Effects of phospholipids on the percutaneous penetration of drugs through the dorsal skin of the guinea pig, in vitro. 3. The effects of phospholipids on several drugs having different polarities

Abstract

We investigated the influence of several phospholipids (PG derivatives, PC derivatives, and PE derivatives) on the percutaneous penetration of drugs that have different n-octanol/water partition coefficients (log P). The log P-values of several compounds showed the following order: bifonazole (BFZ, 3.014) > erythromycin (ETM, 1.206) > tenoxicam (TEX, 0.731) > diclofenac sodium salt (DFS, -0.386). First, the maximum accumulated amount of BFZ in skin increased significantly, by 4.5-fold ( P < 0.001) in the presence of 3% DOPG after 48 h compared to the control. Second, the maximum accumulated amount of DFS passing to the receptor side increased significantly, by approximately 37-fold ( P < 0.05) in the presence of 3% DLPG after 24 h, compared to the control. Third, the maximum accumulated amount of TEX passing to the receptor side was increased significantly, by approximately 183-fold ( P < 0.001) in the presence of 3% DLPG after 24 h, compared to the control. Fourth, the maximum accumulated amount of ETM passing to the receptor side increased significantly, by about 7.5-fold ( P < 0.01) in the presence of 3% DOPC and 3% DLPC after 72 h, compared to the control. Consequently, these results suggest that the respective structures of phospholipids and penetrants are closely related to the degree of percutaneous penetration of drugs. Moreover, phospholipids can be very effective percutaneous penetration enhancers for the majority of certain compounds.