Aluminium Hydroxide: Enhanced absorption with citrates or ascorbic acid. Decreases absorption of allopurinol, tetracyclines, quinolones, cephalosporins, biphosphonate derivatives, corticosteroids, cyclosporin, delavirdine, Fe salts, imidazole antifungals, isoniazid, mycophenolate, penicillamine, phosphate supplements, phenytoin, phenothiazines, trientine. Magnesium Hydroxide: Decreases absorption of tetracyclines and biphosphonates. Separate administration of these and other drugs by around 2 hr.