MONDAY, Oct. 6 (HealthDay News) -- Free prescription drug samples distributed to pediatric patients may be unsafe, research suggests.

The study, published in the October 2008 issue of Pediatrics, examined data on 10,295 children and adolescents from the 2004 Medical Expenditure Panel Survey.

The researchers found that one in 20 American children received free drug samples in 2004. And among those who took at least one prescription drug that year, nearly one in 10 received free samples.

This in concerning, since the researchers also found that some of the most frequently distributed samples may be unsafe.

Four of the 15 most frequently distributed samples in 2004 were identified by the U.S. Food and Drug Administration as having significant new safety concerns, including new black box warnings or significant revisions to existing warnings.

The top 15 samples included (among others) Strattera (atomoxetine) and Adderall (amphetamine/dextroamphetamine), drugs used to treat attention deficit hyperactivity disorder (ADHD).Both of those medications are Schedule II controlled substances, meaning they are controlled and monitored by the Drug Enforcement Agency due to high potential for abuse.

Some physicians welcome the use of free sample medications as a way to get medications to needy patients. But this study's findings showed that few free samples actually go to the children who most need them.

Only 16 percent of the children who received free samples were uninsured for all or part of 2004, and less than one-third had low family incomes, defined as less than $38,000 for a family of four.

"New medications are frequently released before their safety profile is fully understood, and samples tend to be newer medications. Free samples encourage the casual use of medications in our children before enough is known about potential harm," lead author Sarah Cutrona, a physician at Cambridge Health Alliance and an instructor of medicine at Harvard Medical School, said in a news release from the alliance and Hasbro Children's Hospital.

Another of the study's authors, Neal LeLeiko, director of the pediatric gastroenterology and nutrition at Hasbro and a professor of pediatrics at the Warren Alpert Medical School of Brown University, expressed his concern about the distribution of free medication samples.

"Previous findings in adults strongly suggest that free drug samples serve as a marketing tool. Our study shows that samples can pose a serious and unappreciated risk to our children," LeLeiko said in the news release.