Effect of anti-parkinsonism drugs on gastric emptying and intestinal transit in the rat.

The effect of atropine sulfate, trihexyphenidyl HCl, benztropine mesylate, diphenhydramine HCl and ethopropazine HCl on gastric emptying and intestinal transit of a phenol red solution in the rat was examined. Intraperitoneal administration of 0.3 mg/kg atropine, 1.2 mg/kg benztropine and trihexyphenidyl results in a marked decrease in gastric emptying and intestinal transit rate when compared to controls. Oral administration of these agents produced variable and unpredictable results. Single and multiple oral dose (0.6--3 mg/kg) studies with trihexyphenidyl failed to produce any significant decreases in gastric emptying rates. A single oral dose of benztropine (0.6--3 mg/kg) failed to reduce the gastric emptying rate, but multiple dose studies produced a significant decrease in the gastric emptying rate. Effects on gastric emptying and intestinal transit were seen after single and multiple oral doses of diphenhydramine and ethopropazine.