BUCCAL DELIVERY OF PROGESTATIONAL STEROIDS .1. CHARACTERIZATION OF BARRIER PROPERTIES AND EFFECT OF PENETRANT HYDROPHILICITY

In an attempt to characterize the barrier functions of buccal mucosa, a series of systematic studies were performed, using the rabbit as the animal model. The model penetrants used in these studies were progesterone, a lipophilic compound, and the hydroxy derivatives of progesterone, which have approximately similar molecular weights but differ in their hydrophilicity, to study the effect of a systematic variation in lipophilicity on the kinetics and rate of permeation across the rabbit buccal mucosa. The results indicated that transbuccal permeation occurs via both a lipoidal pathway and an aqueous-pore pathway. The mucosal permeability and partition coefficient are both governed by the degree of hydrophilicity, and are increased with removal of the lipid domain from the mucosal membrane.