Studies on Absorption of Drugs. VIII. Physicochemical Factors affecting the Absorption of Sulfonamides from the Rat Small Intestine

Abstract

The absorption of sulfonamides through the rat intestine was studies with an in situ perfusion method employing pH adjusted isotonic saline solutions. The absorption was expressed as the absorbed amounts in one hour and first-order rate constants in terms of the unionized and anionic forms of the drugs. Regression analysis following Hansch, et al. were carried out to correlate the intestinal absorption of the drugs with their physicochemical parameters. Physicochemical parameters, such as partition coefficients from chloroform, n-octyl alcohol and lecithin contained chloroform, adsorption to the rat blood, adsorption to activated charcoal, molecular weight and dissociation constant, were used. The intestinal absorption of sulfonamides was satisfactorily predicted with the use of equations of the regression analysis.