Pfizer Inc has received approval from the U.S. Food and Drug Administration (FDA) for Zoloft (sertraline hydrochloride) for acute and long-term treatment of social anxiety disorder, the company announced.

Zoloft is the first and only selective serotonin reuptake inhibitor (SSRI) approved in the United States for long-term treatment in patients with this condition.

Two double-blind, placebo-controlled trials including more than 600 patients demonstrated that Zoloft was significantly more effective than placebo in reducing the anxiety, fear and avoidance behaviors experienced by people with social anxiety disorder, also known as social phobia. In one of these studies 53 per cent of patients receiving Zoloft responded to treatment compared to 29 per cent of placebo patients. Patients enrolled in the study had a mean duration of social anxiety disorder for nearly 21 years.

"Social anxiety disorder is the most common anxiety disorder in the United States. It affects work functioning, social relationships and also impairs quality of life," said Cathryn Clary, MD, senior medical director, Pfizer Inc. "Zoloft's demonstrated efficacy in both acute and long-term treatment provides an important new option for people suffering from this disorder."

Zoloft was shown to be effective for long-term treatment of social anxiety disorder. In a continuation of a 20-week study, patients who responded to Zoloft were re-randomized to treatment with Zoloft or placebo for 24 weeks. Ninety-six percent of patients who responded to treatment with Zoloft maintained an effective treatment response for 24 weeks as compared to 64 per cent on placebo.

"These study results demonstrate that Zoloft is an effective first-line therapy for social anxiety disorder," said Dr. Michael R. Liebowitz, director of The Anxiety Disorders Clinic at the New York State Psychiatric Institute and Professor of Clinical Psychiatry at Columbia College of Physicians and Surgeons. "Even patients with long-term illness and high levels of symptom severity responded well to treatment with Zoloft."

Social anxiety disorder is an impairing and often chronic disorder. It is characterized by an intense, persistent fear of social or performance situations that may result in scrutiny by others. The individual fears that he or she will act in a way (or show anxiety symptoms) that will be humiliating or embarrassing.

Individuals with social anxiety disorder also experience a range of physical symptoms including sweating, blushing, tremors or heart palpitations when exposed to social or performance situations. Adults with the disorder recognize that their fear is excessive or unreasonable.

Patients with social anxiety disorder may have few friendships, experience trouble dating, be less likely to marry, drop out of school prematurely, reject promotions at work, suffer from low self-esteem and feelings of inferiority, as well as have difficulty being assertive.

Zoloft is also indicated for depression, posttraumatic stress disorder (PTSD), panic disorder (with or without agoraphobia), adult and pediatric obsessive-compulsive disorder (OCD) and premenstrual dysphoric disorder (PMDD). Zoloft is approved for the long-term treatment of PTSD, OCD and panic disorder in adults.

Zoloft is the most prescribed brand of its kind in the United States and is available in 96 countries around the world. Since its approval more than a decade ago, millions of people have been treated with Zoloft.

Patients who are taking monoamine oxidase inhibitors (MAOI) or pimozide should not take Zoloft.

The most common side effects of Zoloft include upset stomach, having trouble sleeping, diarrhea, dry mouth, sexual side effects, feeling unusually sleepy or tired, tremor, indigestion, increase of sweating, feeling agitated and decreased appetite. In clinical studies with Zoloft, few patients were bothered enough by side effects to stop taking their medicine.