Dissolution properties of polyethylene glycols and polyethylene glycol-drug systems

The release of polyethylene glycol from discs prepared using polyethylene glycols of differing molecular weight was determined. The influence of polyethylene glycol weight fraction on the release of hydroflumethiazide and bendrofluazide from drug—polymer solid dispersions was also investigated. While the dissolution of both drugs was considerably enhanced, the dissolution of polyethylene glycol from the solid dispersions was in all cases lower than that of the pure polymer. Comparison of the relative movement of the solid—liquid boundary of each component indicated that both components were being released simultaneously from the disc surface. In addition, the observed maximum enhancements in drug dissolution were orders of magnitude greater than the theoretical values expected, assuming the solution interaction model. It was concluded that molecular dispersion is involved in the release mechanism.