General Information

Prezcobix is a once-daily, fixed-dose combination of darunavir, a human immunodeficiency virus (HIV-1) protease inhibitor, and cobicistat, a CYP3A inhibitor.

Prezcobix is specifically indicated for use in combination with other antiretroviral agents for the treatment of human immunodeficiency virus (HIV-1) infection in treatment-naïve and treatment-experienced adults with no darunavir resistance-associated substitutions (V11I, V32I, L33F, I47V, I50V, I54L, I54M, T74P, L76V, I84V, L89V). 

Prezcobix is supplied as a tablet (800 mg of darunavir and 150 mg of cobicistat) for oral administration. The recommended dose is one tablet taken once daily with food.

Mechanism of Action

Darunavir is an inhibitor of the HIV-1 protease. It selectively inhibits the cleavage of HIV-1 encoded Gag-Pol polyproteins in infected cells, thereby preventing the formation of mature virus particles. Cobicistat is a selective, mechanism-based inhibitor of cytochromes P450 of the CYP3A subfamily. Inhibition of CYP3A-mediated metabolism by cobicistat enhances the systemic exposure of CYP3A substrates.

Side Effects

Adverse effects associated with the use of  darunavir may include, but are not limited to, the following:

• diarrhea
• nausea
• rash
• headache
• abdominal pain
• vomiting

Clinical Trial Results

The FDA approval of Prezcobix was based on a bioequivalence study evaluating the use of a darunavir and cobicistat fixed-dose combination tablet versus single agents and a clinical study evaluating the safety and efficacy of cobicistat-boosted darunavir for the treatment of HIV-1 in adults with no darunavir resistance-associated mutations. The tolerability profile of the fixed dose-combination is similar to that of the two agents taken separately. The efficacy of Prezcobix is based on efficacy demonstrated in clinical trials of darunavir co-administered with ritonavir and pharmacokinetic trials showing similar exposures of darunavir when boosted with cobicistat compared to darunavir boosted with ritonavir.