Polyethyelene Glycols and Drug Release

Abstract

The dissolution rates of several drugs may be increased by incorporation into solid polyethylene glycols1. These dispersions are usually manufactured by heating a physical mixture of the drug and polymer to the fluid state and subsequently cooling to room temperature.

The physical structure of both the drug and the polyethylene glycol will be discussed, as these factors may affect the rate of drug release from the dispersions2,3. The solid state properties of both components have traditionally been studied by X-ray diffraction and/or by differential scanning calorimetry (DSC). The latter technique has facilitated the use of phase diagrams in the investigation of the melting properties of the dispersions, these usually indicating the presence of eutectics, monotectics, solid solutions or glasses. The application of a further technique, dielectric spectroscopy, in the study of molten and solid dispersions will be described.

The mechanisms by which drug dissolution rate may be enhanced will be described. Furthermore, the kinetics of drug release will be discussed in terms of the non-interactive and interactive models proposed by Corrigan4.