Positional isomer of the muscle relaxant dantrolene

Article abstract of DOI:10.1002/jps.2600640641

3 [[ 5 (p Nitrophenyl)furfurylidene]amino]hydantoin, a position isomer of dantrolene, was synthesized and evaluated for skeletal muscle relaxant activity. When using gross observational techniques, the isomer did not produce any evidence of muscle relaxation or any other pharmacological activity at doses from 200 to 1600 mg/kg po. No toxicity was noted over the same dose range. In the pithed rat gastrocnemius muscle preparation, a dose of 25 mg/kg iv administered in tetrahydrofurfuryl alcohol (0.75 ml/kg) caused a 25.3 ± 1.8% decrease in the twitch response. The solvent itself produced no significant effect on the twitch response, while dantrolene administered at the same dose caused a 70% decrease in the twitch response. This twitch inhibition indicates that the isomer has slight contraction antagonist activity but that potency and effectiveness are less than that of dantrolene.