FDA Warns Breastfeeding Moms: Genes and Codeine Risk
Posted Nov 19 2009 10:02pm
With the recent FDA’s activity in personalized medicine, I asked DNA Direct’s director of pharmacogenetics, Dr. Huijun Z. Ring, if she’d give us a guest post.
FDA warns breast-feeding moms of genetic risk for using codeine products Gene test can help to prevent life-threatening side effects in nursing babies
When I was home with my first baby, my training in science and medicine went out the window, and I found myself to be as much of a novice as every other new mother. I wanted to make sure that everything was perfect. Mostly, however, our family went forward by trial and error, learning as we went along how to care for our new member. Gratifyingly, a recent advance in my field of pharmocogenetics will help remove one uncertainty for mothers.
Codeine is a frequently used medication for mothers after child birth and for infants in their first year life. On Aug 17, the FDA issued a Public Health Advisory warning that a rare, but sometimes life-threatening, side effect of codeine in nursing babies could be attributed to a mother’s genetic makeup.
The FDA’s codeine advisory reads, in part, “When codeine enters the body and is metabolized, it changes to morphine, which relieves pain. Many factors affect codeine metabolism, including a person’s genetic make-up. Some people have a variation in a liver enzyme and may change codeine to morphine more rapidly and completely than other people. Nursing mothers taking codeine may also have higher morphine levels in their breast milk. These higher levels of morphine in breast milk may lead to life-threatening or fatal side effects in nursing babies.”"
There is a gene test for determining a patient’s CYP2D6 genotype. The test is not routinely used in clinical practice but is available through a number of different laboratories. The results of this test predict that a person can convert codeine to morphine at a faster rate than average, resulting in higher morphine levels in the blood. When levels of morphine are too high, patients have an increased risk for adverse events.
It has been quite a week for gene tests for drug response. FDA’s codeine warning followed its decision to include genetic information in the label for warfarin, a commonly used blood thinner that is used by some patients at risk for stroke. The AP news on the codeine warning was rated as the second most read news item on MSNBC one day. I have been studying the relationship of genes and drug responses over the past ten years, and came to DNA Direct a year ago to help consumers and physicians use genetic information to select safer and more effective drug treatments. It’s really great to see that my chosen field of science is moving out of the laboratory and starting to help ordinary people in their everyday life now.
How DNA Direct can help you: DNA Direct offers the 2D6 gene test for $250. The results of this test predict whether a person can convert codeine to morphine at a faster rate than average, which would lead to an increase risk of side effects. DNA Direct also offers a three-gene drug response panel for $630, which covers 50% of all commonly prescription and over-the-counter medications.