An in vivo procedure for estimating spasmolytic activity in the rat by measuring smooth muscle contractions to topically applied acetylcholine.

An in vivo procedure for evaluating potential organ selectivity of spasmolytics has been developed. This involves the determination of comparative potencies, expressed as DR10 of spasmolytics against contractions induced by topical application of acetylcholine on rat colon, rectum and urinary bladder. Experiments with two well known spasmolytics, namely N-butyl-scopolammonium bromide and dicyclomine HCl yielded results consistent with data reported in the literature. This procedure provides a rapid, inexpensive and rather accurate estimate of organ selectivity of spasmolytics.