Coadministration with atazanavir/cobicistat has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Coadministration of atazanavir/ritonavir increased raltegravir AUC (41%), Cmax (24%) and Cmin (77%). However, concomitant use of raltegravir and atazanavir/ritonavir did not result in a unique safety signal in clinical studies, therefore, no dose adjustment of raltegravir is required. Atazanavir/cobicistat is expected to produce a similar effect on raltegravir. No dose adjustment is required for raltegravir if co-administered with atazanavir/cobicistat. Note: coadministration of once daily raltegravir (1200 mg once daily) is not recommended. Coadministration of raltegravir (1200 mg single dose) and atazanavir alone increased raltegravir AUC (67%), Cmax (16%) and Cmin (26%).