Drug combination against multiple resistant nematodes: albendazole-ivermectin kinetic interaction and clinical efficacy in lambs

ENTROCASSO, C.; ALVAREZ, L.; MANAZZA, J.; LIFSCHITZ, A.; BORDA, B.; VIRKEL, G.; MOTTIER, L.; LANUSSE, C.; ENTROCASSO, C.; ALVAREZ, L.; MANAZZA, J.; LIFSCHITZ, A.; BORDA, B.; VIRKEL, G.; MOTTIER, L.; LANUSSE, C.

Gent, Belgica

Conferencia; 21International Conference of the World Association for the Advancement of Veterinary Parasitology; 2007

World Association for the Advancement of the Veterinary Parasitology

  It has been suggested that drug combinations may be efficacious against resistant nematode strains where the failure of individual drugs is documented. The trials reported here were addressed to compare the clinical efficacy and plasma pharmacokinetic behaviour of albendazole (ABZ) and ivermectin (IVM) given either separately or co-administered to lambs naturally infected with resistant nematodes. Seventy parasitized lambs were involved in the following trials:  a) “Clinical efficacy study”: The animals were allocated into 7 groups (n= 10), untreated control  and treated either with ABZ iv (Group I), IVM iv (Group II), ABZ iv + IVM iv (Group III), ABZ ir (Group IV), IVM sc (Group V) and ABZ ir + IVM sc (Group VI). The efficacy of the different treatments was estimated by the FECRT. b) “Pharmacokinetic study”: Animals from Groups I to VI (n= 6) were used in this trial. Plasma samples were collected over 15 days post-treatment and drug concentrations measured by HPLC. Parametric and non-parametric statistical tests were applied. The following egg output reduction values were obtained: 67.1% (Group I), 78.3% (Group II), 91.9% (Group III), 44.3% (Group IV), 77.9% (Group V) and 68.6% (Group VI). The drug-drug kinetic interaction accounted for: 1) a higher IVM plasma AUC obtained in the ABZ iv + IVM iv (Group III) compared to the IVM alone treatment (Group II); 2) a higher ABZ-sulphoxide AUC value obtained in the presence of IVM (Group VI) compared to ABZ alone (Group IV). Finally, the co-administration ABZ-IVM results in a non-adverse kinetic interaction, which may facilitate an additive drug effect against resistant nematodes.