Poly (ethylene carbonate), poly (propylene carbonate), and poly (ethylene propylene carbonate) were examined as to their biodegradability, permeability, and drug release characteristics.
Poly (ethylene carbonate) degraded but poly (propylene carbonate) did not in the peritoneal cavity of rats and the peritoneal cavity and subcutaneous tissue of guinea pigs. Mixtures of the two polymers degraded at a rate in proportion to poly (ethylene carbonate) content. Degradation rate in the peritoneal cavity was faster than that in subcutaneous tissue in guinea pigs.
Membranes free from pores were obtained from poly (ethylene carbonate). Permeability of drugs through them depended on lipophilicity indicating role of solubility of the drugs in the membrane material for permeation.
Release rate of tegafur from poly (ethylene carbonate) implants was faster than that from poly (propylene carbonate) implants. Blood level profiles were obtained after implantation of implants in rats.
Microspheres containing local anesthetics were prepared by a solvent evaporation process and effects of drug content and polymer on release profiles were examined
in vitro. Duration of local anesthesia after administration of dibucaine microspheres in guinea pigs was demonstrated.
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