CONCURRENT ADMINISTRATION WITH ALUMINIUM, CALCIUM OR MAGNESIUM SALTS MAY REDUCE ITS ABSORPTION. VITAMINE D INCREASES THE G.I. ABSORPTION OF IT AND INCREASES THE POTENTIAL FOR HYPERPHOSPHATAEMIA. CONCURRENT USE WITH DIURETICS OR OTHER DRUGS MAY LEAD TO INCREASED RISK OF HYPOCALCAEMIA. CONCURRENT USED WITH CALCIUM SUPPLEMTNTS OR CALCIUM-CONTAINING ANTACIDS MAY INCREASE THE RISK OF ECTOPIC CALCIFICATION.