Forest Laboratories Inc has submitted a supplemental New Drug Application (sNDA) to the U.S. Food and Drug Administration to expand the labeling of Lexapro (escitalopram oxalate) to include the treatment of generalized anxiety disorder (GAD). The sNDA is based on three placebo-controlled studies in patients suffering from GAD. Lexapro, the single-isomer of Celexa (citalopram HBr), is a newly approved selective serotonin reuptake inhibitor (SSRI) for the initial and maintenance treatment of major depressive disorder.

Anxiety disorders are the most common mental illness in the U.S., affecting 19.1 million adults, and they cost the U.S. more than $42 billion a year. The prevalence of generalized anxiety disorder (GAD) is estimated to be 4 million or 2.8% of the U.S. population, and it affects women twice as often as men. According to The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), the essential feature of GAD is excessive anxiety and worry (apprehensive expectations) about every day events or activities for a period of six months or more. This constant worry affects daily functioning and can cause physical symptoms. For a diagnosis to be made, worry must be present more days than not for at least six months. GAD frequently co-occurs with mood disorders, including depression. Additionally, up to 80% of people suffering from depression also experience symptoms of anxiety.

Lexapro is the product of a relatively new approach that involves the removal of one of two enantiomers from Celexa to create a single-enantiomer drug. Celexa is a racemic mixture of two mirror-image halves called the S- and R-enantiomers. With Lexapro, the R-enantiomer (that does not contribute to Celexa's antidepressant activity) has been removed, leaving only the therapeutically active S-enantiomer.

Forest Laboratories licensed Lexapro from the Danish pharmaceutical firm H. Lundbeck A/S, which developed both citalopram and escitalopram in Europe.