抄録
Examinations on the effect of poly (vinylpyrrolidone) (PVP) on the gastrointestinal absorption of salicylic acid and related compounds in rats, and also on the intermolecular interaction between several compounds related to salicylic acid and PVP revealed that the absorption of small-molecule compounds from the stomach (absorption analysed by the loop method) and small intestine (by the circulation method) was inhibited by the presence of PVP and degree of inhibition decreased in the order of 2, 4-dihydroxybenzoic acid, p-aminosalicylic acid, salicylic acid, salicylamide, and o-anisic acid. This order of inhibition was independent of the easiness of absorption of these compounds in the absence of PVP. The inhibitory effect of PVP on the absorption was observed to be reflected on the blood level pattern of salicylic acid administered orally. Intermolecular interaction of 12 compounds related to salicylic acid with PVP was analysed by the equilibrium dialysis method. It was found that the degree of the interaction, expressed in terms of R-value, ran parallel with the degree of inhibition of the gastrointestinal absorption by PVP. From the relationship between the chemical structure and R, it was presumed that hydrogen bonding through the phenolic hydroxyl group of the small-molecule compounds played an important role in the interaction with PVP. Such a presumption was supported by the results of infrared spectroscopic examinations.
