Coadministration has not been studied but a clinically significant interaction is not expected. Nizatidine is primarily eliminated via tubular secretion and glomerular filtration in urine. Coadministration of famotidine (another H2 receptor antagonist) and twice daily raltegravir (400 mg twice daily) increased raltegravir AUC, Cmax and C12h by 44%, 60% and 6%. 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.