In vitro release of trypanocidal drugs from biodegradable implants based on poly(epsilon-caprolactone) and poly(D,L-lactide).

In this study, commercial available poly(epsilon-caprolactone)s and poly(d,l-lactide)s of different molecular masses were used. Slow release devices (SRD) were obtained as rods of suitable diameters by extrusion of polymer-drug mixtures (75:25, w/w) which were prepared by the solution casting method. The rods were coated by dipping them in a methylene chloride solution of the core polymer. The in vitro release of the selected drugs, isometamidium chloride (IMM) and ethidium bromide (EtBr) from such rods was carried out in phosphate buffer (PB) pH 7.4 at 37 degreesC. The release data show that the release of IMM is faster than for EtBr. During the first stage, the release of IMM is governed by osmotic pressure whereas the release of EtBr is mainly diffusion controlled. The in vitro release of these drugs is governed by polymer matrix degradation at the later stage of the release process. The in vitro release could be controlled by drug loading, polymer molecular mass, polymer mixtures, coating thickness and device geometry.