Korean J Gastroenterol.  2001 Dec;38(6):399-404.

Effects of CYP2C19 Polymorphism on Intragastric Acidity during Omeprazole Administration

• Park SH
• Kim JW
• Lee SY
• Choi MG
• Kim JK
• Chung IS
• Chung GW
• Sun HS
• Park DH

Abstract

BACKGROUND/AIMS: CYP2C19 has an important role in the catabolism of several proton pump inhibitors. However, the relative contribution of CYP2C19-mediated metabolism varies among the different proton pump inhibitors. We investigate to determine the effect of CYP2C19 genotype status on intragastric pH during dosing with omeprazole.
METHODS
The subjects were 16 healthy volunteers. Their CYP2C19 genotype status was determined by a polymerase chain reaction-restriction fragment length polymorphism method. Twenty-four-hour monitoring of intragastric acidity were performed on the day without medication and day 4 after omeprazole administration.
RESULTS
A single dose of omeprazole significantly decreased 24 hour intragastric acidity (1.7+/-0.3 vs. 5.1+/-0.4). Subjects were divided into three groups on the basis of their CYP2C19 genotype status: homozygous extensive metabolizers (Ho-EMs, n=5), heterozygous extensive metabolizers (Ht-EMs, n=6), and poor metabolizers (PMs, n=5). Median 24 hour intragastric pH in the Ho-EM group was 3.1 compared with 5.5 in Ht-EM group and 5.9 in PM group(P < 0.05). The median pH during omeprazole administration was influenced by CYP2C19 genotype. On the other hand, the Helicobacter pylori infection did not influence the median intragastric pH during omeprazole administration (p= NS).
CONCLUSIONS
The effects of omeprazole on intragastric acidity is influenced by the CYP2C19 polymorphism.

MeSH Terms

Genotype
Hand
Healthy Volunteers
Helicobacter pylori
Hydrogen-Ion Concentration
Metabolism
Omeprazole*
Proton Pump Inhibitors
Omeprazole
Proton Pump Inhibitors