dantrolene sodium: clinical use

Prescribing considerations

• Define functional goals carefully: reducing tone can impair posture, balance or function where spasticity is compensatory.
• Assess hepatic, respiratory and cardiac status before oral treatment.
• Review concomitant sedatives, hepatotoxic medicines and neuromuscular blockers.
• Counsel about weakness, driving impairment, alcohol avoidance and photosensitivity.
• Intravenous treatment complements rather than replaces cooling, trigger withdrawal and other malignant-hyperthermia supportive measures.

Contraindications and cautions

• Oral formulation: hepatic disease, impaired respiratory function, severe myocardial impairment, pregnancy, breastfeeding, wheat allergy, and situations where increased tone is needed for function, posture or balance.
• Both formulations: hypersensitivity to dantrolene or formulation excipients.

Monitoring

• Obtain baseline and regular liver-function tests during oral therapy; stop and assess if results become abnormal or clinical hepatotoxicity develops.
• Monitor functional benefit, muscle weakness, respiratory function and sedation.
• Review severe diarrhoea and symptoms suggesting pleural, pericardial or pulmonary complications.
• During intravenous use, monitor physiological and metabolic features of malignant hyperthermia, potassium and the injection site.

Clinical pharmacology

Dantrolene acts directly on skeletal muscle by inhibiting calcium release from the sarcoplasmic reticulum. It is hepatically metabolised; an active hydroxylated metabolite contributes to its effect, with renal and biliary elimination.

Formulation and product differences

• Oral hard capsules contain lactose monohydrate and wheat starch; the very low gluten content is considered unlikely to affect coeliac disease, but wheat allergy is a contraindication.
• The intravenous product is a powder containing mannitol and sodium hydroxide. It requires reconstitution and filtration with the supplied single-use device before intravenous administration.
• Extravasation of the alkaline intravenous solution can cause tissue necrosis; intra-arterial administration must be avoided.

Capsule

Route: Oral

Strengths: 25 mg, 100 mg