One of the main benefits touted by Lilly is that Strattera is the only ADHD drug on the market that is not a stimulant, meaning users are less likely to abuse it.
The makers of Adderall and Concerta have advertised their drugs in magazines geared to parents of kids with ADHD. And Lilly has been running television ads aimed at adults who may not realize they have the disorder. ADHD symptoms include impulsivity, trouble concentrating, disorganization, procrastination and hyperactivity.
Several factors could be responsible for the increased diagnosis of ADHD in adults. Awareness of the disorder is growing among the public and doctors, the study said, and additional research indicates a large percentage of children with the disorder will continue to exhibit symptoms into adulthood.
That percentage could be as large as two-thirds, according to the American Academy of Family Physicians. Further, parents of children newly diagnosed with ADHD are realizing they have the same symptoms.
Joel Martin, an assistant professor of psychology at Butler University, said it is unclear whether the various studies have merit or whether they are contributing to
Sagging sales of Eli Lilly and Co.'s Strattera drug could get a lift from research that found prescriptions for attention deficit hyperactivity disorder are growing at a faster rate among adults than children.
From 2000 to 2004, use of drugs for ADHD patients doubled among adults but rose only 56 percent among children, according to data compiled by Medco Health Solutions, one of the country's largest prescription benefit managers.
Strattera has been on the market since 2002 and, at the time, was the only ADHD drug approved by the Federal Drug Administration for use among both children and adults. Shire Pharmaceutical Group's Adderall and Johnson & Johnson's Concerta since have taken a share of the market.
Competition and Lilly's addition of a safety warning to the Strattera label in December, after two patients taking the drug experienced severe liver injury, have softened sales.
Sales of Strattera generated during the second quarter totaled $123.5 million, a 31-percent decrease compared with the same quarter last year. Through the first two quarters of this year, sales were off 24 percent from 2004.
A largely untapped adult market naturally would benefit Lilly, said Al Rauch, a pharmaceutical analyst at AG Edwards & Sons Inc. in St. Louis.
"If the adult market greatly expands, Strattera could become one of Lilly's major products," Rauch said, "but now it's not a major drug in [its] pipeline."
Lilly antipsychotic drug Zyprexa, by comparison, generated sales of more than $1 billion during the second quarter.
While as many as 8 million adults in the United States have ADHD-making it the second-most-common psychological problem in adults after depression-only 15 percent are aware of having the condition, the Medco study said.
Tony Butler, a pharmaceutical analyst at New York-based Lehman Brothers Inc., said the adult market presents opportunities, but he questioned whether Strattera will have an impact.
"Will the sales of Strattera be able to grow from here? I think that could be an overmedicated society.
"The data simply isn't in yet," he said. "There are certainly varying opinions in the psychological community whether this is a fad diagnosis or not. But there is no data to convincingly suggest one way or the other."
For Lilly's part, the pharmaceutical giant has worked with WebMD on a physician-finder program for people wanting to seek medical advice about ADHD. It also posts a questionnaire geared toward adults on its Strattera.comWeb site.
The survey can help determine whether a trip to the doctor is necessary, said Jennifer Bunselmeyer, Lilly spokeswoman for Strattera.
"One of the focuses of Lilly's efforts is to heighten the awareness of this disorder," she said. "It's important to remember that the vast majority of adults with ADHD are undiagnosed."
An analysis from the American Psychiatric Association reported that U.S. household income losses due to ADHD total nearly $77 billion annually, making it one of the costliest medical conditions in the nation.