Updates to the Database of ARV Drug Interactions

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HIV Meds Quarterly ARV Updates

Winter 2010

Susa Coffey, MD, HIV InSite Medical Editor

Ian R. McNicholl, PharmD, BCPS (Added Qualifications-Infectious Diseases), HIV InSite Pharmacy Editor

The following table summarizes recent additions to the HIV InSite Database of Antiretroviral Drug Interactions. For a full description of the updates, including references to the studies from which the data were derived, go to the database, click on a specific drug name, and search for the interacting agent.

New ARV Interactions (November 2009-March 2010)
Drug One	Drug Two	Clinical Effects	Mechanisms	Management
Source: McNicholl I. HIV InSite Database of Antiretroviral Drug Interactions. University of California San Francisco: Center for HIV Information; 2009
Darunavir	Buprenorphine		Inhibition of CYP 3A4 by darunavir/ritonavir	No dosage adjustment necessary
Darunavir	Digoxin			Monitor digoxin level and adjust digoxin dosage based on clinical signs and digoxin level
Darunavir	Omeprazole			No dosage adjustment necessary
Darunavir	Rifabutin	Inhibition of CYP 3A4 by darunavir/ritonavir		No dosage adjustment necessary; potentially could use rifabutin 150 mg QOD
Darunavir	Warfarin	↓ warfarin effects (eg, ↓ INR, ↑ risk of clotting)	Induction of CYP 3A4 by darunavir	Monitor INR and adjust warfarin as indicated
Efavirenz	Levonorgestrel	↓ levonorgestrel effects	Induction of levonorgestrel metabolism by efavirenz	Use backup form of birth control (eg, barrier)
Etravirine	Clopidogrel	Possibly ↓ clopidogrel effects	Activation of clopidogrel to its active metabolites may be ↓ by etravirine	Avoid combination; consider alternative agents
Etravirine	Fluconazole	↑ etravirine effects	Inhibition of CYP 3A4 by fluconazole	Dosage adjustment not established
Etravirine	Lopinavir/ritonavir	Potentially ↓ etravirine effects	Potential induction of CYP 3A4, 2C9, and 2C19 by lopinavir/ritonavir	No dosage adjustment necessary
Etravirine	Voriconazole	Possibly ↑ etravirine effects	Inhibition of CYP 3A4 by voriconazole	No dosage adjustment necessary
Fosamprenavir	Posaconazole	↓ posaconazole and fosamprenavir efficacy		Do not coadminister
Indinavir	Ginseng			No dosage adjustment necessary
Lopinavir/ritonavir	Buprenorphine	No significant change		No dosage adjustment necessary
Lopinavir/ritonavir	Naloxone	No significant change		No dosage adjustment necessary
Nevirapine	Lumefantrine		Unknown	No dosage adjustment necessary
Nevirapine	Tenofovir	Potential early virologic failure		Use caution when coadministering tenofovir, didanosine, and either efavirenz or nevirapine in treatment-naive patients
Raltegravir	Famotidine		Possibly owing to increased bioavailability because of ↑ gastric pH	No dosage adjustment necessary
Raltegravir (400 mg BID)	Omeprazole (20 mg QD)		Possibly owing to increased bioavailability because of ↑ gastric pH	No dosage adjustment necessary
Raltegravir (400 mg Q12H)	Omeprazole (20 mg QD x 4 days)		Possibly owing to increased bioavailability because of ↑ gastric pH	No dosage adjustment necessary

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