May reduce absorption of drugs w/ a gastric pH-dependent bioavailability eg, azole antifungals (ketoconazole, itraconazole, posaconazole) & erlotinib. Substantial reduction in the bioavailability of HIV medications eg, atazanavir. Increased levels of methotrexate (at high dose eg, 300 mg). May reduce absorption of vit B12
. Monitor prothrombin time/INR in patients treated w/ coumarin anticoagulants eg, phenprocoumon, warfarin.