Cobicistat (150 mg once daily) must be co-administered with darunavir (800 mg once daily), taken orally, once daily with food. Safety and efficacy have not been established for use of cobicistat with darunavir when used in any other dosing regimen. Cobicistat co-administered with darunavir should not be used in combination with another antiretroviral agent that requires pharmacoenhancement by means of co-administration with an inhibitor of CYP3A4 to reach the desired therapeutic plasma concentrations (i.e., another protease inhibitor or elvitegravir). Dosing recommendations for such combinations have not been established and co-administration may result in decreased plasma concentrations of darunavir and/or the other antiretroviral agents that require pharmacoenhancement leading to loss of antiviral activity and development of resistance.

 

Cobicistat is a CYP3A inhibitor indicated to increase systemic exposure of atazanavir or darunavir (once daily dosing regimen) in combination with other antiretroviral agents in the treatment of HIV-1 infection. Cobicistat (150 mg once daily) must be coadministered with atazanavir (300 mg once daily) or darunavir (800 mg once daily). The use of cobicistat is not recommended with darunavir 600 mg twice daily.