Dantrolene plasma and urine concentrations after oral pretreatment for malignant hyperthermia: report of a case.

Dantrolene plasma concentrations and renal clearance calculations in a patient undergoing major surgery are reported. The family history was positive for malignant hyperthermia. Following oral pretreatment the plasma concentrations in this patient were not noticeably different from values obtained in a study in awake volunteers and which were thought to be effective. This is the first report of dantrolene measurements made during anaesthesia and in the post-operative period.