Review: mixing new cocktails: drug interactions in antiretroviral regimens.

Current highly active antiretroviral therapy (HAART) for the treatment of HIV infection requires the concomitant administration of three or four different agents, often with a high potential for drug-drug interactions. Additionally, some HIV-positive patients still require concomitant treatment with drugs for opportunistic infections, some require medication to treat unrelated medical conditions and/or the metabolic complications of antiretroviral therapy, others may self-medicate with herbal formulations and/or over-the-counter drugs, and still others many take drugs for recreational reasons or to manage addiction. Therefore, the virtually limitless number of drug combinations that may be taken by patients undergoing treatment of HIV infection makes drug-drug interactions almost inevitable. Managing these interactions is one of the major challenges associated with the multidrug regimens used for HIV therapy. This paper provides an overview of the most common interactions between antiretrovirals in the same and different classes-nucleoside analogue reverse transcriptase inhibitors (NRTI), protease inhibitors (PI), and non-nucleoside reverse transcriptase inhibitors (NNRTI)-by focusing on principles rather than specific interactions. The paper also addresses interactions between these antiretrovirals and other commonly used medications that may be prescribed concomitantly.