Controlled release from solid dispersion composed of poly(ethylene oxide)-Carbopol (R) interpolymer complex with various cross-linking degrees of Carbopol (R)

Solid dispersion composed of the poly(ethylene oxide) (PEO)-Carbopol(R) (CP ) interpolymer complex containing phenacetin (PHE) was prepared by using si x grades of CP having various cross-linking degrees. We attempted to contro l the medicine release from the PEO-CP solid dispersion by varying the CP g rade. The powder X-ray diffraction pattern and differential scanning calori metry curves suggested that PHE existed in the amorphous state, and PEO in the crystalline state disappeared in the solid dispersions. The release pro file of PHE varied depending on the CP grade. A small release rate was obse rved at CP910 and CP971P that are cross-linked at low and middle degrees, r espectively. The Fourier transform-infrared (FT-IR) spectra showed that the amount of the PEO-CP complex formed by hydrogen bonding changed depending on the CP grade. With the cross-linked CP, a good correlation was observed between the hydrogen bonding percent and the percent released of the PHE af ter 60 min (D-60 (min)), indicating that PHE release was controlled by the amount of PEO-CP complex formation in the solid dispersion. These results s how that it is feasible to control the medicine release from PEO-CP solid d ispersion by varying the CP grade. (C) 2000 Elsevier Science B.V. All right s reserved.