Dantrolene is a directly acting muscle relaxant. It is chemically and pharmacologically different from neuromuscular blockers as the effect superficially resembles that of centrally acting muscle relaxants.
Mechanism of action.
- It Interferes with calcium release within skeletal muscle cells from the sarcoplasmic reticulum.
- Intracellular release of Ca2+ needed for excitation-contraction coupling will hence be interfered with.
Clinical uses.
- The drug of choice for malignant hyperthermia.
- Reduces spasticity in upper motor neuron disorders, hemiplegia, paraplegia, cerebral palsy, and multiple sclerosis.
- Treatment of Wolfram Syndrome.
- Post-operation muscle pain.
- To reduce succinylcholine-induced fasciculations.
Adverse effects.
- Muscular weakness is a dose-limiting side effect.
- Sedation, malaise, and lightheadedness.
- Serious liver toxicity
- Diarrhea, anorexia, nausea, and vomiting.
Drug interaction
- Increases toxicity of verapamil by pharmacodynamic synergism.
- Carbamazepine decreases the level and effect of the drug by affecting hepatic/intestinal enzyme CYP3A4 metabolism.
- Alprazolam and dantrolene both increase sedation in patients.
Contraindication.
· Hypersensitive patients.
· Impaired hepatic, cardiac, or pulmonary function.
· Upper motor neuron disorder.
· Patients with spasticity to maintain upright posture & balance.
