Delayed or reduced absorption of folic acid, thiazide diuretics, propranolol, digoxin and related glycosides, loperamide, phenylbutazone, barbiturates, oestrogens, progestogens, thyroid hormones, warfarin and other coumarin-derivative anticoagulants, iron salts, deferasirox and some antibacterials (e.g. tetracycline, penicillin G). May prevent absorption of fat-soluble vit. Slightly decreased rate of absorption of clofibrate. May interfere w/ absorption of oral phosphate supplements.