Letter to the Editor
The information under Carcinogenicity states that pulmonary tumours were found in all six studies done in mice including one with dosing only every fourth week; there were also malignant tumours in the liver and malignant lymphomas. In rats, there were liver and mammary tumours. And finally, the drug is genotoxic - it damages the DNA directly.
Under the heading Nursing Mothers, it says, 'because of the potential for tumorigenicity shown for metronidazole in mouse and rat studies, a decision should be made whether to discontinue nursing or to discontinue the drug'. It further states that, 'metronidazole is secreted in human milk in concentrations similar to those found in plasma'.
Based on this information, I take issue with the reviewer who says that, based on this book, she is reassured that metronidazole 'will do the baby no harm'. On the contrary, there is tremendous potential for harm and the US product information actually says not to nurse when using metronidazole. So much for the usefulness of this book!
Public Citizen's Health Research Group
Washington DC, USA
- Falagas ME, Walker AM, Jick H, Ruthazer R, Griffith J, Snydman DR. Late incidence of cancer after metronidazole use: a matched metronidazole user/nonuser study. Clin Infect Dis 1998;26:384-8.
- Bendesky A, Menendez D, Ostrosky-Wegman P. Ismetronidazole carcinogenic? Mutat Res 2002;511:133-44.
- Fahrig R, Engelke M. Reinvestigation of in vivo genotoxicity studies in man. I. No induction of DNA strand breaks in peripheral lymphocytes after metronidazole therapy. Mutat Res 1997;395:215-21.
- Dobias L, Cerna M, Rossner P, Sram R. Genotoxicity and carcinogenicity of metronidazole. Mutat Res1994;317:177-94.
- Thomson MICROMEDEX. Metronidazole. Healthcare Series Vol. 123 [subscription required].
- Schreiber A, Krause M, Zips D, Dorfler A, Richter K, Vettermann S, et al. Effect of the hypoxic cell sensitizer isometronidazole on local control of two human squamous cell carcinomas after fractionated irradiation. Strahlenther Onkol 2004;180:375-82.
- Skoropad VY, Berdov BA, Zagrebin VM. Preoperative radiotherapy in combination with metronidazole for resectable gastric cancer: long-term results of a phase 2study. Eur J Surg Oncol 2003;29:166-70.
- Drinkwater P. Metronidazole. Aust N Z J Obstet Gynaecol1987;27:228-30.
- Einarson A, Ho E, Koren G. Can we use metronidazole during pregnancy and breastfeeding? Putting an end to the controversy. Can Fam Physician 2000;46:1053-4.
- Hale TW. Medications and mother's milk 2002. 10th ed.Amarillo, TX: Pharmasoft Publishing; 2002.
- Briggs GG, Freeman RK, Yaffe SJ. Drugs in pregnancy and lactation. 5th ed. Baltimore, MD: Williams & Wilkins; 1998.
- Weiner CP, Buhimschi C. Drugs for pregnant and lactating women. New York: Churchill Livingstone; 2004.
- Paediatric Pharmacopoeia. 13th ed. Melbourne: Women's and Children's Health, Royal Children's Hospital; 2002.
- Passmore CM, McElnay JC, Rainey EA, D'Arcy PF. Metronidazole excretion in human milk and its effect on the suckling neonate. Br J Clin Pharmacol 1988;26:45-51.
- Bar-Oz B, Bulkowstein M, Benyamini L, Greenberg R, Soriano I, Zimmerman D, et al. Use of antibiotic and analgesic drugs during lactation. Drug Saf 2003;26:925-35.
The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.