Antagonism of anthracene-9-carboxylic acid as screening test for muscle relaxants.

Veratrinic response produced by anthracene-9-carboxylic acid in mice has been used as a model for studying effect of variety of drugs which induce muscle relaxation. None of the drugs listed as general depressants, central muscle relaxants, neuromuscular blocking agents and anti-convulsants were effective even at doses causing 100% loss of righting reflex. Local anaesthetics/direct acting muscle relaxants were effective. This simple model employed in conjunction with Straub's tail test can differentiate various categories of muscle relaxants and their mechanism of action.