Comparative pharmacokinetic and pharmacodynamics response of single and double intraruminal doses of ivermectin and moxidectin in nematode-infected lambs.

M. LLOBERAS, L. ALVAREZ, C. ENTROCASSO, BALLENT, M., G. VIRKEL, LUQUE, S., C. LANUSSE, A. LIFSCHITZ.

NEW ZEALAND VETERINARY JOURNAL

NEW ZEALAND VETERINARY ASSOC INC

Año: 2015 vol. 131 p. 304 - 309

0048-0169

Aims: The current work assessed the relationship between anthelmintic activity and parasite exposure to ivermectin and moxidectin administered at 0.2 and 0.4 mg/kg to lambs naturally infected with nematodes. The drug concentrations achieved in the host (bloodstream, gastrointestinal content/tissues) and accumulated within Haemonchus contortus were simultaneously evaluated with the clinical efficacy. The aim of the current work was to compare the pharmacokinetics, distribution and efficacy of single and double intraruminal doses of ivermectin and moxidectin in nematode-infected lambs, and to determine the ex-vivo accumulation of these anthelmintics by H. contortus. Methods: Fifty five Romney Marsh lambs were used to perform the in vivo pharmaco-parasitological experiments and the ex vivo assay. A faecal egg count reduction test and a controlled efficacy trial were done. Ivermectin and moxidectin concentrations in plasma, tissues of parasite location and H. contortus were evaluated by HPLC. Additionally, the ex vivo drug accumulation of ivermectin and moxidectin in H. contortus was studied. Results: The peak plasma concentrations and the area under the concentration vs time curve for both ivermectin and moxidectin were higher for the 0.4 compared with 0.2 mg/kg treatments (p