RESUMO
Albendazole (ABZ), a benzimidazole widely used to control gastrointestinal parasites, is poorly soluble in water, resulting in variable and incomplete bioavailability. This has favored the appearance ABZ-resistant nematodes and, consequently, an increase in its clinical ineffectiveness. Among the pharmaceutical techniques developed to increase drug efficacy, cyclodextrins (CDs) and other polymers have been extensively used with water-insoluble pharmaceutical drugs to increase their solubility and availability. Our objective was to prepare ABZ formulations, including ß-cyclodextrin (ßCD) or hydroxypropyl-ß-cyclodextrin (HPßCD), associated or not to the water-soluble polymer polyvinylpyrrolidone (PVP). These formulations had their solubility and anthelmintic effect both evaluated in vitro. Also, their anthelmintic efficacy was evaluated in lambs naturally infected with gastrointestinal nematodes (GIN) through the fecal egg count (FEC) reduction test. In vitro, the complex ABZ/HPßCD had higher solubility than ABZ/ßCD. The addition of PVP to the complexes increased solubility and dissolution rates more effectively for ABZ/HPßCD than for ABZ/ßCD. In vivo, 48 lambs naturally infected with GIN were divided into six experimental groups: control, ABZ, ABZ/ßCD, ABZ/ßCD-PVP, ABZ/HPßCD, and ABZ/HPßCD-PVP. Each treated animal received 10 mg/kg of body weight (based on the ABZ dose) for three consecutive days. After 10 days of the last administered dose, treatment efficacy was calculated. The efficacy values were as follows: ABZ (70.33%), ABZ/ßCD (85.33%), ABZ/ßCD-PVP (82.86%), ABZ/HPßCD (78.37%), and ABZ/HPßCD-PVP (43.79%). In vitro, ABZ/HPßCD and ABZ/HPßCD-PVP had high solubility and dissolution rates. In vivo, although the efficacies of ABZ/ßCD, ABZ/ßCD-PVP, and ABZ/HPßCD increased slightly when compared to pure ABZ, this increase was not significant (P > 0.05).