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Safety in Numbers

Pioneering birth defects study at BU is expanding

| From Research Magazine | By Bari Walsh

Illustration by James Steinberg from ispot

When the thalidomide tragedy of the 1960s revolutionized the drug regulatory system in the United States and elsewhere, the only group that did not benefit from the new safety net was the same group devastated by thalidomide’s destructive effects: pregnant women and their babies.

The drug, touted as safe and effective, was given to treat morning sickness in pregnancy; after its dire consequences became apparent, in children born with shortened limbs and other malformations, thalidomide was quickly banned, and stricter testing protocols for medications and pesticides were later mandated.

“But when a drug comes onto the market today, it has almost never been tested in pregnant women,” says Allen Mitchell, a School of Public Health professor of epidemiology, a School of Medicine professor of pediatrics, and director of the Slone Epidemiology Center. There are good reasons for that, he says—ethical clinical trials would be impossible to construct—“but it means that the only time you can study the safety and risks of a drug in pregnancy is when it’s in the marketplace.”

Since 1976, Mitchell and his colleagues at Slone have done precisely that, collecting data on prenatal drug exposures in more than 40,000 women through Mitchell’s pioneering Birth Defects Study (BDS). Now the study is being expanded with a significant federal investment and an infrastructure that promises an unprecedentedly comprehensive view of risk and safety. The goal is to provide critical risk and safety data for women and their doctors, with the initial focus on seasonal flu vaccine, antiviral medicines used to prevent or treat flu, and commonly prescribed asthma medications. As the study expands, it will also gather data on the wide range of medications used by pregnant women, including over-the-counter headache cures and herbal remedies. Thus, the study will identify as early as possible which medications are relatively safe and which might pose a risk to the fetus.

BDS is one of two data collection components collaborating with the American Academy of Allergy, Asthma, and Immunology on what is being called the first broad-based, systematic study of the risks of vaccines and medicines in pregnancy. The new study—Vaccines and Medication in Pregnancy Surveillance System (VAMPSS)—was launched in September 2009 with the initial mandate to look at H1N1 vaccine, seasonal flu vaccine, two antiviral flu medications, and asthma drugs. It will combine the strengths of complementary—but separately implemented—epidemiological techniques, a case-control surveillance method developed by the Slone Center, and pregnancy registries (cohort studies) conducted by a network of specialists who collaborate through the Organization of Teratology Information Specialists.

Mitchell’s group identifies women in four regions of the country who have given birth to children with defects, and a smaller group of women with normal outcomes, and then conducts carefully constructed interviews designed to identify every drug or herbal remedy they took during pregnancy. Among its many findings, the BDS study has shown that antidepressant use in pregnancy is generally safe, but that among a popular group of antidepressants, SSRIs, Prozac carries the lowest risk of birth defects and Paxil the highest. That finding wound up on the medication label, and Paxil use in pregnancy has since dropped, Mitchell says.

“The Food and Drug Administration has not only the legal authority but a legal mandate to demand post-marketing safety studies for drugs that were not adequately studied in pregnancy prior to marketing—which means just about everything,” Mitchell says. The agency has been slow to flex that authority, he adds, but that may be changing. “There is considerable excitement at the FDA, and also at the Centers for Disease Control and Prevention, the National Institutes of Health, and in practitioner groups, about what our study will yield.”

This article originally appeared in Boston University’s Research Magazine 2010.

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