Drug Interaction Report

There is currently no information in the medical literature regarding a potential interaction between nelfinavir and H2-receptor antagonists. Nelfinavir peak plasma concentration (Cmax), systemic exposure (AUC) and trough plasma concentration (Cmin) decreased by 37%, 36% and 39%, respectively, when nelfinavir (1250 mg twice daily) was coadministered with omeprazole (40 mg once daily 30 minutes before nelfinavir) for 4 days, presumably due to decreased solubility of nelfinavir as gastric pH increased. Although theoretically possible, it is not certain to what extent such an interaction may occur with H2-receptor antagonists, or whether it is clinically relevant. Caution may be advisable during coadministration.

H2 antagonists may reduce the clearance of nicotine. Cimetidine, 600 mg given twice a day for two days, reduced clearance of an intravenous nicotine dose by 30%. Ranitidine, 300 mg given twice a day for two days, reduced clearance by 10%. The clinical significance of this interaction is not known. Patients should be monitored for increased nicotine effects when using the patches or gum for smoking cessation and dosage adjustments should be made as appropriate.