The effects of diethylcarbamazine citrate on smooth muscle

The effect of the anthelmintic drug diethylcarbamazine citrate (DECC) was examined on the guinea-pig isolated ileum, rabbit duodenum, chick oesophagus, rat portal vein and pig coronary artery. DECC contracted all the gastrointestinal smooth muscle preparations. The contractions were antagonized by hexamethonium and atropine but they were not affected by mepyramine or methysergide in concentrations that abolished, or markedly reduced, responses to histamine and 5-hydroxytryptamine. DECC inhibited the responses of the guinea-pig ileum to other spasmogens, namely, acetylcholine, histamine and nicotine. Physostigmine markedly potentiated the responses of the chick oesophagus and the rabbit duodenum to DECC. DECC relaxed the potassium chloride-induced contractions of the pig coronary artery strips; these relaxations were not modified by propranolol or calcium chloride. There was no evidence that DECC released histamine from skin or muscle.