MESNA IS USED FOR THE PROPHYLAXIS OF UROTHELIAL TOXICITY IN PATIENTS BEING TREATED WITH THE ANTINEOPLASTICS IFOSFAMIDE OR CYCLOPHOSPHAMIDE. IN THE KIDNEY MESNA DISULPHIDE IS REDUCED TO FREE MESNA WHICH HAS THIOL GROUPS THAT REACT WITH THE METABOLITES OF IFOSFAMIDE AND CYCLOPHOSPHAMIDE, INCLUDING ACROLEIN, CONSIDERED TO BE RESPONSIBLE FOR THE TOXIC EFFECTS ON THE BLADDER.