Dantrolene sodium

Indications & Dose:

Malignant hyperthermia

• BY RAPID INTRAVENOUS INJECTION

Adult: Initially 2–3 mg/kg, then 1 mg/kg, repeated if necessary; maximum 10 mg/kg per course Chronic severe spasticity of voluntary muscle

• BY MOUTH

Adult: Initially 25 mg daily, then increased to up to 100 mg 4 times a day, dose increased at weekly intervals; usual dose 75 mg 3 times a day

IMPORTANT SAFETY INFORMATION

Should only be administered by, or under the direct supervision of, personnel experienced in the use of dantrolene when used for malignant hyperthermia. 

Contraindications:

With oral use Acute muscle spasm . avoid when spasticity is useful, for example, locomotion 

Side Effects:

Common or very common

With oral use Abdominal pain . anorexia . asthenia . chills . diarrhoea (withdraw if severe, discontinue treatment if recurs on re-introduction) . dizziness . drowsiness . fatigue . fever . headache . hepatotoxicity . nausea . pericarditis . pleural effusion . rash . respiratory depression . seizures . speech disturbances . visual disturbances . vomiting

Uncommon

With oral use Confusion . constipation . crystalluria . depression . dysphagia . dyspnoea . erratic blood pressure . exacerbation of cardiac insufficiency . haematuria . increased sweating . increased urinary frequency . insomnia . nervousness . tachycardia . urinary incontinence . urinary retention

Frequency not known

With intravenous use Dizziness . erythema . hepatotoxicity . injection-site reactions . pulmonary oedema . rash . swelling . thrombophlebitis . weakness

SIDE-EFFECTS

Hepatotoxicity Potentially life-threatening hepatotoxicity reported—discontinue if abnormal liver function tests or symptoms of liver disorder; reintroduce only if complete reversal of hepatotoxicity.

PREGNANCY

With intravenous use Use only if potential benefit outweighs risk.

With oral use Avoid use in chronic spasticity— embryotoxic in animal studies.

BREAST FEEDING

With intravenous use Present in milk—use only if potential benefit outweighs risk.

With oral use Present in milk—manufacturer advises avoid use in chronic spasticity.

Cautions:

With intravenous use Avoid extravasation (risk of tissue necrosis) With oral use Females (hepatotoxicity) . history of liver disorders (hepatotoxicity) . if doses greater than 400mg daily (hepatotoxicity) . impaired cardiac function . impaired pulmonary function . patients over 30 years (hepatotoxicity) . therapeutic effect may take a few weeks to develop—discontinue if no response within 6–8 weeks With oral use Caution if concomitant use of hepatotoxic drugs

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