Physicochemical stability of poly(lactide-co-glycolide) nanocapsules containing the local anesthetic Bupivacaine

Abstract

Neste trabalho foi realizada a preparação de nanocápsulas de poli (DL-lactídeo-co-glicolídeo) (PLGA) como um sistema carreador para o anestésico local bupivacaína. A preparação foi caracterizada e sua estabilidade físico-química avaliada. Os resultados da caracterização mostram uma distribuição de tamanho com um índice de polidispersão de 0,12, um diâmetro médio de 148 nm, um potencial zeta de -43,5 mV e uma eficiência de associação da BVC nas nanocápsulas de 75,8%. As propriedades físico-químicas das suspensões (diâmetro hidrodinâmico, índice de polidispersão, potencial zeta e eficiência de associação do fármaco) contendo nanocápsulas poliméricas foram avaliadas em função do tempo a fim de determinar sua estabilidade. Nenhuma grande alteração foi observada em função tempo para as suspensões de nanocápsulas avaliadas, sendo consideradas estáveis por um período de armazenagem de 120 dias a temperatura ambiente. Os resultados aqui apresentados, os quais se referem ao estudo desta nova formulação para anestésico local bupivacaína mostram-se promissores para futuros estudos in vivo.This paper describes the preparation of poly(DL-lactide-co-glicolide) (PLGA) nanocapsules as a drug carrier system for the local anesthetic bupivacaine. The system was characterized and its stability investigated. The results showed a size distribution with a polydispersity index of 0.12, an average diameter of 148 nm, a zeta potential of -43.5 mV and an entrapment efficiency of 75.8%. The physicochemical properties of polymeric nanocapsule suspensions (average diameter, polydispersity, zeta potential and drug association efficiency) were evaluated as a function of time to determine the formulation stability. The formulation did not display major changes in these properties over the time, and it was considered stable up to 120 days of storage at room temperature. The results reported here which refer to the initial characterization of these new formulations for the local anesthetic bupivacaine show a promising potential for future in vivo studies.Keywords: bupivacaine, local anesthetic, polymeric nanocapsules, PLGA, physical-chemical stability IntroductionNumerous studies today are focusing on the development of new pharmaceutical formulations based on nanocarriers, which have demonstrated several advantages over conventional formulations, making this research line a promising and innovative area of the pharmaceutical sector. 1,2Polymer nanoparticles (PN) are carriers of drugs or other active molecules whose sizes range from 10 to 1000 nm. Nanospheres (NS) or nanocapsules (NC) can be obtained, depending on the method of preparation and the materials employed. NC consists of a polymer casing and a nucleus (usually oily). The drug inside the NC may be dissolved in the oily nucleus or adsorbed on the polymeric wall. NS, on the other hand, consists of a polymer matrix and their composition does not include oil. In this system, the drug may be adsorbed or dispersed in the polymeric matrix. [2][3][4][5][6] Several polymers are used in the prepa...

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