DEVELOPMENT OF A NOVEL HYDROPHOBIC POLYMERIC MATRIX FOR STEROIDAL DRUG RELEASE: IN VITRO AND IN VIVO STUDIES

V. HEREDIA, I. D. BIANCO, G. CUESTA, H. TRÍBULO, S. FAUDONE , S. CUFFINI, R. ALASINO AND D. M. BELTRAMO

Simposio; III Simposio Binacional de Polímeros Argentino-Chileno (ARCHIPOL III); 2005

Silicone hydrophobic elastomers are one of the most frequently used  in controlled delivery systems of steroid molecules, with aim of controlling estrus cycle in livestock. Commercially available intravaginal devices have a silicone rubber skin with an homogeneous dispersion of 1-2 g micronized progesterone (P4). The commonest silicone elastomer is polydimethyl siloxane (PDMS) (Rathbone et al., 2002). Thermoset rubbers, like PDMS, are three-dimensional molecular networks, with long molecules held together by chemical bonds. Other hydrophobic elastomers, polyisoprene (PI), are also thermoset rubbers. PI contains carbon-carbon backbones, unlike PDMS, which have flexible siloxane backbones (Hamed, 1999). Here we report an in vitro and in vivo kinetics study on progesterone release from a polymeric matrix of PI in comparison with PDMS. The goal of this PI matrix was to improve the P4 release in order to reduce the inicial drug loaded within the intravaginal device. The in vitro studies showed herein indicate that P4 release rate is regulated by the matrix area and the polymorphic form of the drug. In vivo studies show that critical plasma levels of progesterone (2ng/ml) were reached with the commercial silicone device (CIDR) and PI devices containing 1.9 g and  0.5g. P4 respectively.