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Clinical Trial
. 2002 Nov;54(5):540-3.
doi: 10.1046/j.1365-2125.2002.01686.x.

Inducibility of CYP1A2 by omeprazole in vivo related to the genetic polymorphism of CYP1A2

Xing-Mei Han  1 , Dong-Sheng Ouyang, Xiao-Ping Chen, Yan Shu, Chang-Hong Jiang, Zhi-Rong Tan, Hong-Hao Zhou
Affiliations
Clinical Trial

Inducibility of CYP1A2 by omeprazole in vivo related to the genetic polymorphism of CYP1A2

Xing-Mei Han et al. Br J Clin Pharmacol. 2002 Nov.

Abstract

Aims: 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.

Conclusion: The CYP1A2*1C and CYP1A2*1F genetic polymorphisms influenced the induction of CYP1A2 activity in vivo by omeprazole.

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Figures

Figure 1
Figure 1
Influence of 7 days of omeprazole treatment on the plasma caffeine metabolic ratio (1,7X/1,3,7X). ○: CYP1A2*1F/CYP1A2*1F genotypes, n = 6; ×: CYP1A2*1C/CYP1A2*1F genotypes, n = 6.
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