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Fluoxetine: Difference between revisions

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Link legal-status field to the USLegal: namespace
 
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{{MedTemplate
{{MedTemplate
| generic          = fluoxetine
| generic          = Fluoxetine
| brand            = Prozac
| brand            = Prozac
| structure        = Fluoxwhite.svg
| structure        = Fluoxwhite.svg
| class            = SSRI, Anxiolytic, Antidepressant
| classes          = [[:Category:Selective Serotonin Reuptake Inhibitors (SSRIs)|SSRI]], [[:Category:Anxiolytics|Anxiolytic]], [[:Category:Antidepressants|Antidepressant]]
| mechanism        = [https://pmc.ncbi.nlm.nih.gov/articles/PMC9666396/ TrkB/BDNF]
| uses              = <vote slug="anxiety-use">Anxiety</vote>, <vote slug="premature-ejaculation-use">Premature ejaculation</vote>, <vote slug="low-mood-use">Low mood</vote>
| uses              = Anxiety, premature ejaculation, low mood
| starting_dose    = 10 mg
| formula          = C17H18F3NO
| preparations      = 10 mg, 20 mg, 40 mg caps
| mass              =  
| fda_max          = 40 mg/d
| cas              =  
| pill_id            =
| atc              =  
* '''10 mg:''' green/cream capsule, "PLIVA 647"
* '''20 mg:''' green/cream capsule, "PROZAC 20"
* '''40 mg:''' olive/cream capsule, "DISTA 3107"
* '''Oral solution:''' 20 mg / 5 mL, clear
| routes            = Oral
| routes            = Oral
| onset            =  
| onset            =  
| duration          = Very long
| duration          = Very long
| halflife          = 1-4 days (7-15 days for norfluoxetine)
| halflife          = 1–4 days (7–15 days for norfluoxetine)
| bioavailability  = 70-90%
| bioavailability  = 70–90% (oral)
| pregnancy        = Category C
| pregnancy        = Category C<ref name="lactmed">S0</ref>
| legal            = Rx-only
| legal            = [[USLegal:Prescription only|Rx-only]] in US
| intro            = Fluoxetine is the first of a long line of SSRIs to come. It is remarkable in its extremely long half life and relative lack of withdrawal syndrome. It can also be very useful it helping taper and terminate other SxRI medicines.
| mechanism        = TrkB/BDNF<ref name="trkb">S1</ref> <vote slug="ssri-claim">Fluoxetine is a selective serotonin reuptake inhibitor.</vote>
| pharmacology      =
| intro            = Fluoxetine, marketed as Prozac, was the first selective serotonin reuptake inhibitor ([[:Category:Selective_Serotonin_Reuptake_Inhibitors_(SSRIs)|SSRIs]]) brought to market and the medicine that opened the SSRI era. It was discovered at Eli Lilly's laboratories in Indianapolis on 24 July 1972 by a team that included the chemists Bryan Molloy and Klaus Schmiegel and the pharmacologist David Wong,<ref name="wong1974">Wong DT, Horng JS, Bymaster FP, Hauser KL, Molloy BB. A selective inhibitor of serotonin uptake: Lilly 110140, 3-(p-trifluoromethylphenoxy)-N-methyl-3-phenylpropylamine. Life Sciences. 1974;15(3):471-479. PMID: 4549929.</ref> approved by the FDA in December 1987, and launched in the United States as Prozac in January 1988. It is notable for the extremely long half-life of its active metabolite norfluoxetine, which gives the medicine an unusually mild discontinuation profile and makes it useful as a bridge in tapering patients off shorter-acting serotonergic medicines.
| pharmacokinetics  =
| history          = The compound that became fluoxetine emerged from an Eli Lilly program that began in the late 1960s under Molloy and Schmiegel, who synthesized a series of aryloxyphenylpropylamines starting from the antihistamine [[Diphenhydramine|diphenhydramine]] as a structural lead. Wong, who had followed the European literature implicating serotonin in mood regulation, proposed screening the new compounds specifically for serotonin uptake inhibition. On 24 July 1972 the team identified the compound then designated Lilly 110140 as a potent and selective inhibitor of serotonin uptake in rat brain synaptosomes. The finding was published in 1974 as the first description of what is now known as a selective serotonin reuptake inhibitor.<ref name="wong1974"/>
| indications      = Anxiety disorders broadly, including panic attacks, social anxiety,
 
| dosing            = Start no higher than 10 mg for first dose! Participant may increase by 10 mg every 2-12 weeks, or never increase if they are satisfied with the 10 mg effect.
Lilly renamed the compound fluoxetine in 1975, filed an investigational application with the FDA, and pursued clinical development through the late 1970s and early 1980s. The FDA approved fluoxetine for major depressive disorder in December 1987, and Lilly launched it as Prozac in January 1988. The marketing name itself was a departure: medicines had historically been named to reflect chemical structure, and Prozac was among the first to be commissioned from an outside naming firm. Within five years of launch Prozac was one of the most prescribed medicines in the United States, and Peter Kramer's 1993 book Listening to Prozac made the SSRI era a subject of popular discussion. Lilly's US patent expired in August 2001, after which generic fluoxetine became broadly available.
| effects          = anxiolysis, delayed ejaculation, improved mood (?)
 
| adverse          = Nausea, GI upset,  
Fluoxetine is a prescription-only medicine in the United States. It remains on the WHO Model List of Essential Medicines and is one of the most widely prescribed serotonergic medicines worldwide. The serotonergic framing under which the medicine was discovered and marketed has not aged uniformly well; the TrkB/BDNF account of its mechanism, developed primarily in the 2000s, is the principal contemporary alternative and is reflected in the mechanism field above.
| contraindications = none strict
| indications      = <problem ref="depression" author="MDElliottMD"/>
| interactions      = 2D6 - many
<problem ref="anxiety-disorders" author="MDElliottMD">
Including generalized anxiety, panic, and social anxiety.
</problem>
<problem ref="panic" author="MDElliottMD"/>
<problem ref="social-anxiety" author="MDElliottMD"/>
<problem ref="ocd" author="MDElliottMD"/>
<problem ref="ptsd" author="MDElliottMD">
Potentially.
</problem>
 
<problem ref="premature-ejaculation"/>
 
| dosing            = <titration slug="standard" author="MDElliottMD" title="Standard adult or child">
Start no higher than 10 mg for the first dose. May increase by 10 mg every 2–12 weeks, or remain at 10 mg if the response is adequate, up to a typical starting maximum of 40 mg. Absolute max: 80 mg.
</titration>
 
<titration slug="ocd" author="MDElliottMD" title="OCD">
Start at 10 mg daily; increase by 10–20 mg every 2–6 weeks, up to 80 mg. OCD typically requires elevated doses (60–80 mg).
</titration>
| effects          =  
* <effect ref="anxiolysis" author="MDElliottMD">Classically starting at 3–4 weeks and improving for another 8–12.</effect>
* <effect ref="delayed-ejaculation" author="MDElliottMD"/>
* <effect ref="mood-enhancement" author="MDElliottMD"/>
* <effect ref="nausea" author="MDElliottMD">Common, often improves over 1–2 weeks.</effect>
* <effect ref="decreased-libido" author="MDElliottMD"/>
* <effect ref="temporary-erectile-dysfunction" author="MDElliottMD"/>
* <effect ref="persistent-sexual-dysfunction" author="MDElliottMD">Historically [https://pmc.ncbi.nlm.nih.gov/articles/PMC11450419/ associated with SSRIs].</effect>
 
<effect ref="anorgasmia" author="MDElliottMD"/>
| pk_absorption    = 70–90%<ref name="statpearls">S3</ref> oral bioavailability.
| pk_distribution  = Fluoxetine has plasma protein binding of approximately 94.5%, bound to albumin and alpha-1 glycoprotein. Fluoxetine readily crosses the blood–brain barrier, with a brain-to-plasma ratio of 2.6:1 in humans. The volume of distribution (Vd) of fluoxetine and its metabolite ranges between 20 to 42 L/kg. Some studies report that fluoxetine has the maximum volume of distribution (Vd) of any SSRI (between 14 and 100 L/kg).<ref name="statpearls"/>
| pk_metabolism    = Fluoxetine's active metabolite is norfluoxetine, produced when the cytochrome P450 enzyme ([[Enzyme:CYP2D6|CYP2D6]]) acts on it. Prescribers must remember that fluoxetine has several med-med interactions due to its metabolism through the CYP2D6 isoenzyme. Additionally, norfluoxetine can have an inhibitory effect on [[Enzyme:CYP3A4|CYP3A4]]. Fluoxetine has a half-life of 2 to 4 days, and its active metabolite norfluoxetine has a half-life of 7 to 9 days. Approximately 7% of individuals definitively exhibit poor metabolism of fluoxetine due to reduced activity of CYP2D6.<ref name="statpearls"/>
| pk_elimination    =
| pharmacodynamics  =  
| interactions      = <pharmaInteractions/>
| pregnancy_details =  
| pregnancy_details =  
| monitoring        = none
| monitoring        = None required
| counseling        =  
| counseling        =  
| anecdotes        =  
| anecdotes        = <anecdote slug="2026-05-12" perspective="provider" author="MDElliottMD">
| seealso          =  
Fluoxetine is great for getting off other SxRIs! Especially [[Venlafaxine|venlafaxine]] and [[Duloxetine|duloxetine]].
| references        =  
</anecdote>
| seealso          = [[Sertraline]], [[Duloxetine]]
| references        = <references/>
}}
}}
[[Category:Selective Serotonin Reuptake Inhibitors (SSRIs)]]
[[Category:Antidepressants]]
[[Category:Medicines]]
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