Quantitative structure-transportability relationship for the release of a series of substituted pyridines from a planar polydimethylsiloxane matrix

Abstract

The release of 10 substituted pyridines into water, loaded at their solubility limit in a silica-filled polydimethylsiloxane planar matrix, was studied using a quantitative structure-transportability relationship (QSTR) approach. Compounds contained seven different functional groups and a wide range of solubility in both water and the polymer matrix. Release was matrix diffusion controlled with initial release following the square root of time relationship. The release coefficients (slopes of the linear Q vs t plots) were found to be significantly related to structural characteristics of the pyridines. Hydrogen bonding between the pyridines and polymer matrix was found to be one of the factors governing the release rate. Using multiple linear regression, the release coefficients are described by a simple equation involving only the pyridine melting point and the hydrogen bonding parameter. Thus, the release rates of pyridines loaded at their solubility limit can be estimated using easily accessible physico-chemical properties by a QSTR approach without using the actual solubility and diffusion coefficient in the matrix.