Deeper into knowledge of eprinomectin: pharmacokinetics, efficacy, cross-resistance

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00027162%3A_____%2F25%3AN0000049" target="_blank" >RIV/00027162:_____/25:N0000049 - isvavai.cz</a>

Result on the web

<a href="https://waavp2025.com/" target="_blank" >https://waavp2025.com/</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Deeper into knowledge of eprinomectin: pharmacokinetics, efficacy, cross-resistance

Original language description

This contribution was presented as a poster at the 30th Conference of the World Association for the Advancement of Veterinary Parasitology (WAAVP 2025), held in Curitiba, Brazil, from 17 to 21 August 2025. Introduction: Eprinomectin is widely used in veterinary medicine for controlling parasitic nematodes. However, its transdermal absorption and efficacy require optimization. This study aimed to develop and evaluate novel pour-on formulations of eprinomectin, assessing their pharmacokinetic properties and anthelmintic efficacy against Haemonchus contortus in sheep. Objective: The primary objective was to formulate new eprinomectin pour-on compositions and compare their pharmacokinetics and efficacy with commercial references in preclinical trials. Methods: Several formulations were developed using self-emulsifying microemulsions containing surfactants, co-surfactants, and penetration enhancers. In vitro permeation studies were conducted using Franz diffusion cells with synthetic membranes and porcine skin. Two optimized formulations (F1, F2) were selected for in vivo pharmacokinetic and efficacy studies in sheep. Drug absorption was evaluated through plasma concentration-time profiles (Cmax, Tmax, AUC). Efficacy was assessed using the faecal egg count reduction test (FECRT). Results: Pharmacokinetic analysis showed that Cmax values for F1 (4.4 ng/ml) and F2 (4.8 ng/ml) were comparable to the reference product (4.4 ng/ml), with AUC values of 667 and 735 ng·h/ml, respectively. Despite adequate drug exposure, FECRT results indicated suboptimal efficacy (F1: 0.0%; F2: 23.1%) compared to the reference product (46.1%). Molecular analysis confirmed H. contortus resistance to eprinomectin, likely due to previous ivermectin treatments in the original sheep flock. Conclusion: Although the novel formulations achieved bioequivalent pharmacokinetic profiles, their clinical efficacy was compromised by anthelmintic resistance. Future studies should explore alternative formulations or combination therapies to address resistance challenges in parasitic nematodes.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

40301 - Veterinary science

Project

<a href="/en/project/TN02000017" target="_blank" >TN02000017: National Centre for Biotechnology in Veterinary Medicine</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů