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Stability of ivermectin in rumen fluids
Author(s) -
ANDREW N. W.,
HALLEY B. A.
Publication year - 1996
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1111/j.1365-2885.1996.tb00052.x
Subject(s) - ivermectin , rumen , biology , chemistry , food science , zoology , fermentation
To determine whether ivermectin is metabolized in the rumen, in vitro studies were conducted with the tritium‐labelled H 2 B 1a component of ivermectin in rumen fluid from sheep and cattle. No detectable metabolism occurred over 24 h in in vitro incubations at 38°. The viability of the microbes in the rumen fluids was demonstrated by the conversion of 17% and 11% of [ 14 C]cellulose to 14 CO 2 in 24 h in the incubations with sheep and steer rumen fluids respectively. The results indicate that ivermectin is not metabolized in the rumen. Based on the lack of in vitro metabolism of ivermectin in rumen fluid, the similarity of in vitro liver microsomal metabolism with in vivo metabolism of the avermectins and the physicochemical properties of the avermectins, any disappearance of ivermectin in vitro from rumen fluid is probably a result of binding to solids or surfaces. Apparent discrimination by dung beetles, where observed, between control faeces and faeces from cattle or sheep treated with ivermectin or abamectin therefore must be attributable to chance, to factors unrelated to treatment or to factors such as changes in amino acid composition rather than the production of volatile metabolites of ivermectin.