OBJECT DRUGS

Antivirals:

• Amprenavir (Agenerase)
• Atazanavir (Reyataz)
• Daclatasvir (Daklinza)
• Darunavir (Prezista)
• Delavirdine (Rescriptor)
• Etravirine (Intelence)
• Fosamprenavir Lexiva
• Indinavir (Crixivan)
• Lopinavir (Kaletra)
• Maraviroc (Selzentry)
• Nelfinavir (Viracept)
• Rilpivirine (Edurant)
• Ritonavir (Norvir)
• Saquinavir (Invirase)
• Telaprevir (Incivek)

PRECIPITANT DRUGS

Antimicrobials:

• Ciprofloxacin (Cipro, etc.)
• Clarithromycin (Biaxin, etc.)
• Erythromycin (E-Mycin, etc.)
• Fluconazole (Diflucan)
• Itraconazole (Sporanox, etc.)
• Ketoconazole (Nizoral, etc.)
• Posaconazole (Noxafil)
• Quinupristin (Synercid)
• Telithromycin (Ketek)
• Troleandomycin (TAO)
• Voriconazole (Vfend)

Comment:

Inhibitors of CYP3A4 may increase the serum levels of the antivirals resulting in increased side effects. Ritonavir may substantially increase voriconazole plasma concentrations, especially in patients deficient in CYP2C19.

Class 3: Assess Risk & Take Action if Necessary

• Consider Alternative:
• Azole Antifungals: Itraconazole and ketoconazole are potent inhibitors of CYP3A4; fluconazole appears weaker, but in larger doses it also inhibits CYP3A4. Terbinafine (Lamisil) does not appear to affect CYP3A4, and would not be expected to interact with these antivirals.
• Macrolide Antibiotics: Unlike erythromycin, clarithromycin and troleandomycin, azithromycin (Zithromax) and dirithromycin* do not appear to inhibit CYP3A4. (*not available in US)
• Telithromycin: The use of azithromycin (Zithromax) or a quinolone antibiotic other than ciprofloxacin should be considered.
• Circumvent/Minimize: Consider reducing the dose of the antiviral if enzyme inhibitors are coadministered.
• Monitor:Monitor for antiviral toxicity.