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CYP2C19 genotype status and intragastric pH during dosing with lansoprazole or rabeprazole
K Adachi1, T Katsube, A Kawamura
1Department of Internal Medicine II, Shimane Medical University, Izumo, Shimane, Japan. kadachi@shimane-med.ac.jp
Background:
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.
Aim:
To determine the effect of CYP2C19 genotype status on intragastric pH during dosing with lansoprazole or rabeprazole.
Subjects And Methods:
The subjects were 20 male volunteers without Helicobacter pylori infection. Their CYP2C19 genotype status was determined by a polymerase chain reaction-restriction fragment length polymorphism method. Twenty-four-hour monitoring of intragastric acidity was performed three times: once without medication, once on the last day of a 7-day course of rabeprazole, and once on the last day of a 7-day course of lansoprazole.
Results:
Subjects were divided into three groups on the basis of their CYP2C19 genotype status: homozygous extensive metabolizers (homo-EMs, n=7), heterozygous extensive metabolizers (hetero-EMs, n=9), and poor metabolizers (PMs, n=4). The median pH during rabeprazole administration was not influenced by CYP2C19 genotype. On the other hand, the median pH in PMs during lansoprazole dosing was higher than in homo-EMs and hetero-EMs. The percentage of time with pH < 4.0 had a similar tendency to that of median pH.
Conclusion:
CYP2C19 genotype status influences gastric acid suppression by lansoprazole, but not by rabeprazole.