Profiling of free and conjugated [3H]zeranol metabolites in pig plasma.
Extraction and high-performance liquid chromatographic (HPLC) procedures are described that permit the complete analysis of free and conjugated zeranol metabolites in plasma from pigs implanted with [3H]zeranol. Free metabolites (9.0%) are extracted and then analysed by radio-HPLC on a reversed phase C18 column. They are distributed between three compounds that have been identified by gas chromatography-mass spectrometry as taleranol, zeranol and zeralanone. Direct radio-HPLC of the pre-extracted, deproteinated and Sep-Pak C18-purified plasma on a reversed-phase C18 column using tetrabutylammonium as an ion-pairing agent showed four main peaks: one corresponds to a weakly retained unidentified compound(s) (20%) and the other three were identified as the taleranol, zeranol and zeralanone glucuro conjugates. However, the total recovery is only about 25% owing to strong affinity of this polar material for the plasma proteins. Enzymatic deconjugation of the pre-extracted plasma followed by radio-HPLC analysis of the freed metabolites led to a good recovery of the radioactivity (81.8%) and allowed the quantitation of the different metabolites. These preliminary results indicate that zeranol is metabolized in the pig following pathways similar to those in other tested species.
Bories
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INRA, Laboratoire des Xénobiotiques, Toulouse, France.
Suarez
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AF
D000818:Animals; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D005260:Female; D012118:Resorcinols / Q000097:blood*; D013552:Swine; D015029:Zeranol / Q000097:blood* / Q000493:pharmacokinetics
D012118:Resorcinols; D015029:Zeranol