Dantrolene sodium: urinary metabolites and hepatotoxicity

Dantrolene is metabolized by the hepatic MFO system to hydroxydantrolene which is conjugated with glucuronic acid or with sulfate. Dantrolene is also metabolized by nitroreductase to aminodantrolene. The aminodantrolene inhibits the hepatic MFO system. Acetylation of aminodantrolene blocks the inhibitory effects of aminodantrolene on the hepatic MFO system. Intermediates in the nitroreductase pathway form glucuronide and mercapturic acid conjugates. The mercapturic acid conjugation reaction is a detoxification mechanism for an electrophilic metabolite of dantrolene.