Pharmacologic Mechanism of Action
The SSRIs are a well-known group of prescription drugs, which presumably enhance the activity of the neurotransmitter serotonin by interfering with its reabsorption back into axon endings that have released it. There is evidence that depression, in many people, may be associated with low levels of serotonin activity. By making this chemical more available, SSRIs may "correct" this deficiency.

Studies at clinically relevant doses in humans have demonstrated that fluoxetine blocks the uptake of serotonin into platelets. Studies in animals also suggest that fluoxetine is a much more potent uptake inhibitor of serotonin than of norepinephrine.

SSRIs are no more effective than the older antidepressants (TCAs), but have less annoying side effects as well as fewer risks in most individuals. Patients are more willing to take the medication and physicians have fewer concerns about overdose or potentially dangerous cardiovascular side effects. There has been only a single recorded case of an SSRI overdose being fatal, which is an important consideration when treating depression. Patients also like the once-a-day dosing.

Indications
Depression: Fluoxetine HCl is indicated for the treatment of depression (see web site listed below for information on other disorders that it is indicated for). The efficacy of fluoxetine HCl was established in 5- and 6-week trials with depressed outpatients whose diagnoses corresponded most closely to the DSM-III category of major depressive disorder.

The antidepressant action of fluoxetine HCl in hospitalized depressed patients has not been adequately studied.

The efficacy of fluoxetine HCl in maintaining an antidepressant response for up to 38 weeks following 12 weeks of open-label acute treatment (50 weeks total) was demonstrated in a placebo-controlled trial. The usefulness of the drug in patients receiving fluoxetine HCl for extended periods should be reevaluated periodically.

Dosage and Administration
Initial Treatment: In controlled trials used to support the efficacy of fluoxetine, patients were administered morning doses ranging from 20 mg to 80 mg/day. Studies comparing fluoxetine 20, 40, and 60 mg/day to placebo indicate that 20 mg/day is sufficient to obtain a satisfactory antidepressant response in most cases. Consequently, a dose of 20 mg/day, administered in the morning, is recommended as the initial dose.

A dose increase may be considered after several weeks if no clinical improvement is observed.

Doses above 20 mg/day may be administered on a once a day (morning) or b.i.d. (i.e., twice a day) schedule and should not exceed a maximum dose of 80 mg/day.

As with other antidepressants, the full antidepressant effect may be delayed until 4 weeks of treatment or longer.

Side Effects
SSRIs can produce stomach upset, headache, nervousness, dizziness, and insomnia (much like having had too much caffeine) until you get used to the drug. Sexual dysfunction may occur in a smaller number of individuals. SSRIs should not be used with other medications or herbal remedies without your doctor's approval because some cause dangerous interactions. This is especially true for other depression remedies.

Cost
As relatively new drugs, SSRIs are not cheap (no generics available yet). Besides the cost of visiting your caregiver, a 3-month supply of the 20-mg dose of Prozac averages around $200. The cost may be lower depending on the individual's medical insurance. This medication may be prescribed after professional diagnosis at the college health center.

Resource:  Much of the material on this sheet is quoted directly from http://www.rxlist.com/cgi/generic/fluoxetine.htm and is used with permission.