Description and Brand Names

Drug information provided by: Merative, Micromedex®

Descriptions

Fenfluramine is used alone or with other medicines (eg, stiripentol, clobazam) to treat seizures in patients with Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS).

This medicine is available only under a restricted distribution program called Fintepla® REMS (Risk Evaluation and Mitigation Strategy Program.

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of fenfluramine in children younger than 2 years of age. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of fenfluramine in the elderly. However, elderly patients are more likely to have age-related liver, kidney, or heart problems, which may require caution and an adjustment in the dose for patients receiving this medicine.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Furazolidone
• Iproniazid
• Isocarboxazid
• Linezolid
• Methylene Blue
• Moclobemide
• Nialamide
• Phenelzine
• Procarbazine
• Rasagiline
• Safinamide
• Selegiline
• Tranylcypromine

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Abiraterone Acetate
• Alfentanil
• Almotriptan
• Amineptine
• Amitriptyline
• Amitriptylinoxide
• Amoxapine
• Amphetamine
• Anileridine
• Apalutamide
• Benzhydrocodone
• Benzphetamine
• Brompheniramine
• Buprenorphine
• Bupropion
• Buspirone
• Butorphanol
• Carbamazepine
• Celecoxib
• Chlorpheniramine
• Ciprofloxacin
• Citalopram
• Clobazam
• Clomipramine
• Cocaine
• Codeine
• Cyclobenzaprine
• Desipramine
• Desvenlafaxine
• Dextroamphetamine
• Dextromethorphan
• Dibenzepin
• Difenoxin
• Dihydrocodeine
• Diphenoxylate
• Dolasetron
• Doxepin
• Duloxetine
• Eletriptan
• Enoxacin
• Enzalutamide
• Escitalopram
• Ethylmorphine
• Fedratinib
• Fentanyl
• Fluoxetine
• Fluvoxamine
• Fosphenytoin
• Frovatriptan
• Gepirone
• Granisetron
• Hydrocodone
• Hydromorphone
• Hydroxytryptophan
• Imipramine
• Ketobemidone
• Lasmiditan
• Levomilnacipran
• Levorphanol
• Lisdexamfetamine
• Lithium
• Lofepramine
• Lorcaserin
• Lumacaftor
• Melitracen
• Meperidine
• Methadone
• Methamphetamine
• Milnacipran
• Mirtazapine
• Mitotane
• Morphine
• Morphine Sulfate Liposome
• Nalbuphine
• Naratriptan
• Nefazodone
• Nicomorphine
• Nortriptyline
• Oliceridine
• Ondansetron
• Opipramol
• Opium
• Opium Alkaloids
• Oxycodone
• Oxymorphone
• Palonosetron
• Papaveretum
• Paregoric
• Paroxetine
• Pentazocine
• Phenytoin
• Piritramide
• Protriptyline
• Quinidine
• Remifentanil
• Rifampin
• Rizatriptan
• Sertraline
• Sibutramine
• Stiripentol
• St John's Wort
• Sufentanil
• Sumatriptan
• Tapentadol
• Terbinafine
• Tianeptine
• Tilidine
• Tramadol
• Trazodone
• Trimipramine
• Tryptophan
• Venlafaxine
• Vilazodone
• Vortioxetine
• Ziprasidone
• Zolmitriptan

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Depression or
• Eye or vision problems or
• Heart disease or
• Hypertension (high blood pressure) or
• Lung or breathing problems—Use with caution. May make these conditions worse.

• Kidney disease, moderate or severe or
• Liver disease—Use is not recommended in patients with these conditions.

Proper Use

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

It is very important that you understand the requirements of the Fintepla® REMS program, and become familiar with the Fintepla® medication guide. Read and follow these instructions carefully. Ask your doctor if you have any questions. Ask your pharmacist for the medication guide if you do not have one.

You may take this medicine with or without food.

Measure the medicine with a marked oral syringe. The average household teaspoon or tablespoon may not hold the right amount of liquid.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (solution):
  • For treatment of seizures in patients with Dravet syndrome and Lennox-Gastaut syndrome:
    • Adults and children 2 years of age and older—Dose is based on body weight and must be determined by your doctor. At first, 0.1 milligram per kilogram (mg/kg) of body weight 2 times a day. Your doctor may adjust your dose as needed and tolerated. However the dose is usually not more than 17 mg (with stiripentol and clobazam) or 26 mg per day (without stiripentol).
    • Children younger than 2 years of age—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Throw away any unused medicine 3 months after first opening the bottle.

Precautions

It is important that your doctor check your or your child's progress at regular visits to make sure this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Do not use this medicine if you are using or have used an MAO inhibitor (eg, isocarboxazid [Marplan®], linezolid [Zyvox®], methylene blue injection, phenelzine [Nardil®], selegiline [Eldepryl®], or tranylcypromine [Parnate®]) within the past 14 days.

This medicine may cause a heart problem called valvular heart disease and pulmonary arterial hypertension (high blood pressure in the lungs). Your doctor may want you or your child to undergo an echocardiogram test first before using this medicine, every 6 months during treatment, and once 3 to 6 months after the last dose to check for these unwanted effects. Tell your doctor if you or your child have a decreased ability to exercise, swelling of the feet or lower legs, trouble breathing, chest pain or discomfort, or fainting.

This medicine may cause decreased appetite and weight loss, which could especially affect your child's growth and development. Talk to your doctor if you have any concerns.

Check with your doctor right away if you or your child have anxiety, restlessness, a fast heartbeat, fever, sweating, muscle spasms, twitching, nausea, vomiting, diarrhea, or see or hear things that are not there. These may be symptoms of a serious condition called serotonin syndrome. The risk may be higher if you or your child also take certain other medicines that affect the serotonin levels in the body.

This medicine may make you or your child dizzy or drowsy. Do not drive or do anything else that could be dangerous until you or your child know how this medicine affects you.

This medicine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. Also tell your doctor if you or your child have sudden or strong feelings, such as feeling nervous, angry, restless, violent, or scared. If you or your caregiver notice any of these side effects, tell your doctor right away.

Do not stop using this medicine without checking first with your doctor. Your doctor may want you or your child to gradually reduce the amount you are using before stopping completely. This will decrease your or your child's chance of having withdrawal symptoms such as dizziness, nausea, headaches, vomiting, increased sweating, irritability, nightmares, seizures, prickling or tingling feelings, or worsening of seizures.

This medicine may be habit-forming. If you feel that the medicine is not working as well, do not use more than your prescribed dose.

Your or your child's blood pressure might get too high while you are using this medicine. This may cause headaches, dizziness, or blurred vision. You or your child might need to measure your blood pressure at home. If you think your or your child's blood pressure is too high, call your doctor right away.

This medicine may cause your eyes to dilate (mydriasis) and glaucoma. Check with your doctor right away if blurred vision, difficulty with reading, eye pain, or any other change in vision occurs during or after treatment. Your doctor may want your or your child's eyes be checked by an ophthalmologist (eye doctor).

Check with your doctor before using this medicine with alcohol or other medicines that affect the central nervous system (CNS). The use of alcohol or other medicines that affect the CNS with fenfluramine may worsen the side effects of this medicine, such as dizziness, poor concentration, drowsiness, unusual dreams, and trouble with sleeping. Some examples of medicines that affect the CNS are antihistamines or medicine for allergies or colds, sedatives, tranquilizers, or sleeping medicines, medicine for depression, medicine for anxiety, prescription pain medicine or narcotics, medicine for attention deficit and hyperactivity disorder, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John's wort) or vitamin supplements.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

1. Blurred vision
2. body aches or pain
3. change in hearing
4. change in walking and balance
5. chest tightness
6. chills
7. cough
8. cough producing mucus
9. decreased appetite
10. decreased weight
11. diarrhea
12. difficulty breathing or swallowing
13. dizziness
14. dryness or soreness of the throat
15. ear drainage
16. earache or pain in the ear
17. epileptic seizure that will not stop
18. falls
19. fever
20. headache
21. hoarseness
22. irritability
23. loss of voice
24. muscle pain or weakness
25. nausea
26. nervousness
27. pounding in the ears
28. rash
29. runny or stuffy nose
30. shakiness and unsteady walk
31. slow or fast heartbeat
32. sneezing
33. stomach pain
34. tremor
35. unsteadiness, trembling, or other problems with muscle control or coordination
36. unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
37. voice changes

Less common

1. Bladder pain
2. bloody or cloudy urine
3. bruise
4. confusion
5. decreased urination
6. difficult burning or painful urination
7. dry mouth
8. fainting
9. frequent urge to urinate
10. lightheadedness
11. loss of bladder control
12. lower back or side pain
13. negative attitude
14. rapid breathing
15. repetitive movements
16. skin rash, encrusted, scaly and oozing
17. sunken eyes
18. thirst
19. urination at night
20. wrinkled skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

1. Constipation
2. drooling
3. increased saliva
4. vomiting

:Less common

1. Trouble sleeping

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Portions of this document last updated: April 01, 2024

Original article: https://www.mayoclinic.org/ar/drugs-supplements/fenfluramine-oral-route/description/drg-20490822