Desenvolvimento e caracteriza??o de sistemas autoemulsion?veis (SEDDS) contendo ravuconazol para o tratamento da doen?a de Chagas experimental.

Programa de P?s-Gradua??o em Ci?ncias Farmac?uticas. CIPHARMA, Escola de Farm?cia, Universidade Federal de Ouro Preto.Os sistemas lip?dicos autoemulsion?veis (SEDDS) de uso oral tem sido alvo de intensas pesquisas nos ?ltimos anos, visando o aumento da biodisponibilidade de f?rmacos pouco sol?veis. O ravuconazol (RAV), Classe II no sistema de classifica??o biofarmac?utica, atua inibindo a enzima CYP51 respons?vel pela principal etapa da bioss?ntese do ergosterol e representa um f?rmaco promissor para o tratamento da doen?a de Chagas. O presente estudo teve por objetivo desenvolver e caracterizar SEDDS contendo RAV e avaliar a efic?cia em modelo experimental murino de infec??o aguda pelo T. cruzi. Foram desenvolvidas formula??es de SEDDS do tipo IIIA, contendo diferentes concentra??es do surfactante Labrasol?, que ap?s a emulsifica??o, geraram nanoemuls?es com di?metros hidrodin?micos m?dios em torno de 250 nm e potencial zeta entre -45 e -57 mV, sem precipita??o do RAV sob dilui??o e com perfil polidisperso em termos de natureza das nanoestruturas formadas quando analisados pela t?cnica de AF4. O SEDDS aumentou a taxa de dissolu??o do RAV in vitro em compara??o com o f?rmaco livre, de forma dependente da concentra??o de Labrasol? no meio de libera??o. O SEDDS contendo baixo teor de surfactante (10% v/v) mostrouse seguro no tratamento de animais s?os e infectados por T. cruzi por per?odos de 20 a 40 dias. A formula??o SEDDS melhorou significativamente a atividade in vitro anti-T. cruzi no n?vel de IC50 do RAV. Doses di?rias de 15mg/kg de RAV-SEDDS durante 20 dias resultaram em atividade supressiva, mas n?o curativa frente ? infec??o com a cepa Y de T. cruzi. O tratamento com a dose di?ria de 20 mg/kg de RAV-SEEDS por 30 dias resultou em 70% de cura, contra 40% para o RAV livre e 50% para benznidazol. A administra??o prolongada de RAV-SEEDS e RAV livre por 40 dias curou 100% dos animais, e resultou tamb?m em 90% de cura com o benznidazol. Estes resultados est?o em acordo com atividade in vitro de RAV-SEDDS, onde foi verificada a redu??o significativa nos valores de IC50, mas n?o para IC90, em rela??o ao RAV livre. O tratamento da infec??o frente ? cepa Colombiana, resistente ao benznidazol com 20 mg/kg/dia de RAV ou RAV-SEDDS por 40 dias apresentou atividade supressiva da parasitemia, com 10% e 20% de cura respectivamente, e 50% de cura para os animais tratados com benznidazol. Esses resultados mostraram que o tratamento em fase inicial da infec??o por longo prazo aumenta a efic?cia com ambos os f?rmacos, e que os SEDDS contendo RAV s?o um sistema promissor de baixo custo, de f?cil produ??o e adequado para a administra??o oral na terapia da doen?a Chagas.Lipid-based self-emulsifying drug delivery systems (SEDDS) for the oral administration of drugs have been the subject of intense research in recent years, with the aim of increasing the bioavailability of poorly soluble drugs. Ravuconazole (RAV), a Class II drug in the biopharmaceutical classification system, is an inhibitor of CYP51, an enzyme responsible for the main step in ergosterol biosynthesis and represents a promising drug for the treatment of Chagas disease. The aim of the present study was to develop and characterize SEDDS containing RAV and to evaluate the efficacy in a murine experimental model of acute T. cruzi infection. SEDDS type IIIA formulations containing different concentrations of Labrasol? surfactant were developed, which after emulsification generated nanoemulsions with mean hydrodynamic diameters around 250 nm and zeta potentials between -45 and -57 mV without precipitation of RAV under dilution. The nanostructures had polydispersed profiles when analyzed by the AF4 technique. The SEDDS increased the dissolution rate of RAV in vitro compared to the free drug, depending on the concentration of Labrasol? in the release medium. A SEDDS containing low surfactant content (10% v/v) was found to be safe during treatment of healthy animals and animals infected with T. cruzi for periods of 20 to 40 days. The SEDDS formulation significantly improved in vitro anti-T. cruzi activity at the IC50 level of RAV. Daily doses of 15 mg / kg of RAV-SEDDS for 20 days resulted in suppressive, but not curative, activity against infection with the T. cruzi Y strain. Treatment with the daily dose of 20 mg / kg of RAV-SEEDS for 30 days resulted in 70% cure, against 40% for free RAV and 50% for benznidazole. Prolonged administration of RAV-SEEDS and free RAV for 40 days cured 100% of the animals, and also resulted in 90% cure with benznidazole. These results are in agreement with in vitro activity of RAV-SEDDS, where a significant reduction in IC50 values, but not IC90, was found in comparison with free RAV. The treatment of the infection against the benznidazole-resistant Colombian strain with 20 mg/kg/day of RAV or RAVSEDDS for 40 days presented suppressive activity on parasitemia, with 10% and 20% of cure, respectively, and 50% of cure for animals treated with benznidazole. These results showed that early-stage treatment of long-term infection increases efficacy with both drugs and that a RAV-containing SEDDS is a promising low-cost, easy-to-produce system suitable for oral administration in Chagas disease therapy