Background: When administered at a standard dose, proton pump inhibitors (PPIs) do not always provide sufficient acid inhibition for all subjects, particularly in extensive metabolizers (EMs) of CYP2C19. Whether esomeprazole at a dose of 20 mg four times daily dosing (q.i.d.) can attain sufficient acid inhibition throughout 24 h in EMs remains unclear. We therefore investigated the efficacy of esomeprazole q.i.d. for acid inhibition.
Methods: In a randomized cross-over design, 30 Helicobacter pylori-negative healthy young Japanese volunteers received esomeprazole at a dose of 20 mg two times a day (b.i.d.) or q.i.d. for 7 days. A pH monitoring was conducted before the trial as a control and on day 7 of both regimens.
Results: Median pH values in the q.i.d. regimen were significantly higher than those with the b.i.d. regimen in EMs (b.i.d.: 5.3, q.i.d.: 6.6, p = 0.022), intermediate metabolizer (IM) (b.i.d.: 5.5, q.i.d.: 6.8, p = 0.005) and poor metabolizer (PM) (b.i.d.: 6.2, q.i.d.: 7.0, p = 0.047), respectively. Median pH with the b.i.d. regimen differed significantly by CYP2C19 genotypes (p = 0.004), but not the q.i.d. regimen (p = 0.384).
Conclusion: Esomeprazole q.i.d. achieved potent acid inhibition in all Helicobacter pylori-negative subjects, irrespective of CYP2C19 genotype, which might be one of the rescue regimens for patients' refractory to PPI treatment.