Trial reportBritish journal of clinical pharmacology1999
Reliability of the omeprazole hydroxylation index for CYP2C19 phenotyping: possible effect of age, liver disease and length of therapy.
Trial report in British journal of clinical pharmacology, 1999. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 11 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
11 citing papers in PubMed, 40 citations in OpenAlex.
- Hydroxylation index of omeprazole in relation to CYP2C19 polymorphism and sex in a healthy Iranian population.Daru : journal of Faculty of Pharmacy, Tehran University of Medical Sciences · 2014Trial
- Omeprazole limited sampling strategies to predict area under the concentration-time curve ratios: implications for cytochrome P450 2C19 and 3A phenotyping.European journal of clinical pharmacology · 2012Trial
- Estimation of CYP2C19 activity by the omeprazole hydroxylation index at a single point in time after intravenous and oral administration.European journal of clinical pharmacology · 2007Trial
- Phenotype-genotype analysis of CYP2C19 in Colombian mestizo individuals.BMC clinical pharmacology · 2007Trial
- Different inhibitory effect of fluvoxamine on omeprazole metabolism between CYP2C19 genotypes.British journal of clinical pharmacology · 2004Trial
- Evaluation of CYP2C19 activity using microdosed oral omeprazole in humans.European journal of clinical pharmacology · 2022Article
- Association of CYP2C19 Polymorphism With Proton Pump Inhibitors Effectiveness and With Fractures in Real-Life: Retrospective Cohort Study.Clinical pharmacology and therapeutics · 2022Article
- Evaluation of changes in cytochrome P450 2C19 activity in type 2 diabetic rats before and after treatment, by using isolated perfused liver model.Iranian journal of basic medical sciences · 2020Article
- Interethnic variation of CYP2C19 alleles, 'predicted' phenotypes and 'measured' metabolic phenotypes across world populations.The pharmacogenomics journal · 2016Review
- The (R)-omeprazole hydroxylation index reflects CYP2C19 activity in healthy Japanese volunteers.European journal of clinical pharmacology · 2013Article
- The effect of aging on the relationship between the cytochrome P450 2C19 genotype and omeprazole pharmacokinetics.Clinical pharmacokinetics · 2005Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
9 authors at 3 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
aimsTo evaluate the reliability of the omeprazole hydroxylation index as a marker for polymorphic CYP2C19 activity in a Japanese population of healthy young subjects (n = 78) and patients with peptic ulcer (n = 72).
methodsHealthy subjects were administered a single dose of omeprazole (20 mg), whereas patients received 20 mg daily for at least 1 week. The ratio of the serum concentration of omeprazole to hydroxyomeprazole at 3 h postdose was determined and used as a measure of CYP2C19 activity. The CYP2C19 wild type (wt) gene and four mutant alleles associated with the poor metaboliser phenotype of (S)-mephenytoin, CYP2C19*2 in exon 5, CYP2C19*3 in exon 4, CYP2C19m4 in exon 9, and CYP2C19m3 in the initial codon were analysed.
resultsIn the healthy volunteer study there was complete concordance between genotype and phenotype. However, eight of the patients who had the EM genotype had a high value for their hydroxylation index, and were classified as phenotypic PMs. No CYP2C19m4 and CYP2C19m3 mutations were detected in the eight mismatched patients. They were all genotypic heterozygous EMs, elderly (> or = 65 years) and/or had hepatic disease. Therefore, impaired CYP2C19 activity combined with partial saturation of omeprazole metabolism during multiple dosing may have contributed to the discrepancy between CYP2C19 genotyping and phenotyping.
conclusionAlthough omeprazole has been used instead of mephenytoin as a probe for polymorphic CYP2C19, it does not appear to be reliable enough for clinical application in Japanese patients.
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