Formulações de liberação controlada com anestesicos locais - bupivacaina e mepivacaina : preparação, caracterização e ensaios farmacologicos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

Local anesthetics (LA) belong to the class of drugs used for the treatrnent of pain. In order to prolong the duration of action and to reduce their systemic toxicity of LA, many studies have been developed using carriers such as liposomes and cyclodextrins; these vehicles allow controlled release (improving anesthetic effect) and avoid high plasmatic levels of the anesthetics to be reached (reducing the toxicity). This work aimed to prepare, to characterize and to evaluate in vivo drug - delivery systems for bupivacaine (BVC) and mepivacaine (MVC) in liposomes or cyclodextrins, comparing them with the clinically used LA solutions. Mean size diameter analysis showed that the liposomes have diameters of 400 nm and 150 nm, with encapsulation efficiencies higher for BVC than MVC. Regarding to LA systems in cyclodextrins, differences on phase transition temperature and structural changes in the crystal s pattems evidenced LA : J3-CD complexation. Liposomal and ciclodextrin formulations increased the intensity and duration of the motor blockade showing dose-dependent relationships although these parameters did not change, if compared at the sarne concentrations. AIso the systemic antinociceptive effects were similar for ali the formulations tested. Potency and duration of sensory blockade were improved afier injection of complexed BVC and liposomal MVC in relation to the free drug injection (p <0.001). These results can be explained by the controlled release of the LA and increased availability of the LA in their site of injection. Encapsulation of MVC in liposomes increased the amount of available drug for membrane partition while complexation into cyclodextrin increased BVC concentration in the aqueous phase, improving their anesthetic potency in relation to the commercial solutions and these LA. These drug-delivery systems offer a potential new therapeutic option for the treatments of acute and chronic pain using LA

ASSUNTO(S)

anestesia analgesia lipossomos anestesia local ciclodextrinas

ACESSO AO ARTIGO

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