The manufacturer of the attention deficit hyperactivity disorder (ADHD) drug Vyvanse has agreed to study the drug in preschool children, at the request of the U.S. Food and Drug Administration (FDA).
The company, Shire, also makes the ADHD drug Adderall, the only such drug approved to treat children under age 6 in the United States.
A government study published last month found more than 10,000 toddlers in the United States are receiving medication for ADHD outside established guidelines.
The report found children covered by Medicaid are most likely to receive drugs such as Ritalin or Adderall.
The American Academy of Pediatrics does not have guidelines for use of ADHD medications in children ages 3 and younger, because their safety and effectiveness in that age group has not been established.
Because so many young children are taking ADHD drugs, the FDA asked for additional information on the effects of the drugs in this population, according to Reuters.
Shire said the company is designing three clinical trials for children ages 4 to 5, which are expected to begin in the first half of 2015. One study will investigate how the body absorbs, breaks down and excretes the drug. Another will look at the drug's safety and effectiveness in young children, and the third will test the drug's safety over a longer period.
ADHD drugs have been linked with growth suppression in children, the article notes. They also can cause hallucinations, mania and delusions.