Filspari Generic Name & Formulations
Mechanism of Action
Sparsentan is an endothelin type A receptor (ETAR) and the angiotensin II type 1 receptor (AT1R) antagonist. Endothelin-1 and angiotensin II are thought to contribute to the pathogenesis of IgAN via the ETAR and AT1R, respectively.
To reduce proteinuria in adults with primary immunoglobulin A nephropathy (IgAN) at risk of rapid disease progression, generally a urine protein-to-creatinine ratio (UPCR) ≥1.5 g/g.
Filspari Dosage and Administration
Initiate treatment only after measuring ALT/AST levels and total bilirubin. Swallow whole with water prior to AM or PM meal. Take at the same time every day. 200mg once daily for 14 days, then increase to 400mg once daily as tolerated. When resuming after an interruption, consider dose titration starting at 200mg once daily. Dosage adjustment for AST/ALT elevations: see full labeling.
Pregnancy. Concomitant ARBs, ERAs, or aliskiren.
Filspari Boxed Warnings
Hepatotoxicity. Embryo-fetal toxicity.
Measure serum AST/ALT levels and total bilirubin prior to initiation, monthly for the first 12 months or restarting following an interruption due to elevated transaminases, then every 3 months during therapy. Interrupt therapy if AST/ALT levels are abnormal at any time; closely monitor those who develop AST/ALT elevations >3×ULN. Avoid initiation in patients with elevated AST/ALT (>3×ULN). Embryo-fetal toxicity. Advise males and females of reproductive potential to use effective contraception prior to initiation, during and for 1 month after treatment discontinuation. Pregnancy: exclude status prior to initiation, monthly during and for 1 month after treatment. Risk for hypotension; consider adjusting other antihypertensive medications or Filspari if develops. Monitor renal function, serum potassium periodically. Risk for acute renal injury (esp. those with renal artery stenosis, chronic kidney disease, severe CHF, volume depletion). Increased risk for hyperkalemia esp. those with advanced kidney disease or concomitant K+-increasing drugs. Heart failure. Fluid retention. Evaluate if significant fluid retention develops, may need to initiate or modify diuretic treatment, or consider modifying Filspari. Hepatic impairment: avoid. Nursing mothers: not recommended.
Median time to peak plasma concentration: ~3 hours (range, 2–8 hours).
Apparent volume of distribution: 61.4 L (at 400mg). Plasma protein bound: >99%.
Fecal (80%), renal 2%). Half-life: ~9.6 hours. Apparent clearance: 3.88 L/h at initial 400mg dose, then increases to 5.11 L/h.
Must discontinue any RAAS inhibitors, endothelin receptor antagonists, aliskiren prior to initiation. Potentiated by strong CYP3A inhibitors (eg, itraconazole); avoid; if unavoidable, interrupt Filspari. Concomitant moderate CYP3A inhibitors (eg, cyclosporine); monitor BP, serum potassium, edema, renal function regularly. Antagonized by strong CYP3A inducers (eg, rifampin), acid reducing agents (eg, H2 receptor antagonist, PPI); avoid. Separate Filspari dosing by 2hrs before or after use of antacids. Concomitant NSAIDs (including selective COX-2 inhibitors); monitor for worsening renal function or possibly kidney failure. May antagonize CYP2B6 (eg, bupropion), CYP2C9, CYP2C19 substrates; consider adjusting dose and monitor efficacy of substrates. May potentiate sensitive substrates of P-gp and BCRP; avoid. Risk for hyperkalemia when used with K+-sparing diuretics, K+ supplements, K+-containing salt substitutes; monitor serum K+ frequently.
Filspari Adverse Reactions
Peripheral edema, hypotension (including orthostatic hypotension), dizziness, hyperkalemia, anemia; hepatotoxicity, acute kidney injury.
Filspari Clinical Trials
Filspari Patient Counseling