The effect of surface-active substances on the penetration of hexyl resorcinol into Ascaris lumbricoides var. suis

Abstract

Although a Surface-active substance such as bile salt or soap penetrates the pit round worm only extremely slowly, yet it can markedly influence the penetration of hexyl resorcinol when present together. Keeping the hexyl resorcinol concentration fixed, low concentrations of soap bring about an acceleration, high concentrations complete inhibition. Interfacial tension measurements upon the soap/hexyl resorcinol mixtures suggest an explanation for this behavior. Addition of soap in low concentration increases the interfacial activity of the mixture, leading to an increased biological activity. Beyond a certain soap concentration micelles commence to form, and these micelles compete with the biological interface for the fixed amount of drug, reducing the rate and ultimately leading to complete inhibition. This suggested explanation appears to be applicable to other biological systems.