Absorption and Excretion of Drugs. XL. Enhancement of the Rectal Absorption of Pharmaceutical Amines with Lauryl Sulfate and Saccharinate Anions

Abstract

The absorption of ion pair complexes was studied in rats by means of in situ rectal perfusion technique. Two combinations, sodium lauryl sulfate-basic drugs and saccharin sodium-basic drugs were examined in detail. The disappearance from the perfusate of both components were determined in order to elucidate the mechanism of ion pair absorption. Basic drugs except some quaternaries tested were absorbed much faster in the presence of lauryl sulfate and saccharinate anions but the converse could not be applied for the anionic components. Blood level analyses of basic drugs also demonstrated such absorption enhancement effect. Enhancement of the absorption of cationic drugs could better be related to the binding behavior of those drugs to the rectal mucosal preparations than their apparent chloroform or benzene/water partition coefficients.