Anthelmintic Efficacy and Pharmacokinetics of Ivermectin Paste after Oral Administration in Mules Infected by Cyathostomins
Marilena Bazzano1, Alessandra Di Salvo2, Manuela Diaferia2
1School of Biosciences and Veterinary Medicine, University of Camerino, Via Circonvallazione, 62024 Matelica (MC), Italy.
Abstract:
Ivermectin (IVM) is an anthelmintic compound commonly used off-label in mules due to its broad-spectrum of activity. Despite the general use of IVM in mules with the same dose and route of administration licensed for horses, significant pharmacokinetic differences might exist between horses and mules, as already observed for donkeys. The aim of the present study was to evaluate the pharmacokinetic profile and anthelmintic efficacy of an oral paste of IVM in mules naturally infected with cyathostomins. Fifteen adult mules with fecal egg counts (FEC) ≥200 eggs per gram (EPG), with exclusive presence of cyathostomins, were included in the study. All mules were orally treated with IVM according to the manufacturer's recommended horse dosage (200 µg/kg body weight). FECs were performed before (day-10 and day-3) and after treatment at days 14 and 28 by using a modified McMaster method. The FEC reduction (FECR%) was also calculated. Blood samples were collected from five animals at various times between 0.5 h up to 30 days post treatment to determine pharmacokinetic parameters. The maximum IVM serum concentration (Cmax) was 42.31 ± 10.20 ng/mL and was achieved at 16.80 ± 9.96 hours post-treatment (Tmax), area under the curve (AUC) was 135.56 ± 43.71 ng × day/mL. FECR% remained high (>95%) until the 28th day.
Insights
This study found that ivermectin (IVM) oral paste effectively reduced cyathostomin parasite eggs in mules for 28 days. The drug demonstrated a favorable pharmacokinetic profile, supporting its use in equine medicine.
Area of Science:
- Veterinary Pharmacology
- Parasitology
Background:
- Ivermectin (IVM) is widely used off-label in mules for its broad-spectrum anthelmintic properties.
- Pharmacokinetic differences between horses and mules may necessitate specific dosage evaluations, similar to observations in donkeys.
Purpose of the Study:
- To assess the pharmacokinetic profile of oral ivermectin paste in mules.
- To evaluate the anthelmintic efficacy of ivermectin against natural cyathostomin infections in mules.
Main Methods:
- Fifteen mules with confirmed cyathostomin infections received oral ivermectin (200 µg/kg).
- Fecal egg counts (FEC) were monitored pre- and post-treatment (days 14 and 28).
- Serum ivermectin concentrations were measured in five mules over 30 days to determine pharmacokinetic parameters.
Main Results:
- The maximum serum concentration (Cmax) of ivermectin was 42.31 ± 10.20 ng/mL, reached at 16.80 ± 9.96 hours (Tmax).
- The area under the curve (AUC) was 135.56 ± 43.71 ng × day/mL.
- Fecal egg count reduction (FECR%) remained above 95% through day 28.
Conclusions:
- Oral ivermectin paste at the recommended equine dosage is effective in reducing cyathostomin burdens in mules.
- The pharmacokinetic profile supports the efficacy and duration of action observed in this study.
- This research validates the current off-label use of ivermectin in mules for cyathostomin control.
