CH 90 TB - Key points and nursing implication PDF

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Key Points_Ch 90 TB Drugs     

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■ Most people infected with M. tuberculosis remain asymptomatic, although they will harbor dormant bacteria for life (in the absence of drug therapy). ■ Symptomatic TB can result from reactivation of an old infection or from recent person-to-person transmission of a new infection. ■ Drug resistance, and especially multidrug resistance, is a serious impediment to successful therapy of TB. ■ The principal cause of drug resistance in TB is inadequate drug therapy, which kills sensitive bacteria while allowing resistant mutants to flourish. ■ To prevent emergence of resistance, initial therapy of TB should consist of at least two drugs to which the infection is sensitive, and preferably four. Accordingly, isolates from all patients must undergo testing of drug sensitivity, a process that typically takes several weeks. ■ Therapy of TB is prolonged, lasting from a minimum of 6 months to 2 years and even longer. ■ Patient adherence can be greatly increased by using directly observed therapy combined with intermittent, rather than daily, dosing. ■ Three methods are employed to evaluate TB therapy: bacteriologic evaluation of sputum, clinical evaluation, and chest radiographs. ■ The principal first-line drugs for TB are isoniazid, rifampin, pyrazinamide, and ethambutol. For initial therapy of active TB, patients may be given all four drugs. ■ Initial therapy of MDR-TB and XDR-TB may require up to seven drugs. ■ Tuberculosis in HIV-positive patients often can be treated with the same regimens used for HIVnegative patients, although the duration of treatment may be longer. ■ Isoniazid can injure the liver. The greatest risk factor is advancing age. Patients who develop liver injury should discontinue isoniazid immediately. ■ Rifampin induces drug-metabolizing enzymes and can thereby increase the metabolism of other drugs; important among these are oral contraceptives, warfarin, and certain protease inhibitors and NNRTIs used for HIV infection. ■ Like isoniazid, rifampin and pyrazinamide are hepatotoxic. Accordingly, when these three drugs are combined, as they often are, the risk for liver injury can be substantial. ■ Ethambutol can cause optic neuritis. ■ The tuberculin skin test (TST)—used to identify people with LTBI—is performed by giving an intradermal injection of PPD (purified protein derivative) and then measuring the zone of induration (hardness) at the site 48 to 72 hours later. ■ New blood tests, known as interferon gamma release assays (IGRAs), are as sensitive as the TST and more specific. Moreover, results with the IGRAs are available faster (within 24 hours) and don't require a return visit to the office. ■ For years, isoniazid, taken daily for 9 months, has been the preferred treatment for LTBI. However, a much simpler regimen—isoniazid plus rifapentine taken once a week for just 3 months—is just as effective and is likely to replace isoniazid alone as standard treatment.

Summary of Major Nursing Implications Antituberculosis Drugs  Isoniazid  Rifampin  Pyrazinamide  Ethambutol The nursing implications here are limited to the drug therapy of TB.

Implications That Apply to All Antituberculosis Drugs

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Promoting Adherence Treatment of active TB is prolonged and demands concurrent use of two or more drugs; as a result, adherence can be a significant problem. To promote adherence, educate the patient about the rationale for multidrug therapy and the need for long-term treatment. Encourage patients to take their medication exactly as prescribed and to continue treatment until the infection has resolved. Adherence can be greatly increased by using directly observed therapy (DOT) combined with intermittent dosing (rather than daily dosing).

Evaluating Treatment Success is indicated by (1) reductions in fever, malaise, anorexia, cough, and other clinical manifestations of TB (usually within weeks); (2) radiographic evidence of improvement (usually in 3 months); and (3) an absence of M. tuberculosis in sputum (usually after 3 to 6 months).

Isoniazid In addition to the implications that follow, see earlier discussion for implications on Promoting Adherence and Evaluating Treatment that apply to all anti-TB drugs.

Preadministration Assessment Therapeutic Goal Treatment of active or latent infection with M. tuberculosis.

Baseline Data Obtain a chest radiograph, microbiologic tests of sputum, and baseline tests of liver function.

Identifying High-Risk Patients Isoniazid is contraindicated for patients with acute liver disease or a history of isoniazid-induced hepatotoxicity. Use with caution in alcohol abusers, diabetic patients, patients with vitamin B6 deficiency, patients older than 50 years, and patients who are taking phenytoin, rifampin, rifabutin, rifapentine, or pyrazinamide.

Implementation: Administration Routes Oral, IM.

Administration Advise patients to take isoniazid on an empty stomach, either 1 hour before meals or 2 hours after. Advise patients to take the drug with meals if GI upset occurs.

Ongoing Evaluation and Interventions Minimizing Adverse Effects Hepatotoxicity. Isoniazid can cause hepatocellular damage and multilobular hepatic necrosis. Inform patients about signs of hepatitis (jaundice, anorexia, malaise, fatigue, nausea), and instruct them to notify the prescriber immediately if these develop. Evaluate patients monthly for signs of hepatitis. Monthly determinations of AST activity may be ordered. If clinical signs of hepatitis appear or if AST activity exceeds 3 to 5 times the pretreatment baseline, isoniazid should be withdrawn. Daily ingestion of alcohol increases the risk for liver injury; urge the patient to minimize or eliminate alcohol consumption. Peripheral Neuropathy. Inform patients about symptoms of peripheral neuropathy (tingling, numbness, burning, or pain in the hands or feet), and instruct them to notify the prescriber if these occur. Peripheral neuritis can be reversed with small daily doses of pyridoxine (vitamin B 6). In patients at high risk for neuropathy (e.g., alcohol abusers, diabetic patients), give pyridoxine prophylactically.

Minimizing Adverse Interactions Phenytoin. Isoniazid can suppress the metabolism of phenytoin, thereby causing phenytoin levels to rise. Plasma phenytoin should be monitored. If necessary, phenytoin dosage should be reduced.

Rifampin In addition to the implications that follow, see earlier for implications on Promoting Adherence and Evaluating Treatment that apply to all anti-TB drugs.

Preadministration Assessment Therapeutic Goal Treatment of active TB or leprosy.

Baseline Data Obtain a chest radiograph, microbiologic tests of sputum, and baseline tests of liver function.

Identifying High-Risk Patients Rifampin is contraindicated for patients taking delavirdine (an NNRTI) and most protease inhibitors. Use with caution in alcohol abusers, patients with liver disease, and patients taking warfarin.

Implementation: Administration Routes Oral, IV.

Dosage Reduce the dosage in patients with liver disease.

Administration Instruct the patient to take oral rifampin once a day, either 1 hour before a meal or 2 hours after. Administer reconstituted rifampin by slow IV infusion: 100 mL over 30 minutes or 500 mL over 3 hours.

Ongoing Evaluation and Interventions Minimizing Adverse Effects Hepatotoxicity. Rifampin may cause jaundice or hepatitis. Inform patients about signs of liver dysfunction (anorexia, darkened urine, pale stools, yellow discoloration of eyes or skin), and instruct them to notify the prescriber if these develop. Monitor patients for signs of liver dysfunction. Tests of liver function should be made before treatment and every 2 to 4 weeks thereafter. Discoloration of Body Fluids. Inform patients that rifampin may impart a harmless red-orange color to urine, sweat, saliva, and tears. Warn patients that soft contact lenses may undergo permanent staining; advise them to consult an ophthalmologist about continued use of the lenses.

Minimizing Adverse Interactions Accelerated Metabolism of Other Drugs. Rifampin can accelerate the metabolism of many drugs, thereby reducing their effects. This action is of particular concern with oral contraceptives, warfarin, most protease inhibitors, and delavirdine (an NNRTI). Advise women taking oral contraceptives to use a nonhormonal form of birth control. Monitor warfarin effects and increase dosage as needed. Do not combine protease inhibitors or NNRTIs with rifampin. Pyrazinamide and Isoniazid. These hepatotoxic anti-TB drugs can increase the risk for liver injury when used with rifampin.

Pyrazinamide In addition to the implications that follow, see earlier for implications on Promoting Adherence and Evaluating Treatment that apply to all anti-TB drugs.

Preadministration Assessment Therapeutic Goal

Treatment of active and LTBI.

Baseline Data Obtain a chest radiograph, microbiologic tests of sputum, and baseline tests of liver function.

Identifying High-Risk Patients Pyrazinamide is contraindicated for patients with severe liver dysfunction or acute gout. Use with caution in alcohol abusers.

Implementation: Administration Route Oral.

Administration Usually administered once a day.

Ongoing Evaluation and Interventions Minimizing Adverse Effects Hepatotoxicity. Inform patients about symptoms of hepatitis (malaise, anorexia, nausea, vomiting, yellowish discoloration of the skin and eyes), and instruct them to notify the prescriber if these develop. Levels of AST and ALT should be measured before treatment and every 2 weeks thereafter. If severe liver injury occurs, pyrazinamide should be withdrawn. The risk for liver injury is increased by concurrent therapy with isoniazid, rifampin, rifabutin, or rifapentine, all of which are hepatotoxic. Nongouty Polyarthralgias. Polyarthralgias develop in 40% of patients. Advise patients to take an NSAID (e.g., aspirin, ibuprofen) to relieve pain. Some patients may need to stop pyrazinamide or at least reduce the dosage.

Ethambutol In addition to the implications that follow, see earlier for implications on Promoting Adherence and Evaluating Treatment that apply to all anti-TB drugs.

Preadministration Assessment Therapeutic Goal Treatment of active TB.

Baseline Data Obtain a chest radiograph, microbiologic tests of sputum, and baseline vision tests.

Identifying High-Risk Patients Ethambutol is contraindicated for patients with optic neuritis.

Implementation: Administration Route Oral. Administration Usually administered once a day. Advise patients to take ethambutol with food if GI upset occurs.

Ongoing Evaluation and Interventions Minimizing Adverse Effects Optic Neuritis.

Ethambutol can cause dose-related optic neuritis. Symptoms include blurred vision, altered color discrimination, and constriction of visual fields. Baseline vision tests are required. Instruct patients to report any alteration in vision (e.g., blurring of vision, reduced color discrimination). If ocular toxicity develops, ethambutol should be withdrawn at once. a

Patient education information is highlighted as blue text.

Key Points: Ch 92_Antifungals     

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■ Amphotericin B is a drug of choice for most systemic mycoses, despite its potential for serious harm. ■ Amphotericin B binds to ergosterol in the fungal cell membrane, making the membrane more permeable. The resultant leakage of intracellular cations reduces viability. ■ Much of the toxicity of amphotericin B results from binding to cholesterol in host cell membranes. ■ Because absorption of oral amphotericin B is poor, treatment of systemic mycoses requires intravenous administration. ■ Amphotericin B infusion frequently causes fever, chills, rigors, nausea, and headache. Pretreatment with diphenhydramine plus an analgesic can reduce mild symptoms. A glucocorticoid can be used for severe reactions. Meperidine or dantrolene can reduce rigors. ■ Amphotericin B causes renal injury in most patients. Kidney damage can be minimized by infusing 1 L of saline on the days amphotericin is infused. ■ If possible, amphotericin B should not be combined with other nephrotoxic drugs. ■ Itraconazole is active against a broad spectrum of fungi. ■ Itraconazole inhibits cytochrome P450, inhibiting synthesis of ergosterol, an essential component of the fungal cell membrane. Cell membrane permeability increases, causing cellular components to leak out. ■ Itraconazole is an alternative to IV amphotericin for many fungal infections. Advantages are lower toxicity and oral dosing. ■ Itraconazole has two major adverse effects: cardiosuppression and liver damage. ■ Itraconazole inhibits CYP3A4 and can raise the levels of many drugs. High levels of cisapride, pimozide, dofetilide, and quinidine can cause fatal dysrhythmias, so using these drugs with itraconazole is contraindicated. ■ Drugs that reduce gastric acidity can greatly reduce absorption of itraconazole. ■ Topical clotrimazole is a drug of choice for many superficial mycoses caused by dermatophytes and Candida species. ■ Onychomycosis is difficult to treat and requires prolonged therapy. Oral therapy with terbinafine or itraconazole is the preferred treatment. ■ Vulvovaginal candidiasis can be treated with a single oral dose of fluconazole or with short-term topical therapy (e.g., one 1200-mg miconazole vaginal suppository).

Summary of Major Nursing Implications

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The implications here pertain only to the use of antifungal drugs against systemic mycoses.

Amphotericin B Preadministration Assessment Therapeutic Goal Treatment of progressive and potentially fatal systemic fungal infections. Flucytosine may be given to enhance therapeutic effects.

Identifying High-Risk Patients When used as it should be (i.e., for life-threatening infections), amphotericin has no contraindications.

Implementation: Administration Routes Intravenous, intrathecal.

Intravenous Administration Use aseptic technique when preparing infusion solutions. Infuse slowly (over 2 to 4 hours). Check the solution periodically for a precipitate; if one forms, discontinue the infusion immediately. Therapy lasts several months; rotate the infusion site to reduce phlebitis and ensure availability of a usable vein. Dosage must be individualized. Alternate-day dosing may be ordered to reduce adverse effects.

Ongoing Evaluation and Interventions Minimizing Adverse Effects General Considerations. Amphotericin B can produce serious adverse effects. The patient should be under close supervision, preferably in a hospital. Infusion Reactions. Amphotericin can cause fever, chills, rigors, nausea, and headache. Pretreatment with diphenhydramine plus acetaminophen can minimize these reactions. Give meperidine or dantrolene for rigors. If other measures fail, give hydrocortisone to suppress symptoms. Rotate the infusion site to minimize phlebitis. Infusion reactions can be reduced by using a lipid-based formulation rather than conventional amphotericin. Nephrotoxicity. Almost all patients experience renal impairment. Monitor and record intake and output. Test kidney function every 3 to 4 days; if plasma creatinine content rises above 3.5 mg/dL, amphotericin dosage should be reduced. To reduce the risk of renal damage, infuse 1 L of saline on the days when amphotericin is given, avoid other nephrotoxic drugs (e.g., aminoglycosides, cyclosporine, NSAIDs), and use a lipid-based formulation instead of conventional amphotericin. Hypokalemia. Renal injury may cause hypokalemia. Measure serum potassium often. Correct hypokalemia with potassium supplements. Hematologic Effects. Normocytic, normochromic anemia has occurred secondary to amphotericin-induced suppression of bone marrow. Hematocrit determinations should be performed to monitor for this anemia.

Minimizing Adverse Interactions Nephrotoxic Drugs. Unless clearly required, amphotericin should not be combined with other nephrotoxic drugs, including aminoglycosides, cyclosporine, and NSAIDs.

Itraconazole Preadministration Assessment Therapeutic Goal Treatment of systemic and superficial mycoses.

Baseline Data Assess for heart disease or a history thereof. The prescriber may order baseline tests of liver function. Identifying High-Risk Patients. Itraconazole is contraindicated for patients taking pimozide, quinidine, dofetilide, or cisapride. Use with great caution, if at all, in patients with cardiac disease, significant pulmonary disease, active liver disease, or a history of liver injury with other drugs.

Implementation: Administration Route

Oral.

Administration Advise patients to take itraconazole capsules with food and/or a cola beverage to enhance absorption. Advise patients using antacids and other drugs that reduce gastric acidity to take them at least 1 hour before itraconazole or 2 hours after.

Ongoing Evaluation and Interventions Minimizing Adverse Effects Liver Injury. Rarely, itraconazole has been associated with fatal liver failure. If signs of liver injury appear, discontinue itraconazole and obtain tests of liver function. Inform patients about signs of liver dysfunction (persistent nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice, dark urine, pale stools), and instruct them to notify the prescriber if these occur. Cardiac Suppression. Itraconazole can suppress ventricular function, posing a risk of heart failure. Monitor for signs and symptoms of heart failure, and discontinue itraconazole if they develop. Inform patients about signs of heart failure (fatigue, cough, dyspnea, edema, jugular distention), and instruct them to seek immediate medical attention if they occur.

Minimizing Adverse Interactions Pimozide, Quinidine, Dofetilide, and Cisapride. By inhibiting CYP3A4, itraconazole can raise the levels of these drugs, posing a risk of fatal dysrhythmias. Accordingly, concurrent use of these drugs with itraconazole is contraindicated. Cyclosporine, Digoxin, Warfarin, and Sulfonylureas. By inhibiting CYP3A4, itraconazole can raise levels of these drugs. Monitor cyclosporine and digoxin blood levels. Monitor prothrombin time in patients taking warfarin. Monitor blood glucose in patients taking a sulfonylurea. Drugs That Raise Gastric pH. Antacids, H2 antagonists, proton pump inhibitors, and other drugs that decrease gastric acidity can reduce itraconazole absorption. Advise patients using these agents to take them at least 1 hour before itraconazole or 2 hours after.

Flucytosine Preadministration Assessment Therapeutic Goal Treatment of serious infections caused by Candida species and Cryptococcus neoformans. Flucytosine is usually combined with amphotericin B.

Baseline Data Obtain baseline tests of renal function, hematologic status, and serum electrolytes.

Identifying High-Risk Patients Use with extreme caution in patients with kidney disease or bone marrow suppression.

Implementation: Administration Route Oral.

Dosage and Administration Treatment may require ingesting 10 or more capsules 4 times a day. Advise patients to take capsules a few at a time over a 15-minute interval to minimize nausea and vomiting. Dosage must be reduced in patients with renal impairment.

Ongoing Evaluation and Interventions

Monitoring Summary Obtain weekly tests of liver function (serum transaminase and alkaline phosphatase levels) and hematologic status (leukocyte counts). In patients receiving amphotericin B concurrently and in those with pre-existing renal impairment, monitor kidney function and flucytosine levels.

Minimizing Adverse Effects Hematologic Effec...