Malignant Hyperthermia
Preoperatively: Administer 4 to 8 mg/kg/day of oral Dantrium® in 3 or 4 divided doses for one or two days prior to surgery, with the last dose being given approximately 3 to 4 hours before scheduled surgery with a minimum of water.
This dosage will usually be associated with skeletal muscle weakness and sedation (sleepiness or drowsiness); adjustment can usually be made within the recommended dosage range to avoid incapacitation or excessive gastrointestinal irritation (including nausea and/or vomiting).
Post Crisis Follow-up: Oral Dantrium® should also be administered following a malignant hyperthermia crisis, in doses of 4 to 8 mg/kg per day in four divided doses, for a one to three day period to prevent recurrence of the manifestations of malignant hyperthermia.
Dantrium® (dantrolene sodium) has a potential for hepatotoxicity, and should not be used in conditions other than those recommended. Symptomatic hepatitis (fatal and non-fatal) has been reported at various dose levels of the drug. The incidence reported in patients taking up to 400 mg/day is much lower than in those taking doses of 800 mg or more per day. Even sporadic short courses of these higher dose levels within a treatment regimen markedly increased the risk of serious hepatic injury. Liver dysfunction as evidenced by blood chemical abnormalities alone (liver enzyme elevations) has been observed in patients exposed to Dantrium® for varying periods of time. Overt hepatitis has occurred at varying intervals after initiation of therapy, but has been most frequently observed between the third and twelfth month of therapy. The risk of hepatic injury appears to be greater in females, in patients over 35 years of age, and in patients taking other medication(s) in addition to Dantrium® (dantrolene sodium). Dantrium® should be used only in conjunction with appropriate monitoring of hepatic function including frequent determination of SGOT or SGPT. If no observable benefit is derived from the administration of Dantrium® after a total of 45 days, therapy should be discontinued. The lowest possible effective dose for the individual patient should be prescribed.