Some further insights into oxfendazole broad anthelmintic spectrum: Flukicidal efficacy at a high dose in sheep

Although oxfendazole (OFZ) has been traditionally used as a nematodicidal compound, its potential as a flukicidal compound has been explored. The goal of the current trials was to assess the flukicidal efficacy of OFZ administered as a single oral dose (30 mg/kg) to sheep naturally parasitized with Fasciola hepatica, using both the faecal egg count reduction test (FECRT) and the controlled efficacy test (CET). Two independent trials were performed in different farms of Patagonian region of Argentina to assess oxfendazole flukicidal activity in comparison to that of albendazole (ABZ), a well established trematodicidal benzimidazole compound. In Farm I, the efficacy was evaluated by the FECRT. F. hepatica infected sheep were allocated into three (3) experimental groups: Group ABZ_7.5 (n = 15), treated with ABZ at 7.5 mg/kg), Group OFZ₅ (n = 11), and Group OFZ₃₀ (n = 10) orally treated with OFZ at 5 and 30 mg/kg, respectively. FECRT results demonstrated a clear dose-response pattern for OFZ, with flukicidal efficacies of 4.1 % and 67.9 % for the 5 and 30 mg/kg doses, respectively, while ABZ achieved 87 % efficacy. In Farm II, OFZ efficacy was evaluated through both a CET and the FECRT. F. hepatica infected sheep were allocated in two experimental groups: Untreated Control (n = 4) and OFZ₃₀ (n = 5). The FECRT (estimated at 10 days after treatment) indicated high oxfendazole flukicidal efficacy (92 %), whereas the CET revealed substantial inter-animal variability, largely influenced by one sheep carrying a high parasite burden before treatment. The combined findings from the trials reported here indicate that OFZ exhibits dose-dependent flukicidal activity in sheep. Although, its pharmacological potency against liver flukes remains lower than that of ABZ, the obtained results confirms that OFZ have flukicidal activity.