(October 31, 2006) -- Treatment with methylphenidate reduces the symptoms of attention-deficit/hyperactivity disorder (ADHD) in preschoolers and most children tolerate this treatment well, new research suggests. However, the benefit from the drug may be smaller than that observed in school-age children.

Methylphenidate, a mild central nervous system stimulant, is sold as Ritalin, Methylin and under other trade names. It is available in intermediate and long-acting formulations, and comes in tablet, chewable and liquid form.

"These results give us the missing links in the decision to prescribe a drug that's been widely used off-label in preschool-age children," study co-author Dr. Mark Riddle, from Johns Hopkins Children's Center in Baltimore, said in a statement.

Riddle added: "We were able to confirm what many already suspected -- that even lower doses in preschoolers can safely achieve the desired therapeutic effect and indeed that low doses are often optimal."

The findings are based on the Preschool ADHD Treatment Study (PATS), which involved an 8-phase, 70-week treatment schedule in which patients were assigned to receive methylphenidate or an inactive "placebo" treatment. In the course of the trial, the subjects also switched treatment groups. A total of 303 children with ADHD, between 3 and 5 years of age, were included in the study.

The researchers' findings appear in the Journal of the American Academy of Child and Adolescent Psychiatry.

Three doses of methylphenidate (2.5, 5, and 7.5 mg) given three times per day, significantly decreased ADHD symptoms compared with placebo. Although the children also responded to treatment with a 1.25-mg dose, the overall effects of this dosage were not statistically significant. The average optimal daily dose for the entire group was 14.2 mg.

The results also showed that despite the benefits achieved with methylphenidate, only 21 percent of preschoolers on their most effective dose achieved remission.

Methylphenidate was generally well tolerated and discontinuation due to drug-related side effects was rare. Adverse effects linked to the drug included appetite loss, trouble sleeping, stomach ache, social withdrawal and lethargy. Of eight serious adverse events encountered, only one -- a possible seizure -- was thought to have resulted from use of the drug.

"We want parents to know that trained professionals can make an accurate diagnosis and prescribe helpful and safe treatment in preschoolers with ADHD," Riddle said. "But do expect your prescribing physician to monitor side effects closely and regularly and to tweak the dose if necessary."

SOURCE: Journal of the American Academy of Child and Adolescent Psychiatry,

Last updated: 10/06

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