Fenfluramine

The precise mechanism by which fenfluramine exerts its therapeutic effects in the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome is unknown. Fenfluramine and the metabolite, norfenfluramine, exhibit agonist activity at serotonin 5-HT2 receptors.

• FINTEPLA is indicated for the treatment of seizures associated with Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS) in patients 2 years of age and older. FINTEPLA is indicated for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome in patients 2 years of age and older.ICD-10: G40.909

• FINTEPLA is contraindicated in patients with: Hypersensitivity to fenfluramine or any of the excipients in FINTEPLA [see Description (11) ] Concomitant use, or within 14 days of the administration, of monoamine oxidase inhibitors because of an increased risk of serotonin syndrome [see Warnings and Precautions (5.7) ] Hypersensitivity to fenfluramine or any of the excipients in FINTEPLA ( 4 ) Within 14 days of the administration of monoamine oxidase inhibitors due to an increased risk of serotonin syndrome ( 4 )contraindicated

FINTEPLA is to be administered orally and may be taken with or without food. ( 2.2 ) Dravet Syndrome The initial starting and maintenance dosage is 0.1 mg/kg twice daily, which can be increased weekly based on efficacy and tolerability. ( 2.2 ) The maximum daily maintenance dosage of FINTEPLA is 0.35 mg/kg twice daily (maximum daily dosage of 26 mg). ( 2.2 ) Lennox-Gastaut Syndrome The initial starting dosage is 0.1 mg/kg twice daily, which should be increased weekly based on tolerability. ( 2.2 ) The recommended maintenance dosage of FINTEPLA is 0.35 mg/kg twice daily (maximum daily dosage of 26 mg). ( 2.2 ) Dravet Syndrome and Lennox-Gastaut Syndrome Dose adjustment is required in patients taking concomitant stiripentol plus clobazam: the maximum daily maintenance dosage of FINTEPLA is 0.2 mg/kg twice daily (maximum daily dosage of 17 mg). ( 2.2 , 2.3 , 2.4 , 7.1 ) Dosage adjustment is recommended in patients: Taking strong CYP1A2 or CYP2D6 inhibitors ( 2.3 , 7.1 ) With severe renal impairment ( 2.4 , 8.6 ) With mild, moderate, and severe hepatic impairment ( 2.5 , 8.7 ) 2.1 Assessments Prior to Initiating FINTEPLA Prior to starting treatment with FINTEPLA, obtain an echocardiogram assessment to evaluate for valvular heart disease and pulmonary arterial hypertension [see Dosage and Administration (2.6) and Warnings and Precautions (5.1) ] . 2.2 Dosing Information FINTEPLA is to be administered orally and may be taken with or without food.

Decreased Appetite and Decreased Weight: Advise patients that FINTEPLA can cause decreased appetite and decreased weight. ( 5.3 ) Somnolence, Sedation, and Lethargy: Monitor for somnolence and sedation. Advise patients not to drive or operate machinery until they have gained sufficient experience on FINTEPLA. ( 5.4 ) Suicidal Behavior and Ideation: Monitor patients for suicidal behavior and thoughts. ( 5.5 ) Withdrawal of Antiepileptic Drugs: FINTEPLA should be gradually withdrawn to minimize the risk of increased seizure frequency and status epilepticus. ( 5.6 ) Serotonin Syndrome: Advise patients that serotonin syndrome is a potentially life-threatening condition and may occur with FINTEPLA, particularly with concomitant administration of FINTEPLA with other serotonergic drugs. ( 5.7 ) Increase in Blood Pressure: Monitor blood pressure during treatment. ( 5.8 ) Glaucoma: Discontinue therapy in patients with acute decrease in visual acuity or ocular pain. ( 5.9 ) 5.1 Valvular Heart Disease and Pulmonary Arterial Hypertension FINTEPLA can cause valvular heart disease (VHD) and pulmonary arterial hypertension (PAH). There is a known association between serotonergic drugs with 5-HT2B receptor agonist activity, including fenfluramine (the active ingredient in FINTEPLA), and valvular heart disease and pulmonary arterial hypertension.

The following clinically significant adverse reactions are described elsewhere in labeling: Valvular Heart Disease and Pulmonary Arterial Hypertension [see Warnings and Precautions (5.1) ] Decreased Appetite and Decreased Weight [see Warnings and Precautions (5.3) ] Somnolence, Sedation, and Lethargy [see Warnings and Precautions (5.4) ] Suicidal Behavior and Ideation [see Warnings and Precautions (5.5) ] Withdrawal of Antiepileptic Drugs [see Warnings and Precautions (5.6) ] Serotonin Syndrome [see Warnings and Precautions (5.7) ] Increase in Blood Pressure [see Warnings and Precautions (5.8) ] Glaucoma [see Warnings and Precautions (5.9) ] The most common adverse reactions (incidence at least 10% and greater than placebo) in patients with Dravet syndrome were decreased appetite; somnolence, sedation, lethargy; diarrhea; constipation; abnormal echocardiogram; fatigue, malaise, asthenia; ataxia, balance disorder, gait disturbance; blood pressure increased; drooling, salivary hypersecretion; pyrexia; upper respiratory tract infection; vomiting; decreased weight; fall; status epilepticus. ( 6.1 ) The most common adverse reactions (incidence at least 10% and greater than placebo) in patients with Lennox-Gastaut syndrome were diarrhea; decreased appetite; fatigue; somnolence; vomiting. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact UCB, Inc. at 1-844-599-2273 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Pregnancy: Based on animal data, may cause fetal harm ( 8.1 ) 8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to antiepileptic drugs (AEDs), such as FINTEPLA, during pregnancy. Encourage women who are taking FINTEPLA during pregnancy to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry by calling the toll-free number 1-888-233-2334 or visiting http://www.aedpregnancyregistry.org. Risk Summary There are no data on FINTEPLA use in pregnant women. Available data from epidemiologic studies with fenfluramine or dexfenfluramine are insufficient to evaluate for a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. FINTEPLA can cause decreased appetite and decreased weight [see Warnings and Precautions (5.3) ]; monitor for adequate weight gain during pregnancy. In animal studies, administration of fenfluramine throughout organogenesis (rat and rabbit) or throughout gestation and lactation (rat) resulted in adverse effects on development (fetal malformations, embryofetal and offspring mortality and growth impairment) in the presence of maternal toxicity at clinically relevant maternal plasma levels of fenfluramine and its major active metabolite (see Data ) .

Metabolism

The pharmacokinetics of fenfluramine and norfenfluramine were studied in healthy subjects, in pediatric patients with DS, and in pediatric and adult patients with LGS. The steady-state systemic exposure (C max and AUC) of fenfluramine was slightly greater than dose proportional over the dose range of 13 to 51.8 mg twice-daily fenfluramine (i.e., 1 to 4 times the maximum recommended dose).

Overdose has not been observed in the FINTEPLA clinical trial program. However, overdose of fenfluramine, the active ingredient in FINTEPLA, has been reported at higher doses than those included in the clinical trial program. Some of the cases were fatal. Events reported after overdose include mydriasis, tachycardia, flushing, tremors/twitching/muscle spasms, agitation/restlessness/anxiety, increased muscle tone/rigor/opisthotonos, respiratory distress or failure, and seizure. Seizure, coma, and cardiorespiratory arrest were reported in most of the fatal overdoses. There is no available specific antidote to the overdose reactions of FINTEPLA. In the event of overdose, standard medical practice for the management of drug overdosage should be used. An adequate airway, oxygenation, and ventilation should be ensured; monitoring of cardiac rhythm and vital sign measurement is recommended. A certified poison control center should be contacted for updated information on the management of overdose with FINTEPLA.

• Jun 25, 2020NDANDA212102Ucb Inc

1. 1Seizure1,90044%
2. 2Drug Ineffective65715%
3. 3Tricuspid Valve Incompetence50812%
4. 4Decreased Appetite48911%
5. 5Off Label Use48011%
6. 6Somnolence4129.5%
7. 7Weight Decreased3929.1%
8. 8Mitral Valve Incompetence3267.5%
9. 9Fatigue3107.2%
10. 10Diarrhoea2706.2%
11. 11Generalised Tonic-clonic Seizure2355.4%
12. 12Pneumonia2235.2%
13. 13Hospitalisation2004.6%
14. 14Pulmonary Valve Incompetence1914.4%
15. 15Insomnia1844.3%

Recent PubMed references pinned to Fenfluramine as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Efficacy and safety of fenfluramine in Dravet syndrome; A monocentric, observational study focused on initial dose, blood concentration, and reduction of concomitant medications.
  Epilepsy & behavior : E&B · 2026 · Iguchi A, Yamaguchi T, Tsuyusaki Y, et al.
  PMID 42066393DOI 10.1016/j.yebeh.2026.111070
• Beyond seizure control: Functional and caregiver-reported outcomes of long-term fenfluramine treatment in Dravet syndrome.
  Epilepsy & behavior : E&B · 2026 · Massaroni V, Ascione F, Porto C, et al.
  PMID 42001857DOI 10.1016/j.yebeh.2026.111059
• Fenfluramine in SCN1A-related GEFS+: A multicenter observational study on efficacy, EEG improvement, and tolerability.
  Epilepsia open · 2026 · Dell'Isola GB, Muda A, Giordano L, et al.
  PMID 41739881DOI 10.1002/epi4.70187
• Use of fenfluramine in MECP2-related Rett syndrome: Findings from a retrospective multicenter pediatric case series.
  Epilepsy & behavior : E&B · 2026 · Boeri S, Cognolato E, Simonetta D, et al.
  PMID 41724124DOI 10.1016/j.yebeh.2026.110920
• Cost-effectiveness of fenfluramine as add-on treatment in the management of Dravet Syndrome: A real-world multicenter study.
  Epilepsia open · 2026 · Cortesi PA, Fornari C, Boncristiano A, et al.
  PMID 41388477DOI 10.1002/epi4.70200
• Relieving the Weight: Fenfluramine's Re-emergence as Antiseizure Medication for Lennox-Gastaut and Dravet Syndrome.
  The Annals of pharmacotherapy · 2026 · McCay SA, Shiue HJ, Hoerth MT, et al.
  PMID 41324386DOI 10.1177/10600280251396957
• Fenfluramine for developmental and epileptic encephalopathy with spike-wave activation in sleep (DEE-SWAS): An exploratory study.
  Epilepsy research · 2025 · Parra-Díaz P, Gil-Nagel A, Román IS, et al.
  PMID 41175602DOI 10.1016/j.eplepsyres.2025.107687
• Fenfluramine treatment beyond dravet and lennox-gastaut syndromes - A retrospective study suggesting a novel use in genetic, developmental and epileptic encephalopathies (DEEs).
  Seizure · 2025 · Urbina Lopez A, Varughese RT, Marti C, et al.
  PMID 41145080DOI 10.1016/j.seizure.2025.09.013

The 10 most recently updated of 29 ClinicalTrials.gov registrations naming Fenfluramine as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• A Phase 3 Study of Fenfluramine Hydrochloride in Rett Syndrome
  Not yet recruiting · Phase 3 · Interventional · 200 enrolled · UCB BIOSCIENCES, Inc.
  NCT07503444updated 2026-06-12
• Assessment of Safety of the Use of Fenfluramine in Children With Dravet Syndrome Under 24 Months of Age
  Recruiting · Phase 4 · Interventional · 5 enrolled · University of Colorado, Denver
  NCT06598449updated 2026-05-15
• EEG Dynamics in Lennox-Gastaut Syndrome Patients Undergoing Fenfluramine Treatment
  Enrolling by invitation · Observational · 20 enrolled · University of Chicago
  NCT07555171updated 2026-05-07
• Fenfluramine for Adult Dravet Patients
  Terminated · Phase 3 · Interventional · 7 enrolled · University Health Network, Toronto
  NCT05560282updated 2026-05-05
• A Phase 3 Study to Examine the Efficacy and Safety of ZX008 in Subjects With CDKL5 Deficiency Disorder.
  Active not recruiting · Phase 3 · Interventional · 87 enrolled · Zogenix, Inc.
  NCT05064878updated 2026-04-29
• Treatment of Dravet Syndrome With Fenfluramine (Expanded Access Protocol)
  Approved for marketing · Expanded access · University of California, Los Angeles
  NCT04437004updated 2026-04-20
• Treatment of Refractory Infantile Spasms With Fenfluramine
  Recruiting · Phase 2 · Interventional · 10 enrolled · Children's Hospital of Orange County
  NCT04289467updated 2026-04-15
• A Study to Evaluate Safety, Tolerability, and Pharmacokinetics of Fenfluramine (Hydrochloride) in Infants 1 Year to Less Than 2 Years of Age With Dravet Syndrome
  Active not recruiting · Phase 3 · Interventional · 25 enrolled · UCB BIOSCIENCES, Inc.
  NCT06118255updated 2026-04-03
• The FINTEPLA as an Anti-SUDEP Therapy in Dravet Syndrome Project
  Not yet recruiting · Phase 4 · Interventional · 25 enrolled · The University of Texas Health Science Center, Houston
  NCT07112365updated 2026-04-03
• A Study to Assess Drug-drug Interaction of ZX008 in Healthy Male and Female Study Participants
  Completed · Phase 1 · Interventional · 22 enrolled · UCB BIOSCIENCES, Inc.
  NCT06679413updated 2026-03-30

Frequently asked questions

How does Fenfluramine work?

The precise mechanism by which fenfluramine exerts its therapeutic effects in the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome is unknown. Fenfluramine and the metabolite, norfenfluramine, exhibit agonist activity at serotonin 5-HT2 receptors.

What is Fenfluramine used for?

According to FDA labeling, Fenfluramine carries indications including: FINTEPLA is indicated for the treatment of seizures associated with Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS) in patients 2 years of age and older. FINTEPLA is indicated for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome in patients 2 years of age and older.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Fenfluramine?

Fenfluramine is classified as Centrally acting antiobesity products, Other antiepileptics, Monoamine Oxidase Inhibitors, Serotonin Receptor Interactions, Serotonin Uptake Inhibitors, Appetite Suppression, Increased Serotonin Activity.

What are the brand names for Fenfluramine?

Fenfluramine is marketed under brand names including Fintepla.

What are the contraindications for Fenfluramine?

Fenfluramine labeling lists contraindications including: FINTEPLA is contraindicated in patients with: Hypersensitivity to fenfluramine or any of the excipients in FINTEPLA [see Description (11) ] Concomitant use, or within 14 days of the administration, of monoamine oxidase inhibitors because of an increased risk of serotonin syndrome [see Warnings and Precautions (5.7) ] Hypersensitivity to fenfluramine or any of the excipients in FINTEPLA ( 4 ) Within 14 days of the administration of monoamine oxidase inhibitors due to an increased risk of serotonin syndrome ( 4 ). Always consult the full prescribing information and a clinician.