Application of polyvinyl acetate as release controlling agent in 17-β estradiol implant matrices

Abstract

To apply low and high molecular weight polyvinyl acetate (PVAc) as the release controlling agent in 2% 17β-estradiol (E2) implant matrix system, polyvinylpyrrolidone (PVP K30) was used as releasing modifier. Two plasticizers, triethyl citrate (TEC, a water-soluble plasticizer) or diethyl phthalate (DEP, a water-insoluble plastcizer) was incorporated to alter the flexibility of the matrix. Solid dispersion of E2 in polymer was prepared by solvent evaporation method and compressed in a mold to have an implant matrix of 2 mm in diameter and 10 mm in length. Physicochemical characterization of implants was performed using differential scanning calorimetry (DSC), X-ray diffractometry and FTIR spectroscopy. It was observed that E2 released from implants increased with increasing weight percent of plasticizers and PVP K30. E2 matrix implant with 20% DEP and 30% PVP K30 released 48.13% of drug in 28 days. Released kinetic of the PVAc implant matrix was best described by Higuchi model which indicated drug release by diffusion process. PVAc could be applied in E2 matrix implant for long term delivery.