title: Stereoselective metabolism of metoprolol in isolated rat liver.
abstract: OBJECTIVE
  To study the stereoselective pharmacokinetics of the enantiomers of metoprolol (Met).
  
  
  METHODS
  The enantiomers of Met were metabolized in isolated rat liver with hemoglubin-free medium. The enantiomers of Met were analyzed with HPLC.
  
  
  RESULTS
  The linear kinetics were found in 3 doses (0.16, 0.32, and 0.64 mg) of R-(+)- and S-(-)-Met. The time-concentration curve of Met was fitted in first order-kinetics compartment model. There were differences in the pharmacokinetic parameters (K, T1/2, and Cl) between the enantiomers at the same dose (P < 0.01). The ratio of liver clearence of S-(-)-Met/R-(+)-Met was 0.14-0.17.
  
  
  CONCLUSIONS
  Pharmacokinetics of enantiomers of Met in the isolated rat liver were stereoselective, with a preferential clearance of R-(+)-Met, which elimination was not a saturable process.
authors.affiliation: Institute of Clinical Pharmacology, Nanjing Medical University, China.
authors.forename: X X
authors.initials: XX
authors.lastname: Chen
authors.forename: Y D
authors.initials: YD
authors.lastname: Zhang
authors.forename: J P
authors.initials: JP
authors.lastname: Shen
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000493:pharmacokinetics; D000818:Animals; D005260:Female; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D008790:Metoprolol / Q000493:pharmacokinetics*; D051381:Rats; D013237:Stereoisomerism
chemical_list: D000319:Adrenergic beta-Antagonists; D008790:Metoprolol