Prozac Weekly (fluoxetine HCl)
The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
General Information
Prozac Weekly (fluoxetine hydrochloride) has been approved by
the FDA for the continuation treatment phase of major depressive
disorder. The drug is administered on a weekly basis, and it is
indicated for patients whose depressive symptoms have stabilized
and who require continuing treatment to prevent a relapse, or
return of symptoms.
Prozac Weekly contains 90 mg of fluoxetine with an enteric
coating that delays release into the bloodstream. Fluoxetine is
known as a selective serotonin reuptake inhibitor - it is believed
to provide a therapeutic effect by blocking neuronal (nerve cell)
uptake of serotonin, resulting in increased levels of the
hormone.
Major depressive disorders, which include depression, affect an
estimated 340 million people worldwide. If left untreated, the
effects of depression can be devastating, robbing people of the
energy or motivation to perform everyday activities and, in some
cases, leading to suicide. Symptoms of the disorder include
feelings of sadness or emptiness, lack of interest or pleasure in
nearly all activities, and feelings of worthlessness or
inappropriate guilt.
Clinical Results
In clinical trials, researchers examined 501 depressed subjects
who responded well to 13 weeks of therapy with fluoxetine 20 mg.
These subjects were then randomly assigned to treatment with a 90
mg enteric-coated formulation of fluoxetine taken once weekly,
fluoxetine at 20 mg daily or a placebo for a 25-week, double-blind
period.
Rates of relapse for subjects treated either with the enteric
coated or 20 mg formulation of fluoxetine were significantly lower
than for those treated with placebo. Additionally, subjects treated
with either 90 mg or 20 mg fluoxetine rated significantly better on
depression rating scales when compared with subjects assigned to
placebo.
Side Effects
The most commonly observed adverse events associated with the
use of fluoxetine in Untied States controlled trials for
depression, obsessive-compulsive disorder and bulimia combined were
the following:
- Nausea
- Headache
- Insomnia
- Anxiety
- Nervousness
- Somnolence (sleepiness)
Mechanism of Action
The antidepressant, antiobsessive-compulsive, and antibulemic
actions of fluoxetine are presumed to be linked to its inhibition
of CNS neuronal uptake of serotonin. Studies at clinically relevant
doses in man have demonstrated that fluoxetine blocks the uptake of
serotonin into human platelets. Studies in animals suggest that
fluoxetine is a much more potent uptake inhibitor of serotonin than
of norepinephrine.
Antagonism of muscarinic, histaminergic, and a1-adrenergic
receptors has been hypothesized to be associated with various
anticholinergic, sedative, and cardiovascular effects of classic
tricyclic antidepressant (TCA) drugs. Fluoxetine binds to these and
other membrane receptors from brain tissue much less potently in
vitro than do the tricyclic drugs. (from Prozac Prescribing
Information).
Additional Information
