Omeprazole treatment: genotoxicity biomarkers, and potential to induce CYP1A2 activity in humans.

ABSTRACT

Omeprazole is one of the most used acid-suppressing medications. This fact emphasizes the questions concerning the safety of this compound. Healthy volunteers (n=33) were included in this prospective study. All study subjects were analysed for their CYP2C19 genotype. Of the 33 individuals, 24 were homozygous for the wild type CYP2C19*1 allele, 7 were heterozygous for the CYP2C19*2 variant allele, and 2 were homozygous for the CYP2C19*2 variant allele. Before and after 14 days of omeprazole treatment at a daily dose of 20 mg, one blood sample was taken from each individual to determine five cytogenetic biomarkers of genotoxicity chromosome aberrations, micronuclei, proliferating rate index, sister chromatid exchanges, and mitotic index. The only significant change was that of a weak increase in micronuclei count after treatment in relation to baseline values (day 0) (P = 0.026). To assess the potential of omeprazole to induce P450 CYP1A2, the urinary ratio AFMU+1X+1U/17U in the interval of 4-5 hours after caffeine intake was calculated twice (days 0 and 15), using the caffeine test in 27 of the 33 individuals. This result suggests that omeprazole does not increase CYP1A2 activity after 14 days of treatment.