text-align: initial\"> in the <\/span><a style=\"text-align: initial\" href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a><span style=\"text-align: initial\">.  <a href=\"#return-footnote-346-10\" class=\"return-footnote\" aria-label=\"Return to footnote 10\">&crarr;<\/a><\/li><li id=\"footnote-346-11\">uCentral from Unbound Medicine. <a href=\"https:\/\/www.unboundmedicine.com\/ucentral\" target=\"_blank\" rel=\"noopener noreferrer\">https:\/\/www.unboundmedicine.com\/ucentral<\/a> <a href=\"#return-footnote-346-11\" class=\"return-footnote\" aria-label=\"Return to footnote 11\">&crarr;<\/a><\/li><li id=\"footnote-346-12\">\"<a href=\"https:\/\/www.flickr.com\/photos\/104346167@N06\/36640425216\" target=\"_blank\" rel=\"noopener noreferrer\">Metoclopramide<\/a>\" by <a href=\"https:\/\/www.flickr.com\/photos\/104346167@N06\/\" target=\"_blank\" rel=\"noopener noreferrer\">John Campbell<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC0<\/a> <a href=\"#return-footnote-346-12\" class=\"return-footnote\" aria-label=\"Return to footnote 12\">&crarr;<\/a><\/li><li id=\"footnote-346-13\">This work is a derivative of <a style=\"text-align: initial\" href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a><span style=\"text-align: initial\"> by <\/span><a style=\"text-align: initial\" href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a><span style=\"text-align: initial\"> in the <\/span><a style=\"text-align: initial\" href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a><span style=\"text-align: initial\">.  <a href=\"#return-footnote-346-13\" class=\"return-footnote\" aria-label=\"Return to footnote 13\">&crarr;<\/a><\/li><li id=\"footnote-346-14\">\"<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Eichelbaum2.jpg\" target=\"_blank\" rel=\"noopener noreferrer\">Eichelbaum2.jpg<\/a>\" by Michel Eichelbaum is licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/de\/deed.en\" target=\"_blank\" rel=\"noopener noreferrer\">CC BY-SA 3.0 DE<\/a> <a href=\"#return-footnote-346-14\" class=\"return-footnote\" aria-label=\"Return to footnote 14\">&crarr;<\/a><\/li><li id=\"footnote-346-15\">\"<a href=\"https:\/\/en.wikipedia.org\/wiki\/File:000817lg_Zofran_8_MG_Oral_Tablet.jpg\" target=\"_blank\" rel=\"noopener noreferrer\">000817lg Zofran 8 MG Oral Tablet.jpg<\/a>\" by NLM is licensed under <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC0<\/a> <a href=\"#return-footnote-346-15\" class=\"return-footnote\" aria-label=\"Return to footnote 15\">&crarr;<\/a><\/li><li id=\"footnote-346-16\">\"<a href=\"http:\/\/flickr.com\/photos\/intropin\/4499127380\" target=\"_blank\" rel=\"noopener noreferrer\">Ondansetron (1<\/a>)\" by <a href=\"https:\/\/www.flickr.com\/photos\/intropin\/\" target=\"_blank\" rel=\"noopener noreferrer\">M<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC BY-NC 2.0<\/a> <a href=\"#return-footnote-346-16\" class=\"return-footnote\" aria-label=\"Return to footnote 16\">&crarr;<\/a><\/li><li id=\"footnote-346-17\">This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>.  <a href=\"#return-footnote-346-17\" class=\"return-footnote\" aria-label=\"Return to footnote 17\">&crarr;<\/a><\/li><li id=\"footnote-346-18\">This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>. \u00a0 <a href=\"#return-footnote-346-18\" class=\"return-footnote\" aria-label=\"Return to footnote 18\">&crarr;<\/a><\/li><li id=\"footnote-346-19\">\"<a href=\"https:\/\/www.flickr.com\/photos\/115645852@N04\/32335066121\" target=\"_blank\" rel=\"noopener noreferrer\">Marinol - Dronabinol<\/a>\" by <a href=\"https:\/\/www.flickr.com\/photos\/115645852@N04\/\" target=\"_blank\" rel=\"noopener noreferrer\">Steffen Geyer<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC BY-NC 2.0<\/a> &amp; 7.21\"<a href=\"https:\/\/www.publicdomainpictures.net\/en\/view-image.php?image=246405&amp;picture=medical-marijuana\" target=\"_blank\" rel=\"noopener noreferrer\">Medical Marijuana<\/a>\" by <a href=\"https:\/\/www.publicdomainpictures.net\/en\/browse-author.php?a=81846\" target=\"_blank\" rel=\"noopener noreferrer\">Circe Denyer<\/a> is licensed under <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\" rel=\"noopener noreferrer\">CC0<\/a> <a href=\"#return-footnote-346-19\" class=\"return-footnote\" aria-label=\"Return to footnote 19\">&crarr;<\/a><\/li><li id=\"footnote-346-20\">This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>. \u00a0 <a href=\"#return-footnote-346-20\" class=\"return-footnote\" aria-label=\"Return to footnote 20\">&crarr;<\/a><\/li><li id=\"footnote-346-21\">Flake, Z., Linn, B., &amp; Hornecker, J. (2015). Practical selection of antiemetics in the ambulatory setting. <em>American Family Physician, 91<\/em>(5): pp 293-296. <a href=\"#return-footnote-346-21\" class=\"return-footnote\" aria-label=\"Return to footnote 21\">&crarr;<\/a><\/li><li id=\"footnote-346-22\">This work is a derivative of <a href=\"https:\/\/dailymed.nlm.nih.gov\/dailymed\/\" target=\"_blank\" rel=\"noopener noreferrer\">Daily Med<\/a> by <a href=\"https:\/\/www.nlm.nih.gov\/\" target=\"_blank\" rel=\"noopener noreferrer\">U.S. National Library of Medicine<\/a> in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/\" target=\"_blank\" rel=\"noopener noreferrer\">public domain<\/a>.  <a href=\"#return-footnote-346-22\" class=\"return-footnote\" aria-label=\"Return to footnote 22\">&crarr;<\/a><\/li><\/ol><\/div><div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_346_2257\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_346_2257\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_346_1293\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_346_1293\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_346_1288\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_346_1288\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_346_2270\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_346_2270\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_346_1289\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_346_1289\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_346_1290\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_346_1290\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_346_1903\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_346_1903\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_346_2306\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_346_2306\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":2,"menu_order":5,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":"cc-by"},"chapter-type":[49],"contributor":[],"license":[53],"class_list":["post-346","chapter","type-chapter","status-publish","hentry","chapter-type-numberless","license-cc-by"],"part":310,"_links":{"self":[{"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/pressbooks\/v2\/chapters\/346","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/wp\/v2\/users\/2"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/pressbooks\/v2\/chapters\/346\/revisions"}],"predecessor-version":[{"id":347,"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/pressbooks\/v2\/chapters\/346\/revisions\/347"}],"part":[{"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/pressbooks\/v2\/parts\/310"}],"metadata":[{"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/pressbooks\/v2\/chapters\/346\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/wp\/v2\/media?parent=346"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/pressbooks\/v2\/chapter-type?post=346"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/wp\/v2\/contributor?post=346"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-json\/wp\/v2\/license?post=346"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}