Simultaneous analysis of the enantiomers of verapamil and norverapamil in rat plasma by liquid chromatography-tandem mass spectrometry.
An enantioselective micromethod for the simultaneous analysis of verapamil (VER) and norverapamil (NOR) in plasma was developed, validated and applied to the study of the kinetic disposition of VER and NOR after the administration of a single oral dose of racemic-VER to rats. VER, NOR and the internal standard (paroxetine) were extracted from only 100-microL plasma samples using n-hexane and the enantiomers were resolved on a Chiralpak AD column using n-hexane:isopropanol:ethanol:diethylamine (88:6:6:0.1) as the mobile phase. The analyses were performed in the selected reaction monitoring mode. Transitions 456>166 for VER enantiomers, 441>166 for NOR enantiomers and 330>193 for the internal standard were monitored and the method had a total chromatographic run time of 12 min. The method allows the determination of VER and NOR enantiomers at plasma levels as low as 1.0 ng/mL. Racemic VER hydrochloride (10mg/kg) was given to male Wistar rats by gavage and blood samples were collected from 0 to 6.0 h (n=6 at each time point). The concentration of (-)-(S)-VER was three folds higher than (+)-(R)-VER, with an AUC ratio (-)/(+) of 2.66. Oral clearance values were 12.17 and 28.77 L/h/kg for (-)-(S)-VER and (+)-(R)-VER, respectively. The pharmacokinetic parameters of NOR were not shown to be enantioselective.
Mateus
Fabiano Henrique
FH
Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil.
Lepera
José Salvador
JS
Marques
Maria Paula
MP
Boralli
Vanessa Bergamin
VB
Lanchote
Vera Lucia
VL
D000818:Animals; D019540:Area Under Curve; D002121:Calcium Channel Blockers / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D005615:Freezing; D006863:Hydrogen-Ion Concentration; D008297:Male; D008657:Metabolic Clearance Rate; D008832:Microchemistry / Q000379:methods; D008954:Models, Biological; D015394:Molecular Structure; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013696:Temperature; D014700:Verapamil / Q000031:analogs & derivatives* / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics
D002121:Calcium Channel Blockers; D014700:Verapamil