We saw a 50 percent improvement in symptoms compared with placebo, Dr. Ann Childress told Reuters Health. Childress presented her group's findings this week at the American Psychiatric Association annual meeting in New Orleans.

Vyvanse improved symptoms of inattention, hyperactivity and impulsivity compared to placebo, she noted.

Vyvanse is currently approved in the US for treatment of ADHD in children aged 6 to 12 years and in adults.

The 45-center randomized trial involved 309 subjects 13 to 17 years of age with at least moderate symptoms of ADHD. The research team assigned 77 teenagers to the placebo group and the remaining 232 to Vyvanse at 30, 50, or 70 milligrams per day for 4 weeks.

Significant between-group differences, favoring Vyvanse, became evident within the first week and persisted throughout the study. Nearly twice as many subjects in the Vyvanse groups were rated as very much or much improved at the end of the study.

There were no surprises regarding side effects, said Childress, who is from the Center for Psychiatry and Behavioral Medicine in Las Vegas. We had all the 'usual suspects,' including decreased appetite, headache, insomnia, weight decrease, and irritability. The researchers also saw small average increases in pulse and blood pressure with Vyvanse.

Vyvanse maker Shire Plc recently submitted a supplemental New Drug Application for use of Vyvanse in the treatment of adolescents aged 13 to 17 years with ADHD.

Dr. Regina Bussing, a child and adolescent psychiatrist at the University of Florida in Gainesville, told Reuters Health that a big advantage of Vyvanse is that it's not abusable. It becomes effective only after it's been swallowed.

So teenagers, who are prone to experimenting with drugs, can't 'snort' Vyvanse and get high from it, she said. It also has a nice steady release profile and its efficacy is good, she added.

Bussing, who was not involved in the research, noted that the trial findings are particularly welcome. Adolescents are an understudied group with ADHD, so I think that is valuable for practitioners to have data on this particular age group, she said.

The study was supported by Shire Development Inc. Dr. Childress is a consultant and speaker for Shire and has received grant/research support from the company.