CHLORHEXIDINE RELEASE FROM POLY(EPSILON-CAPROLACTONE) FILMS PREPARED BY SOLVENT EVAPORATION

The effect of selected formulation variables on the release of chlorhe xidine from poly(epsilon-caprolactone) films was evaluated in vitro us ing a complete factorial experimental design. Repeated measures analys is of variance showed chlorhexidine type (diacetate or base), drug loa d (10, 20 or 30% w/w), chlorhexidine particle size (< 63 or 63-125 mu m) and film side (upper or lower) significantly affected the percentag e released over 10 and 30 days. Significant interactions were also obs erved between factors. Release from the upper side of films occurred m ore slowly than from the lower side of films for most formulations. Th is difference was particularly apparent for films containing chlorhexi dine diacetate. The general release equation (M(t)/M(infinity) = kt(n) ) was fitted to the release data and constants estimated. The value of n, which indicates the mechanism of release, tended towards 0.5 for r elease at high drug loadings which may suggest release was predominant ly diffusion-controlled from these films. Transecting sections of film , prepared with chlorhexidine diacetate < 63 mu m (drug loading 20% w/ w), and analysing the chlorhexidine content at varying distances from the film surfaces showed a gradient in chlorhexidine concentration thr ough the film, with lower concentrations near the upper side and highe r concentrations near the lower side.