Helicobacter pylori eradication, CYP2C19 and omeprazole doses: Authors' reply


Sirs, There are many factors determining the eradication outcome for Helicobacter pylori, such as drug compliance, regimen selection and antimicrobial resistance. Our article gave evidence to support the host genetic background, such as CYP2C19 metabolizer status, which could be related to the eradication outcome of triple therapy, including clarithromycin, amoxicillin and proton pump inhibitor (PPI).1 As suggested in the Maastricht-2 consensus,2 there are two first-line PPI-based triple therapy regimens: (i) amoxicillin, clarithromycin and PPI; (ii) metronidazole, clarithromycin and PPI. Therefore, the choice between these two regimens is rationally based on the prevalence rate of local metronidazole resistance in the local area.

In Taiwan, the metronidazole resistance is usually as high as 40–50%. Accordingly, the commonly used regimen is amoxicillin, clarithromycin and PPI. Our data show that both the omeprazole- and esomeprazole-based triple therapy would be equally effective for the poor metabolizer. However, the eradication rate of omeprazole-based triple therapy is rather limited for an extensive metabolizer of CYP2C19, in comparison with that of esomeprazole-based triple therapy. We thus indicate that if one selects antibiotics such as amoxicillin and clarithromycin, a stronger PPI such as esomeprazole 40 mg twice daily will be more applicable for the extensive metabolizer, which is around 70% in Taiwan.

Miehlke et al.3 disclosed there was no difference in the eradication rate between omeprazole- and esomeprazole-based triple therapy, using metronidazole and clarithromycin. These data suggested that, although the interaction between CYP2C19 genotypes and PPI is important, other factors (such as antibiotic treatment and resistance) are likely to affect more significantly the efficacy of an eradicating regimen. As western countries have more extensive metabolizers than do eastern countries, it is sensible to test whether there is a difference between omeprazole- and esomeprazole-based triple therapy using amoxicillin and clarithromycin.