A high performance liquid chromatographic method for the determination of febantel and its major metabolites in lamb plasma

Abstract

A high performance liquid chromatographic (HPLC) method for the determination of the anthelminthic pro-benzimidazole febantel and its major metabolites in lamb plasma has been developed. Samples were extracted after addition of albendazole as internal standard, NH4OH and distilled diethyl ether. The extracted phase was dried under a stream of nitrogen redissolved in methanol and chromatographed by HPLC. Detection was by UV absorbance at 292 nm. Recovery from the plasma was 97.2, 97.1, 54.5 and 88.0% for febantel, fenbendazole, oxfendazole and oxfendazole sulphone respectively, and within-day and between-day coefficients of variation were 4.03, 4.69, 3.57 and 5.06% and 4.25, 3.73, 5.12 and 4.12%, respectively, for febantel, fenbendazole, oxfendazole and oxfendazole sulphone. The specificity and sensitivity of this method (limit of detection in plasma 0.025 micrograms/mL and < or = 0.0125 micrograms/mL for febantel and its metabolites, respectively) were sufficiently high to enable us to characterize the time course of the drug in the plasma after oral administration of therapeutic doses to sheep.

Plasma concentrations of fenbendazole (FBZ) and oxfendazole in alpacas (Lama pacos) after single intravenous and oral dosing of FBZ

“…The mobile phase consisted of 0.01 M phosphoric acid (pH 4.0) and acetonitrile (60%:40%, v/v). 1 The vacuum degassed and filtered (0.22 µm pore size filter) mobile phase was delivered at 1.0 mL/min. Column temperature was maintained at 35°C.…”

“…A 200 µL volume of 0.1 N ammonium hydroxide was added to control and spiked plasma to increase pH. 1 The samples were vortexed, and 5 mL of m-tBE was added to each tube, capped, and revortexed for 1 minute. Ether-containing samples were centrifuged at 1,000× g for 10 minutes at 4°C to separate the aqueous layer from ether layers.…”

Review of methodology for the determination of benzimidazole residues in biological matrices

“…Bogan and Marriner [139] adjusted the pH of plasma to pH 7.4 before extracting FBZ, OFZ and ABZ residues with diethyl ether. Bogan's procedure has been applied for isolation of benzimidazole residues from plasma and blood [140][141][142]. Other groups have developed alternative procedures, while substituting solvents such as chloroform [143,144] and ethyl acetate [145][146][147] for diethyl ether.…”

A novel spectrophotometric approach for the determination of febantel in pure and dosage forms

“…Reported methods include determination of FBT in combination with the other anthelmintic drugs like flubendazole, oxfendazole and oxfendazole sulfone etc. These include High performance liquid chromatography (HPLC) (Dusi et al, 2005;Wanda and Anna, 2010;Delatour et al, 1983;Landuyt et al, 1993;Chou et al, 2004) with ultraviolet (UV) (Kawasaki et al, 1999) or gas chromatography/mass spectrometry (GC/MS) (Wilson et al, 1991). So far there is no visible spectrophotometric method developed for the analysis of FBT in pure and dosage forms.…”