Pharmacokinetics and bioequivalence in the pig of two ivermectin feed formulations


  • The author D. Hennessy – Deceased.

Peter Lees, The Royal Veterinary College, Hawkshead Campus, Hatfield, Herts AL9 7TA, UK. E-mail:


Two premix products containing the endectocide ivermectin were compared for pharmacokinetic profiles and bioequivalence in young pigs. Test and reference articles were administered to individual pigs in-feed at 12-h intervals for a total of 14 doses. Plasma concentration–time profiles were compared after provision of the final doses of medicated feed, by which time steady-state concentrations of ivermectin had been achieved. The pharmacokinetic variables monitored were peak concentration (Cmax), area under the curve (AUC)0–last, elimination half-life of the terminal phase (T1/2 λz) and average steady-state concentration (Css), determined by noncompartmental analysis. Logarithmic transformation of the variables was carried out when appropriate. Analysis of data by the Classic Method yielded confidence intervals of 80.59–114.47 (for AUC0–last), 90.38–119.68 (for Cmax) and 84.70–111.96 (for Css). It was concluded that the two articles were bioequivalent for ivermectin.