Prozac Description:

Prozac, also called fluoxetine hydrochloride, is a psychotropic antidepressant administered orally. The drug is used to treat depression, obsessive-compulsive disorder (OCD), bulimia, premenstrual dysphoric disorder and panic disorder. It is also used (off-label) to treat numerous other conditions, such asADHD. It was derived from diphenhydramine, an antihistamine which inhibits reuptake of the neurotransmitter serotonin.

Compared to other selective serotonin reuptake inhibitors (SSRIs), Prozac has a strong affect on energy levels, which makes the drug highly effective in treating clinical depressioncases where depressed mood and lack of energy are prevalent. Though stimulating, it is approved for a variety ofanxiety disorders, such as panic disorder and OCD.

Prozac is manufactured by Eli Lilly and was given FDA approval in December 1987, with US introduction at the beginning of 1988. In the fall of 2001, Eli Lilly lost a patent dispute with Barr Laboratories and now fluoxetine hydrochloride is manufactured and distributed by numerous companies.



Clinical Pharmacology:

The antibulimic, antiobsessive-compulsive, and antidepressant effects of fluoxetine are thought to be associated with its inhibition of central nervous system neuronal uptake of serotonin. Clinical studies in humans have shown fluoxetine blocks the uptake of serotonin into human platelets. Animal studies also point to fluoxetine as a much more potent uptake inhibitor of serotonin than norepinephrine.

Food does not appear to affect the systemic bioavailability of the drug, though it’s possible this may delay its absorption by 1 or 2 hours, which is not particularly clinically significant. Thus, fluoxetine may be administered with or without food.

Indications and Dosage:

Prozac is indicated for treatment of major depressive disorder (MDD), OCD, Bulimia Nervosa, and panic disorder.

The recommended initial dosages vary depending on what condition is being treated. They are as follows:

  • Major Depressive Disorder (MDD) – 20mg/day, with or without food, usually in the morning, with doses above 20mg/day considered after several weeks of insufficient clinical improvement, up to a maximum of 80mg/day
  • Obsessive-Compulsive Disorder (OCD) – 20mg/day, with or without food, usually in the morning, with doses above 20mg/day considered after several weeks of insufficient clinical improvement, up to a maximum of 80/mg day. Average dosage range is 20 to 60mg/day.
  • Bulimia Nervosa – 60mg/day, with or without food, usually in the morning, doses above 60mg/day in bulimics have not been systematically studied
  • Panic Disorder – 10mg/day, with or without food, usually in the morning, increased to 20mg/day after one week, with subsequent increases considered after several weeks of insufficient clinical improvement, with doses above 60mg/day in persons with panic disorder not systematically studied

Prozac Side Effects and Interactions:

Common side effects include restlessness, insomnia, anxiety, headache, asthenia, flu-like symptoms, fever, nausea, diarrhea, anorexia, dry mouth, constipation, flatulence, dyspepsia, vomiting, somnolence, yawn, abnormal vision, sweating, trembling, weakness, weight loss, skin rash, delayed ejaculation in men, decrease in sex drive, and there have been reports of subsequent weight gain. As with other SSRIs, an overdose of fluoxetine or combining it with other antidepressants can lead to serotonin syndrome.

Fluoxetine has a wide range of published interactions, notably with MAOIs (serotonin syndrome).

Information for Parents and Kids:

Prozac is approved for use in children with MDD and OCD. In clinical studies, antidepressants increased risks of suicidality in thought and behavior in children and teenagers with depressive symptoms or other psychiatric disorders. Anyone considering using Prozac or any other antidepressant in a child or adolescent must balance the risk with the clinical need.

Warnings and Precautions:

Patients with MDD, both adults and children, may experience worsening of their depression and/or the emergence of suicidal ideation and behavior (suicidality) or unusual changes in behavior. All pediatric patients being treated with antidepressants for any indication should be closely observed, especially during the first few months of drug therapy, or at times of changes in dosage (increases or decreases).

Prozac use should not be ceased abruptly, or you may experience withdrawal symptoms. The drug should be tapered, as rapidly as is feasible, with recognition that abrupt discontinuation can be associated with certain symptoms.


Because Prozac has a long half-life, extreme symptoms of withdrawal are uncommon and unlikely. Effects associated with abrupt discontinuation of fluoxetine include vertigo/light-headedness, fatigue, nausea, dizziness, headache, insomnia, abdominal cramps, increased or strange dreams, chills, agitation and anxiety.

Over-dosage & Contraindications:

Of the over 1500 known cases of fluoxetine overdose (alone or in combination with other drugs) there have been 195 deaths.

The most common signs and symptoms associated with non-fatal overdose are seizures, nausea, tachycardia, vomiting and somnolence. The largest known ingestion in adult patients was 8 grams in one person who took fluoxetine alone and completely recovered. However, in an individual who took fluoxetine alone, ingestion as low as 520mg has been associated with lethal outcome, but causality has not been determined.

Prozac should not be used by persons hypersensitive to the drug or its ingredients.

There have been reports of serious, sometimes fatal, reactions in people taking fluoxetine in combination with an MAOI, and in patients who have recently ceased taking Prozac and then started MAOI treatment. Some cases resulted in features resembling neuroleptic malignant syndrome. Thus, Prozac should not be used in combination with an MAOI, or within a minimum of two weeks after ceasing MAOI therapy. Due to fluoxetine’s long half-life, at least 5 weeks (or longer, especially if prescribed in chronic or high doses) should be allowed after discontinuing Prozac before starting treatment with an MAOI.

Thioridazine should not be administered with fluoxetine or within a minimum of 5 weeks after Prozac has been discontinued.

Generic Name: fluoxetine

Chemical Formula: C17H18F3NO, HCl

Routes of Administration: oral

Elimination Half Life: approximately 4-6 days

Legal Status: by prescription only

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