Preparation and in vitro evaluation of biodegradable poly(epsilon-caprolactone-co-D,L lactide)(X-Y) devices containing trypanocidal drugs

Poly(epsilon-caprolactone-co-D,L lactide) copolyesters of different compositions were synthesized by bulk polymerization. The copolymers were characterized by H-1-NMR, GPC and DSC analyses. 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 CH2Cl2 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 degrees C. The release experiments show that the release of IMM is faster than for EtBr. During the first stage, for IMM the release is governed by osmotic pressure whereas for EtBr the release 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. For IMM containing devices the in vitro release depends on coating thickness, buffer concentration and ionic buffer strength. The in vitro release of EtBr could be controlled by polymer composition, coating thickness, molecular weight and device geometry.