MECHANISM OF MEDICINE RELEASE FROM SOLID DISPERSION COMPOSED OF POLY(ETHYLENE OXIDE) CARBOXYVINYLPOLYMER INTERPOLYMER COMPLEX AND PH EFFECTON MEDICINE RELEASE

Solid dispersion composed of the poly(ethylene oxide) (PEO)-carboxyvin ylpolymer (CP) interpolymer complex containing phenacetin (PHE) was pr epared using water/ethanol (1/1, v/v) mixture as a solvent. The releas e mechanism of PHE from the solid dispersion and the effect of pH on P HE release were studied. The physicochemical properties of the solid d ispersion were analyzed by powder X-ray diffractometry, thermal analys is and IR spectroscopy. Transmittance of the polymer solution was meas ured to study the complexation between PEO and CP. The degree of PEO-C P complex formation by hydrogen bonding varied depending on the PEO/CP ratio. It was found that the PHE release from the solid dispersion wa s controlled by the degree of the complex formation. With PHE powder, the effect of pH on the dissolution behavior was hardly observed. In c ontrast, the release rate from the solid dispersion increased with a h igher pH. This result is probably caused by the fact that the PEO-CP c omplex is broken at a higher pH. (C) 1998 Elsevier Science B.V. All ri ghts reserved.