Fluoxetine
A long-acting SSRI used for depression, obsessive-compulsive disorder, bulimia nervosa and panic disorder.
Drug card
- Class
- SSRI
- How it works
- Blocking serotonin reuptake, so serotonin stays longer in the synapse
- Used for
- Depression
- Obsessive-compulsive disorder (OCD)
- Bulimia nervosa
- Panic disorder
- Known for
- Trouble sleeping, anxiety and nervousness
- Sexual problems, such as low libido
- Its name
- -oxetine means a selective reuptake inhibitor (fluoxetine type)
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does fluoxetine work?
Fluoxetine blocks the serotonin transporter, with far weaker effects on norepinephrine uptake. Both the parent drug and its active metabolite, norfluoxetine, are eliminated over days to weeks, so a dose change takes several weeks to show fully in blood levels. It is a potent CYP2D6 inhibitor, which can raise levels of tricyclics, haloperidol and clozapine.
Like other selective serotonin reuptake inhibitors: SSRIs block the serotonin transporter (SERT) on presynaptic nerve endings, so released serotonin is cleared more slowly and acts longer on its receptors. The block is immediate but mood lifts only after weeks, so slower receptor adaptations are thought to matter; the exact mechanism is unknown. Unlike tricyclics, they barely affect norepinephrine reuptake or muscarinic, histamine and α1 receptors.
Uses
What is fluoxetine used for?
- Depression
- Obsessive-compulsive disorder (OCD)
- Bulimia nervosa
- Panic disorder
- Bipolar depression, combined with olanzapine
Side effects
Side effects of fluoxetine
- Trouble sleeping, anxiety and nervousnessKnown for
- Sexual problems, such as low libidoKnown for
- Nausea
- Tremor
- Loss of appetite and weight loss
- Rash and allergic reactions
- Serotonin syndromeSerious
- Suicidal thoughts in children and young adultsSerious
- Low sodium (hyponatremia)Serious
- Abnormal bleedingSerious
- QT prolongationSerious
- SeizuresSerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Wait 5 weeks after the last fluoxetine dose before an MAOI or thioridazine is started, as it clears so slowly.
- Contraindicated with pimozide and thioridazine: it raises their levels via CYP2D6 and both prolong QT.
- Monitor tricyclic levels if given together, even soon after fluoxetine has been stopped.
Good to know: Its very long half-life, with norfluoxetine lasting even longer, means its interactions can continue for weeks after the last dose.
Remember it
A way to remember it
SSRI
- S
- Sexual problems
- S
- Serotonin syndrome
- R
- Reduced sodium (hyponatremia)
- I
- Increased bleeding risk
Written for biofideX
Its name
-oxetine means selective reuptake inhibitor (fluoxetine type)
Fluoxetine is an SSRI, duloxetine an SNRI, and atomoxetine, used for ADHD, blocks norepinephrine reuptake alone. Sertraline and citalopram are SSRIs that lack the stem.
- Every drug name stem
Its class
Selective serotonin reuptake inhibitors
Other selective serotonin reuptake inhibitors with a card:
Easily mixed up with serotonin-norepinephrine reuptake inhibitors and tricyclic antidepressants.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Depression, anxiety and sleep
Fluoxetine is one of 15 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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