Influence of CYP2D6 Polymorphism on the Pharmacokinetic/ Pharmacodynamic Characteristics of Carvedilol in Healthy Korean Volunteers

Background: Carvedilol is commonly used to treat hypertension as a beta- and alpha(1)-adrenoreceptor blocker, but it is metabolized by CYP2D6, and CYP2D6*10 allele is dominant in Asian population. The objective of this study was to assess the influence of CYP2D6 polymorphisms on the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of carvedilol in healthy Korean volunteers. Methods: A PK/PD study for a single and multiple dosing of carvedilol were conducted. All volunteers in 3 genotypic groups received single oral dose of carvedilol 12.5 mg for 3 days, then 25 mg QD for 5 days, and 12.5 mg QD for another 3 days. PK parameters for carvedilol and its three metabolites were determined using non-compartmental analysis. For PD properties, blood pressure, heart rate, and the chronotropic dose 25 (CD25) value were obtained. Results: The IM_2 group with two *10 alleles (intermediate metabolizers) exhibited lower clearance of carvedilol as well as higher area under the curve (AUC) for O-desmethyl carvedilol. The ratio of CD25 to baseline at multiple dosing was significantly higher in the combined IM group (IM_1 and IM_2) than in the EM group, however, the ratio of CD25 after single and multiple dosing and the other PD markers were not significantly different between the 3 genotypic groups compared with the baseline. Conclusion: These findings showed that CYP2D6 genotype influenced the PK characteristics of carvedilol and no differences in PD response were observed in Korean healthy volunteers.