Filspari (Sparsentan) for Kidney Disease

Filspari (sparsentan) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) for certain kidney diseases, including primary immunoglobulin A nephropathy (IgAN) in adults and focal segmental glomerulosclerosis (FSGS) in adults and children aged 8 years and older.

How Filspari Works and How It’s Taken

Filspari is a type of medicine called an endothelin and angiotensin 2 receptor antagonist. It works by blocking two pathways in the body that can harm the kidneys. By blocking these pathways, Filspari may help slow kidney function decline in IgAN and reduce proteinuria in FSGS.

Doctors prescribe Filspari to slow kidney function decline in adults with IgAN who are at risk for disease progression. It is also used to reduce proteinuria (protein in the urine) in adults and children aged 8 years and older with FSGS who do not have nephrotic syndrome.

Filspari is given as a tablet by mouth once daily before a morning or evening meal. After 14 days, the dose may be increased as tolerated.

Typical Dosing for IgAN

The recommended starting dose of Filspari is 200 milligrams once daily for 14 days. If tolerated, the dose is then increased to the recommended maintenance dose of 400 milligrams once daily.

Typical Dosing for FSGS

The recommended dose is based on body weight.

For people who weigh more than 50 kilograms, the starting dose is 400 milligrams once daily for 14 days. If tolerated, the dose is increased to the recommended maintenance dose of 800 milligrams once daily.

For people who weigh 50 kilograms or less, the starting dose is 200 milligrams once daily for 14 days. If tolerated, the dose is increased to the recommended maintenance dose of 400 milligrams once daily.

If treatment is restarted after an interruption, a doctor may restart Filspari at 50 percent of the recommended dose and increase it to the recommended dose after 14 days.

This information is based on the prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.

Filspari Side Effects

In clinical studies of Filspari for IgAN in adults and FSGS in adults and children aged 8 years and older, the most common side effects happened in about 6 percent to 23 percent of people. These include:

High potassium in the blood
Low blood pressure (which can include feeling lightheaded when standing up)
Swelling in the legs, ankles, feet, or hands
Dizziness
Anemia (low red blood cells)
Acute kidney injury

Serious Side Effects and Warnings

Filspari can cause serious side effects that may require immediate medical attention. These include:

Hepatotoxicity — Liver problems can show up as nausea or vomiting, pain on the upper right side of the stomach area, tiredness, loss of appetite, yellowing of the skin or eyes, dark urine, fever, or itching.
Embryo-fetal toxicity — This medication may cause serious birth defects if taken during pregnancy.
Hypotension — Blood pressure can drop too low, which may cause dizziness or fainting.
Acute kidney injury — This is a sudden drop in kidney function.
Hyperkalemia — High potassium levels in the blood can affect heart rhythm.
Fluid retention — The body holds onto extra fluid, which can cause swelling.

Get medical help right away if you think you are having a serious reaction.

How To Save on Filspari

Travere Therapeutics, the manufacturer of Filspari, offers Travere TotalCare. Eligible people with commercial insurance may pay as little as $0 per month through the Travere copay support program.

Travere TotalCare also offers support from Nurse Educators, help connecting people with financial support, guidance through the process of starting Filspari and receiving refills, and updates by text, email, or phone in multiple languages, including Spanish and Mandarin.

To learn more, visit Travere TotalCare or call 833-345-7727.

What To Know Before Taking Filspari

Before taking Filspari, tell your doctor about all of your medical conditions, including if you:

Have liver problems
Are pregnant or plan to become pregnant, as Filspari may cause serious birth defects

Before starting Filspari, your doctor will check your liver tests (aminotransferases and total bilirubin) and perform a pregnancy test if you can become pregnant.

Tell your doctor if you have any allergies to sparsentan or any ingredients in Filspari.

Tell your doctor about all medicines you take, including prescription drugs, over-the-counter medicines, vitamins, herbal supplements, and grapefruit. Especially tell your doctor if you take:

Nonsteroidal anti-inflammatory drugs (NSAIDs)
Potassium-containing medicines, potassium supplements, or salt substitutes containing potassium
Blood pressure medicines

Do not take Filspari if you are pregnant, or if you are taking an angiotensin receptor blocker (ARB), an endothelin receptor antagonist (ERA), or aliskiren.

If you miss a dose, take your next dose at the regular time. Do not take two doses at the same time or take extra doses.

If you are pregnant, planning to become pregnant, or breastfeeding while taking Filspari, talk with your doctor about the risks and benefits.

If you can become pregnant, use effective birth control before starting Filspari, during treatment, and for two weeks after stopping treatment. Do not breastfeed during treatment with Filspari.

Community FAQs

These answers are fact-checked by our editorial staff.

How effective is Filspari?

In studies on adults with IgAN, Filspari lowered urine protein levels by 45 percent from baseline at 36 weeks, compared with 15 percent with irbesartan. Over 110 weeks, it also slowed kidney function decline, with an average estimated glomerular filtration rate (eGFR) decline of 3.0 mL/min/1.73 m² per year versus 4.2 mL/min/1.73 m² per year with irbesartan.

In studies on adults and children aged 8 years and older with FSGS without nephrotic syndrome, Filspari reduced urine protein levels by 48 percent from baseline at 108 weeks, compared with 27 percent with irbesartan. This resulted in a 29 percent greater reduction in urine protein levels compared with irbesartan.

These results show benefit in the studied groups, but they do not mean the medicine works the same way for everyone.

How long does Filspari take to work for kidney disease?

The amount of time it takes Filspari to work can vary from person to person. Your doctor will monitor your kidney function and urine protein levels to assess how well Filspari is working.

For adults with IgAN, a reduction in urine protein was measured at 36 weeks in the main clinical study. The study also showed that Filspari slowed the rate of kidney function decline compared with irbesartan over 110 weeks.

For adults and children aged 8 years and older with FSGS without nephrotic syndrome, reductions in urine protein were measured during the main clinical study through 108 weeks.

Clinical studies do not state the earliest time when people may notice a benefit from treatment.

What tests or monitoring are needed with Filspari for kidney disease?

Before starting Filspari, your doctor will check your liver enzymes and total bilirubin with a blood test. These tests should be repeated every three months during treatment to help monitor for liver problems. If you can become pregnant, a pregnancy test is needed before starting treatment.

During treatment, your doctor will also monitor your kidney function and potassium levels with periodic blood tests.