By Pat Anson, Editor

A drug widely prescribed to treat fibromyalgia, neuropathy and other chronic pain conditions increases the risk of major birth defects, according to a new study published in Neurology, the medical journal of the American Academy of Neurology.

Women taking pregabalin were six times more likely to have a pregnancy with a major defect than women who were not taking the drug, the study found. The birth defects included heart defects and structural problems with the central nervous system (CNS) or other organs. Birth defects due to chromosomal abnormalities were not included in the results.

Pregabalin is the generic name of Lyrica, which is approved by the FDA to treat diabetic nerve pain, fibromyalgia, epilepsy, post-herpetic neuralgia caused by shingles and spinal cord injury. It is also prescribed “off label” to treat a variety of other conditions. Lyrica is Pfizer’s top selling drug, generates over $5 billion in annual sales, and is currently approved for use in over 130 countries.

The international study involved nearly 700 pregnant women in seven different countries. Four of the 125 women who took pregabalin during pregnancy had children with central nervous system defects, or 3.2 percent. That compares to a birth defect rate of just 0.5% in the 570 women who did not take pregabalin.

Of the women taking pregabalin, 115 were taking it to treat neuropathic pain, 39 were taking it for psychiatric disorders, including depression and anxiety, five were taking it for epilepsy, and one for restless leg syndrome.

Most of the women started taking pregabalin before they became pregnant. All of them stopped taking the drug at an average of six weeks into their pregnancies.

A small number of women also took another anti-seizure drug during their pregnancy. Women in that group had a 6 percent chance of a major birth defect, compared to 2 percent of the women who did not take another anti-seizure medication.

“We can’t draw any definitive conclusions from this study, since many of the women were taking other drugs that could have played a role in the birth defects and because the study was small and the results need to be confirmed with larger studies, but these results do signal that there may be an increased risk for major birth defects after taking pregabalin during the first trimester of pregnancy,” said study author Ursula Winterfeld, PhD, of the Swiss Teratogen Information Service and Lausanne University Hospital in Lausanne, Switzerland.

“Pregabalin should be prescribed for women of child-bearing age only after making sure that the benefits of the drug outweigh the risks and after counseling them about using effective birth control. In cases where women have taken pregabalin during pregnancy, extra fetal monitoring may be warranted.”

A spokesman for Pfizer said the study was small and the findings could have been influenced by other factors.

"As the authors agree, the study has significant limitations and cannot be used to draw definitive conclusions," Steven Danehy said in an email to Pain News Network. "The study was small, did not account for other medical conditions or medications, and the women taking Lyrica had higher rates of smoking and diabetes, all of which can negatively affect pregnancy outcomes."  

Because women are more likely than men to have a chronic pain condition such as fibromyalgia, they are the biggest consumers of Lyrica.

The FDA warning label for Lyrica does not specifically warn pregnant women not to take the drug. But it does caution them to consult with a doctor if they are pregnant or plan to become pregnant.

“It is not known if Lyrica will harm your unborn baby. You and your healthcare provider will have to decide if you should take Lyrica while you are pregnant. If you become pregnant while taking Lyrica, talk to your healthcare provider about registering with the North American Antiepileptic Drug Pregnancy Registry,” the label says.

The label also cautions men to see a doctor if they plan to father a child while taking Lyrica. 

“Animal studies have shown that pregabalin, the active ingredient in Lyrica, made male animals less fertile and caused sperm to change. Also, in animal studies, birth defects were seen in the offspring (babies) of male animals treated with pregabalin. It is not known if these problems can happen in people who take Lyrica,” the warning label states.