The Food and Drug Administration granted a request by GlaxoSmithKline last month to approve paroxetine HCl (Paxil) for the treatment of generalized anxiety disorder (GAD). The SSRI becomes the first in its class to be approved for GAD.
Although off-label use of the drug has included the treatment of GAD, the final FDA approval adds a government-approved option for physicians treating those who suffer from the debilitating disorder characterized by excessive and global anxiety and worry. Thought to affect more than 10 million Americans, slightly more women than men, the condition is chronic, and some studies have suggested that only one-third of individuals with the disorder seek treatment.
In addition, GAD is highly comorbid, with as many as 90 percent of patients having other psychiatric diagnoses, most commonly depression or panic disorder.
Paroxetine was previously approved for the treatment of depression, panic disorder, obsessive-compulsive disorder, and social anxiety disorder. According to the Pharmaceutical Research Manufacturers Association, paroxetine was the most prescribed SSRI in the year 2000 based on new prescriptions written. More than 70 million prescriptions for the drug have been written worldwide in the nearly 10 years since its introduction for depression. The FDA is considering whether to add the indication of posttraumatic stress disorder to Paxil’s approved uses.
Efficacy data were based on two double-blind, placebo-controlled trials of nearly 900 patients with GAD. Those receiving paroxetine at doses of 20 mg to 50 mg a day demonstrated a nearly 60 percent reduction in anxiety symptoms based on the Hamilton Rating Scale for Anxiety.
Side effects common to the drug include asthenia, infection, sweating, nausea, dry mouth, constipation, decreased appetite, somnolence, dizziness, insomnia, tremor, nervousness, and sexual dysfunction in both men and women.
As with other SSRI antidepressants, patients taking paroxetine are cautioned not to take MAO inhibitors or thioridazine.
Complete revised prescribing information from GlaxoSmithKline is available to clinicians on the Web at www.paxil.com. ▪
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