title: Enantiomeric bioanalysis of simendan and levosimendan by chiral high-performance liquid chromatography.
abstract: rac-Simendan, (+/-)-(R,S)-[[4-(1,4,5,6-tetrahydro-4-methyl-6-oxo-3-pyridazinyl)-phenyl ] hydrazono]propanedinitrile, and the levorotatory enantiomer levosimendan, are drug candidates intended for the treatment of congestive heart failure. An enantiospecific high-performance liquid chromatographic (HPLC) method suitable for determination of the ratio of the enantiomer concentrations in blood plasma samples was developed. Direct resolution of the enantiomers was achieved by using a chiral beta-cyclodextrin stationary phase in reversed phase mode. With an eluent containing 24-33% of methanol in a 0.5% (v/v) triethylammonium acetate buffer, pH 6.0, and a flow rate of 1 ml/min, a resolution (1.2-1.6) adequate for the determinations was achieved. By using UV detection, the relative concentration of the enantiomers in plasma was assessed down to 10 ng/ml. For the racemate, the results indicated a slightly enantioselective disposition and plasma protein binding in rat, dog, and man. The pure enantiomer, levosimendan, was found not to isomerize in vivo.
authors.affiliation: Orion-Farmos, Orion Research, Espoo, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Wikberg
authors.forename: T
authors.initials: T
authors.lastname: Korkolainen
authors.forename: M
authors.initials: M
authors.lastname: Karlsson
mesh_terms: D000818:Animals; D001774:Blood Chemical Analysis / Q000379:methods / Q000706:statistics & numerical data; D001798:Blood Proteins / Q000378:metabolism; D002316:Cardiotonic Agents / Q000032:analysis* / Q000097:blood / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000706:statistics & numerical data; D004285:Dogs; D006801:Humans; D006835:Hydrazones / Q000032:analysis* / Q000097:blood / Q000737:chemistry*; D008297:Male; D015394:Molecular Structure; D011485:Protein Binding; D011724:Pyridazines / Q000032:analysis* / Q000097:blood / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D000077464:Simendan; D013237:Stereoisomerism
chemical_list: D001798:Blood Proteins; D002316:Cardiotonic Agents; D006835:Hydrazones; D011724:Pyridazines; D000077464:Simendan