Coadministration has not been studied but a clinically significant interaction is not expected. Coadministration of omeprazole and raltegravir (400 mg twice daily) increased raltegravir AUC, Cmax and C12h by 37%, 51% and 24%. Population PK analysis showed that the effect of gastric pH altering agents on the pharmacokinetics of once daily raltegravir was minimal (~9% decrease in relative bioavailability), and was not statistically or clinically significant. Concomitant use of raltegravir with proton pump inhibitors and H2 blockers did not result in a unique safety signal in Phase 3 studies. No dose adjustment is required with twice daily or once daily raltegravir.