Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942012000200008
Brazilian Journal of Anesthesiology
Scientific Article

Análise do potencial citotóxico agudo da bupivacaína e bupivacaína em excesso enantiomerico de 50% (S75-R25) incorporadas a microesferas sobre o nervo ciático de ratos

Analysis of the acute cytotoxic potential of bupivacaine and 50% enantiomeric excess bupivacaine (S75-R25) incorporated into microspheres in rat sciatic nerves

Pedro Paulo Tanaka; Maria Fernanda Torres; Sergio Bernardo Tenorio

http://dx.doi.org/10.1590/S0034-70942012000200008 Braz J Anesthesiol, vol.62, n2, p.228-234, 2012
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Resumo

JUSTIFICATIVA E OBJETIVOS: A duração do efeito dos anestésicos locais (AL) pode ser ampliada pela sua incorporação aos sistemas de liberação prolongada como microesferas. No entanto, a possibilidade de que os sistemas de liberação prolongada de AL sejam neurotóxicos não tem recebido a devida atenção na literatura. Este estudo teve o objetivo de investigar os efeitos de microesferas de ácido poliláctico-co-glicólico puras, preenchidas com bupivacaína em excesso enantiomérico de 50% ou com bupivacaína (BP), assim como os efeitos da bupivacaína em excesso enantiomérico de 50% em nervo ciático de ratos Wistar. MÉTODO: Os ratos foram alocados em quatro grupos de acordo com o tempo de avaliação (dois, quatro, seis e oito dias) e denominados conforme a solução injetada sobre o nervo ciático: microsferas com bupivacaína em excesso enantiomérico de 50% (MBE), microesferas com bupivacaína (MB); microesferas puras (MP) e bupivacaína em excesso enantiomérico de 50% (BE). RESULTADOS: Nos cortes histológicos semifinos observou-se distribuição regular homogênea nas fibras de colágeno no endoneuro e nenhuma alteração degenerativa dos axônios ou das bainhas de mielina foi constatada. Nos cortes ultrafinos foram observados axônios mielinizados e fibras de Remak de aspecto normal com axoplasma apresentando distribuição homogênea de neurofilamentos e microtúbulos. A análise histomorfométrica dos axônios não revelou diferença significativa entre os diâmetros dos axônios dos grupos estudados.

Palavras-chave

ANESTÉSICOS, ANESTÉSICOS, ANESTÉSICOS, ANESTÉSICOS, ANIMAL

Abstract

BACKGROUND AND OBJECTIVES: The duration of Local Anesthetic (LA) effects can be expanded by its incorporation into systems of sustained release microspheres. However, the possibility that LA sustained release systems are neurotoxic has not received due attention in literature. The objective of this study was to investigate the effects of pure microspheres of poly(lactic-co-glycolic acid), filled with 50% enantiomeric excess bupivacaine or bupivacaine (BP), as well as the effects of 50% enantiomeric excess bupivacaine in the sciatic nerve of Wistar rats. METHODS: The rats were allocated into four groups according to the evaluation time (two, four, six, and eight days) and nominated according to the injected solution on the sciatic nerve: Microspheres with 50% Enantiomeric excess Bupivacaine (MEB), Microspheres with Bupivacaine (MB), Pure Microspheres (PM), and 50% Enantiomeric excess Bupivacaine (EB). RESULTS: In semi-fine histologic sections, no regular homogeneous distribution of collagen fibers in the endoneurium or degenerative changes of axons and myelin sheaths were observed. In ultrathin sections, we found myelinated axons and normal Remak fibers with axoplasm showing homogeneous distribution of neurofilaments and microtubules. Histomorphometric analysis of axons revealed no significant difference between the axon diameters of the studied groups.

Keywords

Anesthetics, Bupivacaine, Microscopy, Microscopy, Microspheres, Rats, Stereoisomerism

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