RESUMO
CONTEXT: In countries where research budgets are meager as Argentina, the tendency to innovation and improvements in the designs prototypes "made in Argentina" marks a growing trend adopted by researchers. This article presents a diffusion cell of original design, for release studies of Active Pharmaceutical Ingredient (API) from classical topical dosage forms, also includes the methodology for its optimization and validation. The objective was to evaluate and validate a system designed and to compare it to the Franz cells system. METHODS: Parameters, reproducibility and robustness were performed included factors as, stirring conditions, membrane stabilization treatment and temperature variation. Release and retention on membrane assay were performed using two different API and formulations. RESULTS: The method is reproducible and robust for the parameters tested. Release assays show that no significative difference with the Franz Cells system. Our system allows the simultaneous measurement of different parameters, representing an innovation on these methodologies. The LMC was used for assays of in vitro retention on membrane and the values obtained were reproducible and coincident whit values obtained for other authors. CONCLUSIONS: The system designed and the methodology employed, are acceptable for in vitro release studies. The device and method has the characteristics required.
Assuntos
Química Farmacêutica/instrumentação , Liberação Controlada de Fármacos , Membranas Artificiais , Preparações Farmacêuticas/administração & dosagem , Administração Tópica , Química Farmacêutica/métodos , Difusão , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/química , Desenho de Equipamento , Pomadas/química , Permetrina/administração & dosagem , Permetrina/química , Preparações Farmacêuticas/química , Reprodutibilidade dos TestesRESUMO
BACKGROUND: When cases of dengue are reported or the density of adult Aedes aegypti (L.) becomes too high, ultralow-volume (ULV) application of insecticides is the recommended control method. The droplet size of an aerosol insecticide influences its efficiency in killing adult mosquitoes. Many studies have been carried out to determine the optimum droplet size that maximises vector control efforts, but only a few have determined droplet-size spectra for specific equipment using different solvents and comparing thermal and non-thermal aerosols. RESULTS: The present study showed that the droplet size for a water-based adulticide-larvicide formulation was larger than for the same formulation diluted in gasoil or biodiesel. No significant differences in adult mortality were observed between sprayers and solvents, but efficacy decreased with distance from the sprayer nozzle. Adult emergence inhibition was more than 90% when using water as a solvent for both thermal and cold foggers, and the efficacy did not decrease with distance from the sprayer nozzle. On the other hand, oil-based solvents became less effective with distance. CONCLUSION: The use of water as a solvent with both thermal and cold foggers improves the efficacy of the studied formulation containing permethrin as adulticide and pyriproxyfen as larvicide in scaled-up assays. Moreover, it reduces the environmental impact and costs of spraying by comparison with formulations using oil solvents.
Assuntos
Aedes/efeitos dos fármacos , Química Farmacêutica/métodos , Inseticidas/química , Inseticidas/toxicidade , Larva/efeitos dos fármacos , Controle de Mosquitos/métodos , Aedes/crescimento & desenvolvimento , Animais , Larva/crescimento & desenvolvimento , Controle de Mosquitos/instrumentação , Permetrina/química , Permetrina/toxicidade , Piridinas/química , Piridinas/toxicidadeRESUMO
BACKGROUND: The most common ways to control dengue vector Aedes aegypti (L.) are larval source reduction in domestic habitats and ground application of small quantities of aerosol insecticide (ultralow volume). Nevertheless, these actions have been shown repeatedly to be ineffective in controlling Ae. aegypti populations. RESULTS: The efficacy of a new smoke-generating formulation containing pyriproxyfen and permethrin was evaluated in the laboratory. Smoke-generating tablets containing each insecticide individually or combined were prepared, and the recovery of the insecticides from the smoke was determined. Recovery values of over 90% were obtained for pyriproxyfen, and around 50% for permethrin. The biological efficacy of pyriproxyfen released in the smoke was evaluated in the laboratory, on late third-instar or early fourth-instar Ae. aegypti larvae, using different concentrations of pyriproxyfen and exposure times. Adult emergence inhibition (EI) values of 100% were obtained at 30 min, and a dose-dependent effect was observed at 5 min. The effect of pyriproxyfen released in the smoke was due to direct contact with the larvicide in the water rather than by inhalation of the fumes. The efficacy of permethrin released in the fumes was also evaluated as knockdown effect (KT(50)) on adults for a tablet containing permethrin alone or permethrin plus pyriproxyfen. There was no significant difference in KT(50) values obtained for permethrin (KT(50) = 19.9 min) and permethrin plus pyriproxyfen (KT(50) = 19.4 min). CONCLUSION: The excellent laboratory performance of this new formulation on immature stages and adults indicates that a smoke-generating tablet containing pyriproxyfen and permethrin could be a new tool for controlling mosquitoes.
Assuntos
Aedes/efeitos dos fármacos , Inseticidas/farmacologia , Permetrina/farmacologia , Piridinas/farmacologia , Fumaça/análise , Aedes/crescimento & desenvolvimento , Animais , Fumigação , Inseticidas/química , Larva/efeitos dos fármacos , Permetrina/química , Piridinas/químicaRESUMO
The stability to heart of cis-permethrin and beta-cypermethrin in the solid phase was studied and the decomposition products identified. Samples heated at 210 degrees C in an oven in the dark showed that, in the absence of potassium chlorate (the salt present in smoke-generating formulations of these pyrethroids), cis-permethrin was not isomerized, although in the presence of that salt, decomposition was greater and thermal isomerization occurred. Other salts of the type KXO3 or NaXO3, with X being halogen or nitrogen, also led to a considerable thermal isomerization. Heating the insecticides in solution in the presence of potassium chlorate did not produce isomerization in any of the solvents assayed. Salt-catalysed thermal cis-trans isomerization was also found for other pyrethroids derived from permethrinic or deltamethrinic acid but not for those derived from chrysanthemic acid. The main thermal degradation processes of cis-permethrin and beta-cypermethrin decomposition when potassium chlorate was present were cyclopropane isomerization, ester cleavage and subsequent oxidation of the resulting products. Permethrinic acid, 3-phenoxybenzyle chloride, alcohol, aldehyde and acid were identified in both cases, as well as 3-phenoxybenzyl cyanide from beta-cypermethrin. A similar decomposition pattern occurred after combustion of pyrethroid fumigant formulations.