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The (R)-omeprazole Hydroxylation Index Reflects CYP2C19 Activity in Healthy Japanese Volunteers

The (R)-omeprazole Hydroxylation Index Reflects CYP2C19 Activity in Healthy Japanese Volunteers

Satoshi Yamada, Hideo Shiohira, Norio Yasui-Furukori, Tomonori Tateishi, Yumiko Akamine, Tsukasa Uno

Eur J Clin Pharmacol. 2013 Jul;69(7):1423-8.

PMID: 23435615

Abstract:

Purpose:
Omeprazole has (R)- and (S)-enantiomers, which exhibit different pharmacokinetics (PK) among patients with cytochrome P450 (CYP) 2C19 genotype groups. The aim of this study was to investigate whether the 1-point, 4-h postdose (R)-omeprazole hydroxylation index (HI) of racemic omeprazole reflects the three CYP2C19 genotype groups in Japanese individuals.
Methods:
Ninety healthy Japanese individuals were enrolled and classified into the three different CYP2C19 genotype groups: homozygous extensive metabolizers (hmEMs; n = 34), heterozygous EMs (htEMs; n = 44), and poor metabolizers (PMs; n = 12). Blood samples were drawn 4 h after the intake of an oral dose of omeprazole 40 mg, and plasma levels of omeprazole and its metabolites were analyzed by high-performance liquid chromatography (HPLC) using a chiral column.
Results:
Mean plasma concentrations of (R)- and (S)-omeprazole in PMs were significantly higher than those in hmEMs and htEMs, and similar results were obtained in the case of omeprazole sulfone. Additionally, there was a significant difference in plasma concentrations of (R)-5-hydroxyomeprazole among CYP2C19 genotype groups, whereas no significant differences were observed in that of (S)-5-hydroxyomeprazole. Similarly, (R)-omeprazole HI in hmEMs, htEMs, and PMs were 5.6, 3.1, and 0.3, respectively, which were significantly different, but no significant difference was present in the (S)-omeprazole HI.
Conclusion:
Our findings demonstrate that (R)-omeprazole HI correlated better with CYP2C19 genotype groups than racemic-omeprazole HI, and these results may be useful for classification among patients in CYP2C19 genotype groups prior to omeprazole treatment.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP161796776	R-Omeprazole		161796-77-6	Price

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