(Reaffirmed October 2022)
Last updated October 5, 2020
This Practice Advisory addresses the ongoing U.S. Food and Drug Administration (FDA) recall of certain extended release (ER) metformin formulations1 due to the possibility that some formulations contain amounts of nitrosodimethylamine (NDMA) above the FDA's acceptable intake limit. NDMA is a probable human carcinogen (a substance that could cause cancer). The FDA does not expect nitrosamines to cause harm when ingested at or below the acceptable intake limit levels (such low levels of nitrosamines are ingested as part of common diets) even over a long period of time (such as a 70-year lifespan). Nitrosamine impurities may increase the risk of cancer if people are exposed to them at levels above the acceptable intake limit over long periods of time, but shorter-term exposure at levels above the acceptable intake limit is not expected to lead to an increase in the risk of cancer.
Currently, only some extended release formulations have been identified as possibly containing NDMA above acceptable intake limits; the recall has not been applied to immediate release formulations.
Patients should not stop taking ER metformin until communicating with their obstetrician-gynecologist or other women's healthcare practitioner. Patients who have been prescribed ER metformin should be counseled about the potential risk and consideration of alternative management options or immediate release metformin should be considered. Clinicians are advised to periodically check the FDA's website to note if the recall extends to additional metformin formulations.
Please contact [email protected] with any questions.
This Practice Advisory was developed by the American College of Obstetricians and Gynecologists in collaboration with Alison G. Cahill, MD; Aaron B. Caughey, MD, PhD; Cynthia Gyamfi-Bannerman, MD, MSc; and Anjali J. Kaimal, MD, MAS.
A Practice Advisory is issued when information on an emergent clinical issue (e.g. clinical study, scientific report, draft regulation) is released that requires an immediate or rapid response, particularly if it is anticipated that it will generate a multitude of inquiries. A Practice Advisory is a brief, focused statement issued within 24-48 hours of the release of this evolving information and constitutes ACOG clinical guidance. A Practice Advisory is issued only on-line for Fellows but may also be used by patients and the media. Practice Advisories are reviewed periodically for reaffirmation, revision, withdrawal or incorporation into other ACOG guidelines.
This information is designed as an educational resource to aid clinicians in providing obstetric and gynecologic care, and use of this information is voluntary. This information should not be considered as inclusive of all proper treatments or methods of care or as a statement of the standard of care. It is not intended to substitute for the independent professional judgment of the treating clinician. Variations in practice may be warranted when, in the reasonable judgment of the treating clinician, such course of action is indicated by the condition of the patient, limitations of available resources, or advances in knowledge or technology. The American College of Obstetricians and Gynecologists reviews its publications regularly; however, its publications may not reflect the most recent evidence. Any updates to this document can be found on www.acog.org or by calling the ACOG Resource Center.
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The American College of Obstetricians and Gynecologists (ACOG), is the nation's leading group of physicians providing health care for women. As a private, voluntary, nonprofit membership organization of more than 58,000 members, ACOG strongly advocates for quality health care for women, maintains the highest standards of clinical practice and continuing education of its members, promotes patient education, and increases awareness among its members and the public of the changing issues facing women's health care. www.acog.org
