Profile of once-daily darunavir/cobicistat fixed-dose combination for the treatment of HIV/AIDS

Efficacy is the main objective of antiretroviral treatment and adherence is one of the cornerstones to achieve it. For this reason, treatment simplification is of key importance with regard to antiretroviral regimens. Rezolsta® (darunavir/cobicistat) is the first fixed-dose combination containing a protease inhibitor approved for HIV treatment. This coformulation includes darunavir, a protease inhibitor that has shown its efficacy and safety in naïve and treatment-experienced patients, and cobicistat, the new pharmacokinetic enhancer that is expected to replace ritonavir. Bioequivalence between ritonavir and cobicistat as darunavir boosters has been shown in studies involving healthy volunteers. Furthermore, efficacy and safety of darunavir/cobicistat observed in phase III studies, including naïve and pretreated patients without darunavir-associated resistance mutations, are comparable to historical data of darunavir/ritonavir 800/100 mg once-daily formulation. Adverse events with darunavir/cobicistat are scarce and mild, and basically include skin reactions and gastrointestinal disturbances. Although small increases in plasma creatinine are expected in patients receiving cobicistat due to the inhibition of creatinine transporters in kidney tubules, actual glomerular filtrate rate remains unaltered. Cobicistat does not have an inducer effect on metabolic pathways and shows much more selective inhibition than ritonavir. Therefore, isoenzyms different from CYP3A4 are supposed to be less affected by cobicistat, and thus fewer drug-drug interactions are expected.