Failure of ivermectin and eprinomectin to control Amblyomma parvum in goats: characterization of acaricidal activity and drug pharmacokinetic disposition

LIFSCHITZ A,; NAVA S,; GUGLIELMONE A.,; IMPERIALE,F; FARIAS, C.; MANGOLD A,; LANUSSE, C.

VETERINARY PARASITOLOGY

Elsevier Inc

Año: 2008 vol. 156 p. 284 - 292

0304-4017

Accepted Manuscript ABSTRACT The therapeutic efficacies of ivermectin (subcutaneous injection) and eprinomectin (topical treatment) given at two different dosage levels to goats naturally infested with 3 The therapeutic efficacies of ivermectin (subcutaneous injection) and eprinomectin 2(topical treatment) given at two different dosage levels to goats naturally infested with 3The therapeutic efficacies of ivermectin (subcutaneous injection) and eprinomectin 2(topical treatment) given at two different dosage levels to goats naturally infested with 3 Amblyomma parvum were assessed. Treatments included subcutaneous injection of 4 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6were assessed. Treatments included subcutaneous injection of 4 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6 parvum on goats. Treatment with ivermectin resulted in a low number of engorged female ticks in relation to untreated control goats and, at the highest dose rate (0.4 mg/kg), the female engorgement weights were significantly lower and the pre- oviposition period significantly longer than those observed in ticks recovered from 10 untreated control goats. The tick efficacy assessment was complemented in a separate 11group of tick-free goats with a pharmacokinetic characterization of eprinomectin 12(topically administered at 0.5, 1.0 and 1.5 mg/kg) and ivermectin (subcutaneous 13treatment given at (0.2 and 0.4 mg/kg) in goats. Heparinized blood samples were taken 14between 0 and 21 days post-treatment. Higher and more persistent drug plasma 15concentrations were recovered after the subcutaneous treatment with ivermectin 16compared to those obtained for eprinomectin topically administered. The understanding of the relationship among the pattern of drug absorption, the kinetic disposition and the resultant clinical efficacy is relevant to improve the poor performance observed for ivermectin and eprinomectin against A. parvum on goats.  female ticks in relation to untreated control goats and, at the highest dose rate (0.4 8female ticks in relation to untreated control goats and, at the highest dose rate (0.4 8 mg/kg), the female engorgement weights were significantly lower and the pre- oviposition period significantly longer than those observed in ticks recovered from untreated control goats. The tick efficacy assessment was complemented in a separate group of tick-free goats with a pharmacokinetic characterization of eprinomectin (topically administered at 0.5, 1.0 and 1.5 mg/kg) and ivermectin (subcutaneous treatment given at (0.2 and 0.4 mg/kg) in goats. Heparinized blood samples were taken between 0 and 21 days post-treatment. Higher and more persistent drug plasma concentrations were recovered after the subcutaneous treatment with ivermectin compared to those obtained for eprinomectin topically administered. The understanding of the relationship among the pattern of drug absorption, the kinetic disposition and the resultant clinical efficacy is relevant to improve the poor performance observed for ivermectin and eprinomectin against A. parvum on goats. The therapeutic efficacies of ivermectin (subcutaneous injection) and eprinomectin (topical treatment) given at two different dosage levels to goats naturally infested with 3 The therapeutic efficacies of ivermectin (subcutaneous injection) and eprinomectin 2(topical treatment) given at two different dosage levels to goats naturally infested with 3The therapeutic efficacies of ivermectin (subcutaneous injection) and eprinomectin 2(topical treatment) given at two different dosage levels to goats naturally infested with 3 Amblyomma parvum were assessed. Treatments included subcutaneous injection of 4 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6were assessed. Treatments included subcutaneous injection of 4 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6 parvum on goats. Treatment with ivermectin resulted in a low number of engorged female ticks in relation to untreated control goats and, at the highest dose rate (0.4 mg/kg), the female engorgement weights were significantly lower and the pre- oviposition period significantly longer than those observed in ticks recovered from 10 untreated control goats. The tick efficacy assessment was complemented in a separate 11group of tick-free goats with a pharmacokinetic characterization of eprinomectin 12(topically administered at 0.5, 1.0 and 1.5 mg/kg) and ivermectin (subcutaneous 13treatment given at (0.2 and 0.4 mg/kg) in goats. Heparinized blood samples were taken 14between 0 and 21 days post-treatment. Higher and more persistent drug plasma 15concentrations were recovered after the subcutaneous treatment with ivermectin 16compared to those obtained for eprinomectin topically administered. The understanding of the relationship among the pattern of drug absorption, the kinetic disposition and the resultant clinical efficacy is relevant to improve the poor performance observed for ivermectin and eprinomectin against A. parvum on goats.  female ticks in relation to untreated control goats and, at the highest dose rate (0.4 8female ticks in relation to untreated control goats and, at the highest dose rate (0.4 8 mg/kg), the female engorgement weights were significantly lower and the pre- oviposition period significantly longer than those observed in ticks recovered from untreated control goats. The tick efficacy assessment was complemented in a separate group of tick-free goats with a pharmacokinetic characterization of eprinomectin (topically administered at 0.5, 1.0 and 1.5 mg/kg) and ivermectin (subcutaneous treatment given at (0.2 and 0.4 mg/kg) in goats. Heparinized blood samples were taken between 0 and 21 days post-treatment. Higher and more persistent drug plasma concentrations were recovered after the subcutaneous treatment with ivermectin compared to those obtained for eprinomectin topically administered. The understanding of the relationship among the pattern of drug absorption, the kinetic disposition and the resultant clinical efficacy is relevant to improve the poor performance observed for ivermectin and eprinomectin against A. parvum on goats. The therapeutic efficacies of ivermectin (subcutaneous injection) and eprinomectin 2(topical treatment) given at two different dosage levels to goats naturally infested with 3 Amblyomma parvum were assessed. Treatments included subcutaneous injection of 4 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6were assessed. Treatments included subcutaneous injection of 4 ivermectin at 0.2 and 0.4 mg/kg and extra-label pour-on administration of eprinomectin 5at 0.5 and 1 mg/kg b.w. Ivermectin and eprinomectin failed to control Amblyomma 6 parvum on goats. Treatment with ivermectin resulted in a low number of engorged female ticks in relation to untreated control goats and, at the highest dose rate (0.4 mg/kg), the female engorgement weights were significantly lower and the pre- oviposition period significantly longer than those observed in ticks recovered from 10 untreated control goats. The tick efficacy assessment was complemented in a separate 11group of tick-free goats with a pharmacokinetic characterization of eprinomectin 12(topically administered at 0.5, 1.0 and 1.5 mg/kg) and ivermectin (subcutaneous 13treatment given at (0.2 and 0.4 mg/kg) in goats. Heparinized blood samples were taken 14between 0 and 21 days post-treatment. Higher and more persistent drug plasma 15concentrations were recovered after the subcutaneous treatment with ivermectin 16compared to those obtained for eprinomectin topically administered. The understanding of the relationship among the pattern of drug absorption, the kinetic disposition and the resultant clinical efficacy is relevant to improve the poor performance observed for ivermectin and eprinomectin against A. parvum on goats.  female ticks in relation to untreated control goats and, at the highest dose rate (0.4 8female ticks in relation to untreated control goats and, at the highest dose rate (0.4 8 mg/kg), the female engorgement weights were significantly lower and the pre- oviposition period significantly longer than those observed in ticks recovered from untreated control goats. The tick efficacy assessment was complemented in a separate group of tick-free goats with a pharmacokinetic characterization of eprinomectin (topically administered at 0.5, 1.0 and 1.5 mg/kg) and ivermectin (subcutaneous treatment given at (0.2 and 0.4 mg/kg) in goats. Heparinized blood samples were taken between 0 and 21 days post-treatment. Higher and more persistent drug plasma concentrations were recovered after the subcutaneous treatment with ivermectin compared to those obtained for eprinomectin topically administered. The understanding of the relationship among the pattern of drug absorption, the kinetic disposition and the resultant clinical efficacy is relevant to improve the poor performance observed for ivermectin and eprinomectin against A. parvum on goats.