Paul Moayyedi, MB, is a professor of medicine and assistant dean of research in the Faculty of Health Sciences at McMaster University.
High-dose amoxicillin–proton pump inhibitor (PPI) dual therapy is cheaper and easy to perform. Can it be used as the first-choice regimen for Helicobacter pylori eradication in countries with high rates of bacterial resistance to clarithromycin?
I personally would not recommend that. Amoxicillin in vitro seems to be the perfect antibiotic. Nearly every H pylori strain is sensitive to it, and they’re very sensitive to the penicillin. So in theory, it should be very good.
The problem is that very little amoxicillin gets to the gastric mucosa and it is very sensitive to acid; the concentration in the gastric mucosa is low and it is quickly degraded by the acid. So, firstly, if you’re going to use it, you need very high doses of proton pump inhibitors or, more recently, the potassium channel… acid channel blockers, and very high doses of amoxicillin: I gave 1 g 4 times a day for 14 days. That will be the most effective, but still not as effective as the usual first-line recommended therapies. I’d also add metronidazole to that, or a nitroimidazole anyway, because even in the metronidazole-resistant cases I find eradication rates are a little better when you have the three.
Generally even in high-resistance areas I would not use that. I would use bismuth quadruple therapy because I would use tetracycline, which H pylori are very rarely resistant to. Also for metronidazole, even with resistant strains, there is only a slightly reduced eradication rate. So it’s a very good first-line therapy, even in high-resistance populations.