New research suggests that the therapeutic 20
mg daily dose of fluoxetine hydrochloride (Prozac)
prescribed for depression may be effective in
reducing the severity and frequency of panic
attacks as well as other symptoms of panic
disorder. The research was presented today at
the 153rd Annual Meeting of the American
Psychiatric Association in Chicago, Ill.
"This study suggests that fluoxetine (Prozac) can reduce
the severity and frequency of panic attacks at a
dose of 20 mg per day, which is the
recommended dose for the treatment of
depression and is a dose familiar to most health
care professionals," said David Michelson, M.D.,
medical director at Eli Lilly and Company and lead
author of the study.
Key study findings include:
- After six weeks and at endpoint (12 weeks),
fluoxetine was associated with a statistically significant reduction in
severity of global panic
disorder symptoms (p=.035, p=.009) as rated on
the Panic Disorder Severity Scale.
- A statistically significantly greater number of
patients were panic free at six weeks and endpoint compared with
placebo (p=.024, p=.02).
- Fluoxetine was associated with a greater
percentage of patients who
reported a 50 percent or greater reduction in
frequency of full panic
attacks at six weeks and endpoint compared
with placebo (p=.036,
- Fluoxetine demonstrated greater mean
reduction in anxiety and functional
impairment compared with placebo from baseline
to endpoint as ranked by
the Hamilton Anxiety rating scale (p=.043), the
Inventory (p=.005), and Sheehan Work and
Social scales (p=.004, p=.002).
Patients involved in the study met diagnostic
criteria for panic disorder as assessed by the
Structured Clinical Interview for DSM-IV. Data
were gathered from a double-blind, randomized,
parallel, placebo-controlled nine- site trial
conducted with 180 patients in Europe. Patients
were randomized to either fluoxetine at 20
mg/day (initiated at 10 mg/day for one week) or
placebo for 12 weeks. Baseline characteristics
for the groups were similar as rated on the Panic
Disorder Severity Scale (p=.27), CGI-severity
scale (p=.95), and Hamilton Anxiety rating scale
Panic disorder is a potentially debilitating illness
that affects up to three million adults each year
in the United States. Panic disorder includes
recurrent and unexpected panic attacks and can
include a significant change in behavior related
to the attacks and excessive worry regarding
the implication of those attacks. Additionally, the
National Mental Health Association estimates
that approximately 50 percent of people with
panic disorder develop the condition prior to age
24. Women are twice as likely as men to suffer
from the disorder.
A person experiencing a panic attack often
suffers from physical symptoms -- such as rapid
heart rate or choking sensation -- as well as
psychological symptoms, including intense fear
and anxiety. Consequently, many people who
suffer panic attacks can become housebound
from the fear of experiencing a public attack.
Fluoxetine currently is indicated by the U.S.
Food and Drug Administration for the treatment
of depression, obsessive-compulsive disorder and
bulimia nervosa. The most commonly observed
events associated with fluoxetine vs. placebo in
U.S. controlled clinical trials for depression,
obsessive- compulsive disorder and bulimia
combined were nausea (23 vs. 10 percent),
headache (21 vs. 20 percent), insomnia (20 vs.
11 percent), anxiety (13 vs. 8 percent),
nervousness (13 vs. 9 percent) and somnolence
(13 vs. 6 percent). Fluoxetine is contraindicated
until at least two weeks have passed since
discontinuing an MAO inhibitor, and an MAO
inhibitor is contraindicated for at least five
weeks after discontinuation with fluoxetine.
Fluoxetine should be discontinued immediately if
rash or other possibly allergic phenomena appear
for which an alternative etiology cannot be
identified. Safety and effectiveness in pediatric
patients have not been established.
The study was funded by a grant from Lilly
Research Laboratories, a division of Eli Lilly and
Company--the patent holder of fluoxetine (Prozac).