A highly sensitive HPLC method for the assay of propantheline used to measure its uptake by rat intestinal brush border membrane vesicles.

A simple, sensitive, high-performance liquid chromatographic method for propantheline has been developed. Propantheline was quantitatively hydrolysed into xanthene-9-carboxylic acid in neutral or alkaline medium and the hydrolysate assayed by reversed phase high-performance liquid chromatography. This method measured to 2 pmol per injection and was used to investigate the uptake of the drug by rat intestinal brush border membrane vesicles. Propantheline was highly bound to the membrane and this binding was inhibited to varying extents by several quaternary ammonium compounds. Mepenzolate and methylbenactyzium inhibited it significantly, and neostigmine, butylscopolamine and N-methylnicotinamide inhibited it moderately. Choline, acetylcholine and thiamine had no effect.