indication

For the treatment of painful peripheral musculoskeletal conditions and spasticity from upper motor neuron syndromes.

pharmacology

Metaxalone is a skeletal muscle relaxant indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomforts associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Metaxalone does not directly relax tense skeletal muscles in man.

mechanism of action

The mechanism of action of metaxalone in humans has not been established, but may be due to general central nervous system depression.

toxicity

LD₅₀=775mg/kg (Rat, oral); LD₅₀=1690 mg/kg (Mouse, oral). When determining the LD₅₀ in rats and mice, progressive sedation, hypnosis and finally respiratoryfailure were noted as the dosage increased. In dogs, no LD₅₀ could be determined as the higher doses produced an emetic action in 15 to 30 minutes.

biotransformation

Probably hepatic.

absorption

The absolute bioavailability of metaxalone from Skelaxin tablets is not known.

half life

9.2 (+/- 4.8) hours

route of elimination

Metaxalone is metabolized by the liver and excreted in the urine as unidentified metabolites.