FDA Approves MannKind's 10-Second Heart-Failure Autoinjector

FDA has approved a second delivery mechanism for MannKind's furosemide franchise, and this one is built around speed. The FUROSCIX ReadyFlow Autoinjector delivers a full 80 mg/mL subcutaneous dose of furosemide — the loop diuretic used to clear fluid overload — in under 10 seconds. The existing FUROSCIX on-body infusor delivers the same drug over roughly five hours. MannKind announced the approval on 24 July 2026, two days ahead of the supplemental application's 26 July PDUFA target action date.

One drug, a second delivery constituent

FUROSCIX is furosemide — a loop diuretic already familiar in its intravenous and oral forms — reformulated for subcutaneous delivery. The on-body infusor, FDA-approved for adults with CHF-associated edema in 2022 and extended to chronic kidney disease in 2025, wears on the body and infuses over hours, letting a patient avoid an emergency-department visit for routine fluid overload. The ReadyFlow Autoinjector is a second delivery constituent for the same active ingredient and the same core indication, reviewed and approved through a supplemental filing rather than a new drug application, because the underlying drug substance and indication were already established.

What the data showed

MannKind said the pivotal pharmacokinetic study met its primary endpoint: furosemide delivered via the ReadyFlow Autoinjector showed 107.3% bioavailability (90% CI: 103.9–110.8) relative to the existing reference product — a result inside the standard bioequivalence window, supporting the autoinjector as a substitutable delivery route for the same dose rather than a distinct new therapy requiring its own efficacy trial. That is the regulatory logic a supplemental application depends on: change the delivery constituent, hold the drug substance and clinical rationale constant, and let comparative pharmacokinetics carry the review.

Why the delivery time matters operationally

• Time in the chair: the on-body infusor requires roughly five hours of wear; the autoinjector delivers the same dose in under 10 seconds, changing where and how a patient can be treated for a fluid-overload episode.
• Site of care: a faster subcutaneous option widens the settings where treatment can plausibly happen — a clinic visit or at home — instead of requiring the wear time the infusor demands.
• Franchise context: the on-body infusor's indication already extends to pediatric patients weighing 43 kg or more, alongside the adult CHF/CKD population the autoinjector newly serves.
• Company statement: MannKind CEO Michael Castagna said the autoinjector “marks a key milestone in expanding patient options and improving care,” adding that delivering treatment in under 10 seconds “has the potential to transform how adults with chronic heart failure or chronic kidney disease manage episodes of fluid buildup — providing faster relief, reducing hospital admissions, and lowering overall healthcare costs.”

For sponsors developing their own drug-device combinations, the approval is a data point on a familiar question: how much clinical evidence a delivery-device change requires when the drug substance and indication do not move. Here, a comparative pharmacokinetic study — not a new efficacy trial — was the load-bearing evidence, and FDA cleared the supplemental application inside its ordinary review clock, finishing two days early rather than needing extra time.