title: Inducibility of CYP1A2 by omeprazole in vivo related to the genetic polymorphism of CYP1A2.
abstract: OBJECTIVE
  To evaluate the effect of the CYP1A2*1C and CYP1A2*1F polymorphisms on the inducibility of CYP1A2 by omeprazole in healthy subjects.
  
  
  METHODS
  Mutations of CYP2C19 and CYP1A2 were identified by PCR-RFLP. Omeprazole, 120 mg day-1, was given to 12 extensive metabolizers (EM) with respect to CYP2C19 (six CYP1A2*1F/CYP1A2*1F and six CYP1A2*1C/CYP1A2*1F of CYP1A2) for 7 days. CYP1A2 activity was determined on three occasions, namely on day 1, day 9 and day 16 using the caffeine plasma index (the ratio of the concentrations of paraxanthine to caffeine), 6 h after oral administration of 200 mg caffeine.
  
  
  RESULTS
  There was a significant difference (P = 0.002) between the caffeine ratios for CYP1A2*1F/CYP1A2*1F and CYP1A2*1C/CYP1A2*1F genotypes on day 9, but not on day 1 or day 16 (P > 0.05). The changes in the ratios from day 9 to day 1 (48% +/- 20%vs 19% +/- 20%) and from day 9 to day 16 (50% +/- 31%vs 15% +/- 22%) were significantly different (P < 0.05) between the CYP1A2*1F/CYP1A2*1F and CYP1A2*1C/CYP1A2*1F genotypes.
  
  
  CONCLUSIONS
  The CYP1A2*1C and CYP1A2*1F genetic polymorphisms influenced the induction of CYP1A2 activity in vivo by omeprazole.
authors.affiliation: Pharmacogenetics Research Institute, Xiang-Ya School of Medicine, Central South University, Changsha, Hunan 410078, China.
authors.forename: Xing-Mei
authors.initials: XM
authors.lastname: Han
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Ouyang
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Chen
authors.forename: Yan
authors.initials: Y
authors.lastname: Shu
authors.forename: Chang-Hong
authors.initials: CH
authors.lastname: Jiang
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Tan
authors.forename: Hong-Hao
authors.initials: HH
authors.lastname: Zhou
mesh_terms: D000328:Adult; D002110:Caffeine / Q000097:blood; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D009853:Omeprazole / Q000494:pharmacology*; D010726:Phosphodiesterase Inhibitors / Q000097:blood; D011110:Polymorphism, Genetic / Q000235:genetics*
chemical_list: D004791:Enzyme Inhibitors; D010726:Phosphodiesterase Inhibitors; D002110:Caffeine; D019388:Cytochrome P-450 CYP1A2; D009853:Omeprazole