Obese, Lean Kids Break Down Drugs Differently

Study Shows Differences in Metabolism Rates for Medications Taken by Lean and Obese Children

From the WebMD Archives

April 28, 2010 (Anaheim, Calif.) -- Children who are obese appear to metabolize common medications at different rates than their leaner counterparts, according to a new study.

With the pediatric obesity epidemic, the time is ripe for study of the area, says study researcher L'Aurelle Johnson, PhD, assistant professor of experimental and clinical pharmacology at the University of Minnesota, Minneapolis. She presented her findings this week at EB2010, the annual meeting of Experimental Biology.

''We know with the increasing rate of obesity in the pediatric population, more are getting diabetes and cardiovascular problems," she tells WebMD. These chronic conditions are treated with medications, yet little research has focused on whether obese and leaner children metabolize medicines differently.

While 6.5% of children age 6 to 11 were obese in 1980, 19.6% were in 2008, according to the CDC.

Measuring the Breakdown of Medications

Johnson and her colleague, Manoj Chiney, evaluated the metabolism of active ingredients found in an over-the-counter cough syrup and in a soft drink in 16 healthy-weight children and nine obese children. The median age (about half were older, half younger) was 9.

The obese children didn't have chronic diseases and were not on constant medication.

The obese children had a BMI or body mass index above the 95th percentile; the healthy-weight children were between the fifth and 84th percentile, the accepted definition of a healthy weight range.

The researchers measured metabolites, or breakdown products, of the dextromethorphan in the cough syrup and the caffeine in the soft drink to evaluate the metabolism activity.

''Obese kids broke down both drugs at different rates," Johnson tells WebMD. According to Johnson, the obese children had slower rates of breakdown of the cough syrup and higher rates for the soft drink compared to the leaner children.

The metabolizing of a drug is just one part of the picture, she says. Other aspects include the distribution of a drug in the body, the elimination, and other contributing factors.

While there is as yet no practical take-home advice for parents, Johnson says more research is expected to produce a more precise picture of differences. "This is one step closer to personalized medicine in developing a dosing regimen'' that is safe and effective for children who are obese.


Second Opinion

The new research adds valuable information to what's known about drug metabolism, says Margaret James, PhD, professor of pharmacy at the University of Florida, Gainesville, who reviewed the study findings for WebMD.

The bottom line, for scientists, she says, is that "they found differences in how active an enzyme was based on whether the child was lean or obese. This particular enzyme is [already] known to be controlled by genetic makeup."

The finding that obesity may affect it is new, she says.

The findings are ''groundbreaking," says Jayne Reuben, PhD, professor of biomedical sciences at Texas A&M Health Science Center, Dallas, who also reviewed the study findings. The ultimate research goal, she says, is to find doses that are effective and safe for all children, regardless of weight.

WebMD Health News Reviewed by Laura J. Martin, MD on April 28, 2010



L'Aurelle Johnson, PhD, assistant professor of experimental and clinical pharmacology, University of Minnesota, Minneapolis.

Margaret James, PhD, DSc, Jack C. Massey Professor of Pharmacology and Chair, Medicinal Chemistry, University of Florida, Gainesville.

EB 2010, Experimental Biology annual meeting, Anaheim, Calif., April 24-28, 2010.

Jayne Reuben, PhD, professor of biomedical sciences, Texas A&M Health Science Center, Dallas.

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