Simultaneous determination of the enantiomers of pimobendan and its main metabolite in rat plasma by high-performance liquid chromatography.
A high-performance liquid chromatographic method for the simultaneous analysis of the enantiomers of pimobendan and its main metabolite, with an n-hexane-ethanol-acetic acid solvent system, has been developed. After solid-phase extraction from plasma, the enantiomers were separated from each other using a Sumichiral OA-4400 column, which is commercially available and contains a chiral stationary phase composed of (S)-proline and (S)-1-(alpha-naphthyl)ethylamine coated on silica. The enantiomers were detected with a fluorescence detector (excitation at 330 nm, emission at 415 nm). The intra- and inter-day precision studies showed good reproducibilities: the coefficients of variation were less than 10.3% for pimobendan enantiomers and 13.0% for metabolite enantiomers. The calibration curves were linear (r2 > 0.996) in the concentration range 1.25-200 ng/ml. The minimum measurable level was 125 pg per 100 microliters of plasma. The method was used in a preliminary pharmacokinetic study in three male rats after intravenous administration of racemic pimobendan (2 mg/kg).
Department of Biochemistry, Kawanishi Pharma Research Institute, Nippon Boehringer Ingelheim Co., Ltd., Hyogo, Japan.
M
M
Asakura
A
A
Nagakura
S
S
Tarui
R
R
Matsumura
D000818:Animals; D002316:Cardiotonic Agents / Q000097:blood* / Q000378:metabolism / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008297:Male; D011724:Pyridazines / Q000097:blood* / Q000378:metabolism / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism
D002316:Cardiotonic Agents; D011724:Pyridazines; C041648:pimobendan