Background: Metronidazole is an antiprotozoal drug used to treat a broad spectrum of infectious diseases, including Helicobacter pylori (H pylori) infections. In Japan, metronidazole is approved for the eradication therapy of H pylori as a second-line regimen among adults, but it has not yet been approved for use among children and adolescents.
Materials and methods: To perform this narrative review, we searched the relevant literature on important events in the history of the use of metronidazole, its mechanisms of action, its efficacy, and the adverse effects reported in clinical trials or cohort studies in Japan.
Results: At present, metronidazole resistance has not been a serious issue in Japan in large part due to its restricted use. Emerging evidence from randomized controlled trials demonstrates higher eradication rates for metronidazole than for clarithromycin, supporting its use in both first-line and second-line eradication therapies. Among the reported adverse effects, there has been lingering concern over the potential carcinogenicity of metronidazole in humans. However, the possibility of an increased cancer risk is not limited to metronidazole; the long-term use of antibiotics has been linked to increased risk for some site-specific cancers. However, recent prospective studies have suggested that short-term exposure to antibiotics is not associated with an increased cancer risk.
Conclusion: Sensible use of metronidazole backed by research evidence could maximize the benefits associated with H pylori eradication in Japan.
Keywords: Helicobacter pylori; antimicrobial resistance; carcinogenicity; eradication; metronidazole.
© 2019 John Wiley & Sons Ltd.