DURHAM — For older prescription drugs approved before this decade, doctors have no idea how big a dose to give children, and instead rely on the educated guesses of experts.
Now the National Institutes of Health is launching a $95 million, seven-year program to figure out the correct pediatric dosages of drugs long approved for adult use and commonly prescribed to millions of children for infections, seizures, heart problems and other ailments.
Scientists at Duke University's Clinical Research Institute will help lead the Pediatric Trials Network, which was announced Thursday. Wake Forest University researchers will also participate.
"There's no way to know the right dosage [in children] by looking at how adults metabolize the drug," said Dr. Daniel K. Benjamin Jr., a professor of pediatrics at Duke who will lead the new network. "Sometimes it's right, sometimes it's wrong. ... And when I say wrong, I mean really wrong."
In one study recently done at Duke to determine the dosage of an antibiotic used in premature newborns, the standard amount doctors relied on turned out to be way off, Benjamin said. Tiny infants actually needed two times as muchdrug as they were typically given.
The problem lies in how children's bodies work. They're not simply miniature adults, so drug dosages can't be formulated on a quick body mass calculation. Children's immature kidneys, livers and intestines may lack the essential enzymes needed to process a drug in the way that adults do, so they may need more or less of the therapy to get any benefit - or escape harm.
Dr. David T. Tayloe Jr., immediate past president of the American Academy of Pediatrics and a pediatrician in Goldsboro, said the NIH effort to set proper dosages is long overdue.
"Two-thirds of the drugs pediatricians use every day do not have formal indications for use in children," Tayloe said. "In other words, there's been zero acceptable research done on how these drugs really affect children. It's kind of ridiculous."
Benjamin said the research network will begin work immediately and expect to report findings within 18 months. He said at least two drugs a year will be studied, in hopes of eventually clarifying the dosages of 10 to 20 therapies or drug devices over the next seven years.
Group leaders will meet to determine which drugs should be studied. He said the effort will concentrate on drugs prescribed most widely for common pediatric health problems.
Benjamin said the effort will tackle older drugs approved in the 1970s, '80s and '90s. In 1998, Congress began efforts to have drug companies include children in the testing process for marketing approval. As a result, the pediatric dosages for newer drugs are backed by scientific analysis.
Benjamin said those analyses actually heightened concerns about the dosages in the older drugs. As new drugs were being tested, research teams set the initial dosages based on highly educated guesses, but found through the testing process that those first calculations were wrong 35 percent of the time.
"There's no reason for all the new drugs [dosages] to be wrong, and they were correct on the old drugs," Benjamin said. "It's frightening."
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