Atazanavir and Acid-Lowering Therapy
The advent of highly active antiretroviral therapy has improved long-term outcomes for patients infected with HIV, but its use brings many therapeutic challenges. Drug interactions play a predominant role in these challenges and are a constant concern. Concurrent prescription drug therapies and self-medication with nonprescription agents both contribute to the complexity of these therapeutic regimens. Pharmacists must be aware of these factors and should help in identifying potential drug interactions to minimize adverse outcomes in patients.
Atazanavir is a protease inhibitor used in combination with other antiretroviral agents to treat HIV-1 infection. The advantages of atazanavir over other protease inhibitors include once-daily administration and minimal adverse effects on lipid levels. The bioavailability of atazanavir is pH dependent, with greater absorption in acidic environments. HIV-infected patients often receive concomitant acid-lowering therapy, usually to address adverse events related to antiretroviral therapy. In one survey, 88% of HIV-infected patients had received a proton pump inhibitor (PPI), a histamine-2 (H2) receptor antagonist, or an antacid since starting HIV therapy. The manufacturer of atazanavir (Reyataz), Bristol-Myers Squibb, recommends avoiding concomitant use of PPIs, administering antacids or buffered medications at least 1 h before or 2 h after atazanavir, and administering H2 receptor antagonists at least 10 h before or 2 h after atazanavir. Despite these recommendations, it is not always possible to avoid concomitant use of atazanavir and acid-lowering therapies. In cases where the use of both is unavoidable, it is important for clinicians to understand the evidence behind the manufacturer’s recommendations, so they can evaluate for particular patients the clinical relevance of any potential drug interaction. levitra 20 mg
This article documents a qualitative review of the literature regarding recently documented drug interactions between atazanavir and acid-lowering agents, including PPIs, H2 receptor antagonists, and other antacids.