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Ritonavir is commonly used as a pharmacokinetic booster for antiretroviral regimens in the management of human immunodeficiency virus infections. Limitations to ritonavir boosting include increased pill burden, adverse effects, and a wide range of clinically significant drug-drug interactions. Cobicistat is a new pharmacokinetic booster that is a selective inhibitor of cytochrome P450 3A, the main metabolizing pathway of several antiretrovirals. Cobicistat has been studied as a booster for elvitegravir, a second-generation integrase inhibitor, and protease inhibitors. Based on successful clinical trials, a new single-tablet regimen of elvitegravir, cobicistat, emtricitabine, and tenofovir has been approved for the management of treatment-naïve patients. Additional studies are underway investigating the safety and efficacy of cobicistat-boosted protease inhibitor regimens for both treatment-naïve and treatment-experienced patients. Cobicistat is well tolerated and may become a preferred booster for antiretroviral regimens, as it can be coformulated with several agents to create simpler regimens.

The first two integrase strand transfer inhibitors (INSTIs) approved for treatment of patients infected with human immunodeficiency virus (HIV) were raltegravir and elvitegravir. Both raltegravir and elvitegravir are now guideline-preferred agents as part of an antiretroviral regimen for treatment-naive patients. However, raltegravir is dosed twice/day. Elvitegravir is available in a single-tablet regimen and dosed once/day because it is administered with the pharmacokinetic booster cobicistat, a potent CYP3A4 inhibitor that can lead to clinically significant drug-drug interactions. In addition, raltegravir and elvitegravir have a low genetic barrier to resistance and are associated with cross-resistance. Dolutegravir is a new-generation INSTI administered once/day without a pharmacokinetic booster and can be coformulated in a single-tablet regimen. Phase III studies have demonstrated the efficacy and safety of dolutegravir for treatment-naive and treatment-experienced patients. Compared with other INSTIs, dolutegravir has a higher genetic barrier to resistance. Dolutegravir was approved by the U.S. Food and Drug Administration in August 2013 and joins raltegravir and elvitegravir as guideline-preferred agents for the management for HIV-infected treatment-naive patients.

TAF is a novel nucleotide reverse transcriptase inhibitor for the treatment of HIV-1 infection that has efficacy similar to that of TDF and improved safety compared with TDF.