Lilly, which won federal marketing approval for Strattera in November, said more than 46,000 pharmacies have stocked the drug and can begin filling prescriptions. Unlike Ritalin and other drugs to treat ADHD, Strattera is not a stimulant - a factor Lilly hopes will make the medication more convenient to pick up from pharmacies. Because stimulants carry potential for abuse, pharmacies require written prescriptions and do not allow refills.

Strattera, a capsule that can be taken once or twice a day, works by blocking reabsorption of a neurotransmitter that moves messages between brain cells.

The U.S. Food and Drug Administration approved Strattera for treatment of ADHD in children, adolescents and adults.

ADHD is one of the most common behavioral disorders of childhood. Although not widely recognized in adults, experts estimate that 4 percent, or more than 8 million people, have the disorder, Lilly said.

Symptoms include short attention span, impulsive behavior and difficulty focusing and sitting still.

Industry analysts have said Strattera has strong growth potential and could offset recent setbacks for Lilly, including the 2001 loss of patent protection for the anti-depressant Prozac and manufacturing problems at Lilly plants in Indianapolis.