Flibanserin
Flibanserin is an oral medication approved by the FDA in 2015 for hypoactive sexual desire disorder (HSDD) in premenopausal women. Marketed as Addyi, it acts on serotonin and dopamine receptors and is taken daily at bedtime.
- Chemical formula
- C20H21F3N4O
- CAS number
- 167933-07-5
- ATC code
- G02CX02
- Molecular weight
- 390.4 g/mol
- Drug class
- Multifunctional serotonin agonist/antagonist (HSDD)
- Also known as
- BIMT 17, Addyi
What is it?
Flibanserin is a non-hormonal oral medication approved by the FDA in 2015 for the treatment of acquired, generalised hypoactive sexual desire disorder (HSDD) in premenopausal women. It is marketed under the brand name Addyi. Flibanserin was the first medication approved for this indication and represents a different pharmacological approach than PDE5 inhibitors (which target genital blood flow): it acts on central nervous system pathways thought to regulate sexual desire. The molecule was originally investigated as an antidepressant before being repurposed for HSDD.
Mechanism of action
Flibanserin acts as a serotonin 5-HT1A receptor agonist and 5-HT2A receptor antagonist, with additional effects on dopamine and norepinephrine signalling. The hypothesised effect on sexual desire is mediated by reducing serotonin's inhibitory tone on desire pathways and selectively boosting dopamine and norepinephrine in cortical regions. Unlike PDE5 inhibitors, flibanserin does not act on genital blood flow; it targets the central nervous system pathways involved in sexual desire, distinguishing it from sildenafil-based products marketed for women.
Pharmacokinetics
After oral administration, flibanserin reaches peak plasma concentrations in approximately 0.75 to 4 hours. Bioavailability is approximately 33%. The molecule is extensively metabolised in the liver, primarily via CYP3A4, to inactive metabolites. The terminal half-life is approximately 11 hours, supporting once-daily bedtime dosing. Steady-state plasma concentrations are reached within several days. Coadministration with strong CYP3A4 inhibitors (e.g. ketoconazole) is contraindicated due to risk of severe hypotension and syncope.
Indications
Flibanserin is approved by the FDA for hypoactive sexual desire disorder (HSDD) in premenopausal women — specifically, acquired (not lifelong) and generalised (not situational) HSDD, with personal distress, not better explained by another condition or medication. It is not approved for postmenopausal women, men, sexual problems caused by relationship issues or medical conditions, or for sexual performance enhancement. According to the prescribing information, treatment requires careful diagnosis and ongoing assessment.
Safety profile
Common adverse effects include dizziness, somnolence, nausea, fatigue and dry mouth. The most clinically important safety concern is severe hypotension and syncope, particularly when combined with alcohol or strong CYP3A4 inhibitors. The FDA originally required a Risk Evaluation and Mitigation Strategy (REMS) program addressing this risk, modified in 2019 to allow alcohol use only in moderation and at least 2 hours apart from dosing. According to the prescribing information, ongoing assessment of efficacy is required after 8 weeks; the medication should be discontinued if there is no clinical improvement.
Products containing this ingredient
Frequently asked questions
How is flibanserin different from sildenafil for women? ▾
Flibanserin (Addyi) is FDA-approved for HSDD in premenopausal women; sildenafil-based products marketed as 'female Viagra' are not. The mechanisms are entirely different: flibanserin acts on central nervous system serotonin and dopamine pathways involved in sexual desire, while sildenafil targets genital blood flow. Flibanserin is taken daily at bedtime; sildenafil-based products are taken on demand before sexual activity. Flibanserin specifically targets desire (the dominant complaint in HSDD); sildenafil does not act on desire.
How long until flibanserin works? ▾
Some patients report improvement within the first weeks of daily flibanserin, but full effect typically develops over 8 to 12 weeks of continuous treatment. According to the prescribing information, treatment should be discontinued if there is no clinical improvement after 8 weeks of regular use. The clinical effect in trials was modest in absolute terms, with improvements in satisfying sexual events of approximately 0.5 to 1 additional event per month versus placebo.
Can I drink alcohol while taking flibanserin? ▾
Alcohol use with flibanserin requires caution due to the risk of severe hypotension and syncope. The current FDA labeling allows moderate alcohol use only when separated by at least 2 hours from the flibanserin dose, with the medication taken at bedtime. According to the prescribing information, patients should not take flibanserin if they have already consumed 1 to 2 alcoholic drinks that evening. Heavy alcohol use is contraindicated. The original 2015 approval initially restricted alcohol entirely; this was modified in 2019.
Is flibanserin approved for menopausal women? ▾
No. Flibanserin's FDA approval is specifically for hypoactive sexual desire disorder in premenopausal women, based on the populations enrolled in the pivotal clinical trials. Postmenopausal HSDD has different underlying biology and was not the subject of those trials. According to clinical guidelines, postmenopausal women with sexual concerns should be evaluated for other contributing factors including hormonal status, vaginal atrophy and partner-related issues, with treatment options selected accordingly.
What contraindications apply to flibanserin? ▾
Flibanserin is contraindicated with strong CYP3A4 inhibitors (such as ketoconazole, clarithromycin, ritonavir, grapefruit juice in large quantities) due to risk of severe hypotension and syncope. It is also contraindicated in hepatic impairment of any severity and should be used cautiously with alcohol. Other contraindications include known hypersensitivity to the molecule. According to the prescribing information, all current medications and conditions should be reviewed before starting flibanserin.
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