Assessment of the biotransformation of the cardiotonic agent piroximone by high-performance liquid chromatography and gas chromatography-mass spectrometry.
14C-labelled piroximone was administered to rats at a dose of 10 mg/kg body weight. Of the total radioactivity administered, 74.9 +/- 7.9% (n = 4) and 87.8 +/- 1.7 (n = 3) were recovered in the 8-h urine collection after oral and intravenous administration, respectively. Two major metabolites, M1 and M2, were detected in methanol extracts and accounted for 7.1 +/- 1.2% (n = 4) (M1) and 4.3 +/- 0.4% (n = 4) (M2) in response to oral administration and 5.7 +/- 0.8% (n = 3) (M1) and 6.7 +/- 2.0% (n = 3) (M2) in response to intravenous administration. In addition, three minor metabolites were detected; M3 and M4 in the 8-h urine collection and M5 in the 12-h urine collection. Separation of piroximone and metabolites was achieved by high-performance liquid chromatography on a C18 column by gradient elution with 0.05 M ammonium acetate (pH 7) using 0-60% methanol over 20 min at a flow-rate of 1 ml/min, followed by isocratic elution with 60% methanol for 10 min. M1 and M2 were isolated by fraction collection following the addition of 1 mM tetrabutylammonium acetate in the mobile phase. Between each injection a column re-equilibration time of 45 min was necessary to achieve optimum collection of M1 and M2 fractions. Gas chromatography-mass spectrometry of M1 provided evidence for a molecular structure consistent with isonicotinic acid methyl ester. Corroborative evidence for this identification was obtained by comparison with a synthetic standard. Isonicotinic acid is assumed to be the actual metabolite while esterification with methanol had occurred as a result of the work-up procedure.(ABSTRACT TRUNCATED AT 250 WORDS)
Berg-Candolfi
M
M
Department of Clinical Biochemistry, Marion Merrell Dow, Strasbourg, France.
Borlakoglu
J T
JT
Dulery
B
B
Jehl
F
F
Haegele
K D
KD
D000818:Animals; D001711:Biotransformation; D002316:Cardiotonic Agents / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D007093:Imidazoles / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D002316:Cardiotonic Agents; D007093:Imidazoles; C039686:piroximone