Control of medicine release from solid dispersion composed of the poly(ethylene oxide)-carboxyvinylpolymer interpolymer complex by varying molecular weight of poly(ethylene oxide).

Solid dispersion composed of the poly(ethylene oxide) (PEO)-carboxyvinylpolymer (CP) interpolymer complex containing phenacetin (PHE) was prepared by using nine grades of PEO having different molecular weights from 2000 to 4500000. We attempted to control the medicine release from the PEO-CP solid dispersion by varying the molecular weight of PEO. The physicochemical properties of the solid dispersion were analyzed by powder X-ray diffractometry and thermal analysis. The interaction between PEO and CP was analyzed by IR spectroscopy. Transmittance of the polymer solution was measured to study the complexation between PEO and CP. The release profile of PHE varied depending on the molecular weight of PEO. The minimum release rate was observed at the PEO molecular weight of 35000. It was found that the amount of the PEO-CP complex formation by hydrogen bonding changed depending on the molecular weight of PEO. These results indicate that it is feasible to control the medicine release from the PEO-CP solid dispersion by varying the molecular weight of PEO.