FLUoxetine

General

Pronunciation
floo-OX-uh-teen [Pronunciation]

Trade Name(s)

• PROzac

• PROzac Weekly

• Sarafem

Genetic Implications

Pregnancy Category
Category B

Ther. class.
antidepressants

Pharm. class.
selective serotonin reuptake inhibitors ssris

Indications

• Major depressive disorder.

• Obsessive compulsive disorder (OCD).

• Bulimia nervosa.

• Panic disorder.

• Depressive episodes associated with bipolar I disorder (when used with olanzapine).

• Treatment-resistant depression (when used with olanzapine).

• Sarafem: Premenstrual dysphoric disorder (PMDD).

Unlabelled Use(s):
Anorexia nervosa:

» ADHD,

» Diabetic neuropathy,

» Fibromyalgia,

» Obesity,

» Raynaud's phenomenon,

» Social anxiety disorder (social phobia),

» Post-traumatic stress disorder (PTSD).

Action

Selectively inhibits the reuptake of serotonin in the CNS.

Therapeutic Effect(s):

• Antidepressant action.

• Decreased behaviors associated with:

» panic disorder,

» bulimia.

• Decreased mood alterations associated with PMDD.

Pharmacokinetics

Absorption: Well absorbed after oral administration.

Distribution: Crosses the blood-brain barrier.

Protein Binding: 94.5%.

Metabolism and Excretion: Converted by the liver to norfluoxetine (primarily by CYP2D6 isoenzyme), another antidepressant compound; the CYP2D6 enzyme system exhibits genetic polymorphism (~7% of population may be poor metabolizers and may have significantly ↑ fluoxetine concentrations and an ↑ risk of adverse effects). Fluoxetine and norfluoxetine are mostly metabolized by the liver; 12% excreted by kidneys as unchanged fluoxetine, 7% as unchanged norfluoxetine.

Half-life: 1–3 days (norfluoxetine 5–7 days).

TIME/ACTION PROFILE (antidepressant effect)

ROUTE	ONSET	PEAK	DURATION
PO	1–4 wk	unknown	2 wk

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity;

• Concurrent use or use within 14 days of discontinuing MAO inhibitors (fluoxetine should be discontinued at least 5 wk before MAO therapy is initiated);

• Concurrent use of pimozide;

• Concurrent use of thioridazine (fluoxetine should be discontinued at least 5 wk before thioridazine therapy is initiated).

Use Cautiously in:

• History of seizures;

• Debilitated patients (↑ risk of seizures);

• Diabetes mellitus;

• Patients with concurrent chronic illness or multiple drug therapy (dose adjustments may be necessary);

• Hepatic impairment (↓ doses/↑ dosing interval may be necessary);

• May ↑ risk of suicide attempt/ideation especially during early treatment or dose adjustment;

• Patients with ↑ intraocular pressure or at risk for acute narrow-angle glaucoma;

• OB: Use during first trimester may ↑ risk of cardiovascular malformations in infant. Use during third trimester may result in neonatal serotonin syndrome requiring prolonged hospitalization, respiratory and nutritional support. May cause sedation in infant. Use only if potential benefit justifies potential risk to fetus;

• Lactation: May cause sedation in infant; discontinue drug or bottle-feed;

• Pedi: Risk of suicide ideation or attempt may be greater in children or adolescents (safe use in children <8 yr not established);

• Geri: Appears on Beers list. Geriatric patients are at ↑ risk for excessive CNS stimulation, sleep disturbances, and agitation.

Adverse Reactions/Side Effects

CNS: NEUROLEPTIC MALIGNANT SYNDROME, SEIZURES, SUICIDAL THOUGHTS, anxiety, drowsiness, headache, insomnia, nervousness, abnormal dreams, dizziness, fatigue, hypomania, mania, weakness.

EENT: mydriasis, stuffy nose, visual disturbances.

Resp: cough.

CV: chest pain, palpitations.

GI: diarrhea, abdominal pain, abnormal taste, anorexia, constipation, dry mouth, dyspepsia, nausea, vomiting, weight loss.

GU: sexual dysfunction, urinary frequency.

Derm: ↑ sweating, pruritus, erythema nodusum, flushing, rashes.

Endo: dysmenorrhea.

F and E: hyponatremia.

MS: arthralgia, back pain, myalgia.

Neuro: tremor.

Misc: SEROTONIN SYNDROME, allergic reactions, fever, flu-like syndrome, hot flashes, sensitivity reaction.

*CAPITALS indicates life-threatening.
*italic indicates most frequent.

Interactions

Drug-Drug

• Discontinue use of MAO inhibitors for 14 days before fluoxetine therapy; combined therapy may result in confusion, agitation, seizures, hypertension, and hyperpyrexia (serotonin syndrome). Fluoxetine should be discontinued for at least 5 wk before MAO inhibitor therapy is initiated.

• Concurrent use with pimozide may ↑ risk of QT interval prolongation.

• ↑ levels of thioridazine may ↑ risk of QT interval prolongation (concurrent use contraindicated; fluoxetine should be discontinued for at least 5 wk before thioridazine is initiated).

• Inhibits the activity of cytochrome P450 2D6 enzyme in the liver and ↑ effects of drugs metabolized by this enzyme system.

• Medications that inhibit the P450 enzyme system (including ritonavir , saquinavir , and efavirenz ) may ↑ risk of developing the serotonin syndrome). For concurrent use with ritonavir ↓ fluoxetine dose by 70%; if initiating fluoxetine, start with 10 mg/day dose.

• ↓ metabolism and ↑ effects of alprazolam (decrease alprazolam dose by 50%).

• Drugs that affect serotonergic neurotransmitter systems, including linezolid , tramadol , and triptans , ↑ risk of serotonin syndrome.

• ↑ CNS depression with alcohol , antihistamines , other antidepressants , opioid analgesics , or sedative/hypnotics .

• ↑ risk of side effects and adverse reactions with other antidepressants , risperidone , or phenothiazines .

• May ↑ effectiveness/risk of toxicity from carbamazepine , clozapine , digoxin , haloperidol , phenytoin , lithium , or warfarin .

• May ↓ the effects of buspirone .

• Cyproheptadine may ↓ or reverse effects of fluoxetine.

• May ↑ sensitivity to adrenergics and increase the risk of serotonin syndrome.

• May alter the activity of other drugs that are highly bound to plasma proteins .

• ↑ risk of serotonin syndrome with 5HT1 agonists .

• ↑ risk of bleeding with NSAIDS , aspirin , clopidogrel , or warfarin .

Drug-Natural Products
↑ risk of serotonin syndrome with St. John's wort and SAMe .

Route/Dosage

• PO (Adults): Depression, OCD—20 mg/day in the morning. After several weeks, may ↑ by 20 mg/day at weekly intervals. Doses greater than 20 mg/day should be given in 2 divided doses, in the morning and at noon (not to exceed 80 mg/day). Patients who have been stabilized on the 20 mg/day dose may be switched over to delayed-release capsules (Prozac Weekly) at dose of 90 mg weekly, initiated 7 days after the last 20–mg dose. Panic disorder—10 mg/day initially, may ↑ after 1 week to 20 mg/day (usual dose is 20 mg, but may be ↑ as needed/tolerated up to 60 mg/day). Bulimia nervosa—60 mg/day (may need to titrate up to dosage over several days). PMDD—20 mg/day (not to exceed 80 mg/day) or 20 mg/day starting 14 days prior to expected onset on menses, continued through first full day of menstruation, repeated with each cycle. Depressive episodes associated with bipolar I disorder—20 mg/day with olanzapine 5 mg/day (both given in evening); may ↑ fluoxetine dose up to 50 mg/day and olanzapine dose up to 12.5 mg/day; Treatment-resistant depression—20 mg/day with olanzapine 5 mg/day (both given in evening); may ↑ fluoxetine dose up to 50 mg/day and olanzapine dose up to 20 mg/day..

• PO (Geriatric Patients): Depression—10 mg/day in the morning initially, may be ↑ (not to exceed 60 mg/day)..

• PO (Children 7–17 yr): Adolescents and higher weight children—10 mg/day may be ↑ after 2 wk to 20 mg/day; additional increases may be made after several more weeks (range 20–60 mg/day); Lower-weight children—10 mg/day initially, may be ↑ after several more weeks (range 20–30 mg/day)..

Availability

• Tablets: 10 mg, 15 mg, 20 mg

» Cost:
Generic: 10 mg $10.00/90, 20 mg $65.97/90.

• Capsules: 10 mg, 20 mg, 40 mg

» Cost:
Generic: 10 mg $10.00/90, 20 mg $10.00/90, 40 mg $10.00/90.

• Delayed-release capsules (Prozac Weekly): 90 mg

» Cost: $123.99/4.

• Oral solution (mint flavor): 20 mg/5 mL

» Cost:
Generic: $19.99/120 mL.

• In combination with: olanzapine (Symbyax; see combination drugs).

Assessment

• Monitor mood changes. Inform health care professional if patient demonstrates significant increase in anxiety, nervousness, or insomnia.

» Assess for suicidal tendencies, especially during early therapy. Restrict amount of drug available to patient. Risk may be increased in children, adolescents, and adults ≤24 yr. After starting therapy, children, adolescents, and young adults should be seen by health care professional at least weekly for 4 wk, every 3 wk for next 4 wk, and on advice of health care professional thereafter.

» Monitor appetite and nutritional intake. Weigh weekly. Notify health care professional of continued weight loss. Adjust diet as tolerated to support nutritional status.

» Assess for sensitivity reaction (urticaria, fever, arthralgia, edema, carpal tunnel syndrome, rash, hives, lymphadenopathy, respiratory distress) and notify health care professional if present; symptoms usually resolve by stopping fluoxetine but may require administration of antihistamines or corticosteroids.

• Assess for sexual side effects (erectile dysfunction; decreased libido).

• Monitor for development of neuroleptic malignant syndrome (fever, respiratory distress, tachycardia, seizures, diaphoresis, arrhythmias, hypertension or hypotension, pallor, tiredness, severe muscle stiffness, loss of bladder control). Report immediately.

• Assess for serotonin syndrome (mental changes [agitation, hallucinations, coma], autonomic instability [tachycardia, labile BP, hyperthermia], neuromuscular aberrations [hyperreflexia, incoordination], and/or GI symptoms [nausea, vomiting, diarrhea]), especially in patients taking other serotonergic drugs (SSRIs, SNRIs, triptans).

OCD

• Assess for frequency of obsessive-compulsive behaviors. Note degree to which these thoughts and behaviors interfere with daily functioning.

Bulimia Nervosa

• Assess frequency of binge eating and vomiting during therapy.

PMDD

• Monitor mood prior to and periodically during therapy.

Lab Test Considerations

• Monitor CBC and differential periodically during therapy. Notify health care professional if leukopenia, anemia, thrombocytopenia, or increased bleeding time occurs.

» Proteinuria and mild ↑ in AST may occur during sensitivity reactions.

» May cause ↑ in serum alkaline phosphatase, ALT, BUN, creatine phosphokinase; hypouricemia, hypocalcemia, hypoglycemia or hyperglycemia, and hyponatremia.

Potential Nursing Diagnoses

• Ineffective coping (Indications)

• Risk for injury (Side Effects)

• Sexual dysfunction (Side Effects)

Implementation

• Do not confuse fluoxetine with duloxetine, paroxetine, or Loxitane (loxapine). Do not confuse Prozac with Prilosec (omeprazole), Prograf (tacrolimus), or Provera (medroxyprogesterone). Do not confuse Sarafem (fluoxetine) with Serophene (clomiphene).

• PO: Administer as a single dose in the morning. Some patients may require increased amounts, in divided doses, with a 2nd dose at noon.

» May be administered with food to minimize GI irritation. Do not open or crush ER preparations.

Patient/Family Teaching

• Instruct patient to take fluoxetine as directed. If a dose is missed, omit and return to regular schedule. Do not double doses or discontinue without consulting health care professional; discontinuation may cause anxiety, insomnia, nervousness.

• May cause drowsiness, dizziness, impaired judgment, and blurred vision. Caution patient to avoid driving and other activities requiring alertness until response to the drug is known.

• Advise patient, family and caregivers to look for suicidality, especially during early therapy or dose changes. Notify health care professional immediately if thoughts about suicide or dying, attempts to commit suicide, new or worse depression or anxiety, agitation or restlessness, panic attacks, insomnia, new or worse irritability, aggressiveness, acting on dangerous impulses, mania, or other changes in mood or behavior or if symptoms of serotonin syndrome occur.

• Advise patient to avoid alcohol or other CNS depressant drugs during therapy and to consult health care professional before taking other medications or natural/herbal products with fluoxetine.

• Caution patient to change positions slowly to minimize dizziness.

• Inform patient that frequent mouth rinses, good oral hygiene, and sugarless gum or candy may minimize dry mouth. If dry mouth persists for more than 2 wk, consult health care professional regarding use of saliva substitute.

• Caution patient to wear protective clothing and use sunscreen to prevent photosensitivity reactions.

• Inform patient that medication may cause decreased libido.

• Advise patient to notify health care professional if symptoms of sensitivity reaction occur or if headache, nausea, anorexia, anxiety, or insomnia persists.

• Instruct female patients to inform health care professional if pregnancy is planned or suspected, or if breastfeeding.

• Emphasize the importance of follow-up exams to monitor progress.