Controlled clinical studies with an antidote against the urotoxicity of oxazaphosphorines: preliminary results.

A randomized study in 20 patients with cancer was carried out to test the clinical efficacy of sodium-2-mercaptoethane sulfonate (ASTA D-7093; mesnum) as an agent to prevent urotoxic side effects (in particular, hemorrhagic cystitis) during cytostatic therapy with the oxazaphosphorines cyclophosphamide and ifosfamide. Eleven patients received mesnum iv and nine patients received a standard prophylaxis. The frequency of microhematuria was significantly lower in the patients receiving mesnum. A slight microhematuria was observed in one patient. With the standard prophylaxis, all nine patients receiving single-agent therapy with ifosfamide or cyclophosphamide had hematuria and three of these had macrohematuria. According to the available results, a daily mesnum dose of 60% (wt/wt) of the ifosfamide or cyclophosphamide dose is recommended. This dose should be divided into three equal fractions. The first administration should be given concurrently with the cytostatic agent and the subsequent two administrations at 4 and 8 hours after administration of the cytostatic agent. Significantly higher doses of mesnum (eg, 133% of the cyclophosphamide or ifosfamide doses) lead to gastrointestinal disorders, which are easily reversible.