[Pharmacological actions of a new antihypertensive drug, olmidine, on the gastrointestinal tract]

It has been reported that dl-2-(3,4-methylenedioxyphenyl)-2-hydroxyacetamide hydrochloride (Olmidine) shows an antihypertensive action through inhibition of the adrenergic transmission. The present experiment was an attempt to investigate the pharmacological actions of olmidine in the alimentary canal of rat, rabbit and guinea pig. We found that the salivary secretion of rabbit was unaffected by olmidine at a dose of 2 mg/kg i.v., but increased by approximately 3 times that of controls with 10 mg/kg i.v.. Volume of gastric juice, concentration of free HCl, total acidity and pH of gastric juice in Shay rats were unaffected by 20 mg/kg i.p. of olmidine while volume and free HCl were significantly reduced at a dose of 100 mg/kg i.p. of the drug. The pH of gastric juice showed an evident increase to 3.33. Total acidity, however, was unaffected. Bile secretion of rat was decreased by olmidine at a dose of 100 or 500 mg/kg i.p. in a dose-dependent manner. Olmidine did not induce any lesion of gastric mucosa of rats at a dose of 200 mg/kg p.o. or less. Movement of charcoal meal in the small intestine of rats was inhibited by olmidine at doses of 20 to 500 mg/kg p.o.. Olmidine caused a biphasic response, that is contraction followed by a relaxation,in the isolated guinea pig gastrointestinal tracts. The contractile response caused by olmidine was completely inhibited by pretreatment with atropine or scopolamine and converted to one of relaxation which was unaffected by a combined treatment with phentolamine and propranolol. Contractile responses caused by transmural stimulation were significantly potentiated by olmidine, while potentiation of the contractile responses caused by exogenously applied acetylcholine was only slight in the isolated gallbladder from guinea pig.