Hepatitis from dantrolene sodium.

The clinical course and histological changes in the liver during a presumed adverse reaction to the drug dantrolene sodium are described in four patients. After a typical prodrome one developed a moderately severe hepatitis-like illness. Another also had a prodrome but never became jaundiced. In the other two, abnormal liver function tests were detected on routine screening. In each case liver biopsy showed changes typical of an acute hepatitis, but the severity was unrelated to the clinical presentation. In addition, there were also changes in the portal tracts resembling ascending cholangitis. In each case liver function tests returned to normal after withdrawing treatment with dantrolene.