Cobicistat should not be used concurrently with ritonavir due to similar effects of cobicistat and ritonavir on CYP3A. Unlike ritonavir, cobicistat is not an inducer of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19 or UGT1A1. If switching pharmacoenhancer from ritonavir to cobicistat, caution is required during the first two weeks of treatment with cobicistat, particularly if doses of any concomitantly administered medicinal products have been titrated or adjusted during use of ritonavir as a pharmacoenhancer.

 

Coadministration with drugs or regimens containing ritonavir is not recommended due to similar effects of cobicistat and ritonavir on CYP3A. Cobicistat is not interchangeable with ritonavir to increase systemic exposure of darunavir 600 mg twice daily, fosamprenavir, saquinavir, or tipranavir due to lack of exposure data.