Filspari
Filspari (sparsentan) is a medication that works well to lower urine protein levels in people with immunoglobulin A nephropathy (IgAN). It's not known if this means Filspari (sparsentan) slows down worsening kidney function, but this is something that's currently being studied. Filspari (sparsentan) is taken by mouth, typically once daily. Some of the more common side effects it can cause include swelling in the arms and legs, low blood pressure, and dizziness.
What is Filspari (sparsentan)?
What is Filspari (sparsentan) used for?
Lower urine protein levels in adults with immunoglobulin A nephropathy (IgAN)
How Filspari (sparsentan) works
Filspari (sparsentan) is an endothelin type A receptor blocker and an angiotensin II receptor blocker. It blocks two proteins which are thought to worsen IgAN (endothelin and angiotensin II) from binding to their receptors.
Drug Facts
What are the side effects of Filspari (sparsentan)?
Common Side Effects
- Swelling in arms or legs (14%)
- Low blood pressure (14%)
- Dizziness (13%)
- High blood potassium levels (13%)
Other Side Effects
- Low red blood cell count
- Kidney problems
- High liver enzymes
Serious Side Effects
- Serious liver problems: swelling of your stomach, yellowing of your skin or the whites of your eyes, confusion, dark or brown urine
- Severely low blood pressure: dizziness, lightheadedness, feeling faint, tired, confusion
- Serious kidney problems: urinating less often than usual, swelling in your feet, ankles, or hands, unexplained weight gain
- High potassium levels: nausea, muscle weakness, abnormal heartbeat
Source: DailyMed
The following side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
- High potassium level—muscle weakness, fast or irregular heartbeat
- Kidney injury—decrease in the amount of urine, swelling of the ankles, hands, or feet
- Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue
- Low blood pressure—dizziness, feeling faint or lightheaded, blurry vision
- Low red blood cell level—unusual weakness or fatigue, dizziness, headache, trouble breathing
Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):
- Dizziness
- Swelling of the ankles, hands, or feet
Pros and cons of Filspari (sparsentan)
Pros
Works better at lowering urine protein levels than irbesartan (Avapro), an existing IgAN treatment option
Taken by mouth
Taken once daily
Cons
More studies needed to show Filspari (sparsentan) can slow the worsening of kidney problems
Not a cure for IgAN
Can cause dangerously low blood pressure
Not studied in children
Pharmacist tips for Filspari (sparsentan)
Make sure to mark your appointments on your calendar for when you need to see your provider so they can monitor you while you're receiving Filspari (sparsentan). For examples, your provider will need to check your liver health monthly (during you first year of treatment), give you a monthly pregnancy test if you're able to become pregnant, and check your blood potassium level from time to time to make sure it's not too high.
Take Filspari (sparsentan) with water before breakfast or dinner at the same time day every day. If you miss a dose, take the next dose at the regularly scheduled time and don't double or take extra doses to make up for the missed dose.
There isn't a clearly defined length of time you need to take Filspari (sparsentan) because it isn't a cure for IgAN. Your provider will likely have you continue Filspari (sparsentan) treatment as long as it's working to keep your urine protein levels low and you're able to tolerate the side effects. Talk with your provider if you're not sure how long you need to receive Filspari (sparsentan) treatment.
Filspari (sparsentan) interacts with a lot of commonly-used medications (prescription and over-the-counter), including angiotensin receptor blockers (ARBs), endothelin antagonists, and non-steroidal anti-inflammatory drugs (NSAIDs), among many others. Make sure to tell your provider about all of the medications you're taking before starting Filspari (sparsentan). Don't start any new medications without talking to your provider or pharmacist first to make sure the combination is safe to take.
Be sure to drink enough fluids to stay hydrated while taking Filspari (sparsentan) because this can help prevent your blood pressure from dropping too low. But don't drink too much because Filspari (sparsentan) can also cause your body to hold onto too much fluid and swell up. If you're not sure how much is a safe amount of fluid to drink, ask your provider.
If you're able to have children, it's recommended that you use birth control during treatment with Filspari (sparsentan) and for at least 1 month after your last dose. In addition, your provider will give you a pregnancy test before you start Filspari (sparsentan), monthly during your treatment, and a month after your last dose. Let your provider know right away if you get pregnant while taking this medication. Filspari (sparsentan) can potentially harm an unborn baby.
Frequently asked questions about Filspari (sparsentan)
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What are the risks and warnings for Filspari (sparsentan)?
Filspari (sparsentan) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Serious liver damage
Risk factors: History of liver problems | Taking other medications that can cause liver problems | Drinking large amounts of alcohol
Filspari (sparsentan) can cause serious liver problems that can lead to liver failure. Because of this risk, Filspari (sparsentan) is available only through the Filspari REMS program. You'll need to get blood tests to check your liver health before and during treatment to make sure your liver is working properly. Get medical attention right away if you notice symptoms of liver problems, such as swelling of your stomach, stomach pain, yellowing of your skin or the whites of your eyes, stool changes (black, tarry, or bloody stools), nausea, vomiting, confusion, or dark or brown urine. You might need to stop using the medication to prevent further liver damage.
Not for use during pregnancy
Filspari (sparsentan) shouldn't be taken during pregnancy. While it hasn't be studied in human pregnancy, animal studies show that it can cause severe and life-threatening harm to babies. If you're able to have children, your provider will ask you take a pregnancy test before you start Filspari (sparsentan), monthly while you're receiving treatment, and again one month after you stop this medication. Females who are able to get pregnant should use birth control during treatment and for at least 1 month after treatment with Filspari (sparsentan). If you're pregnant or thinking of becoming pregnant, talk to your provider about the risks and benefits of using Filspari (sparsentan) during pregnancy.
Dangerously low blood pressure
Risk factors: Not enough fluid in your body | Having diarrhea or vomiting for a long time | Low salt levels in your body | Taking other medications that can lower your blood pressure
Filspari (sparsentan) can cause your blood pressure to drop too much, which can make you feel dizzy, tired, or lightheaded. Your risk is higher if you're dehydrated or have medical conditions that cause you to become dehydrated, such as diarrhea or vomiting. If you experience these side effects, your provider might need to change or stop your blood pressure medications (if you're taking any). Or, they might need to temporarily lower the dose of or ask you to stop taking Filspari (sparsentan) until your blood pressure returns to a safe range. Make sure to drink enough water while you're receiving treatment. If you feel dizzy, sit down slowly while holding onto something and let your provider know. If you fall and hit your head, get medical help right away. If you feel dizzy, lightheaded, faint, tired, or confused while taking Filspari (sparsentan), contact your provider right away.
Serious kidney damage
Risk factors: Heart failure | Kidney problems | Not enough fluid in your body | Taking other medications that can cause kidney damage
Filspari (sparsentan) can affect your kidneys and cause them to not work as well. This can happen to anyone, but the effects can be more severe in people with heart failure, have existing kidney problems, or who take medications that can worsen kidney problems. Your provider might order lab tests every so often to make sure your kidneys are healthy and working properly. If you develop kidney problems (or if your kidney problems worsen) while taking Filspari (sparsentan), your provider might recommend that you stop taking this medication. Let your provider know if you're urinating less often than usual, as this could be a sign that your kidneys aren't working as well.
High potassium levels
Risk factors: Taking other medications that can raise potassium levels
Filspari (sparsentan) can cause high potassium levels, even in people with healthy kidneys. Your risk is higher if you take other medications that can raise potassium, such as spironolactone (Aldactone) or eplerenone (Inspra). If you experience signs of high potassium levels, such as nausea, muscle weakness, or abnormal heartbeat, tell your healthcare provider right away so they can measure your potassium level. If left untreated, high potassium levels can be dangerous.
Too much fluid
Risk factors: Heart failure
Filspari (sparsentan) can cause fluid to build-up in the body and lead to swelling. If you have heart failure or any other conditions that can be worsened by fluid build up, let your provider know before starting Filspari (sparsentan). They might recommend for you to take a different medication other than Filspari (sparsentan). Contact your provider right away if you notice unusual swelling in your arms or legs, rapid weight gain, or trouble breathing. They might need to prescribe a water pill for you to get rid of any extra fluid.
Filspari (sparsentan) dosage forms
Typical dosing for Filspari (sparsentan)
The typical starting dose is 200 mg by mouth once daily. After 2 weeks, your provider will raise the dose to 400 mg once daily. Swallow the whole tablet with water before breakfast or dinner.
Your dose might be different if you have liver problems, are taking a medication that interacts with Filspari (sparsentan), or are having side effects.
Filspari (sparsentan) contraindications
Pregnancy
Taking angiotensin receptor blockers (ARBs), endothelin antagonists, or aliskiren (Tecturna)
Filspari (sparsentan) images
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References
Best studies we foundDhaun, N., et al. (2012). Endothelin-1 and the kidney — Beyond BP. British Journal of Pharmacology.
Filspari REMS. (n.d.). Patients.
IGA Nephropathy Foundation. (n.d.). FAQ.
MedlinePlus. (2022). Protein in urine.
Montford, J. R., et al. (2017). How dangerous is hyperkalemia? Journal of the American Society of Nephrology.
National Human Genome Research Institute. (2023). Antibody.
National Kidney Foundation. (n.d.). IgA nephropathy.
National Organization for Rare Diseases. (2023). IgA nephropathy.
Travere Therapeutics, Inc. (2023). Filspari- sparsentan tablet, film coated [package insert]. DailyMed.
Travere Therapeutics. (2023). Travere Therapeutics announces FDA accelerated approval of Filspariᵀᴹ (sparsentan), the first and only non-immunosuppressive therapy for the reduction of proteinuria in IgA nephropathy. Globe Newswire.
U.S. Food and Drug Administration. (2023). Risk Evaluation and Mitigation Strategies | REMS.
You and Your Hormones. (2019). Angiotensin.
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