Cobicistat, a pharmacokinetic enhancer that boosts levels of some HIV drugs but has no antiretroviral activity of its own, is now available alone as Tybost (Gilead) and in fixed-dose combinations with the protease inhibitors atazanavir (Evotaz — BMS) and darunavir (Prezcobix — Janssen) for treatment of HIV-1 infection. Both atazanavir and darunavir have traditionally been used in combination with the CYP3A inhibitor ritonavir (Norvir) to boost their serum concentrations, but neither is available in a fixed-dose combination with ritonavir.1,2

Cobicistat has been available in the US since 2012 as one component of Stribild, a fixed-dose combination that includes the integrase strand transfer inhibitor (INSTI) elvitegravir and the nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) emtricitabine and tenofovir disoproxil fumarate ... more      

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