title: The influence of a heavy infection with sensitive and resistant strains of Ostertagia circumcincta and with Trichostrongylus colubriformis on the pharmacokinetics of febantel in lambs.
abstract: Plasma concentrations of febantel and its major metabolites, fenbendazole, oxfendazole and fenbendazole sulphone, were determined after oral administration of 7.5 mg/kg febantel in lambs before and 28 days after infection with 100,000 L3 larvae of a benzimidazole (BZ)-sensitive or BZ-resistant strain of Ostertagia circumcincta or with 75,000 L3 larvae of a BZ-sensitive Trichostrongylus colubriformis strain. The febantel concentrations were always low, and in only a few samples were higher than the limit of detection. A mean decrease in the area under the curve (AUC) for the three metabolites of 10.2%, 16.4% and 4.9% in lambs infected, respectively, with BZ-sensitive O. circumcincta, BZ-resistant O. circumcincta and T. colubriformis was observed. The Cmax for all the metabolites was higher in the BZ-sensitive O. circumcincta group than in the naive sheep, while the Tmax occurred earlier. The Cmax and the Tmax values for all the metabolites were lower in the BZ-resistant O. circumcincta group than in their own naive controls. In the T. colubriformis group the Cmax values of the metabolites were lower and the Tmax occurred much later.
authors.affiliation: Faculteit Diergeneeskunde, Universiteit Gent, Merelbeke, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Landuyt
authors.forename: M
authors.initials: M
authors.lastname: Debackere
authors.forename: J
authors.initials: J
authors.lastname: Vercruysse
authors.forename: Q
authors.initials: Q
authors.lastname: McKellar
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000871:Anthelmintics / Q000493:pharmacokinetics*; D001562:Benzimidazoles / Q000097:blood / Q000494:pharmacology; D004351:Drug Resistance; D005243:Feces / Q000469:parasitology; D005273:Fenbendazole / Q000031:analogs & derivatives / Q000097:blood; D006146:Guanidines / Q000493:pharmacokinetics*; D008297:Male; D010028:Ostertagia / Q000187:drug effects; D010029:Ostertagiasis / Q000188:drug therapy / Q000378:metabolism / Q000469:parasitology / Q000662:veterinary*; D010270:Parasite Egg Count / Q000662:veterinary; D010435:Pepsinogens / Q000097:blood; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy / Q000378:metabolism* / Q000469:parasitology; D014253:Trichostrongylosis / Q000188:drug therapy / Q000378:metabolism / Q000469:parasitology / Q000662:veterinary*; D014254:Trichostrongylus / Q000187:drug effects
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D006146:Guanidines; D010435:Pepsinogens; D005273:Fenbendazole; C011030:oxfendazole; C017309:febantel