Dantrolene sodium acts primarily by affecting
calcium flux across the sarcoplasmic reticulum of skeletal muscle. Recently,
dantrolene has been used very successfully in the treatment of several rare hypercatabolic syndromes which have previously been associated with high mortality rates. In
malignant hyperthermia, where early diagnosis and treatment usually with intravenous
dantrolene in association with other supportive measures (and often subsequent
dantrolene therapy) is performed, recovery is seen in virtually 100% of patients. There is a rapid resolution of
hyperthermia, dysrhythmias,
muscle rigidity,
tachycardia,
hypercapnia, mottled or cyanotic skin, and
metabolic acidosis, and a slower normalisation of
myoglobinuria and elevated serum
creatine phosphokinase levels. In patients with family history or previous episodes of
malignant hyperthermia, prophylactic treatment with
dantrolene prior to anaesthesia prevents the syndrome occurring in most cases. Where
malignant hyperthermia has developed patients have been successfully treated with further
dantrolene therapy.
Dantrolene has also been used successfully in the treatment of a few cases of
heat stroke and the
neuroleptic malignant syndrome--both of which have many similarities to
malignant hyperthermia.
Dantrolene is well established in the treatment of patients with
muscle spasticity where it generally improves at least some of the components of spasticity (i.e. hyper/
hypotonia, clonus,
muscle cramps and
spasms, resistance to stretch and flexor reflexes, articular movement, neurological and motor functions and urinary control). However, in some patients, particularly those with
multiple sclerosis,
dantrolene may not be effective, and in many cases muscular strength may diminish. Long term
dantrolene therapy has been associated with hepatic toxicity and may cause problems in patients treated for disorders of
muscle spasticity. Thus,
dantrolene offers a unique advance in the
therapy available for the treatment of hypercatabolic disorders and is also useful in the treatment of
muscle spasticity of various aetiology.