EVALUATION OF THE COMBINED USE OF IVERMECTIN AND RICOBENDAZOLE IN CATTLE: PHARMACOKINETIC AND/OR PHARMACODYNAMIC INTERACTIONS

CANTON, C.; CEBALLOS, L.; MORENO, L.; FIEL, C.; YAGUEZ, P.; LANUSSE, C.; ALVAREZ, L.

Gramado

Congreso; XVIII Congreso Brasilero de Parasitologia Veterinaria; 2014

Asociacion Brasilera de Parasitologia Veterinaria

The main goal of the current trial was to study the clinical efficacy and the potential pharmacokinetic and/or pharmacodynamic interactions occurring after the subcutaneous (SC) administration of ivermectin (IVM) and ricobendazole (RBZ) given either separately or co-administered to parasitized calves. Sixty (60) male calves naturally infected with gastrointestinal nematodes resistant to IVM were randomly allocated into four groups (n= 15): Control group: animals did not receive anthelmintic treatment; IVM group: animals were treated with IVM by the SC route (0,2 mg/kg); RBZ group: animals were treated with RBZ by the SC route (3,75 mg/kg); IVM+RBZ group: animals were treated by the SC route with IVM and RBZ (0,2 and 3,75 mg/kg, respectively). Eight animals of each treated group were randomly selected to perform the pharmacokinetic study. Plasma samples were taken from these animals up-to 28 days post-treatment. IVM and RBZ were quantified by HPLC. The clinical efficacy was determined by Faecal Egg Count Reduction Test (FECRT). The IVM area under the concentration vs time curve (AUC) obtained after administration of IVM alone (348±80.8 ng.d/ml) was similar to that obtained after IVM was co-administered with RBZ (390±93.2 ng.d/ml). Likewise, RBZ AUC values were similar after RBZ administration alone (10.8±3.44 µg.h/ml) or combined with IVM (10.9±4.70 µg.h/ml). The efficacies were 48% (IVM), 94% (RBZ) and 98% (IVM+RBZ). No significant differences in the egg counts were observed between groups RBZ and IVM+RBZ (P > 0.05). No pharmacokinetic interactions were observed after the combined treatment, with similar pharmacokinetic parameters (P> 0.05) obtained between the single-drug and combined treatments. In conclusion, no therapeutic advantage was observed for the combination IVM+RBZ as compared with the treatment with RBZ alone.