Children who are prescribed medication to treat symptoms of attention-deficit hyperactivity disorder, or ADHD, take the drugs for several years. However, there have been no studies to show how effective or safe the medication is for the long-term, or how to detect rare side effects, according to a report in the journal PLOS ONE.
According to the Centers for Disease Control and Prevention (CDC), 11 percent of children in the United States between the ages of 4 and 17 – or about 6.4 million – are diagnosed with ADHD. The Food and Drug Administration (FDA) has approved 20 drugs to treat the condition. The drugs were approved for pediatric use based on clinical trials that studies short-term outcomes, researchers found.
The study involved a review of 32 clinical trials of the 20 approved drugs. Only five trials were conducted to determine drug safety. Each drug was found to have been tested on a median of 75 patients for a median trial duration of four weeks prior to FDA approval. Eleven of the 20 drugs were tested in fewer than 10 patients, and 14 of the drugs were tested in fewer than 300. Seven of the medications, which had been previously approved for other conditions, were granted approval for ADHD without condition-special testing in children.
“ADHD drugs are so effective at producing a behavioral effect quickly that one can measure a statistically significant treatment effect rapidly and with relatively few patients,” says study senior author Kenneth Mandl, MD, MPH, Boston Children’s chair in biomedical informatics and population health and director of the Intelligent Health Laboratory in Boston Children’s Informatics Program. “However, in the real world, these drugs are prescribed often for years, not for a few weeks, and long-term cognitive effects were never measured during the approval process.”
Six of the drugs that were granted approval were done so based on the manufacturers gathering post-market data to establish long-term safety. However, researchers say they found that only two of the seven actually carried through with that requirement.