Fluoxetine

Antidepressants increase the risk of suicidal thinking and behavior in children, adolescents, and young adults (18 to 24 years of age) with major depressive disorder (MDD) and other psychiatric disorders; consider risk prior to prescribing. Short-term studies did not show an increased risk in patients >24 years of age and showed a decreased risk in patients ≥65 years. Closely monitor all patients for clinical worsening, suicidality, or unusual changes in behavior, particularly during the initial 1 to 2 months of therapy or during periods of dosage adjustments (increases or decreases); the patient’s family or caregiver should be instructed to closely observe the patient and communicate condition with health care provider. A medication guide concerning the use of antidepressants should be dispensed with each prescription. Fluoxetine is FDA approved for the treatment of OCD in children ≥7 years of age and MDD in children ≥8 years of age.

Fluoxetine use has been associated with occurrences of significant rash and allergic events, including vasculitis, lupus-like syndrome, laryngospasm, anaphylactoid reactions, and pulmonary inflammatory disease. Discontinue if underlying cause of rash cannot be identified.

Relatively devoid of these side effects

May impair platelet aggregation resulting in increased risk of bleeding events, particularly if used concomitantly with aspirin, NSAIDs, warfarin or other anticoagulants. Bleeding related to SSRI use has been reported to range from relatively minor bruising and epistaxis to life-threatening hemorrhage.

Has a low potential to impair cognitive or motor performance; caution operating hazardous machinery or driving.

May cause insomnia, anxiety, nervousness, or anorexia.

Bone fractures have been associated with antidepressant treatment. Consider the possibility of a fragility fracture if an antidepressant-treated patient presents with unexplained bone pain, point tenderness, swelling, or bruising (Rabenda 2013; Rizzoli 2012).

May cause mild pupillary dilation, which in susceptible individuals can lead to an episode of narrow-angle glaucoma. Consider evaluating patients who have not had an iridectomy for narrow-angle glaucoma risk factors.

QT prolongation and ventricular arrhythmia including torsade de pointes has occurred. Use with caution in patients with risk factors for QT prolongation (eg, congenital long QT syndrome, history of prolonged QT, family history of prolonged QT or sudden cardiac death), other conditions that predispose to arrhythmias (eg, hypokalemia, hypomagnesemia, recent MI, uncompensated heart failure, bradyarrhythmias or other arrhythmias, concomitant use of other agents that prolong QT interval), or increased fluoxetine exposure (eg, overdose, hepatic impairment, use of CYP2D6 inhibitors, poor CYP2D6 metabolizer status, concomitant use of other highly protein-bound drugs). Consider ECG monitoring when initiating therapy in patients with risk factors for QT prolongation and ventricular arrhythmia. Consider discontinuing fluoxetine if ventricular arrhythmia suspected and initiate cardiac evaluation.

Potentially life-threatening serotonin syndrome (SS) has occurred with serotonergic agents (eg, SSRIs, SNRIs), particularly when used in combination with other serotonergic agents (eg, triptans, TCAs, fentanyl, lithium, tramadol, buspirone, St. John’s wort, tryptophan) or agents that impair metabolism of serotonin (eg, MAO inhibitors intended to treat psychiatric disorders, other MAO inhibitors [ie, linezolid and intravenous methylene blue]). Monitor patients closely for signs of SS such as mental status changes (eg, agitation, hallucinations, delirium, coma); autonomic instability (eg, tachycardia, labile blood pressure, diaphoresis); neuromuscular changes (eg, tremor, rigidity, myoclonus); GI symptoms (eg, nausea, vomiting, diarrhea); and/or seizures. Discontinue treatment (and any concomitant serotonergic agent) immediately if signs/symptoms arise.

May cause or exacerbate sexual dysfunction.

SSRIs and SNRIs have been associated with the development of SIADH; hyponatremia has been reported rarely (including severe cases with serum sodium • Weight loss: May cause anorexia and/or weight loss. Use caution in patients where weight loss is undesirable. Disease-related concerns:

Use with caution in patients with a history of MI or unstable heart disease; experience in these patients is limited.

Use with caution in patients with diabetes mellitus; may alter glycemic control and may require adjustment of antidiabetic medication; hypoglycemia and hyperglycemia has been observed during and after cessation of therapy, respectively.

Use with caution in patients with hepatic impairment; clearance is decreased and plasma concentrations are increased; a lower dosage may be needed in patients with cirrhosis.

May worsen psychosis in some patients or precipitate a shift to mania or hypomania in patients with bipolar disorder. Monotherapy in patients with bipolar disorder should be avoided. Patients presenting with depressive symptoms should be screened for bipolar disorder. Fluoxetine monotherapy is not FDA approved for the treatment of bipolar depression.

Use with caution in patients with severe renal impairment; a lower dosage or less frequent dosing may be needed.

Use with caution in patients with a previous seizure disorder or conditions predisposing to seizures such as brain damage or alcoholism. Concurrent drug therapy issues:

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information. Special populations:

May also cause agitation, sleep disturbances, and excessive CNS stimulation in older adults. Dosage form specific issues:

Some dosage forms may contain sodium benzoate/benzoic acid; benzoic acid (benzoate) is a metabolite of benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol derivative with caution in neonates. See manufacturer’s labeling. Other warnings/precautions:

Abrupt discontinuation or interruption of antidepressant therapy has been associated with a discontinuation syndrome. Symptoms arising may vary with antidepressant however commonly include nausea, vomiting, diarrhea, headaches, light-headedness, dizziness, diminished appetite, sweating, chills, tremors, paresthesias, fatigue, somnolence, and sleep disturbances (eg, vivid dreams, insomnia). Less common symptoms include electric shock-like sensations, cardiac arrhythmias (more common with tricyclic antidepressants), myalgias, parkinsonism, arthralgias, and balance difficulties. Psychological symptoms may also emerge such as agitation, anxiety, akathisia, panic attacks, irritability, aggressiveness, worsening of mood, dysphoria, mood lability, hyperactivity, mania/hypomania, depersonalization, decreased concentration, slowed thinking, confusion, and memory or concentration difficulties. Greater risks for developing a discontinuation syndrome have been associated with antidepressants with shorter half-lives, longer durations of treatment, and abrupt discontinuation. For antidepressants of short or intermediate half-lives, symptoms may emerge within 2 to 5 days after treatment discontinuation and last 7 to 14 days (APA 2010; Fava 2006; Haddad 2001; Shelton 2001; Warner 2006).

May increase the risks associated with electroconvulsive therapy; consider discontinuing, when possible, prior to ECT treatment.

Due to the long half-life of fluoxetine and its metabolites, the effects and interactions noted may persist for prolonged periods following discontinuation.