Stereoselective disposition of talinolol in man

✍ Scribed by Michael Zschiesche; Girum Lakew Lemma; Klaus-Jürgen Klebingat; Gerd Franke; Bernd Terhaag; Anna Hoffmann; Thomas Gramatté; Heyo K. Kroemer; Werner Siegmund

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 168 KB
• Volume: 91
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.10054

✦ Synopsis

The disposition of the b-blocking drug talinolol is controlled by P-glycoprotein in man. Because talinolol is marketed as a racemate, we reevaluated the serum-concentration time pro®les of talinolol of a previously published study with single intravenous (30 mg) and repeated oral talinolol (100 mg for 14 days) before and after comedication of rifampicin (600 mg per day for 9 days) in eight male healthy volunteers (age 22±26 years, body weight 67±84 kg) with respect to differences in the kinetic pro®les of the two enantiomers S(À) talinolol and R() talinolol. Additionally, the metabolism of talinolol in human liver microsomes was examined. After oral administration, S(À) talinolol was slightly less absorbed and faster eliminated than R() talinolol. The absolute bioavailabilty of the R() enantiomer of talinolol was slightly but signi®cantly higher than of its S(À) enantiomer. Coadministration of rifampicin further intensi®ed this difference in the disposition of R() and S(À) talinolol (p `0.05). Formation of 4-trans hydroxytalinolol was the major metabolic pathway in human liver microsomes. All Cl int values of S(À) were higher than of R() talinolol; 0.1 mM ketoconazole inhibited the formation of all metabolites. In conclusion, the stereoselectivity of talinolol disposition is of minor importance, and most likely caused by presystemic biotransformation via CYP3A4. The less active R() talinolol might be suitable for phenotyping P-glycoprotein expression in man.