The effect of pH and organic ester penetration enhancers on skin permeation kinetics of terbutaline sulfate from pseudolatex-type transdermal delivery systems through mouse and human cadaver skins.

The purpose of this research was to prepare a pseudolatex transdermal delivery system for terbutaline sulfate and to evaluate the effect of pH and organic ester penetration enhancers on permeation kinetics of terbutaline sulfate through mice abdominal skin and human cadaver skin. An increase in the permeation flux by increasing pH was observed. The distribution coefficient of terbutaline sulfate between 1-octanol and buffers of different pH values was also pH-dependent. Furthermore, the change of the permeability coefficient with pH correlated well with the distribution coefficient by a 2-degree polynomial equation. The permeation profile and related kinetic parameters of terbutaline sulfate was determined in presence of 3 ester-type permeation enhancers incorporated in the films, viz methyl laureate, isopropyl lanolate, and isopropyl myristate. Among the 3, the more pronounced enhancing effect was obtained with isopropyl myristate, regarding the permeation flux, permeability coefficient, and diffusion coefficient. This was attributed to solubility parameter of isopropyl myristate being closer to the solubility parameter of human skin, and such a pronounced enhancing effect was probably caused by its passage across the skin barrier through the lipid pathway.