Spasmolytic constituents of Cedrus deodara (Roxb.) Loud: pharmacological evaluation of himachalol.

Himachalol has been identified as the major antispasmodic constituent in the wood of Cedrus deodara. The pharmacological studies of himachalol on various isolated smooth muscles (guinea pig ileum, rabbit jejunum, rat uterus, and guinea pig seminal vesicle) and against different agonists (acetylcholine, histamine, serotonin, nicotine, and barium chloride) indicated spasmolytic activity similar to that of papaverine. It was a more potent antagonist of barium chloride-induced spasm of guinea pig ileum than papaverine but less effective in reverting a similar spasm of rabbit jejunum and had no relaxing effect alone. In the conscious immobilized cat, intragastric administration of himachalol or papaverine (100 mg/kg) produced equal inhibition of carbachol-induced spasm of the intestine, lasting about 2 hr, but himachalol had a faster onset of action. Himachalol was devoid of spasmolytic effect on the bronchial musculature of guinea pig but was 3.3 times more potent than papaverine in antagonizing epinephrine-induced contraction of the guinea pig seminal vesicle. Intravenous injection of himachalol (3-10 mg/kg) in the cat produced a dose-dependent fall in blood pressure and an increased femoral blood flow.