A postsynaptic muscle relaxant that lessens excitation-contraction coupling in muscle cells.

It inhibits Ca2+ ions release from sarcoplasmic reticulum stores by antagonizing ryanodine receptors.

The primary agent used for the treatment and prevention of malignant hyperthermia.

Dantrolene is a direct-acting skeletal-muscle relaxant and is effective in treating malignant hyperthermia (MH) by reducing heat production and rigidity. 

Used in the management of neuroleptic malignant syndrome, muscle spasticity related to strokes, paraplegia, cerebral palsy, or patients with multiple sclerosis. and 2,4-dinitrophenol poisoning.

A muscle relaxant that appears to work directly on the ryanodine receptor to prevent the release of calcium.

After the introduction of treatment with dantrolene, the mortality of malignant hyperthermia fell from 80% to less than 5%.

Remains the only drug known to be effective in the treatment of MH.

Trade name Dantrium

Pregnancy category US: C-Risk not ruled out.

Routes of administration- Oral, intravenous

Bioavailability 70%.


Excretion- Biliary, renal


Pre-existing liver disease

Compromised lung function

Severe cardiovascular impairment

Patients under five years of age

Individuals needing good muscular balance or strength to maintain an upright position, motor function, or proper neuromuscular balance.

Pregnancy studies are lacking.

May cause hypotonia in the newborn.

Should not be given to breastfeeding mothers.

Central nervous system side effects; speech and visual disturbances, mental depression, confusion, hallucinations, headache, insomnia and exacerbation or precipitation of seizures, and increased nervousness.

Infrequently causes respiratory depression.

GI side effects include bad taste, decreased appetite, nausea, vomiting, abdominal cramps, and diarrhea.

Liver side effects may be seen either as asymptomatic elevation of liver fn toon tests, or, most severe, as fatal and nonfatal liver inflammation.

It is hepatotoxic and should probably be avoided if liver function test results are very abnormal. 

Pleural effusion, pericarditis, bone marrow damage, diffuse muscle pains, backache, dermatologic reactions, transient cardiovascular reactions, and crystals in the urine have additionally been seen.

Muscle weakness may persist for several days after treatment.

Not known whether it has carcinogenic effects.

Depresses excitation-contraction coupling in skeletal muscle by acting as a receptor antagonist to the ryanodine receptor, and decreasing free intracellular calcium concentration.

It may interact with the following drugs:

Calcium channel blockers

Nondepolarizing neuromuscular blocking agents

CMS depressants

Hormonal therapy

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