[13 cases of drug-induced calculi]

All urinary stones should undergo detailed studies to identify those related to drug therapy. Among 520 stones analyzed by infrared spectrophotometry, we found 13 drug-induced stones (13/520: 2.5%). Drug-induced stones were caused by glafenine in 7 cases, piridoxylate in 4 cases, triamterene in one case and an unknown organic compound in one case. Glafenine stones appear to develop more readily in infected urine. Triamterene stones are often associated with uric acid disorders. Piridoxylate induces the formation of glyoxylate which is responsible for hyperoxaluria and formation of oxalocalcium stones.