H2Bloc Drug Interactions

No drug interactions of clinical importance have been identified.
Antacids: May reduce famotidine uptake and cause lower levels of famotidine. Famotidine should be administered 1 to 2 hours before antacids.
Atazanavir: Alterations of gastric pH may affect the bioavailability of certain drugs, resulting in reduced absorption of atazanavir.
Ketoconazole and Itraconazole: Absorption of these drugs may be reduced by famotidine; give 2 hours before famotidine administration.
Probenecid: Inhibits renal tubular secretion of famotidine and causes a 50% increase in plasma levels of famotidine. Concomitant use should be avoided.
Sucralfate: Inhibits absorption of famotidine; give 2 hours after famotidine administration Famotidine does not interact with cytochrome P450-linked drug metabolizing enzyme system.
Compounds metabolized by this system which have been tested in man include warfarin, propranolol, theophylline, phenytoin, diazepam, aminopyrine, and antipyrine. Indocyanine green as an index of hepatic blood flow and/or hepatic drug extraction has been tested and no significant effects have been found.
Tell the doctor if patient is taking other medicines, including vitamins, supplements, and herbal medicines.