HYDROPHOBICITY PARAMETER FROM HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY ON AN IMMOBILIZED ARTIFICIAL MEMBRANE COLUMN AND ITS RELATIONSHIP TO BIOACTIVITY

There are numerous measures of hydrophobicity employed in the quantita tive structure-bioactivity relationship studies. Individual bioactivit y parameters may appear best predicted by the specific hydrophobicity parameters. Introduction of an original reversed-phase material, the i mmobilized artificial membranes (IAMs) opened new perspectives for bio activity predictions in the case of the hydrophobicity-driven processe s. Comparative studies of performance of the HPLC-derived hydrophobici ty measures demonstrate the advantages of the IAM-derived hydrophobici ty parameters in predicting the human skin permeation by non-ionizable agents as exemplified by steroid hormones. On the other hand, the ski n permeation data of agents ionized at physiological pH appeared less dependent of the retention on IAMs. The IAM columns increase the means of characterization of various aspects of hydrophobicity. Their advan tages over the slow equilibrium methods of hydrophobicity determinatio n are the simplicity of operation and the suitability of the generated retention measures for predicting specific bioactivity parameters.