Abstract: This invention provides compositions for enhancing penetration of physiologically active agents through the skin or mucosal membranes and for retaining these agents in body tissues, said composition comprising effective amounts of a physiologically-active agent and a compound represented by the general formula ##STR1## wherein X may represent sulfur, oxygen or nitrogen; a and b may be 0 or 1, c may be 0, 1 or 2, except that when X is oxygen, a, b and c are 0, when X is nitrogen c is 0 and only one of a or b is 1, and when X is sulfur a and b are 0; A is a branched or a straight chain, divalent aliphatic radical having from 0 to 2 double bonds; R' is selected from the group consisting of H, a lower alkyl group having from 1 to 4 carbon atoms, phenyl, lower alkyl or halogen substituted phenyl, acetamido, halogen, piperidinyl, lower alkyl or halogen substituted piperidinyl, carbalkoxy, carboxamide, and alkanoyl; and R is hydrogen or a lower alkyl group having from 1 to 4 carbon atoms, ##STR2## wherein R" is H or