ESTIMATION OF ANTISPASMODIC POTENCY OF DICYCLOMINE IN COMPARISON TO ATROPINE ON ISOLATED RAT COLON

Pain from a spastic viscus occurs in the form of cramps, with the pain increasing to a high degree of severity and then subsiding. This process continues intermittently, once every few minutes. The intermittent cycles result from periods of contraction of smooth muscle. For instance, each time a peristaltic wave travels along an overly excitable spastic gut, a cramp occurs. Anti-cholinergic agents like atropine are administered for relief of the abdominal colic but it often produces side effects like palpitation, dry mouth, urinary retention, mydriasis. Drug like dicyclomine are preferred in the treatment of intestinal spasm, which is not producing severe type of side effect due to blockade of muscarinic receptors. Dicyclomine is a competitive antagonist at muscarinic cholinergic neurons. Rats were divided into two groups (N=6), fasted for 24-hours before the experiment but water was supplied ad libitum, were sacrificed by cervical dislocation. The abdomen of the rat was opened; the part of colon was dissected out which was fixed to stand and the tension adjusted such that is gives maximum contractions. All the drug containing solutions were freshly prepared before the experiments Dicyclomine, Atropine and Acetylcholine respectively. Muscarinic receptor blocker Atropine was added to the biophase in addition to selected sub maximal dose and the contraction of muscle till the 70-80% of inhibition was produced and the difference from selected dose contractions was recorded. Same procedure repeated with Dicyclomine. The dose of dicyclomine that caused half-maximal acetylcholine-induced isolated rat colonic smooth muscle contraction was 0.30 ? 0.17 ?g, while that of atropine it was found to be 31. 48 ?22.73 ?g. There is highly significant difference (P < 0.01). Atropine was 103.87 times more potent as an antispasmdic drug than dicyclomine.