Pharmacological evaluation of a combined albendazole, ivermectin and levamisole formulation in lambs.

SUAREZ, G.; ALVAREZ, L.; CASTELLS, D.; MORENO, L.; FAGGIOLINO, P.; LANUSSE, C.

Calgary, Canada

Congreso; 22 International Conference of the World Association for the Advancement of Veterinary Parasitology; 2009

Asociacion Mundial para el avance de la Parasitología Veterinaria

The goals of the current trial were: a) to characterize the plasma pharmacokinetics (PK) of albendazole (ABZ), ivermectin (IVM) and levamisole (LVS) administered either alone or co-administered to lambs; b) to compare the efficacy of the same drugs given separately or co-administered to lambs infected with resistant nematodes. Fifty (50) Corriedale lambs naturally infected with multiple resistant gastrointestinal nematodes were involved.  a) “PK  study”: The animals were allocated into four groups (n=10 each) and intraruminally treated either with ABZ (5 mg/kg), IVM (0.2 mg/kg), LVS (8 mg/kg) or with a combined formulation of ABZ+IVM+LVS (RaiderPlus®, Cibeles, Uruguay) at the same dose rates for each active ingredient. Blood samples were collected over 15 days post-treatment and drug plasma concentrations measured by HPLC. b) “Clinical efficacy trial”: An untreated control group (n=10) was included. The efficacy estimation was performed by the faecal egg count reduction test (FECRT). Although LVS kinetics was unaffected, significantly lower (65%) ABZ-sulphoxide and higher (66%) IVM plasma availabilities were obtained after treatment with the combined formulation in comparison to those obtained after the treatment with each drug alone. FECRT values were 64% (ABZ), 83% (IVM), 55% (LVS) and 91% (combined formulation). However, no differences (P>0.05) were observed on faecal egg counts among experimental groups. In conclusion, a PK interaction among drugs was observed and the combined formulation did not offer a clinically relevant increase in efficacy against resistant nematodes. Thus, further understanding of potential pharmacological interactions is needed before drug combined formulations are introduced into the pharmaceutical market.