Drug reference

dantrolene

Muscle Relaxant · Antispasticity Agent

Also known as dantrolene sodium

Muscle RelaxantAntispasticity Agent

CDSCO approvedSchedule H

EXCRETION

—

not curated

INTERACTIONS

12 major

SEVERE in our sources

PREGNANCY

—

not curated

Top interactionssee all 12 →

AlfentanilSevereDatabaseDDInter
BenzhydrocodoneSevereDatabaseDDInter
BuprenorphineSevereDatabaseDDInter
ButorphanolSevereDatabaseDDInter

Mechanism

Dantrolene acts directly on skeletal muscle by antagonizing the ryanodine receptor (RyR1) on the sarcoplasmic reticulum, reducing calcium release during excitation-contraction coupling. Unlike centrally acting muscle relaxants (tizanidine, baclofen), it does not affect neuronal transmission — its action is entirely peripheral. This unique mechanism makes it the specific treatment for malignant hyperthermia (where mutant RyR1 channels release excessive calcium) and neuroleptic malignant syndrome.

Indications

Neuroleptic malignant syndromeMuscle cramps (off-label)Muscle stiffness (off-label)Spasticity (off-label)Increased muscle tone (off-label)Spasticity in multiple sclerosis (off-label)Chronic muscle spasticity associated with upper motor neuron disorders (spinal cord injury, stroke, cerebral palsy, or multiple sclerosis)Management and prevention of malignant hyperthermiaNeuroleptic malignant syndrome (off-label)Treatment of muscle spasms in stroke or spinal injuryTreatment of malignant hyperthermiareduces spasticity in upper motor neurone disordersreduces spasticity in hemiplegiareduces spasticity in paraplegiareduces spasticity in cerebral palsyreduces spasticity in multiple sclerosismalignant hyperthermia

Dosing

Adult: Malignant hyperthermia: initially 2-3 mg/kg IV, then 1 mg/kg repeated if needed; max 10 mg/kg per course. Chronic spasticity: initially 25 mg daily, increased weekly to 75 mg TDS; max 100 mg QDS.
Max dose: 10 mg/kg (MH); 400 mg/day (spasticity)

Pharmacokinetics

Half-life

8-12 hours

Metabolism

Hepatic metabolism

Excretion

excreted by kidney

Contraindications

Use should be reserved for nonambulatory patients with severe spasticity (due to generalized weakness)

Side effects

Common

muscular weakness (dose limiting)sedationmalaiselight headednessother central effects (less pronounced than with centrally acting muscle relaxants)troublesome diarrhoea

Serious