The FDA granted marketing approval for Shire Inc.'s Vyvanse (lisdexamfetamine dimesylate) for the treatment of attention-deficit/hyperactivity disorder (ADHD) in adults. The drug was first approved in February 2007 for use in children ages 6-12. (See BioWorld Today, Feb. 27. 2007.)

The product was developed by Virginia-based New River Pharmaceuticals under a collaborative agreement with Basingstoke, UK-based Shire, which acquired New River last year for $2.6 billion in cash. (See BioWorld Today, Feb. 21, 2007.)

Vyvanse is the only once-daily prodrug stimulant approved in the U.S. to treat adults with ADHD. Since it was introduced into the U.S. market for children, the product has achieved a market share of 6.9 percent, Shire said in a statement. There have been more than 1 million prescriptions filled for the drug since July, the firm added.

"Many people may think of ADHD as only a childhood disorder, but the fact is that the majority of children diagnosed with ADHD still have symptoms as an adult," said David Goodman, assistant professor of psychiatry at Johns Hopkins University School of Medicine. "These symptoms can significantly impact them at work, home and in relationships, where they have important responsibilities," he added.

New River developed as a prodrug - meaning the drug's metabolite is the biologically active substance - to curb the new product's potential for abuse. Enzymes in the digestive system convert Vyvanse to dextroamphetamine.