Antivirals - antiretrovirals

DRUGS TO TREAT INFECTIONS ANTIVIRALS - ANTIRETROVIRALS Non-nucleoside reverse transcriptase inhibitors 

Primary drug Secondary drug ANTIVIRALS - ANTIRETROVIRALS Effect Mechanism Precautions 

NNRTIs ANALGESICS-OPIOIDS Methadone levels may be significantly 1 by efavirenz and nevirapine t CYP3A4- and CYP2B6-mediated metabolism of methadone Monitor closely for opioid withdrawal, t dose as necessary. Likely to need dose titration of methadone (mean 22% but up to 186% t) 

NNRTIs MACROLIDES -CLARITHROMYCIN 1.1 efficacy of clarithromycin but t efficacy and adverse effects of active metabolite 2. Rash occurs in 46% of patients when efavirenz is given with clarithromycin 1. Uncertain possibly due to altered CYP3A4-mediated metabolism 2. Uncertain 1. Clinical significance unknown no dose adjustment is recommended when clarithromycin is co-administered with nevirapine, but monitor LFTs and activity against Mycobacterium avium intracellulare complex closely 2. Consider alternatives to darithromycin for patients on efavirenz 

EFAVIRENZ RIFABUTIN Possible 1 efficacy of rifabutin i bioavailability t rifabutin dose by 50% for daily treatment, or double the dose if patient is on two or three times a week treatment 

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