Influence of food on the effect of propantheline and L-hyoscyamine on salivation.

The absorption of a quartenary (propantheline, 30 mg) and a tetiary (1-hyoscyamine, 0.8 mg) anticholinergic compound was studied in 8 healthy volunteers by measuring the effects on salivation. Both compounds were administered as rapidly disintegrating tablets, 1-hyoscyamine also in a slow-release formulation (Egazil Durules). The three preparations and placebo were administered under fasting conditions and with a standardized light meal using a randomized cross-over design. Salivation measurement were performed with a citric acid stimulation method every hour for 10 hours. In the fasting patient, all three anticholinergic test preparations decreased the salivation significantly. When taken with food, the effect of propantheline was almost abolished, while the effects of the 1-hyoscyamine preparations were uninfluenced. It was concluded that the clinical effects of proprantheline might be extremely varying depending how the drug is taken in relation to meals. In contrast the clinical effects of 1-hyoscyamine seem to be independent of food intake.