N-acetylcysteine and sodium 2-mercaptoethane sulfonate as sources of urinary thiol groups in the rat.

Increasing the urinary output of free thiol groups protects against cyclophosphamide-induced bladder toxicity. In the present study, intact rats, isolated perfused kidneys, and freshly isolated cells from various rat organs are used to compare the efficacy of N-acetylcysteine and sodium 2-mercaptoethane sulfonate (mesna) as sources of urinary thiols. In intact rats given a single i.v. dose of mesna, urinary thiol output is approximately 10-fold higher than in rats given an equimolar dose of N-acetylcysteine. this is partly due to the fact that N-acetylcysteine is rapidly absorbed by various types of cells, whereas mesna is transported selectively to the kidney, and partly to different renal handling of the two compounds. The results suggest that mesna is a more favorable drug than N-acetylcysteine for increasing urinary thiol excretion.