<p>Calcium supplement, antacids and some oral medications will interfere with absorption of Alendronate if taken at the same time. Intravenous ranitidine makes the bioavailability of oral Alendronate double. Incidence of upper gastro-intestinal adverse events associated with NSAID and aspirin appears to be greater with concomitant administration of Alendronate. Mineral oils, orlistat, and bile acid sequestrants (e.g., cholestyramine, colestipol) may impair the absorption of vitamin D. Anticonvulsants, cimetidine, and thiazides may increase the catabolism of vitamin D.</p>