Korsuva (difelikefalin acetate)

Frequently asked

Common questions about Korsuva's patent landscape

When will generics enter the market for Korsuva?

Nominal patent expiry shows the cliff window: Nov 10, 2026 (when the foundational composition patent expires) to Nov 11, 2027 (when the last US OB patent falls). In practice, generics typically enter mid-window via negotiated settlement — Hatch-Waxman settlements often produce delayed-entry agreements between the brand and the first ANDA filer, typically trading a 180-day exclusivity for an entry date months to years past the patent. Exact entry depends on patent challenges, design-around feasibility, and settlement negotiations.

What's the difference between "cliff opens" and "cliff closes"?

Cliff opens (Nov 10, 2026) marks Korsuva's foundational composition patent expiry — the earliest theoretical date for generic entry. Cliff closes (Nov 11, 2027) is when the last US patent in the thicket finally falls — after which the market has no patent-based barriers. The gap between these two dates is the lifecycle-extension window: secondary patents (formulations, methods of use, manufacturing) that can block generics even after the composition patent has expired.

Why is Korsuva in the Orange Book?

Korsuva is regulated via the FDA 505(b) NDA pathway for small-molecule drugs and listed in the FDA Orange Book (small molecules). Small-molecule NDA holders must list approved-use patents in the Orange Book under Hatch-Waxman. The patents shown here come directly from FDA Orange Book listings.

What's a patent family and why does it matter?

A patent family is a group of patent applications and grants worldwide that share the same priority filing (the earliest invention disclosure). One US patent often expands to 20–40+ filings across different jurisdictions — each grant in a different country protecting the same underlying invention. Korsuva has 4 families that resolve to 98 international documents across 27 countries. Families matter because generic entry requires clearing patent barriers in each market separately — a US generic launch is independent of EU or Japan launches.

How were these Korsuva patents identified?

Korsuva's 12 US patents come directly from the FDA Orange Book, which small-molecule NDA holders are required to list under Hatch-Waxman. We then expand each Orange Book patent to its full international family using the BigQuery patent family graph (priority date + global jurisdictions). The US patent list is FDA-authoritative.

What does the "Multiplier" stat mean?

The multiplier shows how many international patent documents exist for every US patent in Korsuva's thicket — calculated as 98 international documents ÷ 12 US patents = 8×. A high multiplier (>10×) indicates an aggressive global filing strategy — the sponsor has filed in many countries to maximize geographic protection. A low multiplier suggests the patent estate is US-centric, with limited international protection.