Ac. Chukwudebe et al., METABOLISM OF THIABENDAZOLE IN LAYING HEN AND LACTATING GOATS, Journal of agricultural and food chemistry, 42(12), 1994, pp. 2964-2969
Thiabendazole (TBZ), an anthelminthic and fungicide of the benzimidazo
le class, was rapidly metabolized by lactating goats and laying hens.
In lactating goats dosed orally with 120 mg of [C-14]TBZ daily for 7 c
onsecutive days and sacrificed at about 24 h after the final dose, an
average of 74% of the total administered dose was accounted for in the
matrices analyzed. Nearly all of this recovered radioactivity was fou
nd in the excreta (urine, 69%; feces, 28%) with very little (less than
or equal to 3%) in milk: and tissues (liver, kidney, fat; muscle). In
laying hens dosed orally with 3.19 mg of [C-14]TBZ daily for 10 conse
cutive days and sacrificed at about 24 h after the final dose, an aver
age of about 97% of the total administered dose was accounted for in t
he matrices analyzed. Nearly all (>99%) of this recovered radioactivit
y was found in the excreta with very little in the eggs (similar to 0.
16%) and tissues (0.29%). Enzyme preparations (Glusulase, sulfatase, b
eta-glucuronidase) and strong acid hydrolyses were used to release TBZ
and its metabolites from hen and goat tissues and matrices. On the ba
sis of these enzymic and acid hydrolyses, and subsequent HPLC radiochr
omatographic and GC/MS analyses of the extracts, the major metabolite
of TBZ in the excreta, edible tissues, milk, and eggs was determined t
o be 5-hydroxythiabendazole or its O-sulfate conjugate. Minor amounts
of benzimidazole and TBZ were also found in most of the goat and hen t
issues examined. The results of this study show that the metabolic fat
es of TBZ in lactating goats and laying hens are similar, predominantl
y involving hydroxylation at the 5-position followed by sulfation.