title: Liquid-chromatographic assay of ibuprofen enantiomers in plasma.
abstract: This stereospecific "high-performance" liquid-chromatographic (HPLC) assay is suitable for pharmacokinetic studies of ibuprofen (IB). Very efficient extraction of the drug and internal standard, (+/-)-2-(4-benzoylphenyl)butyric acid, from plasma with isooctane/isopropanol (95/5, by vol) is followed by sequential reaction of the enantiomers with ethyl chloroformate and (S)-(-)-1-(1-naphthyl)ethylamine. The reactions take place at ambient temperature in less than 4 min. The naphthylethylamide derivatives of IB enantiomers and internal standard are then extracted into chloroform. After the organic layer is evaporated, the reconstituted residue is chromatographed at ambient temperature on a C18 reversed-phase column with a mobile phase of acetonitrile/water/acetic acid/triethylamine (55/45/0.1/0.02 by vol) at a flow rate of 1 mL/min. The IB diastereoisomers, detected at 232 nm, are free of interfering peaks and have a resolution factor of 2.2. Within the examined enantiomer concentration range of 0.1 to 20 mg/L in plasma, the peak-area ratios varied linearly with the corresponding IB concentrations. We used the assay to study the pharmacokinetics of IB enantiomers in plasma of a subject who took a single 600-mg dose of racemic drug.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Mehvar
authors.forename: F
authors.initials: F
authors.lastname: Jamali
authors.forename: F M
authors.initials: FM
authors.lastname: Pasutto
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005021:Ethylamines; D005561:Formates; D005563:Formic Acid Esters; D006801:Humans; D007052:Ibuprofen / Q000097:blood* / Q000493:pharmacokinetics; D007202:Indicators and Reagents; D009281:Naphthalenes; D013237:Stereoisomerism
chemical_list: D005021:Ethylamines; D005561:Formates; D005563:Formic Acid Esters; D007202:Indicators and Reagents; D009281:Naphthalenes; C007658:ethyl chloroformate; C055450:1-(1-naphthyl)ethylamine; D007052:Ibuprofen