INVESTIGADORES
LANUSSE Carlos Edmundo
congresos y reuniones científicas
Título:
Pharmacokinetic and field efficacy evaluations of alternative drug-based strategies to optimize control of resistant nematodes in cattle
Autor/es:
CANTÓN, CANDELA; CEBALLOS, LAURA; DOMINGUEZ, MARÍA PAULA; BALLENT, MARIANA; LIFSCHITZ, ADRIAN LUIS; ALVAREZ, LUIS IGNACIO; LANUSSE, CARLOS EDMUNDO
Lugar:
Bonn
Reunión:
Congreso; 29° Annual Meeting of the German Society for Parasitology; 2021
Resumen:
Considering the increasing development of anthelmintic resistance, combinations of drugs from different chemical families, pharmacokinetic-based optimization approaches to enhance parasite exposure, and the indication of less-used anthelmintic molecules (i.e. monepantel) have been proposed as valid strategies to manage and/or delay the development of anthelmintic resistance in cattle nematodes. Different pharmaco-parasitological assessments including the concomitant administration of different chemical compounds by different routes of administration (subcutaneous and oral), and the strategic use of monepantel (MNP), were performed on a large scale commercial cattle farm in Argentina. Two nematodicidal combinations of a macrocyclic lactone (ML) and a benzimidazole (BZD) were evaluated in a multi-resistant scenario. Ivermectin (IVM)+ricobendazole (RBZ) both given subcutaneously and abamectin (ABM)+oxfendazole (OFZ) both given orally were assessed in calves naturally infected with gastrointestinal nematodes resistant to both chemical families. The observed pharmacokinetic (PK) data demonstrated that the co-administration of two anthelmintics did not modify the plasma PK disposition of either drug in cattle. In fact, no adverse PK interactions were observed after each combined treatment. Similar PK parameters (P>0.05) were obtained between the single-drug and the combined-based strategies. While the observed initial efficacies were 40% (IVM), 64% (RBZ) and 90% (IVM+RBZ), after fourth year repeated annual use of the same combination, the efficacy of the IVM+RBZ decreased to 75%. To optimize drug activity against those highly bi-resistant nematode population, oral treatments were assayed. Efficacies of ABM alone, OFZ alone and the co-administration ABM+OFZ were 62%, 88% and 99%, respectively. Overall, the efficacies of the combined treatments against multiresistant nematodes were greater than an additive effect. Moreover, an egg reduction of 98% demonstrated the high efficacy of the less used MNP molecules against nematodes resistant to ML and BZD in cattle. In conclusion, all the described drug-based anthelmintic approaches should be strategically considered when dealing with multiresistant parasites in cattle. The rational use of these strategies should be strongly supported by pre-treatment diagnosis and considering the epidemiological situation of each individual farm.