Plasma pharmacokinetics and faecal excretion of ivermectin (Eqvalan® paste) and doramectin (Dectomax®, 1%) following oral administration in donkeys

Ivermectin (IVM- Eqvalan® paste, 1.87%) and doramectin (DRM-Dectomax® 1%) were each administered orally to donkeys at 200 μg kg−1 bodyweight. Blood and faecal samples were collected at predetermined times over 30 days and plasma pharmacokinetics and faecal excretion determined. Maximum plasma concentrations (Cmax) of IVM (23.6 ng ml−1) and DRM (33.9 ng ml−1) were obtained at (tmax) 19.2 and 24 h, respectively. The area under the concentration curve (AUC) of DRM (228.9 ng day ml−1) was significantly larger than that of IVM (119.3 ng day ml−1) and mean residence time (MRT) was 6.5 days for IVM and 9.1 days for DRM. The highest (dry weight) faecal concentrations (9.33 μg g−1 - IVM, 12.12 μg g−1 - DRM) were detected at 55.9 and 48.0 h, respectively and each compound was detected (⩾0.05 μg g−1) in faeces between 11 h and 9 days following oral administration in donkeys.