DANTROLENE SODIUM: USE, SAFETY AND MECHANISM
Compound | Use | Safety |
Dantrolene Na |
RESTRICTED USE Upper motor neuron lesions Malignant hyperthermia, Neuroleptic malignant syndrome |
Liver toxicityLung toxicity
Myalgia Diplopia |
Site of action:
Distal to Nicotinic receptor and the NM junction.
Mechanism:
- Decreases the depolarization triggered release of Ca++ from sarcoplasmic reticulum
- Uncouples membrane depolarization and muscle contraction
- No effects on neuromuscular transmission and muscle action potential
Action on the body:
- Some direct action on motor neurons –> used in treating neuroleptic malignant syndrome
- With fluorinated anaesthetics sometimes cause ↑ Ca++ output from sarcoplasmic reticulum –> used to treat malignant hyperthermia
- ↓ spasticity in hemiplegia, paraplegia, cerebral palsy, multiple sclerosis; but also ↓ voluntary power: so benefit is neutralized
Other general notes:
- Orange-red urine
- Causes muscle weakness NOT paralysis; muscle responds to direct electrical stimulation (contrast: muscle does not respond to direct stimulation in case of NM blocking agents)
- Fast twitching white muscle more affected than slow red muscle
- Effects superficially similar to centrally acting skeletal muscle relaxants
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