title: Stereoselective determination of R(-)- and S(+)-MK-571, a leukotriene D4 antagonist, in human plasma by chiral high-performance liquid chromatography.
abstract: A stereoselective high-performance liquid chromatographic method that utilizes fluorescence detection was developed for the selective and sensitive quantification of R(-)- and S(+)-enantiomers of MK-571 (1), a potent and specific leukotriene D4 antagonist, in human plasma. Racemic 1 was isolated from the acidified plasma using solid-phase extraction and the resulting residue was successfully reacted with isobutyl chloroformate and R(+)-1-(1-naphthyl)ethylamine in triethylamine-acetonitrile medium to form the diastereomer of each enantiomer. A structural analogue of 1 was used as internal standard. The derivatized sample was dissolved in 1,1,2-trichlorotrifluoroethane and an aliquot was chromatographed on a (R)-urea chiral column using a mobile phase containing 89% triethylamine-pentane (3:1000, v/v), 10% 2-propanol, and 1% acetonitrile at a flow-rate of 1.5 ml/min. The fluorescence response (excitation wavelength, 350 nm; emission wavelength, 410 nm) was linear (r2 greater than 0.999) for concentrations of enantiomers of 1 from 0.05 micrograms/ml, the lowest quantitation limit, up to 2.5 micrograms/ml. Intra-day coefficients of variation at 0.05 microgram/ml were 2.4% for the R(-)-isomer and 2.0% for S(+)-isomer. The corresponding inter-day coefficients of variation for R(-)- and S(+)-1 were 2.6 and 3.6%, respectively. The utility of the methodology was established by analysis of plasma samples from male volunteers receiving single intravenous and oral doses of racemic 1.
authors.affiliation: Merck Sharp & Dohme Research Laboratories, West Point, PA 19486.
authors.forename: R S
authors.initials: RS
authors.lastname: Robinett
authors.forename: J Y
authors.initials: JY
authors.lastname: Hsieh
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006801:Humans; D008297:Male; D011422:Propionates / Q000097:blood*; D011804:Quinolines / Q000097:blood*; D013189:SRS-A / Q000037:antagonists & inhibitors*; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism
chemical_list: D011422:Propionates; D011804:Quinolines; D013189:SRS-A; C059141:verlukast