A bioequivalence study on two closantel oral suspensions in sheep: an Iranian product (fascinil®) versus flukiver® as a reference product

Background: Closantel is a broad-spectrum antiparasitic agent and is widely used for the control of Fasciola spp. and Haemonchus spp. infestations in sheep and cattle. OBJECTIVES: The present study was carried out to evaluate the bioequivalence of a domestic closantel formulation, Fascinil® (Damloran Pharmaceutical Co., Iran), in comparison with Flukiver® (Janssen pharmaceutical Co., Belgium) in sheep. METHODS: In a parallel design, twenty-eight male sheep, 4- 5 months of age, were randomly divided into two groups. First group received a single dose of Fascinil® oral suspension as a test product at 10 mg/kg BW, and the second group received Flukiver® as a reference product with the same dose. Blood samples were taken on 0, 4, 8, 12, 16, 20, 24, 32, 48, and 72 hours after drug administration, and the plasma concentrations of closantel were determined using a high performance liquid chromatographic (HPLC) method. Pharmacokinetic analysis was performed; in addition, the areas under the plasma concentration-time curves at 0-72h (AUC0-72), maximum plasma concentrations (Cmax), and times to reach Cmax (Tmax) of the closantel in test and reference groups were compared. RESULTS: There were no significant differences in the AUC0-72 (2913.00±648.18, 2957.88± 623.41 µg.h/mL), Cmax (62.22±7.74, 71.71±13.03µg /mL), and Tmax (23.38±4.27, 23.23±4.28h) between Fascinil® and Flukiver®, respectively. The 90% confidence intervals for test: reference ratios of these pharmacokinetic (PK) parameters were within bioequivalence acceptable range (80-120%). CONCLUSIONS: It is concluded that the test product (Fascinil®) and Flukiver® are bioequivalent, and they can be used as interchangeable anthelmintic drugs.