Fintepla Drug Interactions: What to Avoid and What to Tell Your Doctor

Fintepla (fenfluramine) has several important drug interactions that every patient and caregiver needs to know about. Some interactions are dangerous and contraindicated; others simply require dose adjustments or careful monitoring. Before starting Fintepla, review this guide and share a complete medication list with your doctor.

Absolute Contraindication: MAOIs (Monoamine Oxidase Inhibitors)

Fintepla is absolutely contraindicated with MAOIs. Do not take Fintepla if you are currently taking an MAOI, or if you have taken one in the past 14 days. Combining these drugs can cause serotonin syndrome — a potentially life-threatening condition involving dangerously high serotonin levels.

Common MAOIs to avoid with Fintepla:

Phenelzine (Nardil)

Tranylcypromine (Parnate)

Isocarboxazid (Marplan)

Linezolid (Zyvox) — an antibiotic with MAOI activity

Selegiline (Eldepryl) and rasagiline (Azilect) — used for Parkinson's disease

Also: after stopping Fintepla, wait at least 14 days before starting an MAOI. This bidirectional washout period is critical.

High Caution: Serotonergic Drugs (SSRIs, SNRIs, TCAs, Triptans)

Because Fintepla works by releasing serotonin, combining it with other medications that increase serotonin activity raises the risk of serotonin syndrome. This includes many commonly prescribed medications:

SSRIs (selective serotonin reuptake inhibitors): Fluoxetine (Prozac), sertraline (Zoloft), escitalopram (Lexapro), citalopram (Celexa), paroxetine (Paxil)

SNRIs (serotonin-norepinephrine reuptake inhibitors): Venlafaxine (Effexor), duloxetine (Cymbalta), desvenlafaxine (Pristiq)

TCAs (tricyclic antidepressants): Amitriptyline (Elavil), nortriptyline (Pamelor), imipramine (Tofranil)

Triptans: Sumatriptan (Imitrex), rizatriptan (Maxalt), used for migraines

Bupropion (Wellbutrin): Also has serotonergic activity

Tramadol: An opioid pain reliever with serotonergic activity

Lithium: Used for bipolar disorder; increases serotonin activity

If a patient needs both Fintepla and one of these medications, the prescribing team must carefully weigh the risk of serotonin syndrome and monitor closely. Do not stop taking these medications without medical guidance.

CYP Enzyme Interactions: Drugs That Affect Fintepla Blood Levels

Fintepla is metabolized primarily by CYP1A2, CYP2B6, and CYP2D6 enzymes in the liver. Drugs that affect these enzymes can significantly change how much fenfluramine is in the bloodstream.

Strong CYP1A2 or CYP2D6 Inhibitors (Increase Fintepla Levels)

These drugs block the enzymes that break down Fintepla, causing it to build up to higher levels than intended:

Fluvoxamine (Luvox) — CYP1A2 inhibitor: Increases fenfluramine exposure (AUC) by 102%. When combined, max Fintepla dose is 20 mg/day.

Paroxetine (Paxil) — CYP2D6 inhibitor: Increases fenfluramine exposure by 81%. When combined, max Fintepla dose is 20 mg/day.

Other CYP1A2 inhibitors (ciprofloxacin, enoxacin, mexiletine) and CYP2D6 inhibitors (bupropion, quinidine, fluoxetine) may also increase Fintepla levels. Dosage adjustments are required.

Strong CYP Inducers (Decrease Fintepla Levels — Reduced Efficacy)

These drugs speed up the breakdown of Fintepla, potentially making it less effective:

Rifampin (CYP1A2/CYP2B6/CYP3A inducer): Decreases fenfluramine AUC by 58%. Avoid coadministration; if necessary, monitor for reduced seizure control.

St. John's Wort (herbal supplement): CYP3A4 inducer; reduces Fintepla levels. Avoid this supplement while on Fintepla.

Other CYP inducers: Carbamazepine (Tegretol), phenytoin (Dilantin), phenobarbital, and oxcarbazepine may reduce Fintepla levels. These medications are also generally contraindicated in Dravet syndrome.

Dose Adjustment Required: Stiripentol (Diacomit) + Clobazam (Onfi)

Stiripentol is commonly combined with Fintepla in Dravet syndrome treatment. Stiripentol inhibits multiple CYP enzymes and affects how Fintepla is metabolized. When Fintepla is used together with stiripentol and clobazam, the maximum daily dose of Fintepla must be reduced to 17 mg/day (compared to 26 mg/day without stiripentol).

Dietary Supplement Interactions

St. John's Wort: Avoid — reduces Fintepla levels AND has serotonergic properties, creating a double interaction risk

Tryptophan supplements: A serotonin precursor; may increase serotonin syndrome risk when combined with Fintepla

What to Tell Your Doctor Before Starting Fintepla

Before starting Fintepla, provide your doctor with a complete list of: all prescription medications, all over-the-counter medications (including pain relievers, antihistamines), all supplements and herbal products, and any recent antibiotic or antifungal treatments. Interactions can be subtle and dose-dependent. For more on Fintepla's side effects, see Fintepla Side Effects: What to Expect. And if you need help locating a pharmacy to fill your prescription, medfinder can help.