Mesna is used to protect the bladder against some of the harmful effects of certain cancer medications known as oxazaphosphorines (e.g., cyclophosphamide, ifosfamide). After injection, mesna stays in the blood and is quickly moved to the kidney. Once in the kidney, it attaches to the byproducts of cancer medications that can cause harm to the bladder, making them harmless.
This medication is used to reduce the risk of bleeding in the bladder (hemorrhagic cystitis), which is a very serious side effect of treatment with a cancer chemotherapy drug called ifosfamide. Mesna helps to protect the lining of the bladder against damage from ifosfamide. The body breaks down ifosfamide to form a product that can harm the bladder, and mesna works by making this product less harmful.