The pharmacology of clodanolene sodium, a new skeletal muscle contraction antagonist.

ABSTRACT

The pharmacology of hydrated 1 less than ([5-(3,4-dichlorophenyl)-2-furanyl]methylene) amino greater than-2,4,-imidazolidinedione sodium salt (clodanolene sodium), as skeletal-muscle contraction antagonist, is presented. Clodanolene sodium is remarkable in that it has no measurable direct effect on the peripheral or central nervous systmes. Skeletal muscle relaxation can be achieved with this drug at doses that do not affect motor coordination. Rats receiving clodanolene sodium for up to 30 days evidenced a downward trend in gross observation score of skeletal muscle relaxation, but the extent of twitch inhibition was the same on day 30 as on day 1. In an animal model of muscle spasticity (Straub-tail mouse), clodanolene sodium has been shown to be more efficacious for induction of skeletal muscle relaxation than neuromuscular blocking agents, local anesthetics, or centrally-acting muscle relaxants. Clodanolene sodium's mode of action has been identified as specific for skeletal muscle. It has no measurable effect on neuromuscular transmission or on the electrically excitable surface membrane. Indirect evidence indicates that the site of action of clodanolene sodium, like that of dantrolene sodium, is within the muscle cell and is related to caffeine-sensitive calcium stores. Its skeletal-muscle relaxant activity, we suggest results from a decrease in the release of calcium from the sarcoplasmic reticulum.