title: Effect of CYP3A5*3 genotype on the pharmacokinetics and pharmacodynamics of amlodipine in healthy Korean subjects.
abstract: OBJECTIVE
  1,4-Dihydropyridine calcium channel blockers, including amlodipine, are mainly metabolized by cytochrome P450 (CYP) 3A. We investigated the effect of CYP3A5*3 genotype on the pharmacokinetics and pharmacodynamics of amlodipine in healthy Korean male subjects.
  
  
  METHODS
  Forty healthy male participants were enrolled and genotyped for the CYP3A5*3 gene. Each subject ingested a 5-mg dose of amlodipine, and plasma amlodipine concentrations were measured for 144 hours after dosing. Blood pressure and pulse rate were also measured for pharmacodynamic analysis.
  
  
  RESULTS
  Among the 40 volunteers, 24 were CYP3A5*3/*3 carriers and 16 were CYP3A5*1 carriers (CYP3A5*1/*1 in 2 and CYP3A5*1/*3 in 14). The difference in the oral clearance of amlodipine approached statistical significance between the 2 major genotype groups, with CYP3A5*1 carriers (27.0 +/- 8.2 L/h) showing 20% lower clearance than CYP3A5*3/*3 carriers (32.4 +/- 10.2 L/h) (P = .063). However, the mean area under the plasma concentration-time curve of amlodipine was 200.9 +/- 61.9 ng . h/mL for CYP3A5*1 carriers and 167.6 +/- 45.0 ng . h/mL for CYP3A5*3/*3 carriers (P = .029). Moreover, the peak plasma concentration was significantly higher in CYP3A5*1 carriers (3.8 +/- 1.1 ng/mL) than in CYP3A5*3/*3 carriers (3.1 +/- 0.8 ng/mL) (P = .037). Pharmacodynamically, blood pressure and pulse rate were not significantly different between the 2 groups.
  
  
  CONCLUSIONS
  CYP3A5*3/*3 carriers exhibited lower plasma amlodipine concentrations than CYP3A5*1 carriers. These findings suggest that the polymorphic CYP3A5 gene affects the disposition of amlodipine and provides a plausible explanation for interindividual variability in amlodipine disposition.
authors.affiliation: Department of Clinical Pharmacology, Anam Hospital, Korea University College of Medicine, Sungbuk-gu, Seoul, South Korea.
authors.forename: Kyoung-Ah
authors.initials: KA
authors.lastname: Kim
authors.forename: Pil-Whan
authors.initials: PW
authors.lastname: Park
authors.forename: Ock-Je
authors.initials: OJ
authors.lastname: Lee
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: Choi
authors.forename: Bon Hong
authors.initials: BH
authors.lastname: Min
authors.forename: Kyung-Ho
authors.initials: KH
authors.lastname: Shin
authors.forename: Boe-Gwun
authors.initials: BG
authors.lastname: Chun
authors.forename: Jae-Gook
authors.initials: JG
authors.lastname: Shin
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Park
mesh_terms: D000328:Adult; D017311:Amlodipine / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D019540:Area Under Curve; D001794:Blood Pressure / Q000187:drug effects; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D005838:Genotype; D006207:Half-Life; D006801:Humans; D007723:Korea; D008297:Male; D008657:Metabolic Clearance Rate; D010597:Pharmacogenetics; D011110:Polymorphism, Genetic / Q000235:genetics*
chemical_list: D017311:Amlodipine; D003577:Cytochrome P-450 Enzyme System; C510164:CYP3A5 protein, human; D051544:Cytochrome P-450 CYP3A