Studies on the efficacy and depressant potential of muscle relaxants in mice

Abstract

Abstract The present study was undertaken to confirm and extend previous observations on the use of morphine‐induced Straub tail and rotarod performance in mice as a means of assessing the efficacy of a compound as a muscle relaxant and its potential for depressant side‐effects, respectively. The ratio of the rotarod to Straub tail ED 50 s was calculated as an index of specificity. Our results generally confirmed previous reports in the case of diazepam, chlordiazepoxide and dantrolene. Additionally, the recently introduced muscle relaxants, cyclobenzaprine, baclofen, and DS 103‐282 were found effective in blocking Straub tail and their reported clinical specificity was reflected by the specificity observed in the mouse tests. DS 103–282 was found to be the most potent and specific. It is concluded that muscle relaxants with specificity ratios significantly greater than 1.0 appear to have comparatively few depressant effects at therapeutic doses. The relatively simple methods used in the present study appear to be useful in the initial assessment of compounds as potential muscle relaxants.