Pharmacokinetics of fenbendazole following intravenous and oral administration to pigs.
OBJECTIVE
To determine pharmacokinetics and metabolic patterns of fenbendazole after IV and oral administration to pigs.


METHODS
4 mixed-breed female pigs weighing 32 to 45 kg.


METHODS
Fenbendazole was administered IV at a dose of 1 mg/kg. One week later, it was administered orally at a dose of 5 mg/kg. Blood samples were collected for up to 72 hours after administration, and plasma concentrations of fenbendazole, oxfendazole, and fenbendazole sulfone were determined by use of high-pressure liquid chromatography. Plasma pharmacokinetics were determined by use of noncompartmental methods.


RESULTS
Body clearance of fenbendazole after IV administration was 1.36 L/h/kg, volume of distribution at steady state was 3.35 L/kg, and mean residence time was 2.63 hours. After oral administration, peak plasma concentration of fenbendazole was 0.07 microg/ml, time to peak plasma concentration was 3.75 hours, and mean residence time was 15.15 hours. Bioavailability of fenbendazole was 27.1%. Oxfendazole was the major plasma metabolite, accounting for two-thirds of the total area under the plasma concentration versus time curve after IV and oral administration. Fenbendazole accounted for 8.4% of the total AUC after IV administration and 4.5% after oral administration.


CONCLUSIONS
Results indicate that fenbendazole was rapidly eliminated from plasma of pigs. The drug was rapidly absorbed after oral administration, but systemic bioavailability was low.
Petersen
M B
MB
Department of Pharmacology and Pathobiology, Royal Veterinary and Agricultural University, Copenhagen, Denmark.
Friis
C
C
D000284:Administration, Oral; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001562:Benzimidazoles / Q000097:blood; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D018592:Cross-Over Studies; D005260:Female; D005273:Fenbendazole / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D007275:Injections, Intravenous / Q000662:veterinary; D013552:Swine / Q000378:metabolism*
D000871:Anthelmintics; D001562:Benzimidazoles; D005273:Fenbendazole; C011030:oxfendazole