PreparaÃÃo e caracterizaÃÃo de microesferas de copolÃmeros de Ãcido lÃtico e glicÃlico (PLGA) contendo sulfato de quinina

AUTOR(ES)

LÃcio Figueira Pimentel

DATA DE PUBLICAÇÃO

2004

RESUMO

The aim of this work is the development of new microencapsulated formulations of quinine sulphate intended for the antimalarial therapy. The physicochemical characterization of these microparticles, their in vitro kinetic release, preliminary stability study, and their in vivo antimalarial activity were evaluated. The poly- lactide-co-glycolide microspheres associated with quinine sulphate (QS-MS) were obtained through a multiple emulsion, followed by solvent evaporation method. The morphology of the microspheres were evaluated by optical and scanning electron microscopy. . The optimized formulation was used to determine the release kinetic profile of quinine from the optimized formulation was determined by the dissolution technique with phosphate buffer 7.4 medium. A High Performance Liquid Chromatography (HPLC) assay was used to determine the quinine sulphate content. A preliminary stability studies was performed by following the lost of quinine sulphate content in the microspheres at 25ÂC. The in vivo antimalarial activity was evaluated in female Swiss mice infected with Plasmodium berghei by the four-day suppressive test. The animals were treated with free and quinine-sulphate-loaded microspheres. The untreated animal group and a group treated with unloaded microspheres were used as a control. The quinine-sulphate-loaded microspheres showed spherical shaped particles with a smooth surface, homogeneity, and particle size with a mean diameter of 3.53 Â 1.53 mm. The encapsulation efficiency was 50.34 Â 0.62%. Lyophilized microspheres presented stability over 230 days, when stored at 25ÂC. The in vitro release profile of quinine-sulphate-loaded microspheres exhibited a bimodal behavior. A burst effect of 42% was observed in the first hour, followed by a gradual drug release, achieving a release of 72% after 144 hours. Microspheres of quinine sulphate administered by subcutaneous route in mice were not able to reduce the infection of P. berghei at dose of 20 mg/kg/day for four days. However, a dose of 120 mg/kg/day was used in the same test and the first achievements shown that such a dose can used to investigate the antimalarial activity of formulation. A parenteral formulation of quinine sulphate- loaded microspheres is therefore offered as a strategy to achieve a controlled delivering for the malaria treatment

ASSUNTO(S)

microesferas de sulfato de quinina plasmodium berghei terapia antimalÃrica farmacia microesferas de plga

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