Interaction between ivermectin and abamectin: pharmacokinetic and pharmacodinamic assessent in cattle.

LIFSCHITZ, A.; FIEL, C.; DOMINGUEZ, P.; VIRKEL, G.; CANTON, C.; LANUSSE, C.; BALLENT, M.

Liverpool

Congreso; 25th International Conference of the World Association for the Adavancement of Veterinary Parasitology; 2015

Combined preparations are available pharmacological tools proposed to delay the development of anthelmintic resistance. However, the pharmacological consequences produced after the coadministration of anthelmintics drugs should be evaluated. The current work investigated the pharmacokinetic and pharmacodynamic interaction after the coadministration of ivermectin (IVM) and abamectin (ABM) to cattle.The experimental trial was performed in two phases. In phase I, twenty four (24) Aberdeen angus-Heresford cross breed calves experimentally infected with a susceptible strain of Cooperia spp were subcutaneously treated with IVM (0.1 mg/kg), ABM (0.1 mg/kg) or IVM+ABM (0.05 mg/kg of each compound). In phase II, thirty two (32) calves naturally infected with a resistant strain of Cooperia spp received the same treatments than in phase I but at the therapeutically dose rate of 0.2 mg/kg. Blood samples were taken up to 21 days post-treatment to determine ML concentrations by HPLC. The indirect estimation of the efficacy was performed by faecal egg count reduction test (FECRT). In calves infected with resistant parasites, higher faecal eggs reduction was obtained after the IVM+ABM administration (89 %) compared to the ABM (76.9 %) and IVM (55 %) alone (single?) treatments. The ML plasma concentrations were between 1.66 and 4.38- fold higher during the elimination phase (13-20 days) in the co-administered animals. The better performance observed after the co-administration of IVM and ABM may be based on pharmacodynamic features related to the relative potency of MLs and on the P-glycoprotein-mediated transport interaction at the host and parasite level.