ER doctors issued about 560,000 to 880,000 prescriptions for codeine to kids each year between 2001 and 2010, according to an analysis of hospital survey data collected annually by the U.S. Centers for Disease Control and Prevention.
"We have hundreds of thousands of children still getting codeine, even though there are better and safer alternatives available," said study author Dr. Sunitha Kaiser, an assistant clinical professor of pediatrics at the University of California, San Francisco (UCSF).
The study was published online April 21 in the journal Pediatrics.
These prescriptions continued to be handed out despite repeated warnings from the American Academy of Pediatrics (AAP) that differences in children's metabolisms can cause the effects of codeine to swing from ineffective to toxic.
Codeine is classified as a narcotic drug.
Doctors prescribe codeine to kids for pain relief and as a cough suppressant, Kaiser said.
The human body must metabolize codeine for the drug to have any effect, essentially converting it into morphine, said Dr. Alan Woolf, a pediatrician at Boston Children's Hospital, who wrote an accompanying commentary to Kaiser's study.
But kids' ability to metabolize codeine varies wildly. About a third are not able to metabolize codeine well, and thus receive no pain relief from taking it. At the same time, as many as one in 12 rapidly metabolize codeine, accumulating toxic amounts of morphine in their systems that could harm or kill them, according to a UCSF news release.
"You'd have to know a child's genetics to predict for sure how they're going to metabolize the drug," Woolf said.
"This is not a drug that is so safe or effective, and maybe it's time we move on because we have an array of therapies that are effective," he added.
Concerns over codeine have led drug regulators in Canada and the European Union to restrict its use to people older than 12. And in 2012 the World Health Organization removed codeine from its list of essential drugs, the study authors noted in background information.
The AAP warned doctors twice -- in guidelines issued in 1997 and 2007 -- to avoid prescribing codeine to children.
This is the first study to attempt an estimate on the number of children being prescribed codeine in U.S. emergency rooms and to see if those warnings made any difference, Kaiser said.
She and her colleagues used a nationwide survey on hospital and outpatient care, performed annually by the U.S. National Center for Health Statistics, to determine the frequency of codeine prescriptions to children aged 3 to 17 during ER visits from 2001 through 2010.
The researchers found that rates of codeine prescriptions decreased from 3.7 percent to 2.9 percent during the 10-year period.
However, that small percentage still represents hundreds of thousands of prescriptions. The researchers also saw no decline in codeine prescriptions associated with professional recommendations against codeine use issued in 2006 by the AAP and the American College of Chest Physicians.
"When the American Academy of Pediatrics says something, as a practicing pediatrician I tend to listen to it and treat it with respect," Woolf said. "And yet on this issue, that guidance hasn't been effective."
The study authors estimated that each year up to 57,000 children who metabolize codeine quickly are at risk of overdose. Moreover, as many as 250,000 children who metabolize the drug poorly are at risk for low levels leading to inadequate pain relief.
Woolf said he believes doctors continue to prescribe codeine out of habit.
"Codeine is an old drug. It's a very well recognized, very commonly used. You might say it's well-worn drug that everybody knows about," he said. "My suspicion is many clinicians don't really put it in the same category as other narcotics like Demerol or oxycodone."
It also could be that doctors are so overwhelmed by the rush of new medical information and guidelines that they simply haven't gotten the memo, Kaiser said.
Kaiser and Woolf both said there's no good reason to ever prescribe codeine to young children.
Other pain relievers like ibuprofen, hydrocodone or even morphine itself are safer and more reliable, they said.
As far as cough suppression, Kaiser said clinical trials have shown that no drug or over-the-counter syrup beats dark honey in safety and effectiveness. Experts say that children under the age of 1 shouldn't be given honey, however.
Woolf said: "Codeine has never been shown by any well-controlled scientific study to have an effect on the severity or duration of children's coughs or colds. It's never been shown to be effective, and it's never been shown to be safe."
Several hospitals have created a simple and direct solution to the problem, Kaiser said -- they have removed codeine from their formularies, thus eliminating the temptation for doctors to prescribe it.
"That's an incredibly effective means, because physicians tend to reach for the drugs that are most easily available through their formulary," she said.
For more facts on codeine, visit the U.S. National Library of Medicine.