Filspari (Sparsentan) for Kidney Disease

Overview
Filspari, approved by the U.S. Food and Drug Administration (FDA) in 2023, is prescribed to slow kidney function decline in adults with primary immunoglobulin A nephropathy (IgAN), a condition characterized by the buildup of IgA antibodies in the kidneys, which can lead to progressive kidney damage. To qualify for this treatment, patients must have IgAN and be at risk for disease progression. Filspari is also known by its drug name, sparsentan.

Filspari is an endothelin and angiotensin 2 receptor antagonist. It is thought to work by blocking specific pathways that contribute to kidney damage, helping to preserve kidney function in individuals with IgAN.

How do I take it?
Prescribing information states that Filspari is taken as an oral tablet. The treatment begins with a lower dose taken once daily, which is increased to a higher dose taken once daily after 14 days, as tolerated. People taking Filspari are advised to swallow the tablets whole with water before either the morning or evening meal. Filspari should be taken exactly as prescribed by a health care provider.

Side effects
Common side effects of Filspari include hyperkalemia (high potassium levels), hypotension (low blood pressure, including dizziness when standing), peripheral edema (swelling of the extremities), dizziness, anemia (low red blood cell count), and acute kidney injury.

Rare but serious side effects may include hepatotoxicity (liver damage or failure), embryo-fetal toxicity (risk of severe birth defects), and fluid retention, which can worsen heart or kidney conditions. Regular monitoring of liver function, kidney function, and potassium levels is required during treatment.

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Label: Filspari — Sparsentan Tablet, Film Coated — DailyMed