Obese, Lean Kids Break Down Drugs Differently
Study Shows Differences in Metabolism Rates for Medications Taken by Lean and Obese Children
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
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
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
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.
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.