fenfluramine

What is the most important information I should know about fenfluramine?

Do not use fenfluramine if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, and tranylcypromine. Wait at least 14 days after stopping an MAO inhibitor before you take fenfluramine.

Fenfluramine may cause weight loss, which could affect growth in children. Weigh yourself regularly and tell your doctor if you lose weight. You may need to stop taking fenfluramine if you lose too much weight.

Some people have thoughts about suicide while taking fenfluramine. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

What is fenfluramine?

Fenfluramine is used to treat seizures caused by Dravet syndrome and Lennox-Gastaut syndrome in people at least 2 years old.

Fenfluramine can cause serious side effects on your heart and lungs. This medicine is available only under a special program. You must be registered in the program and understand the risks and benefits of this medicine.

Fenfluramine may also be used for purposes not listed in this medication guide.

What should I discuss with my healthcare provider before taking fenfluramine?

Do not use fenfluramine if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

Tell your doctor if you have ever had:

• heart problems;
• weight loss;
• depression, a mood disorder, or suicidal thoughts or actions;
• a drug or alcohol addiction; or
• liver or kidney disease.

Some people have thoughts about suicide while taking fenfluramine. Your doctor will need to check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.

Tell your doctor if you also use stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. An interaction with fenfluramine could cause a serious condition called serotonin syndrome.

Tell your doctor if you are pregnant or breastfeeding.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of fenfluramine on the baby.

How should I take fenfluramine?

Your doctor will perform tests to make sure you do not have conditions that would prevent you from safely using fenfluramine.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.

You may take fenfluramine with or without food.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Follow your care provider's instructions about giving fenfluramine through a feeding tube if needed.

Fenfluramine may cause decreased appetite and weight loss. Weigh yourself regularly and tell your doctor if you lose weight. You may need to stop taking fenfluramine if you lose too much weight. Weight loss may affect growth in children.

Your heart function will need to be checked using an electrocardiograph or ECG (sometimes called an EKG).

Keep track of your medicine. You should be aware if anyone is using it improperly or without a prescription.

Throw away any unused fenfluramine 3 months after you first opened the bottle or after the "discard" date on the label, whichever comes first.

Do not stop using fenfluramine suddenly, even if you feel fine. Stopping suddenly may cause increased seizures. Follow your doctor's instructions about tapering your dose.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

What should I avoid while taking fenfluramine?

Avoid taking an herbal supplement containing St. John's wort.

What are the possible side effects of fenfluramine?

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.

• chest pain, pounding heartbeats or fluttering in your chest;
• shortness or breath;
• blue colored skin or lips;
• swelling in your lower legs; or
• unusual tiredness or weakness, feeling like you might pass out.

• loss of appetite and weight loss;
• worsening seizures;
• blurred vision, tunnel vision, eye pain or redness, or seeing halos around lights;
• nausea or vomiting; or
• increased blood pressure --severe headache, blurred vision, pounding in your neck or ears, anxiety, nosebleed.

Fenfluramine can affect weight or growth in children. Tell your doctor if your child is not growing at a normal rate while using this medicine.

Common side effects may include:

• increased blood pressure;
• drowsiness;
• decreased weight;
• loss of appetite, vomiting, diarrhea, constipation;
• seizures that do not stop;
• feeling weak or tired;
• fever, infections;
• abnormal heart function tests;
• problems with balance, walking, or muscle movement;
• drooling; or
• cold symptoms such as stuffy nose, sneezing, sore throat.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect fenfluramine?

Sometimes it is not safe to use certain medicines at the same time. Some drugs can affect your blood levels of other drugs you use, which may increase side effects or make the medicines less effective.

Tell your doctor about all your other medicines, especially:

• stiripentol; or
• clobazam.

This list is not complete. Other drugs may affect fenfluramine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Where can I get more information?

Your pharmacist can provide more information about fenfluramine.