Stribild® (Elvitegravir/Cobicistat/Emtricitabine/Tenofovir Disoproxil Fumarate): A New Paradigm for HIV-1 Treatment

Stribild (R) (elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate) is a new single-tablet, fixed-dose formulation approved by both the US Food and Drug Administration and the European Medicine Agency as antiretroviral therapy. It is the first once-a-day therapy option containing an integrase inhibitor and cobicistat, a novel pharmacokinetic boosting agent without activity on HIV. Stribild (R) has demonstrated non-inferior virological efficacy and a similar recovery of CD4(+) T-cells when compared to Atripla (R) (efavirenz/emtricitabine/tenofovir) and to ritonavir-boosted atazanavir plus emtricitabine/tenofovir in two large, phase III randomized clinical trials at 48, 96, and 144 weeks. These results are consistent in all CD4(+) and HIV RNA strata. Although well-tolerated, self-limiting nausea has been reported in more than 10% of patients in both trials. Cobicistat has clinically significant drug-drug interactions with drugs that are metabolized by the cytochrome P450 3A4 subfamily enzymes, and causes a minimal reversible decrease of the estimated glomerular filtration rate due to inhibition of molecular transporters of creatinine in kidney tubules. Elvitegravir primary resistance mutations associated with treatment failure often lead to cross-resistance to raltegravir.