Coadministration with Stribild has not been studied. Atorvastatin is metabolized by CYP3A4. Coadministration with elvitegravir/cobicistat is expected to increase atorvastatin concentrations. Coadministration of atorvastatin (10 mg single dose) and elvitegravir/cobicistat (150/150 mg once daily, administered with emtricitabine and tenofovir alafenamide as Genvoya) was studied in 16 subjects. Elvitegravir Cmax, AUC and Cmin decreased by 9%, 8% and 12%, respectively. Atorvastatin Cmax and AUC increased by 132% and 160%. If the use of atorvastatin is considered necessary, start with the lowest dose of atorvastatin and titrate carefully while monitoring for safety. A daily dose of 40 mg atorvastatin should not be exceeded with careful safety monitoring. (Note, American treatment guidelines recommend a maximum daily dose of 20 mg for atorvastatin.) In addition, caution is recommended in elderly individuals as they may be more susceptible to developing statin related adverse effects. No interaction is expected with emtricitabine or tenofovir-DF.