Genetic polymorphism of S-mephenytoin 4??-hydroxylation in African-Americans

Edeki, Timi; Goldstein, Joyce A.; Morais, S. M. F. De; Hajiloo, L.; Butler, M.; Chapdelaine, P.; Wilkinson, Grant R.

doi:10.1097/00008571-199608000-00009

Cited by 44 publications

(30 citation statements)

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“…42,45 Now these results can be clearly explained by interethnic variations in the CYP2C19 genotype. Among North American and European populations, 56.7-81.0% of patients are homo-EMs, 18.0-37.2% are hetero-EMs, and PMs are less than 6.1%, [46][47][48][49][50] and thus omeprazole 40 mg is required to achieve stronger gastric acid suppression than H 2 -RAs. However, in Orientals, homo-EMs are only 27.7-38.2% and the rest of the population has an intermediate or reduced capacity to metabolize omeprazole; 30,[51][52][53] and therefore strong gastric acid suppression can be obtained even with omeprazole 20 mg or less.…”

Section: Discussionmentioning

confidence: 99%

Effect of omeprazole 10 mg on intragastric pH in three different CYP2C19 genotypes, compared with omeprazole 20 mg and lafutidine 20 mg, a new H₂‐receptor antagonist

Shimatani

Inoue

Kuroiwa

et al. 2003

Aliment Pharmacol Ther

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SUMMARYBackground: Omeprazole 10 mg is used as maintenance therapy for gastro-oesophageal reflux disease, but previous reports have not mentioned the potency of its acid suppression. Aim: To evaluate the potency of acid suppression with omeprazole 10 mg, in relation to CYP2C19 genotypes. Methods: Eighteen healthy subjects without Helicobacter pylori participated. After a 7-day regimen of omeprazole 10 mg, 20 mg, lafutidine 20 mg (a novel H 2 -receptor antagonist) or water only (baseline data), intragastric pH was measured for 24 h. Results: With omeprazole 10 mg, greater differences were observed than 20 mg in median pH values and pH > 4 holding time ratios between poor metabolizers (PMs, n ¼ 6) and the others [homozygous extensive metabolizers (homo-EMs, n ¼ 6) and heterozygous extensive metabolizers (hetero-EMs, n ¼ 6)]. With lafutidine 20 mg, these parameters were not influenced by the genotype. The potency of acid suppression was: omeprazole 20 mg lafutidine 20 mg > omeprazole 10 mg in homo-EMs, omeprazole 20 mg > omeprazole 10 mg lafutidine 20 mg in hetero-EMs, and omeprazole 20 mg omeprazole 10 mg > lafutidine 20 mg in PMs. Conclusions: Omeprazole 10 mg strongly suppresses acid secretion, but depending on the CYP2C19 genotypes shows greater interindividual variations in suppression than 20 mg.

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Section: Discussionmentioning

confidence: 99%

Effect of omeprazole 10 mg on intragastric pH in three different CYP2C19 genotypes, compared with omeprazole 20 mg and lafutidine 20 mg, a new H₂‐receptor antagonist

Shimatani

Inoue

Kuroiwa

et al. 2003

Aliment Pharmacol Ther

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“…Detection of CYP2C19*2 and CYP2C19*3 mutant alleles was performed by PCR/RFLP, as described elsewhere [25–27]. PCR products were digested with the restriction endonucleases Sma I and BamH I to detect the CYP2C19*2 allele and the CYP2C19*3 allele respectively.…”

Section: Methodsmentioning

confidence: 99%

Effects of erythromycin on voriconazole pharmacokinetics and association with CYP2C19 polymorphism

Shi

Yan

Zhu

et al. 2010

Eur J Clin Pharmacol

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PurposeTo assess the impacts of erythromycin on the pharmacokinetics of voriconazole and its association with CYP2C19 genotypes in healthy Chinese male subjects.MethodsA single-center, open, crossover clinical study with two treatment phases was carried out. Eighteen healthy male volunteers, including 6 CYP2C19 homozygous extensive metabolizers (EMs, *1/*1), 6 heterozygous EMs (HEMs, *1/*2 or *1/*3), and 6 CYP2C19 poor metabolizers (PMs, *2/*2 or *2/*3), were enrolled in this study. A single oral dose of 200 mg voriconazole was administrated to all subjects after 3-day pretreatment with either 500 mg erythromycin or placebo three times daily. Periods were separated by a washout period of 14 days. Serial venous blood samples were collected, and plasma concentrations of voriconazole were determined by HPLC.ResultsCmax, AUC0–24, and of voriconazole were increased significantly, while oral clearance of voriconazole was decreased significantly by erythromycin administration (p < 0.001, respectively). Compared with individuals with CYP2C19 PM genotypes, individuals with CYP2C19 EM and HEM genotypes showed significantly decreased T½, AUC0–24, , and increased oral clearance of voriconazole (p < 0.05, respectively). In addition, significant increases in AUC0–24 and and decreases in oral clearance of voriconazole after erythromycin treatment were observed in CYP2C19 HEMs and PMs (p < 0.05, respectively), but not in CYP2C19 EMs.ConclusionBoth CYP2C19 genotypes and CYP3A4 inhibitor erythromycin can influence the plasma concentration of voriconazole, and erythromycin increases plasma concentration of voriconazole in a CYP2C19 genotype-dependent manner.

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“…We considered that Helicobacter pylori (H. pylori)-negative cytochrome P450 (CYP) 2C19 extensive metabolizers were the most appropriate subjects for this study, because they comprise 93.9% to 99% of the European and North American and 77.5% to 87.4% of the Asian populations [22][23][24][25][26][27][28][29][30]; as well as most GERD patients are H. pylorinegative [31,32].…”

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confidence: 99%

Which Has Superior Acid-Suppressive Effect, 10 Mg Omeprazole Once Daily or 20 Mg Famotidine Twice Daily? Effects of Single or Repeated Administration in Japanese Helicobacter Pylori-Negative CYP2C19 Extensive Metabolizers

Shimatani

Inoue²,

Kuroiwa

et al. 2007

Dig Dis Sci

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Low-dose omeprazole is superior to full-dose famotidine in maintenance therapy for gastroesophageal reflux disease, whereas "on-demand" famotidine is more effective for relief of episodes of heartburn. To explain this apparent discrepancy, intragastric pH was measured for 24-hr seven times in eight Japanese Helicobacter pylori-negative cytochrome P450 2C19 extensive metabolizers; on Days 1, 8, and 15 of repeated administration of 10 mg of omeprazole once daily and of 20 mg of famotidine twice daily and before medication. During repeated administration of omeprazole, mean intragastric pH and % time that intragastric pH > 4.0 were significantly higher and became greater. With famotidine, although these parameters were significantly higher, the degrees became smaller. Consequently, acid-suppressive effect was in the order; omeprazole < famotidine on Day 1, omeprazole approximately famotidine on Day 8, and omeprazole >famotidine on Day 15. This discrepancy possibly results from the "potentiation" of acid-suppressive effect of omeprazole and the "tolerance" phenomenon in respect to famotidine.

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Genetic polymorphism of S-mephenytoin 4??-hydroxylation in African-Americans

Cited by 44 publications

References 0 publications

Effect of omeprazole 10 mg on intragastric pH in three different CYP2C19 genotypes, compared with omeprazole 20 mg and lafutidine 20 mg, a new H₂‐receptor antagonist

Effect of omeprazole 10 mg on intragastric pH in three different CYP2C19 genotypes, compared with omeprazole 20 mg and lafutidine 20 mg, a new H₂‐receptor antagonist

Effects of erythromycin on voriconazole pharmacokinetics and association with CYP2C19 polymorphism

Which Has Superior Acid-Suppressive Effect, 10 Mg Omeprazole Once Daily or 20 Mg Famotidine Twice Daily? Effects of Single or Repeated Administration in Japanese Helicobacter Pylori-Negative CYP2C19 Extensive Metabolizers

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Genetic polymorphism of S-mephenytoin 4??-hydroxylation in African-Americans

Cited by 44 publications

References 0 publications

Effect of omeprazole 10 mg on intragastric pH in three different CYP2C19 genotypes, compared with omeprazole 20 mg and lafutidine 20 mg, a new H2‐receptor antagonist

Effect of omeprazole 10 mg on intragastric pH in three different CYP2C19 genotypes, compared with omeprazole 20 mg and lafutidine 20 mg, a new H2‐receptor antagonist

Effects of erythromycin on voriconazole pharmacokinetics and association with CYP2C19 polymorphism

Which Has Superior Acid-Suppressive Effect, 10 Mg Omeprazole Once Daily or 20 Mg Famotidine Twice Daily? Effects of Single or Repeated Administration in Japanese Helicobacter Pylori-Negative CYP2C19 Extensive Metabolizers

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Effect of omeprazole 10 mg on intragastric pH in three different CYP2C19 genotypes, compared with omeprazole 20 mg and lafutidine 20 mg, a new H₂‐receptor antagonist

Effect of omeprazole 10 mg on intragastric pH in three different CYP2C19 genotypes, compared with omeprazole 20 mg and lafutidine 20 mg, a new H₂‐receptor antagonist