Evaluation of the efficacy of albendazole sulphoxide and praziquantel in combination on Taenia crassiceps cysts: in vitro studies

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Abstract
Objectives: Praziquantel and albendazole are currently used for chemotherapeutic treatment of neurocysticercosis. Albendazole has been found to be more effective than praziquantel; however, it is well known that not all patients will show a complete resolution of cysts. Searching for more effective treatments, this study was designed to evaluate the effect of the combination of praziquantel and albendazole sulphoxide in a Taenia crassiceps in vitro model as well as the kind of interaction between both drugs. Methods: In order to determine the concentration that produced 50% effect (EC50), T. crassiceps cysts were incubated in culture medium containing praziquantel (0.005–0.04 μg/mL), albendazole sulphoxide (0.021–0.16 μg/mL) or the combination of praziquantel and albendazole sulphoxide in a fixed-dose ratio (1 : 1). The experimental concentration (EC50Exp) of the combination was determined from the concentration-response curve constructed from the combined drug treatment. Isobolographic analyses were used to define the nature of the interaction between praziquantel and albendazole sulphoxide. Morphological and ultrastuctural alterations after different treatments over the parasite tissue were observed by light and transmission electron microscopy. Results: The changes in ultrastructure were more marked with the praziquantel and albendazole sulphoxide combination. Also the cysticidal effect of the combination was observed earlier than that of each drug alone. When isobolographic analysis was employed, we found that the experimental EC50 value (0.042 μg/mL) was not significantly different from the theoretical EC50 value (0.035 μg/mL), which indicates an additive interaction between praziquantel and albendazole sulphoxide. Conclusions: Our study suggests that the combination of praziquantel and albendazole sulphoxide could potentially improve the current neurocysticercosis treatment.