Body's Response to Drugs, Toxins Varies With Age

Scientists found big differences between children and adults

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FRIDAY, Feb. 17, 2006 (HealthDay News) -- When it comes to drug reactions and response to environmental toxins, age matters, a new study finds.

Scientists say they've uncovered dramatic metabolic differences in how infants, children and adults process potentially dangerous chemicals.

According to a team at the Medical College of Wisconsin, as people age, they undergo major changes in the types and levels of enzymes in the body that deal with drugs and environmental toxins. Depending on the particular compound and other factors, these enzymes can activate drugs, deactivate them, or do both. The same is true for environmental chemicals.

The study authors believe this information may help predict an individual child's response to drug treatment or his or her susceptibility to an adverse drug reaction.

The findings were presented Thursday at the annual meeting of the American Association for the Advancement of Science in St. Louis.

Certain enzymes that are known to share regulatory mechanisms in adults appear to use different regulatory mechanisms in infants and children, the study found. The researchers also identified a period of higher-than-normal variability for several enzymes in 3- to 6-month-old infants. This suggests that the onset or increased expression of these enzymes may vary considerably among individual infants within that age range.

"The dramatic changes observed in enzyme expression must be considered when examining issues of drug effectiveness and safety during early life stages," study leader Ronald N. Hines, professor of pediatrics and of pharmacology and toxicology, said in a prepared statement.

"Additional studies are needed to understand how these dramatic changes are regulated, and the molecular basis for differences among individuals, to better predict drug and toxicant responses in children," Hines said.

More information

The U.S. Food and Drug Administration has information about personalized medicine.

SOURCE: Medical College of Wisconsin, news release, Feb. 16, 2006

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