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All about: Fluoxetine Hydrochloride

Big Image Pronouncation: (flew-OX-uh-teen HIGH-droe-KLOR-ide)
Class: SSRI

Trade Names:
- Tablets 10 mg
- Capsules 10 mg
- Capsules 20 mg
- Capsules 40 mg
- Solution, oral 20 mg per 5 mL

Trade Names:
Prozac Weekly
- Capsules, delayed-release 90 mg

Trade Names:
- Capsules 10 mg
- Capsules 20 mg

Apo-Fluoxetine (Canada)
CO Fluoxetine (Canada)
Gen-Fluoxetine (Canada)
Nu-Fluoxetine (Canada)
PMS-Fluoxetine (Canada)
ratio-Fluoxetine (Canada)

Mechanism of Action


Presumed to be linked to inhibition of CNS neuronal reuptake of serotonin.



T max is 6 to 8 h. C max is 15 to 55 ng/mL (40 mg dose). Food does not affect systemic bioavailability, but may delay absorption 1 to 2 h.


Protein binding is about 94.5%.


Major metabolite is norfluoxetine (active) formed by demethylation. Primary route is hepatic (CYP2D6).


The t ½ is 1 to 16 days (including active metabolite). Primary route is renal excretion of inactive metabolites.

Special Populations

Hepatic Function Impairment

The t ½ for fluoxetine and norfluoxetine is prolonged.

Indications and Usage


Major depression in adults and children as defined in the DSM-IV; obsessive-compulsive disorder (OCD) as defined in the DSM-III-R; bulimia nervosa; panic disorder as defined in the DSM-IV.


Premenstrual dysphoric disorder.

Unlabeled Uses

Posttraumatic stress disorder; Raynaud phenomenon; generalized anxiety disorder; hot flashes; second-line prophylaxis of migraines.


Concurrent thioridazine use with or within a minimum of 5 wk after discontinuing fluoxetine; concurrent use with or within a minimum of 14 days of discontinuing an MAOI and at least 5 wk should be allowed after stopping fluoxetine before starting an MAOI, especially if fluoxetine has been prescribe chronically or at high doses.

Dosage and Administration

Major Depressive Disorder

PO Initial: 20 mg/day; increase after several weeks if insufficient clinical improvement noted (max, 80 mg/day). Weekly dosing (90 mg delayed-release capsule) may be started 7 days after last 20 mg/day dose. If response is not satisfactory, consider reestablishing daily dosage regimen.

Children 8 yr of age and older

PO Initial: 10 mg/day; increase after 1 wk if insufficient clinical improvement noted (max, 20 mg/day).

Obsessive Compulsive Disorder

PO Initial: 20 mg once daily in the morning; increase after several weeks if insufficient clinical improvement noted (max, 80 mg/day).

Children 7 years of age and older

PO Initial: 10 mg/day; increase after 2 wk (several weeks in lower weight children) if insufficient clinical improvement noted (max, 60 mg/day).

Bulimia Nervosa

PO Initial: 60 mg daily in the morning; for some patients it may be advisable to titrate up to this target dose over several days.

Panic Disorder

PO Initial: 10 mg/day; increase to 20 mg/day after 1 wk. Further dose increases may be considered after several wk if no clinical improvement noted (max, 60 mg/day).

Premenstrual Dysphoric Disorder ( Sarafem only)

PO Initial: 20 mg/day continuously (every day of menstrual cycle) or intermittently (starting 14 days prior to anticipated onset of menstruation through first full day of menses and repeating with each new cycle); dose may be increased if no clinical improvement noted (max, 80 mg/day).

General Advice

  • Capsule, tablet, oral solution, and delayed-release capsules are bioequivalent.
  • Administer without regard to meals. Administer with food if GI upset occurs.
  • Doses above 20 mg/day may be administered on a once-a-day (morning) or twice-daily schedule (eg, morning and noon).
  • Measure and administer prescribed dose of oral solution using dosing syringe, dosing spoon, or dosing cup.


Store at controlled room temperature (59° to 86°F). Protect from light.

Drug Interactions

5-HT 1 agonists (eg, sumatriptan)

Weakness, hyperreflexia, and incoordination have been reported rarely.


Potentiation of impairment of mental and motor skills. Coadministration is not recommended.


Coadministration of alprazolam and fluoxetine has resulted in increased alprazolam levels and decreased psychomotor performance. Half the initial alprazolam dose and titrate to lowest effective dose. Diazepam t ½ may be prolonged.


Effects of buspirone may be decreased.


Increased carbamazepine levels, causing toxicity.


Elevated serum clozapine levels have occurred. Closely monitor patients on coadministration.


Concentrations of cyclosporine may be elevated, increasing the risk of toxicity.


Decreased or reversed effects of fluoxetine.


The pharmacologic effects of digoxin may be increased, possibly because of displaced protein binding.


Serum concentrations of haloperidol may be increased.

Hydantoins (eg, phenytoin)

Increased hydantoin levels, causing toxicity.

Linezolid, metoclopramide, ritonavir, sibutramine, sympathomimetics (eg, amphetamine), tramadol

Risk of serotonin syndrome may be increased.


Lithium levels may be increased or decreased by fluoxetine with possible neurotoxicity and increased serotonergic effects.


Combination may lead to serious, possibly fatal, reactions. Discontinue MAOI at least 14 days before starting fluoxetine; discontinue fluoxetine at least 5 wk before starting MAOI.

NSAIDs (eg, aspirin, ibuprofen)

The risk of GI bleeding may be increased.


A case of life-threatening sinus bradycardia has been reported.


Fluoxetine may inhibit the metabolism of propafenone, elevating propafenone levels and increasing the pharmacologic and adverse reactions.


Concurrent use is contraindicated because of risk of prolongation of QTc interval and development of serious ventricular arrhythmias (eg, torsades de pointes) and sudden death.


Plasma levels may be increased by fluoxetine.

Tricyclic antidepressants

Increased toxic effects of tricyclic antidepressant. Dosage of tricyclic antidepressants may need to be reduced and plasma concentrations may need to be monitored when fluoxetine is coadministered or has been recently discontinued.


The risk of CNS symptoms and peripheral toxicity may be increased.


The anticoagulant effects of warfarin may be increased, possibly because of displaced protein binding.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Vasodilatation (at least 5%); hemorrhage, hypertension, palpitations (at least 1%); atrial fibrillation, cardiac arrest, cerebral vascular accident, QT prolongation, ventricular tachycardia (including torsades de pointes arrhythmia) (postmarketing).


Abnormal dreams, abnormal thinking, anxiety, asthenia, dizziness, headache, insomnia, decreased libido, nervousness, somnolence, tremor (at least 5%); agitation, hyperkinesias, personality disorder (children [at least 2%]); agitation, amnesia, confusion, emotional lability, sleep disorder (at least 1%); mania/hypomania (children [at least 1%]); confusion, dyskinesia, movement disorders and worsening of pre-existing movement disorders, neuroleptic malignant syndrome, suicidal ideation, violent behaviors (postmarketing).


Rash, sweating (at least 5%); pruritus (at least 2%); epidermal necrolysis, erythema nodosum, exfoliative dermatitis, Stevens-Johnson syndrome (postmarketing).


Pharyngitis (at least 5%); abnormal vision (at least 2%); epistaxis (children [at least 2%]); ear pain, taste perversion, tinnitus (at least 1%); cataract, optic neuritis (postmarketing).


Abdominal pain, anorexia, constipation, diarrhea, dry mouth, dyspepsia, nausea (at least 5%); flatulence, vomiting (at least 2%); increased appetite (at least 1%).


Abnormal ejaculation, impotence (at least 5%); menorrhagia, urinary frequency (children [at least 2%]); urinary frequency (at least 1%); gynecomastia, kidney failure, priapism, vaginal bleeding after drug withdrawal (postmarketing).


Aplastic anemia, immune-related hemolytic anemia, pancytopenia, thrombocytopenia (postmarketing).


Cholestatic jaundice, hepatic failure/necrosis (postmarketing).


Weight loss (at least 2%); weight gain (at least 1%); hyperprolactinemia, hypoglycemia (postmarketing).


Rhinitis, sinusitis, yawning (at least 5%); eosinophilic pneumonia, pulmonary embolism, pulmonary hypertension (postmarketing).


Accidental injury, flu syndrome, infection, pain (at least 5%); fever (at least 2%); thirst (children [at least 2%]); chest pain, chills (at least 1%); misuse/abuse, pancreatitis, serotonin syndrome, sudden unexpected death, thrombocytopenic purpura (postmarketing).



Antidepressants increased the risk of suicidal thinking and behavior (suicidality) in short-term studies in children and adolescents with major depressive disorder and other psychiatric disorders. When considering the use of any antidepressant in a child or adolescent, balance this risk with clinical need. Children or adolescents should be observed closely for clinical worsening, suicidality, or unusual changes in behavior during the initial few months of therapy, or at times of dose changes, either increases or decreases. Families and caregivers should be advised of the need for close observation and communication with the prescriber.


Monitor children and adults for clinical worsening, suicidality, and unusual changes in behavior, especially during the first few months of therapy, or at times of dose changes, either increases or decreases. Children should be evaluated at least weekly with face-to-face contact with the patient or their family members or caregiver during the first 4 wk of therapy, then every other week for the next 4 wk, then at 12 wk, and as clinically indicated thereafter. Frequently assess patient for response to treatment. Periodically review therapy to determine if therapy needs to be continued without change or if a dose change (eg, increase, decrease, discontinuation) is indicated.


Category C . Neonates exposed to venlafaxine late in the third trimester have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding. Consider potential risks and benefits of treatment when treating women during the third trimester.


Excreted in breast milk.


Safety and efficacy has not been established in children younger than 8 yr of age with depression, or younger than 7 yr of age with OCD. Safety and efficacy not established ( Sarafem ).


Consider lower or less frequent dosing when initiating therapy in elderly patients.

Hepatic Function

Use lower or less frequent dose in patients with cirrhosis.

Hazardous Tasks

May impair judgment, thinking, or motor skills.

Abnormal bleeding

Bleeding episodes have occurred in patients treated with psychotropic drugs that interfere with serotonin reuptake.

Activation of mania/Hypomania

Has been reported. Use cautiously in patients with history of mania.

Anxiety and insomnia

Treatment-emergent anxiety, nervousness, or insomnia have been reported.

Concomitant illness

Use with caution in patients with diseases or conditions that could affect hemodynamic responses or metabolism. Consider using lower or less frequent dosing.

Discontinuation of treatment

Withdrawal symptoms have been reported following rapid discontinuation of therapy. If treatment is to be discontinued, or the dose reduced, gradually taper the dose and monitor patient for withdrawal symptoms (eg, dysphoric mood, irritability, agitation, dizziness, abnormal skin sensations, anxiety, confusion, headaches, lethargy, emotional lability, insomnia, hypomania). If significant withdrawal symptoms develop, reinstitute previous dosing schedule and attempt a less rapid tapering regimen after patient has stabilized.

Dose changes

Because of the long elimination t ½ of fluoxetine and norfluoxetine, changes in dose will not be fully reflected in plasma for several weeks, affecting titration to final dose and withdrawal from treatment.

Glycemic control

Hypoglycemia has occurred during treatment with fluoxetine and hyperglycemia has developed following discontinuation of fluoxetine; dosage adjustment of insulin and/or oral hypoglycemic drugs may be necessary.


Hyponatremia and/or SIADH may occur. Use with caution in patients who are elderly, volume-depleted, or taking diuretics.

Rash/Allergic events

Various types of rashes and/or urticaria have been reported, some with systemic signs and symptoms (eg, fever, arthralgia, edema, respiratory distress, lymphadenopathy, vasculitis). Discontinue fluoxetine upon appearance of rash of other possibly allergic phenomena.

Screening for bipolar disorder

A major depressive episode may be the initial presentation of bipolar disorder and treating such an episode with an antidepressant alone may increase the likelihood of precipitating a mixed/manic episode in patients at risk for bipolar disorder. Screen patients with depression for risk of bipolar disorder prior to initiating therapy with an antidepressant.


May occur; use with caution in patients with a history of seizures or with conditions that potentially lower the seizure threshold.

Weight changes

Weight gain as well as decreased appetite and weight loss may occur in adult patients. Decreased weight gain has been reported in children. Document patient weight prior to and periodically during prolonged treatment.



Events reported with overdose of fluoxetine, alone or coadministered with other drugs, include abnormal accommodation, abnormal gait, confusion, unresponsiveness, nervousness, pulmonary dysfunction, vertigo, tremor, elevated BP, impotence, movement disorder, hypomania, seizures, somnolence, nausea, tachycardia, vomiting, coma, delirium ECG abnormalities (eg, QT interval prolongation), hypotension, mania, neuroleptic malignant syndrome-like reaction, pyrexia, stupor, syncope, death in children.

Patient Information

  • Advise patient, their family, or caregiver to read the Medication Guide before starting therapy and with each refill, especially if the patient is a child or adolescent.
  • Advise patient that dose will usually be started low and then increased until max benefit is obtained.
  • Instruct patient to take prescribed dose without regard to meals but to take with food if stomach upset occurs.
  • Advise patient or caregiver using oral solution to measure and administer prescribed dose using dosing syringe, dosing spoon, or dosing cup.
  • Advise patient that if a dose is missed to take it as soon as possible and then return to the normal schedule. However, if it is almost time for the next dose, to skip the missed dose and take the next dose at the regularly scheduled time. Instruct patient that if a dose is skipped not to double the dose to catch up.
  • Instruct patient not to change the dose or stop taking unless advised by health care provider.
  • Instruct patient not to stop taking the medication when they feel better.
  • Caution patient that unless advised by health care provider, not to take aspirin or aspirin-containing products, NSAIDs, ginkgo biloba, or any other medication or herb that can affect coagulation because of increased risk of serious bleeding.
  • Instruct patient to contact health care provider if symptoms do not appear to be getting better, are getting worse, or if bothersome adverse reactions (eg, excessive drowsiness, diarrhea, tremors, nausea, diarrhea, nervousness, changes in sexual function) occur.
  • Advise patient to take frequent sips of water, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
  • Instruct diabetic patient to monitor blood glucose more frequently when drug is started or dose is changed and to inform health care provider of significant changes in readings.
  • Advise patient being treated for depression, and family or caregiver of patient, to be alert for abnormal changes in mood or thinking and to immediately report any of the following to health care provider: change in personality; change in mood; anxiety; agitation; panic attacks; insomnia; irritability; hostility or aggressiveness; impulsivity; akathisia (psychomotor restlessness); suicidal thoughts or behavior. Advise families and caregivers of patients to observe for emergence on a day-to-day basis, since changes may be abrupt.
  • Instruct patient or caregiver to immediately report rash, hives, or itching to health care provider.
  • Advise patient that if medication needs to be discontinued, it will be slowly withdrawn unless safety concerns (eg, rash) require a more rapid withdrawal.
  • Advise patient that drug may impair judgment, thinking, or motor skills, or cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness or coordination until tolerance is determined.

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