March of Dimes
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  Medications That Interfere With Folic Acid Raise Risk of Serious Birth Defects, Study Shows

WHITE PLAINS, N.Y., DEC. 4, 2000 - Women of childbearing age and their health care providers must be alert to interactions between common prescription drugs and the B vitamin folic acid that may increase the risk of serious birth defects, the March of Dimes warned today. The March of Dimes comments came in response to a study of folic acid antagonists during pregnancy and the risk of birth defects in a recent issue of The New England Journal of Medicine.

"Folic acid is crucial to the prevention of several serious birth defects, and certain prescription drugs interfere with the body's ability to use folic acid," said Donald R. Mattison, M.D., medical director of the March of Dimes. "It's very important for every woman of childbearing age to discuss her medications with her physician. If she's capable of having a baby, or if she's pregnant, it may be necessary to switch medications or to increase her daily supplement of folic acid above 400 micrograms, as well as to monitor her blood levels carefully."

Prescription drugs that interfere with folic acid that were reported in today's article were: phenobarbital, phenytoin (Dilantin), carbamazapine (Tegretol), and primidone (Mysoline), used primarily to prevent seizures; the antibiotic combination of trimethoprim and a sulfonamide (Bactrim, Septra), commonly used for urinary tract infections; triamterene (Dyrenium), a diuretic used for high blood pressure; and sulfasalazine (Azulfidine), used for ulcerative colitis and other inflammatory conditions.

Oral contraceptives and tetracycline also are reported to interfere with folic acid, Dr. Mattison said. Other widely-prescribed medications that are reported to interfere with folic acid are: the anticonvulsant valproic acid (Depakene); cimetidine (Tagamet), used to treat heartburn and reflux; beta-blockers and calcium-channel blockers, used for high blood pressure and certain heart disorders; and cholestyramine (Locholest, Questran), used to lower cholesterol levels.

The March of Dimes recommends that all women of childbearing age consume 400 micrograms of folic acid daily as part of a healthy diet, beginning before pregnancy, to prevent birth defects of the brain and spine known as neural tube defects (NTDs). NTDs, which include spina bifida and anencephaly, are among the most serious and common birth defects in the United States. Each year, an estimated 2,500 babies are born with NTDs, and many additional affected pregnancies result in miscarriage or stillbirth.

"Folic Acid Antagonists During Pregnancy and the Risk of Birth Defects," by Sonia Hernandez-Diaz, M.D., Dr.P.H., and colleagues at the Slone Epidemiology Unit, Boston University School of Public Health and the Department of Epidemiology, Harvard School of Public Health, was published in NEJM, volume 343, number 22, pages 1608-1614, November 30, 2000.


The March of Dimes is a national voluntary health agency whose mission is to improve the health of babies by preventing birth defects and infant mortality. Founded in 1938, the March of Dimes funds programs of research, community services, education, and advocacy to save babies.
 
  © 2008 March of Dimes Birth Defects Foundation. All rights reserved. The March of Dimes is a not-for-profit organization recognized as tax-exempt under Internal Revenue Code section 501(c)(3). Our mission is to improve the health of babies by preventing birth defects and infant mortality.