![Therapeutic Window<\/a>\" by Shefaa Alasfoor is licensed under](\"https:\/\/commons.wikimedia.org\/wiki\/File:Theuraputic_window.png\"){kind=link}
Peak and Trough Levels<\/h3>\nNow let's apply the idea of therapeutic window to the administration of medications requiring the monitoring of peak and trough levels, which is required in the administration of some IV antibiotics. It is important for the dosage of these medications to be titrated<\/strong> to achieve a desired therapeutic effect for the patient.\u00a0 Titration is often accomplished by closely monitoring the blood levels of the medication. A drug is said to be within the \"therepeutic window\" when the serum blood levels of an active drug remain consistently above the level of effective concentration (so that the medication is achieving its desired therapeutic effect) and consistently below the toxic level (so that no toxic effects\u00a0 are occurring). A peak<\/strong> drug level is drawn at the time when the medication is being administered and is known to be at the highest level in the bloodstream.\u00a0 A trough<\/strong> level is drawn when the drug is at its lowest in the bloodstream right before the next dose is given. Medications have a predicted reference range of normal values for peak and trough levels. These numbers assist the pharmacist and provider in gauging how the body is metabolizing, protein-binding, and excreting the drug, and assist in the adjustment of the prescribed drug doses to keep the medication within the therapeutic window.\u00a0 When administering IV medications that require peak or trough levels, it is vital for the nurse to time the administration of\u00a0 the medication according to the timing of these blood draws.\u00a0 [footnote]This work is a derivative of Principles of Pharmacology<\/a> by LibreTexts<\/a> licensed under CC BY-NC-SA 4.0<\/a>.[\/footnote]<\/sup>\nTherapeutic Index<\/h2>\n[pb_glossary id=\"106\"]Therapeutic Index[\/pb_glossary] <\/strong>is a quantitative measurement of the relative safety of a drug.\u00a0 It is a comparison of the amount of drug that produces a therapeutic effect versus the amount of drug that produces a toxic effect.\n\n \t- A large (or high) therapeutic index number means there is a large therapeutic window between the effective concentration and the toxic concentration of a medication, so the drug is relatively safe.<\/li>\n \t
- A small (or low) therapeutic index number means there is a small therapeutic window between the effective concentration and the toxic concentration.\u00a0 \u00a0A drug with a narrow therapeutic range (i.e., having little difference between toxic and therapeutic doses) often has the dosage titrated according to measurements of the actual blood levels achieved in the person taking it.\u00a0 For example, patients who start taking phenytoin to control seizures have the drug levels in their blood stream measured frequently.<\/li>\n<\/ul>\n \n\n
<\/p>\n\n<\/div>\n
\n\nCritical Thinking Activity 1.10a![\"Image](\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2021\/12\/ORN-Icons_internet-copy_internet-copy-300x300-1.png\")
<\/h2>\n<\/header>\n\n\nMr. Parker has been receiving gentamicin 80 mg IV three times daily to treat his infective endocarditis. He has his gentamicin level checked one hour after the end of his previous gentamicin infusion was completed.\u00a0 The result is 30 mcg\/ml. Access the link below to determine the nurse's course of action.\n\nView information on Therapeutic Drug Levels<\/a>\n\n (Within the activity link, be sure to select \"click to keep reading\" in order to view drugs that are commonly checked, their target levels, and what abnormal results mean).<\/em>\n\nBased on the results in the above patient scenario, what action will the nurse take based on the result of the gentamicin level of 30 mcg\/mL?\n\n<\/div>\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>","rendered":"Now that the basic concepts of medication onset, peak, and duration have been discussed, it is important to understand the value of the therapeutic window and therapeutic index in medication administration.<\/p>\n![\"Image](\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2019\/09\/image11-300x214.png\" "\\"\"Therapeutic")
Figure 1.7 Therapeutic Window<\/figcaption><\/figure>\nTherapeutic Window<\/h2>\n
For every drug, there exists a dose that is minimally effective (the Effective Concentration) and another dose that is toxic (the Toxic Concentration). Between these doses is the therapeutic window<\/a>,<\/strong> \u00a0where the safest and most effective treatment will occur (see Figure 1.7).[1]<\/sup><\/a>\u00a0 Think of this area as the dosing “sweet spot.”<\/p>\nFor example, warfarin (Coumadin) is a medication used to prevent blood clotting and is monitored using a blood test called INR. Too high of a dose of warfarin would cause the INR to increase above the therapeutic window and put the patient at risk of bleeding. Conversely, too low of a dose of warfarin would cause the INR to be below the therapeutic window and put the patient at risk of clotting.\u00a0 It is vital that the nurse frequently monitors INR levels for a patient receiving warfarin to ensure the dosage appropriately reaches the therapeutic window and does not place the patient at risk for bleeding or clotting.<\/p>\n
Peak and Trough Levels<\/h3>\n
Now let’s apply the idea of therapeutic window to the administration of medications requiring the monitoring of peak and trough levels, which is required in the administration of some IV antibiotics. It is important for the dosage of these medications to be titrated<\/strong> to achieve a desired therapeutic effect for the patient.\u00a0 Titration is often accomplished by closely monitoring the blood levels of the medication. A drug is said to be within the “therepeutic window” when the serum blood levels of an active drug remain consistently above the level of effective concentration (so that the medication is achieving its desired therapeutic effect) and consistently below the toxic level (so that no toxic effects\u00a0 are occurring). A peak<\/strong> drug level is drawn at the time when the medication is being administered and is known to be at the highest level in the bloodstream.\u00a0 A trough<\/strong> level is drawn when the drug is at its lowest in the bloodstream right before the next dose is given. Medications have a predicted reference range of normal values for peak and trough levels. These numbers assist the pharmacist and provider in gauging how the body is metabolizing, protein-binding, and excreting the drug, and assist in the adjustment of the prescribed drug doses to keep the medication within the therapeutic window.\u00a0 When administering IV medications that require peak or trough levels, it is vital for the nurse to time the administration of\u00a0 the medication according to the timing of these blood draws.\u00a0 [2]<\/sup><\/a><\/sup><\/p>\nTherapeutic Index<\/h2>\n
Therapeutic Index<\/a> <\/strong>is a quantitative measurement of the relative safety of a drug.\u00a0 It is a comparison of the amount of drug that produces a therapeutic effect versus the amount of drug that produces a toxic effect.<\/p>\n\n- A large (or high) therapeutic index number means there is a large therapeutic window between the effective concentration and the toxic concentration of a medication, so the drug is relatively safe.<\/li>\n
- A small (or low) therapeutic index number means there is a small therapeutic window between the effective concentration and the toxic concentration.\u00a0 \u00a0A drug with a narrow therapeutic range (i.e., having little difference between toxic and therapeutic doses) often has the dosage titrated according to measurements of the actual blood levels achieved in the person taking it.\u00a0 For example, patients who start taking phenytoin to control seizures have the drug levels in their blood stream measured frequently.<\/li>\n<\/ul>\n
<\/p>\n
\n\n<\/div>\n
\n\n\nCritical Thinking Activity 1.10a<\/h2>\n<\/header>\n\nMr. Parker has been receiving gentamicin 80 mg IV three times daily to treat his infective endocarditis. He has his gentamicin level checked one hour after the end of his previous gentamicin infusion was completed.\u00a0 The result is 30 mcg\/ml. Access the link below to determine the nurse’s course of action.<\/p>\n
View information on Therapeutic Drug Levels<\/a><\/p>\n (Within the activity link, be sure to select “click to keep reading” in order to view drugs that are commonly checked, their target levels, and what abnormal results mean).<\/em><\/p>\nBased on the results in the above patient scenario, what action will the nurse take based on the result of the gentamicin level of 30 mcg\/mL?<\/p>\n<\/div>\n
Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.<\/p>\n<\/div>\n<\/div>\n
- \"Therapeutic Window<\/a>\" by Shefaa Alasfoor is licensed under CC BY-SA 3.0<\/a> ↵<\/a><\/li>
- This work is a derivative of Principles of Pharmacology<\/a> by LibreTexts<\/a> licensed under CC BY-NC-SA 4.0<\/a>. ↵<\/a><\/li><\/ol><\/div>definition<\/span>
![\"Illustration](\"https:\/\/pressbooks.publishdot.com\/nursingpharmacology\/wp-content\/uploads\/sites\/5\/2019\/09\/image11-1.png\" "\\"\"OSC")
Figure 3.8 Comparison of beta-lactam ring structure across different classes of medications, spectrum of activity and routes of administration[footnote]\"<\/span>OSC Microbio 14 02 BetaLactam.jpg<\/a>\" by <\/span>CNX Openstax<\/a> is licensed under<\/span> CC BY 4.0<\/a> Access for free at <\/span>https:\/\/openstax.org\/books\/microbiology\/pages\/14-3-mechanisms-of-antibacterial-drugs<\/a>[\/footnote]<\/span><\/sup><\/figcaption><\/figure>\nCephalosporins are a slightly modified chemical \"twin\" to penicillins due to their beta lactam chemical structure. (See Figure 3.8 for a comparison of the beta-lactam ring structure, spectrum of activity, and route of administration across different classes of medications.) Because of these similarities, some patients who have allergies to penicillins may experience cross-sensitivity to cephalosporins.<\/span><\/p>\nIndications:<\/strong> Cephalosporins are used to treat skin and skin-structure infections, bone infections, genitourinary infections, otitis media, and community-acquired respiratory tract infections.<\/p>\nMechanism of Action:<\/strong> Cephalosporins are typically bactericidal and are similar to penicillin in their action within the cell wall. Cephalosporins are sometimes grouped into \"generations\" by their antimicrobial properties. The 1st-generation drugs are effective mainly against gram-positive organisms. Higher generations generally have expanded spectra against aerobic gram-negative bacilli. The 5th-generation cephalosporins are active against methicillin-resistant Staphylococcus aureus<\/a> (MRSA) or other complicated infections. [1]<\/sup><\/a><\/sup><\/p>\nSpecific Administration Considerations:<\/strong> Patients who are allergic to pencillins may also be allergic to cephalosporins. Patients who consume cephalosporins while drinking alcoholic beverages may experience disulfiram-like reactions including severe headache, flushing, nausea, vomiting, etc.[2]<\/sup><\/a>\u00a0<\/sup>Additionally, like penicillins, cephalosporins may interfere with coagulability and increase a patient's risk of bleeding. Cephalosporin dosing may require adjustment for patients experiencing renal impairment. Blood urea nitrogen (BUN) and creatinine should be monitored carefully to identify signs of nephrotoxicity.<\/p>\nPatient Teaching & Education:<\/strong> Patients who are prescribed cephalosporins should be specifically cautioned about a disulfiram reaction, which can occur when alcohol is ingested while taking the medication.\u00a0 Additionally, individuals should be instructed to monitor for rash and signs of superinfection (such as black, furry overgrowth on tongue; vaginal itching or discharge; loose or foul-smelling stool) and report to the prescribing provider.<\/p>\nIt is also important to note that cephalosporin can enter breastmilk and may alter bowel flora of the infant. Thus, use during breastfeeding is often discouraged.[3]<\/sup><\/a><\/sup><\/p>\nNow let's take a closer look at the cephalosporin medication grid in Table 3.6.[4]<\/sup><\/a><\/sup><\/p>\nTable 3.6 Cephalosporin Medication Grid<\/p>\n
- \n \t
- A large (or high) therapeutic index number means there is a large therapeutic window between the effective concentration and the toxic concentration of a medication, so the drug is relatively safe.<\/li>\n \t
- A small (or low) therapeutic index number means there is a small therapeutic window between the effective concentration and the toxic concentration.\u00a0 \u00a0A drug with a narrow therapeutic range (i.e., having little difference between toxic and therapeutic doses) often has the dosage titrated according to measurements of the actual blood levels achieved in the person taking it.\u00a0 For example, patients who start taking phenytoin to control seizures have the drug levels in their blood stream measured frequently.<\/li>\n<\/ul>\n \n\n
<\/p>\n\n<\/div>\n
\n\n Critical Thinking Activity 1.10a
<\/h2>\n<\/header>\n\n\nMr. Parker has been receiving gentamicin 80 mg IV three times daily to treat his infective endocarditis. He has his gentamicin level checked one hour after the end of his previous gentamicin infusion was completed.\u00a0 The result is 30 mcg\/ml. Access the link below to determine the nurse's course of action.\n\nView information on Therapeutic Drug Levels<\/a>\n\n (Within the activity link, be sure to select \"click to keep reading\" in order to view drugs that are commonly checked, their target levels, and what abnormal results mean).<\/em>\n\nBased on the results in the above patient scenario, what action will the nurse take based on the result of the gentamicin level of 30 mcg\/mL?\n\n<\/div>\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>","rendered":"Now that the basic concepts of medication onset, peak, and duration have been discussed, it is important to understand the value of the therapeutic window and therapeutic index in medication administration.<\/p>\n
Figure 1.7 Therapeutic Window<\/figcaption><\/figure>\n Therapeutic Window<\/h2>\n
For every drug, there exists a dose that is minimally effective (the Effective Concentration) and another dose that is toxic (the Toxic Concentration). Between these doses is the therapeutic window<\/a>,<\/strong> \u00a0where the safest and most effective treatment will occur (see Figure 1.7).[1]<\/sup><\/a>\u00a0 Think of this area as the dosing “sweet spot.”<\/p>\n
For example, warfarin (Coumadin) is a medication used to prevent blood clotting and is monitored using a blood test called INR. Too high of a dose of warfarin would cause the INR to increase above the therapeutic window and put the patient at risk of bleeding. Conversely, too low of a dose of warfarin would cause the INR to be below the therapeutic window and put the patient at risk of clotting.\u00a0 It is vital that the nurse frequently monitors INR levels for a patient receiving warfarin to ensure the dosage appropriately reaches the therapeutic window and does not place the patient at risk for bleeding or clotting.<\/p>\n
Peak and Trough Levels<\/h3>\n
Now let’s apply the idea of therapeutic window to the administration of medications requiring the monitoring of peak and trough levels, which is required in the administration of some IV antibiotics. It is important for the dosage of these medications to be titrated<\/strong> to achieve a desired therapeutic effect for the patient.\u00a0 Titration is often accomplished by closely monitoring the blood levels of the medication. A drug is said to be within the “therepeutic window” when the serum blood levels of an active drug remain consistently above the level of effective concentration (so that the medication is achieving its desired therapeutic effect) and consistently below the toxic level (so that no toxic effects\u00a0 are occurring). A peak<\/strong> drug level is drawn at the time when the medication is being administered and is known to be at the highest level in the bloodstream.\u00a0 A trough<\/strong> level is drawn when the drug is at its lowest in the bloodstream right before the next dose is given. Medications have a predicted reference range of normal values for peak and trough levels. These numbers assist the pharmacist and provider in gauging how the body is metabolizing, protein-binding, and excreting the drug, and assist in the adjustment of the prescribed drug doses to keep the medication within the therapeutic window.\u00a0 When administering IV medications that require peak or trough levels, it is vital for the nurse to time the administration of\u00a0 the medication according to the timing of these blood draws.\u00a0 [2]<\/sup><\/a><\/sup><\/p>\n
Therapeutic Index<\/h2>\n
Therapeutic Index<\/a> <\/strong>is a quantitative measurement of the relative safety of a drug.\u00a0 It is a comparison of the amount of drug that produces a therapeutic effect versus the amount of drug that produces a toxic effect.<\/p>\n
- \n
- A large (or high) therapeutic index number means there is a large therapeutic window between the effective concentration and the toxic concentration of a medication, so the drug is relatively safe.<\/li>\n
- A small (or low) therapeutic index number means there is a small therapeutic window between the effective concentration and the toxic concentration.\u00a0 \u00a0A drug with a narrow therapeutic range (i.e., having little difference between toxic and therapeutic doses) often has the dosage titrated according to measurements of the actual blood levels achieved in the person taking it.\u00a0 For example, patients who start taking phenytoin to control seizures have the drug levels in their blood stream measured frequently.<\/li>\n<\/ul>\n
<\/p>\n
\n\n<\/div>\n
\n\n\n Critical Thinking Activity 1.10a
<\/h2>\n<\/header>\n\nMr. Parker has been receiving gentamicin 80 mg IV three times daily to treat his infective endocarditis. He has his gentamicin level checked one hour after the end of his previous gentamicin infusion was completed.\u00a0 The result is 30 mcg\/ml. Access the link below to determine the nurse’s course of action.<\/p>\n
View information on Therapeutic Drug Levels<\/a><\/p>\n
(Within the activity link, be sure to select “click to keep reading” in order to view drugs that are commonly checked, their target levels, and what abnormal results mean).<\/em><\/p>\n
Based on the results in the above patient scenario, what action will the nurse take based on the result of the gentamicin level of 30 mcg\/mL?<\/p>\n<\/div>\n
Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.<\/p>\n<\/div>\n<\/div>\n
- \"Therapeutic Window<\/a>\" by Shefaa Alasfoor is licensed under CC BY-SA 3.0<\/a> ↵<\/a><\/li>
- This work is a derivative of Principles of Pharmacology<\/a> by LibreTexts<\/a> licensed under CC BY-NC-SA 4.0<\/a>. ↵<\/a><\/li><\/ol><\/div>
definition<\/span>Figure 3.8 Comparison of beta-lactam ring structure across different classes of medications, spectrum of activity and routes of administration[footnote]\"<\/span>OSC Microbio 14 02 BetaLactam.jpg<\/a>\" by <\/span>CNX Openstax<\/a> is licensed under<\/span> CC BY 4.0<\/a> Access for free at <\/span>https:\/\/openstax.org\/books\/microbiology\/pages\/14-3-mechanisms-of-antibacterial-drugs<\/a>[\/footnote]<\/span><\/sup><\/figcaption><\/figure>\n Cephalosporins are a slightly modified chemical \"twin\" to penicillins due to their beta lactam chemical structure. (See Figure 3.8 for a comparison of the beta-lactam ring structure, spectrum of activity, and route of administration across different classes of medications.) Because of these similarities, some patients who have allergies to penicillins may experience cross-sensitivity to cephalosporins.<\/span><\/p>\n
Indications:<\/strong> Cephalosporins are used to treat skin and skin-structure infections, bone infections, genitourinary infections, otitis media, and community-acquired respiratory tract infections.<\/p>\n
Mechanism of Action:<\/strong> Cephalosporins are typically bactericidal and are similar to penicillin in their action within the cell wall. Cephalosporins are sometimes grouped into \"generations\" by their antimicrobial properties. The 1st-generation drugs are effective mainly against gram-positive organisms. Higher generations generally have expanded spectra against aerobic gram-negative bacilli. The 5th-generation cephalosporins are active against methicillin-resistant Staphylococcus aureus<\/a> (MRSA) or other complicated infections. [1]<\/sup><\/a><\/sup><\/p>\n
Specific Administration Considerations:<\/strong> Patients who are allergic to pencillins may also be allergic to cephalosporins. Patients who consume cephalosporins while drinking alcoholic beverages may experience disulfiram-like reactions including severe headache, flushing, nausea, vomiting, etc.[2]<\/sup><\/a>\u00a0<\/sup>Additionally, like penicillins, cephalosporins may interfere with coagulability and increase a patient's risk of bleeding. Cephalosporin dosing may require adjustment for patients experiencing renal impairment. Blood urea nitrogen (BUN) and creatinine should be monitored carefully to identify signs of nephrotoxicity.<\/p>\n
Patient Teaching & Education:<\/strong> Patients who are prescribed cephalosporins should be specifically cautioned about a disulfiram reaction, which can occur when alcohol is ingested while taking the medication.\u00a0 Additionally, individuals should be instructed to monitor for rash and signs of superinfection (such as black, furry overgrowth on tongue; vaginal itching or discharge; loose or foul-smelling stool) and report to the prescribing provider.<\/p>\n
It is also important to note that cephalosporin can enter breastmilk and may alter bowel flora of the infant. Thus, use during breastfeeding is often discouraged.[3]<\/sup><\/a><\/sup><\/p>\n
Now let's take a closer look at the cephalosporin medication grid in Table 3.6.[4]<\/sup><\/a><\/sup><\/p>\n
Table 3.6 Cephalosporin Medication Grid<\/p>\n
- This work is a derivative of Principles of Pharmacology<\/a> by LibreTexts<\/a> licensed under CC BY-NC-SA 4.0<\/a>. ↵<\/a><\/li><\/ol><\/div>
- \"Therapeutic Window<\/a>\" by Shefaa Alasfoor is licensed under CC BY-SA 3.0<\/a> ↵<\/a><\/li>