Study Shows Prozac Can Reduce Symptoms Of Panic Disorder
INDIANAPOLIS, IN -- Nov. 16, 1998 --
A study published in this month's issue of The American Journal of Psychiatry provides data that Eli Lilly and Co.'s Prozac® (fluoxetine hydrochloride) significantly reduced the symptoms of panic disorder, a potentially debilitating illness that affects up to three million adults each year in the United States.
Researchers found that Prozac not only reduced panic attack symptoms but also phobic symptoms, anxiety and depressive symptoms. The strong correlation between overall improvement in panic disorder and improvement in individual symptoms suggests that improvement in panic attack frequency alone is less important than changes in multiple symptoms of the disorder.
The placebo-controlled study is the first known published data of its kind to examine Prozac's role in the treatment of panic disorder. Prozac currently is indicated by the U.S. Food and Drug Administration for the treatment of depression, obsessive compulsive disorder and bulimia nervosa.
Panic disorder includes recurrent unexpected panic attacks and can include a significant change in behaviour related to the attacks and excessive worry regarding implications of the attacks. At least 1.6 percent of adults in the U.S., or nearly three million people, will suffer from panic disorder at some point in their lives, according to the National Institute of Mental Health.
Additionally, the National Mental Health Association estimates that approximately 50 percent of all people who suffer from panic disorder develop the condition prior to age 24. Women are twice as likely as men to suffer from panic disorder.
"Prozac proved an effective, well-tolerated agent for the treatment of panic disorder," said David Michelson, M.D., a clinical research physician at Lilly and lead author of the study. "Although reduction in panic attack frequency is a component of Prozac's therapeutic effect, the effect on phobic avoidance, anxiety and depressive symptoms also appear to be critical factors in clinical improvement."
The multi-site trial examined 243 patients diagnosed with panic disorder. The subjects were randomly assigned to daily treatment with 10 milligrams of Prozac, 20 milligrams of Prozac or placebo. Patients completing 10 weeks of acute treatment entered a 24-week continuation phase, with patients randomised to continued therapy with the acute phase dose or placebo.
Patients were assessed weekly for the first two weeks of the acute phase, and at four-week intervals for the remainder of the study. Primary measures were change in total panic attack frequency, clinician-rated CGI-improvement scores, clinician and patient-rated panic and phobic disorder scales (PPDS), Hamilton Anxiety rating scale (HAM-A), Hamilton Depression rating scale (HAM-D) and Sheehan Disability scale.
Overall response to treatment of panic disorder was statistically significantly greater for patients treated with Prozac compared to treatment with placebo. Total panic attack frequency was significantly reduced for patients receiving 10 milligrams of Prozac compared with placebo and treatment with 20 milligrams of Prozac also demonstrated statistically significantly greater improvement over placebo in patient-rated panic attacks, anxiety, phobic avoidance and overall functioning.
Although panic attacks alone are a core part of the diagnostic criteria for panic disorder, much of the morbidity associated with the illness and resulting functional impairment result from other symptoms, including anxiety, depression and phobic avoidance. Data published in The American Journal of Psychiatry, meanwhile, suggest that panic attack frequency alone is unsatisfactory as a measure of treatment outcomes. Clinical improvement could be better reflected by multidimensional measures specific to panic disorder that assess panic attack frequency as just one of several important variables, Dr. Michelson explained.
The most commonly observed events associated with the use of Prozac (versus placebo) in U.S.-controlled clinical trials for depression, obsessive compulsive disorder and bulimia combined were nausea (23 versus 10 percent), headache (21 versus 20 percent), insomnia (20 versus 11 percent), anxiety (13 versus eight percent), nervousness (13 versus nine percent) and somnolence (13 versus six percent).
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