Overview
DESCRIPTION The chemical formula of dantrolene sodium is hydrated 1-[[[5-(4-nitrophenyl)-2-furanyl]methylene]amino]-2, 4-imidazolidinedione sodium salt. It is an orange powder, slightly soluble in water, but due to its slightly acidic nature the solubility increases somewhat in alkaline solution. The anhydrous salt has a molecular weight of 336.
Mechanism of Action
CLINICAL PHARMACOLOGY In isolated nerve-muscle preparation, dantrolene sodium has been shown to produce relaxation by affecting the contractile response of the skeletal muscle at a site beyond the myoneural junction, directly on the muscle itself. In skeletal muscle, dantrolene sodium dissociates the excitation-contraction coupling, probably by interfering with the release of Ca ++ from the sarcoplasmic reticulum. This effect appears to be more pronounced in fast muscle fibers as compared to slow ones, but generally affects both. A central nervous system effect occurs, with drowsiness, dizziness, and generalized weakness occasionally present. Although dantrolene sodium does not appear to directly affect the CNS, the extent of its indirect effect is unknown.
Indications
- INDICATIONS AND USAGE In Chronic Spasticity: Dantrolene sodium is indicated in controlling the manifestations of clinical spasticity resulting from upper motor neuron disorders (e.g., spinal cord injury, stroke, cerebral palsy, or multiple sclerosis). It is of particular benefit to the patient whose functional rehabilitation has been retarded by the sequelae of spasticity. Such patients must have presumably reversible spasticity where relief of spasticity will aid in restoring residual function.
Common Doses
- 25 mg
- 50 mg
- 100 mg
- 0.5 mg
Dosage
DOSAGE AND ADMINISTRATION For Use in Chronic Spasticity: Prior to the administration of dantrolene sodium , consideration should be given to the potential response to treatment. A decrease in spasticity sufficient to allow a daily function not otherwise attainable should be the therapeutic goal of treatment with dantrolene sodium . Refer to INDICATIONS AND USAGE section for description of response to be anticipated. It is important to establish a therapeutic goal (regain and maintain a specific function such as therapeutic exercise program, utilization of braces, transfer maneuvers, etc.
Black Box Warning
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.
Contraindications
- CONTRAINDICATIONS Active hepatic disease, such as hepatitis and cirrhosis, is a contraindication for use of dantrolene sodium . Dantrolene sodium is contraindicated where spasticity is utilized to sustain upright posture and balance in locomotion or whenever spasticity is utilized to obtain or maintain increased function.
Side Effects
- ADVERSE REACTIONS The most frequently occurring side effects of dantrolene sodium have been drowsiness, dizziness, weakness, general malaise, fatigue, and diarrhea. These are generally transient, occurring early in treatment, and can often be obviated by beginning with a low dose and increasing dosage gradually until an optimal regimen is established. Diarrhea may be severe and may necessitate temporary withdrawal of dantrolene sodium therapy. If diarrhea recurs upon readministration of dantrolene sodium , therapy should probably be withdrawn permanently.
Interactions
- Drug Interactions: Drowsiness may occur with dantrolene sodium therapy, and the concomitant administration of CNS depressants such as sedatives and tranquilizing agents may result in further drowsiness. While a definite drug interaction with estrogen therapy has not yet been established, caution should be observed if the two drugs are to be given concomitantly. Hepatotoxicity has occurred more often in women over 35 years of age receiving concomitant estrogen therapy. Cardiovascular collapse in patients treated simultaneously with verapamil and Dantrolene Sodium is rare.