Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: fluoxetine

BRAND NAME: Prozac, Serafem

DRUG CLASS AND MECHANISM: Fluoxetine is an oral drug that is used for treating depression. It is in a class of drugs called selective serotonin reuptake inhibitors (SSRIs), a class that also contains citalopram (Celexa), paroxetine (Paxil) and sertraline (Zoloft). Fluoxetine affects neurotransmitters, the chemicals that nerves within the brain use to communicate with each other. Neurotransmitters are manufactured and released by nerves and then travel and attach to nearby nerves. Thus, neurotransmitters can be thought of as the communication system of the brain. Serotonin is one neurotransmitter that is released by nerves in the brain. The serotonin either travels across the space between nerves and attaches to receptors on the surface of nearby nerves or it attaches to receptors on the surface of the nerve that produced it, to be taken up by the nerve and released again (a process referred to as re-uptake).

Many experts believe that an imbalance among neurotransmitters is the cause of depression. Fluoxetine works by preventing the reuptake of one neurotransmitter, serotonin, by nerve cells after it has been released. Since uptake is an important mechanism for removing released neurotransmitters and terminating their actions on adjacent nerves, the reduced uptake caused by fluoxetine increases free serotonin that stimulates nerve cells in the brain. The FDA approved Fluoxetine in December 1987.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Capsules: 10, 20, and 40 mg. Capsules (delayed release): 90 mg. Tablets: 10, 15, and 20 mg. Oral suspension: 20mg/5ml

STORAGE: Fluoxetine should be stored at room temperature 15-30°C (59-86°F).

PRESCRIBED FOR: Fluoxetine is used for treating depression, bulimia, obsessive-compulsive disorder (OCD), panic disorder, and premenstrual dysphoric disorder (PMDD).  It also is used in combination with olanzapine (Zyprexa) for treatment of resistant depression and treatment of depression associated with bipolar disorder.

DOSING: Depression in adults is treated with 20-80 mg of fluoxetine daily. The recommended dose for treating depression in children is 10-20 mg daily. After 13 weeks of daily administration, once weekly dosing may be effective in some patients.

Bulimia is treated with 60 mg of fluoxetine daily. Long-term treatment for up to 52 weeks has been shown to be beneficial in maintaining remission.

Obsessive-compulsive disorder in adults and children is treated with 20-60 mg daily and panic disorder is managed with 10-60 mg daily. The recommended regimen for PMDD is 20 mg administered every day of the menstrual cycle or daily for 14 days prior to the onset of menstruation through the first day of menses.

The recommended treatment for resistant depression is 20-50 mg of fluoxetine and 5-20 mg olanzapine once daily in the evening while the recommended treatment for depression associated with bipolar disorder is 20-50 mg fluoxetine and 5-12.5 mg olanzapine once daily in the evening

DRUG INTERACTIONS: Fluoxetine should not be taken with any of the monoamine oxidase inhibitor (MAOI) class of antidepressants [for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), selegiline (Eldepryl), and procarbazine (Matulane)] or other drugs that inhibit monoamine oxidase [for example, linezolid (Zyvox)]. Such combinations may lead to confusion, high blood pressure, tremor, hyperactivity, coma, and death. Fluoxetine should not be administered for at least 14 days after stopping MAOIs.  Because fluoxetine is active in the body for several weeks, MAOIs should not be administered for at least 5 weeks after fluoxetine has been stopped.  Similar reactions occur when fluoxetine is combined with other drugs, for example, tryptophan, St. John's wort, meperidine (Demerol), and tramadol (Ultram) that increase serotonin in the brain.

Fluoxetine may increase the effect of warfarin (Coumadin), leading to excessive bleeding. Warfarin  therapy should be monitored more frequently in patients who are also taking fluoxetine. Combining SSRIs with aspirin, nonsteroidal anti-inflammatory drugs or other drugs that affect bleeding may increase the likelihood of upper gastrointestinal bleeding.

PREGNANCY: Use of fluoxetine during the third trimester of pregnancy may lead to adverse effects in the newborn.

NURSING MOTHERS: Fluoxetine is excreted in breast milk. Therefore, taking fluoxetine while nursing is not recommended.

SIDE EFFECTS: Fluoxetine, as with most antidepressants, can cause nausea, headaches, anxiety, insomnia, drowsiness, and loss of appetite. Fluoxetine has been implicated in serious skin rashes and vasculitis (inflammation of small blood vessels). Increased blood pressure can occur, and blood pressure should be monitored. Seizures have been reported as has sexual dysfunction. Some patients may experience withdrawal reactions upon stopping fluoxetine. Symptoms of withdrawal include anxiety, nausea, nervousness, and insomnia. The dose of fluoxetine should be gradually reduced when therapy is discontinued.

Antidepressants increased the risk of suicidal thinking and behavior in short-term studies in children and adolescents with depression and other psychiatric disorders. Anyone considering the use of fluoxetine or any other antidepressant in a child or adolescent must balance this risk of suicide with the clinical need. Patients who are started on therapy should be closely observed for clinical worsening, suicidal thoughts, or unusual changes in behavior.

Reference: FDA Prescribing Information