ALUMINIUM, CALCIUM,AND MAGNESIUM SALTS MAY DECREASE THE ABSORPTION OF FLUORIDE. HYPERCALCAEMIA HAS OCCURRED WHEN CALCIUM SALTS ARE COADMINISTERED WITH THIAZIDE DIURETICS OR VITAMIN D. VITAMIN D INCREASES THE G.I. ABSORPTION OF CALCIUM AND THIAZIDE DIURETICS DECREASE ITS URINARY EXCRETION. CALCIUM ENHANCES THE EFFECTS OF DIGITALIS GLYCOSIDES ON THE HEART AND MAY PRECIPITATE DIGITALIS INTOXICATION. CALCIUM INTERFERES WITH THE ABSORPTION OF MANY DRUGS BY MAKING CHELATING AGENTS. ABSORPTION OF ORAL ANTIBACTERIALS ARE AFFECTED BY CONCURRENT ADMINISTRATION OF CALCIUM SALTS