Coadministration has not been studied. Concentrations of apixaban are expected to increase due to potent CYP3A4 and P-gp inhibition by elvitegravir/cobicistat, thereby increasing the bleeding risk. The product labels for apixaban do not recommend the concomitant use with strong dual CYP3A4 and P-gp inhibitors, although the US label gives the option to use apixaban at a reduced dose if needed. Note, patients already receiving apixaban at a dose of 2.5 mg twice daily should avoid coadministration with strong dual CYP3A4 and P-gp inhibitors. Of interest, there are case reports of no adverse outcomes in HIV infected patients treated with a reduced dose of apixaban (2.5 mg twice daily) while on ritonavir or cobicistat boosted regimens which supports the option of dose reduction given in the US label. Based on metabolism and clearance a clinically significant interaction with emtricitabine and tenofovir-DF is unlikely.