What are the FDA-approved indications for fluoxetine?
Major depressive disorder, Obsessive-compulsive disorder (OCD), Bulimia nervosa, Panic disorder, Premenstrual dysphoric disorder (PMDD, brand Sarafem)
What is fluoxetine’s unique role in pediatric psychiatric treatment?
Fluoxetine is the only FDA-approved antidepressant for depression in children age 8 and older, with the best evidence among SSRIs for treating depression in children and adolescents
What is the typical starting dose of fluoxetine for adults?
20 mg once daily (QD)
How should fluoxetine be titrated in adults?
Can be titrated in 20 mg increments to FDA maximum of 80 mg QD. Wait approximately 4 weeks between dose increases, or titrate faster if targeting a prior effective dose
What is the maximum recommended dose of fluoxetine for obsessive-compulsive disorder?
120 mg daily. OCD often requires heroically high doses of SSRIs, and fluoxetine is safe at these levels
What is the dosing strategy for fluoxetine in premenstrual dysphoric disorder (PMDD)?
20 mg QD starting 14 days prior to anticipated menses onset through first full day of menstruation, repeating with each cycle. No proven benefit to exceeding 20 mg/day for PMDD
What is fluoxetine’s elimination half-life and what is its clinical significance?
Half-life is approximately 7 days. With chronic use, remains detectable in body up to 5 weeks after discontinuation. This long half-life means missed doses are less consequential than with other antidepressants
How should a missed fluoxetine dose be managed?
If a dose is missed one day, it is acceptable to take a double dose the next day due to fluoxetine’s long half-life (this is NOT recommended for most other psychotropics)
How does fluoxetine compare to other SSRIs in terms of activation?
Fluoxetine is the most activating/energizing SSRI. More likely to cause anxiety and insomnia compared to other SSRIs
Why is fluoxetine relatively safe in patients with sleep apnea?
Fluoxetine is a respiratory stimulant, making it safer than other SSRIs in this population
What is fluoxetine’s effect on weight?
Not expected to cause weight gain and may result in modest weight loss
For adults, why might lexapro or sertraline be preferred over fluoxetine?
Lexapro and Zoloft are generally preferred because fluoxetine interacts with numerous medications and has a higher burden of drug interactions
Which CYP enzymes does fluoxetine inhibit and what is the clinical consequence?
Inhibitor of CYP2D6 and CYP2C19. This results in numerous interactions that markedly increase blood levels of various substrate drugs (victim drugs). Fluoxetine is a less potent inhibitor than fluvoxamine or fluconazole
When discontinuing fluoxetine 40 mg or less, what is the recommended approach?
May be acceptable to stop without tapering due to its long half-life, though some patients may require a hyperbolic taper
When discontinuing fluoxetine doses higher than 40 mg, what is recommended?
Taper over several months
Will fluoxetine discontinuation cause serotonin withdrawal symptoms?
No. Due to its long half-life, fluoxetine ‘tapers itself’ off over weeks when stopped abruptly, so serotonin withdrawal symptoms are not expected
What washout period is recommended when switching from fluoxetine to another SSRI or SNRI?
A washout period should be considered before starting the new serotonergic agent, though risk of serotonin syndrome is minimal with some overlap of two SSRIs or an SSRI and SNRI, so waiting is not mandatory
What washout period is required when switching from fluoxetine to an MAOI?
At least 5 weeks after stopping fluoxetine before starting an MAOI (to avoid serotonin syndrome). For other SSRIs, only 2 weeks is required
What are the approved indications for SYMBYAX (fluoxetine/olanzapine)?
Acute depressive episodes of bipolar I disorder and treatment-resistant major depression
What are the available fixed-dose combinations for SYMBYAX and when is it taken?
Fixed doses are 3/25 mg, 6/25 mg, 6/50 mg, and 12/50 mg olanzapine/fluoxetine, taken in the evening
What is a clinical concern with SYMBYAX that providers may underestimate?
Olanzapine’s potential for causing significant weight gain and diabetes. Heavy marketing to primary care physicians may have led to underestimation of these risks
What is the most troublesome side effect of fluoxetine among SSRIs?
Sexual dysfunction (consistent with other SSRIs)
What is the safety profile of fluoxetine in overdose?
Fluoxetine is safe. Risk of death with single-drug overdose is no more than 1 in 10,000
If fluoxetine were newly introduced today, would it likely receive FDA approval?
Unlikely, due to the magnitude of its drug interactions through CYP enzyme inhibition
