Avaliação in vitro das características de liberação de indometacina a partir de dispositivos oculares implantáveis

• Ano de defesa: 2010
• Autor(a) principal: Moura, Renata Kely de Paulo
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraí­ba; BR; Farmacologia; Programa de Pós Graduação em Produtos Naturais e Sintéticos Bioativos; UFPB
• Palavras-chave em Português: Implantes oculares; Indometacina; PLA; PLGA; Ocular implants; indomethacin; CNPQ::CIENCIAS BIOLOGICAS::FARMACOLOGIA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/tede/6857

The anatomy and physiology of the eye, together with its protective barriers represent challenges to effective ocular drug delivery systems. The pharmacological treatment of eye diseases had been limited to conventional drug formulations, which are not satisfactory for diseases affecting the posterior segment of the eye. The delivery of therapeutic doses at tissues from the posterior segment in order to minimize adverse systemic and regional effects is the main goal in the treatment of ocular diseases. With this aim, several studies have been conducted to develop new ocular drug delivery systems, such as those involving ocular implants. These implants are prepared using a variety of different polymers that can be either biodegradable or non-biodegradable. Polymers derived from lactic and glycolic acid have revealed to be promising materials for the formulation of ocular implants, mainly due to their biocompatibility and biodegradability. In this study, two different biodegradable indomethacin implants formulated based on a copolymer of lactic/glicolic acid (PLGA 50:50) and D,L-lactic acid (D,L-PLA) were characterized by differential scanning calorimetry (DSC), in vitro release using dissolution apparatus and scleral diffusion (from rabit´s eye) using Franz chambers. The study was done in collaboration with 3T Biopolymers (São Paulo, Brazil) that provided samples of the polymers and implants for analyses. The results of the validation of the HPLC method for indomethacin quantification were within the limits set forth by Brazilian legislation (RE 899, 2003, ANVISA). The results of DSC analysis revealed absence of any evidence of physico-chemical interactions between the drug and polymer. The suppression of the indomethacin melting peak is probably due to changes from the crystalline to the amorphous state of the drug following lyophilization or by dilution effects. Preliminary in vitro release data revealed a triphasic profile for indomethacin release from the PLGA-based implants and a biphasic one for the PLA implants. The implants formulated with PLGA promoted a faster release of indomethacin (103.64%) compared with implants formulated with PLA (49.9%) during the thirty days of the experiment. The release profile of indomethacin was determined by the rate of degradation of polymers, which also determined the scleral diffusion of indomethacin from PLGA and PLA (1.7 x 10-5 cm / s and 0.24 x 10-5 cm / s, respectively). The scleral diffusion experiments using Franz difusion chambers have shown that the rabit sclera is permeable to indomethacin and polarized light microscopy revealed that the structure of the scleral collagen fibers were not significantly altered during the diffusion experiments. The drug-release systems studied were able to release indomethacin in a sustained fashion, serving as a model for the formulation of indomethacin implants that could be used in the future for the treatment of ocular diseases such as the cystoid macular edema.