Metabolism of Thiabendazole in Laying Hen and Lactating Goats

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

“…The major residue found in tissue at 1 day post-treatment was TBZ, with lower levels of 5-OH-TBZ present. The same study showed that at 1 day post-treatment, 5-OH-TBZ was the major residue detected in the tissues of laying hen, with lower levels of TBZ found [101]. Residues occurred mainly in the kidney with lower levels found in the liver.…”

“…At later withdrawal periods (>2 days), residues were mainly found in the liver [100]. Chukwudebe et al [101] investigated the fate of TBZ residues in goats treated with oral doses (120 mg per animal daily for 7 days). Residues were shown to occur mainly in the liver and kidney.…”

“…Tocco et al [66] later used similar procedures to deconjugate 5-OH-TBZ residues present in the milk of cows and goats treated with TBZ. Chukwudebe et al [101] completed a more detailed study into the metabolism of TBZ in laying hens and lactating species, using enzymatic and acid hydrolysis, and found that conjugates were mainly present as sulfates. VandenHeuvel et al [122] also deconjugated 5-OH-TBZ by enzymatic and acid hydrolysis in a study in bluegill sunfish.…”

NHR-176 regulates cyp-35d1 to control hydroxylation-dependent metabolism of thiabendazole in Caenorhabditis elegans

“…This hydrophilic compound is likely to be rapidly excreted and was also detected in culture medium after 6 h of TBZ exposure in gfp controls (result not shown). Glucosidation is not a common pathway in mammals and has not been reported in any studies which have investigated metabolism of TBZ or ABZ in mammals [10,11,[46][47][48][49]. Interestingly, glucose conjugates of ABZ have also been reported in C. elegans and the parasitic nematode Haemonchus contortus which suggests that bio-transformation pathways could be conserved in strongylid nematodes [36,50].…”

“…Biotransformation of this commonly used anthelmintic has been studied in mammals. TBZ is extensively metabolized via hydroxylation of the benzimidazole (BZ) ring at the 5-positition to form 5-hydroxythiabendazole, which is further metabolized to glucuronide and sulfate conjugates [10,11]. TBZ induces the expression of CYP families CYP1A and CYP2B in rats in vivo [12] and rabbit CYP1A2 in vitro [13].…”