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Overview: Filspari (sparsentan) is used to treat an autoimmune condition that affects the kidneys called immunoglobulin A nephropathy (IgAN). It is also used to treat a rare kidney condition called focal segmental glomerulosclerosis (FSGS). Filspari works by blocking receptors that are linked to inflammation and damage to the kidneys. Common side effects include high potassium levels, low blood pressure, fluid retention, and dizziness. Filspari can also cause liver damage, which can be serious.

Uses

What is Filspari used for?

Filspari (sparsentan) is commonly used for the following kidney conditions.

Learn more about Filspari for Focal Segmental Glomerulosclerosis (FSGS)

Filspari may also be used for other conditions as determined by your health care provider.

How does Filspari work (mechanism of action)?

Filspari works by blocking certain receptors in the body that are thought to be involved in kidney damage. This may help protect the kidneys in some people with IgAN or FSGS. 

How is Filspari supplied (dosage forms)?

Brands and other names

  • Filspari

Dosage forms and strengths

  • 200 mg oral tablets
  • 400 mg oral tablets

How should I store Filspari?

Store Filspari in its original container at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. 

Side Effects

What are the most common side effects of Filspari?

The most common side effects of Filspari are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • High potassium levels (see below)
  • Low blood pressure (see below)
  • Fluid retention (see below)
  • Kidney problems (see below)
  • Dizziness
  • Low red blood cell levels (anemia)

There may be other side effects of Filspari that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of Filspari?

While less common, the most serious side effects of Filspari are described below, along with what to do if they happen.

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking Filspari. Keep all appointments to have your blood checked. Call your health care provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Low Blood Pressure. Filspari may cause low blood pressure or a sudden drop in blood pressure when standing up from a seated or lying position (orthostatic hypotension). To help prevent this, be careful not to get up too quickly. If you feel dizzy, sit or lie down right away until the dizziness stops, then take your time getting up again. Tell your health care provider right away if you have any of the following symptoms.

  • Dizziness, feeling lightheaded, or fainting
  • Confusion
  • Feeling weak or tired
  • Blurred vision

Worsening Kidney Damage. Kidney damage can happen when taking Filspari. Call your health care provider right away if you have any of the following symptoms of kidney damage.

  • Reduced need to pee
  • Swelling in your feet, ankles, or legs
  • Weakness or unusual tiredness
  • Trouble catching your breath or chest pain or pressure
  • Confusion
  • Nausea
  • Seizures

High Potassium Levels (Hyperkalemia). Filspari can cause a high potassium level (hyperkalemia), which can be serious and may lead to death. Your health care provider may check your potassium levels, especially if you take certain other medicines. Call your health care provider right away if you have any of the following symptoms of a high potassium level.

  • Muscle weakness or unusual tiredness
  • Slow heartbeat or feeling of skipped heartbeats
  • Nausea or vomiting
  • Trouble breathing
  • Abnormal heart rhythm

Fluid Retention (Edema). Filspari can cause fluid retention, also called peripheral edema. Fluid retention can cause serious issues in people with certain conditions, such as heart failure or kidney problems. Call your health care provider right away if you have any of the following symptoms.

  • Chest pain
  • Irregular heartbeat
  • Shortness of breath
  • Stretched or shiny skin
  • Unusual weight gain
  • Swelling of your ankles, feet, legs, or hands

Severe Allergic Reactions. Filspari may cause allergic reactions, which can be serious. Stop taking Filspari and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use Filspari?

Allergies to Ingredients. People who are allergic to any of the following should not take Filspari.

  • Filspari
  • Sparsentan
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in Filspari.

Pregnancy. People who are pregnant should not use this medicine. See the Pregnancy section for more details.

Drug Interactions. Filspari should not be taken while you are using certain other medicines. Before taking Filspari, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

What should I know about Filspari before using it?

Do not take Filspari unless it has been prescribed to you by a health care provider. Take it as prescribed.

Take Filspari around the same time each day prior to your morning or evening meal. If you cannot swallow Filspari whole, you can crush the tablet and mix it with water right before taking it. Read and follow the instructions that come with your medicine.

Do not share Filspari with other people, even if they have the same condition as you. It may harm them.

Keep Filspari out of the reach of children.

Filspari can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how Filspari affects you.

This medicine can cause harm to a fetus. Your health care provider will make sure you are not pregnant before starting this medicine. If you can become pregnant, you should use an effective birth control method before starting Filspari, during treatment,  and for two weeks after stopping it. Talk to your health care provider about effective birth control methods. 

You will need to get blood work prior to starting this medicine and every few months while you are taking it. This is important to monitor the health of your liver and kidneys, and to make sure your potassium levels are safe. 

Filspari is only available through a special program, from certain pharmacies, and to certain people. Keep all of your appointments, including labs or other testing, while taking Filspari. If you have any questions about this program you can go to www.filsparirems.com or call 833-513-1325.

What should I tell my health care provider before using Filspari?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if Filspari is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

Pregnancy. Filspari may cause harm to a fetus. Tell your health care provider if you are or plan to become pregnant. If you become pregnant, stop taking Filspari right away and contact your health care provider. 

Breastfeeding. It is not known if Filspari passes into breast milk. Do not breastfeed while you are taking Filspari. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should stop breastfeeding or stop Filspari.

How can I get more information about Filspari?

For more information about Filspari, you can visit the drugmaker's website at www.filspari.com or call them at 833-345-7727.

Interactions

Does Filspari interact with foods or drinks?

Eating grapefruit or drinking grapefruit juice while taking Filspari may increase the risk for serious side effects. It is best to limit or avoid grapefruit and grapefruit juice while taking Filspari. 

It is unknown if drinking alcohol will affect Filspari. The risk of dizziness and liver damage may be increased if you drink alcohol while taking Filspari. It is best to limit or avoid alcohol while taking Filspari. 

Does Filspari interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking Filspari.

  • An angiotensin-converting enzyme (ACE) inhibitor, such as enalapril or lisinopril, which is a medicine for high blood pressure, heart failure, and certain kidney problems
  • An angiotensin II receptor blocker (ARB), such as losartan or valsartan, which is a medicine for high blood pressure, heart failure, and other heart conditions
  • Aliskiren (Tekturna), which is a medicine for high blood pressure
  • An endothelin receptor antagonist, such as bosentan or macitentan, which is a medicine for pulmonary arterial hypertension (PAH)
  • A proton pump inhibitor (PPI), such as omeprazole (Prilosec), pantoprazole (Protonix), or rabeprazole (Aciphex)
  • An H2 blocker, such as cimetidine (Tagamet), famotidine (Pepcid, Zantac), or nizatidine (Axid)
  • A nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, naproxen, and others, which is in many prescription and OTC products for pain, swelling, and fever
  • A supplement or salt substitute containing potassium
  • A diuretic, also called a water pill, which is a medicine used to reduce edema (fluid retention) and blood pressure
  • Potassium chloride (Klor-Con and others), which is a medicine used to raise potassium levels

Many other medicines may alter the blood levels of Filspari, and vice versa. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with Filspari. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much Filspari?

If you or someone else has used too much Filspari, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of Filspari?

If you miss a dose, skip the missed dose and only take the next dose. Do not take double or extra doses.