Plasma Kallikrein Inhibitor international drug patents, generic suppliers and generics

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Biocryst	ORLADEYO	berotralstat dihydrochloride	CAPSULE;ORAL	214094-001	Dec 3, 2020		RX	Yes	No	⤷ Start Trial	⤷ Start Trial			Y	⤷ Start Trial
Biocryst	ORLADEYO	berotralstat dihydrochloride	CAPSULE;ORAL	214094-001	Dec 3, 2020		RX	Yes	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Biocryst	ORLADEYO	berotralstat dihydrochloride	CAPSULE;ORAL	214094-002	Dec 3, 2020		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial			Y	⤷ Start Trial
Biocryst	ORLADEYO	berotralstat dihydrochloride	PELLETS;ORAL	219776-001	Dec 11, 2025		RX	Yes	No	⤷ Start Trial	⤷ Start Trial			Y	⤷ Start Trial
Biocryst	ORLADEYO	berotralstat dihydrochloride	PELLETS;ORAL	219776-002	Dec 11, 2025		RX	Yes	No	⤷ Start Trial	⤷ Start Trial			Y	⤷ Start Trial
Biocryst	ORLADEYO	berotralstat dihydrochloride	PELLETS;ORAL	219776-003	Dec 11, 2025		RX	Yes	No	⤷ Start Trial	⤷ Start Trial			Y	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

Last updated: July 18, 2026

Executive summary

The plasma kallikrein inhibitor class is commercially led by ecallantide (KALBITOR) for hereditary angioedema (HAE).
The near-term market dynamics are shaped by: (1) limited current entrants for plasma kallikrein inhibition, (2) uptake of competing HAE modalities (C1 inhibitor products, bradykinin B2 antagonists, and kallikrein-active small molecules where applicable), and (3) expiring or already-expired patent and exclusivity rights around older biologics.
The patent estate risk profile is driven by formulation/manufacturing process patents, method-of-use claims, and biologic-specific exclusivities rather than a broad set of late-stage “new uses,” because the core mechanism is already established.

Scope note (class definition used for analysis): “Plasma kallikrein inhibitor” below centers on targeting plasma kallikrein (KLK) in HAE via kallikrein antagonism (most directly: ecallantide). The analysis emphasizes the patent and regulatory status of the class’s established FDA-marketed product.

Which plasma kallikrein inhibitor drugs are on the market for hereditary angioedema?

Featured snippet answer: Ecallantide (KALBITOR) is the principal FDA-marketed plasma kallikrein inhibitor for hereditary angioedema in the US.

Ecallantide (KLK inhibitor) commercial role

Indication: acute attacks of HAE in patients 16 years and older (US labeling has historically included age restrictions; check current label for exact wording).
Mechanism: recombinant protein that inhibits plasma kallikrein activity, reducing bradykinin generation downstream.
Competitive position: faces pressure from other HAE classes with broader home use and/or less specialized administration patterns (class examples include C1 esterase inhibitor therapies and bradykinin pathway agents).

Market dynamics: what matters for payer and provider adoption

Administration and setting: injectable biologics often drive channel constraints (infusion center, clinic, inpatient vs outpatient readiness).
Rapid-onset efficacy expectations for acute attacks: acute therapy choice depends on onset, historical response rates, and site readiness.
Safety and REMS-style constraints where applicable: biologics with special handling or anaphylaxis risk can affect formulary decisions.
Cost and rebate dynamics: HAE market pricing is negotiated with limited competitors, so shifts in patent status can rapidly change payer behavior.

What patents protect ecallantide (KALBITOR) and the plasma kallikrein inhibition mechanism?

Featured snippet answer: Protection typically clusters around (1) protein composition/sequence, (2) formulation and delivery, (3) manufacturing process, and (4) method-of-use for HAE.

Patent clusters that usually control freedom-to-operate for plasma kallikrein inhibitors

Because ecallantide is a protein biologic, the defensible IP landscape usually splits into:

1) Composition and biologic identity patents

Protein sequence and variants (if any).
Active protein definition and stereochemical or structural constraints.
Critical epitopes and binding interface characterization.

2) Formulation and delivery patents

Stabilizers and excipients designed for cold-chain stability.
Container closure system requirements.
Lyophilized vs liquid presentation and reconstitution processes (where relevant).

3) Manufacturing process patents

Cell line engineering and upstream fermentation controls.
Purification steps and viral inactivation parameters.
Aggregation control, filtration, chromatography parameters.
Characterization methods used to define acceptable product quality.

4) Method-of-use and administration patents

Dosing regimens.
Patient subpopulations and attack timing (e.g., onset-to-treatment windows).
Settings for administration (clinic/hospital) and procedural steps.

How to interpret patent estate strength for biologics in this class

For a protein biologic, “generic” is not the relevant competitor; the later-stage competitive risk is typically follow-on biologics and/or new biologic products with different manufacturing strategies, plus alternative drug classes for HAE.

When do ecallantide patents and FDA exclusivities expire in the US?

Featured snippet answer: For biologics, the practical exclusivity timeline is determined by patent expiry plus any remaining biologics exclusivity (12 years for approval pathway exclusivity after the first licensure reference product), then follow-on application and patent challenges as applicable.

Key exclusivity constructs that govern timing

Biologics exclusivity: the baseline regulatory exclusivity for a reference biologic.
Orange Book listed patents (where applicable): these can create bottlenecks for follow-on entrants depending on listing status and the nature of claims.
Patent term adjustments and patent-specific extensions: can move the effective “last date” later than filing dates suggest.

What drives entry timing even after expiration

Even with patent expiry, real entry timing depends on:

Manufacturing scale-up and validated analytical methods for biologic comparability.
Ability to meet post-approval comparability requirements for follow-on biologics.
Labeling and clinical bridging strategies that reduce clinical development cost.

What is the Orange Book status of plasma kallikrein inhibitors like ecallantide?

Featured snippet answer: Ecallantide is a biologic, so the US patent listing is typically reflected through FDA systems for biologics-related patent transparency rather than a classic small-molecule Orange Book pattern.

How to read FDA listing signals for this class

Look for:
- Product-specific patents listed against the biologic license.
- Purportedly “use” patents (dosing/indication) that can deter later entrants.
- Formulation/manufacturing patents that are not “method-of-treatment” but can still block.

Where litigation usually concentrates

For biologics, disputes concentrate on:
- Whether an entrant’s product infringes under claim construction.
- Whether listed patents are properly relevant to the approved product.
- Validity defenses tied to obviousness, anticipation, and written description.

(For a litigation-ready analysis, a complete patent list with numbers and expiration dates is required. That list is not included in the input here, so detailed patent-by-patent expiry sequencing is not produced.)

How strong is the patent estate for plasma kallikrein inhibition drugs like ecallantide?

Featured snippet answer: Strength tends to be moderate-to-strong when the estate includes manufacturing and formulation controls, but it can weaken if the portfolio is concentrated in early composition claims that have already expired.

Patent strength drivers specific to protein kallikrein inhibitors

Manufacturing process dependence: entrants must demonstrate non-infringement or license rights for process-linked claims.
Formulation specificity: even if the active protein is known, stabilization and container closure combinations can remain protected.
Method-of-use breadth: if method claims are narrow, design-around may be possible via label differences.
Claim scope and claim construction outcomes: biologics cases often hinge on infringement under functional and structural claim language.

Competitive implication for R&D

If the remaining estate is formulation and manufacturing, “same active, different process” strategies may still face infringement risk.
If the estate is method-of-use and attack timing, clinical and label strategy can reduce exposure by shifting usage.

Which companies are developing or challenging plasma kallikrein inhibitors for HAE?

Featured snippet answer: Competitive pressure is primarily indirect from other HAE classes, while direct follow-on biologics competition depends on the specific reference product’s estate and regulatory pathway.

Common competitive categories that affect market share

C1 esterase inhibitor replacement therapies (plasma-derived and recombinant).
Bradykinin B2 receptor antagonists for acute attacks (oral and injectable products compete on convenience and speed).
Newer mechanisms targeting upstream steps in bradykinin generation pathways.

Why entrants may avoid direct “kallikrein-only” differentiation

The market is already segmenting by:
- Route of administration.
- Home treatment feasibility.
- Safety profile and payer preference.
If a competitor can offer a less constrained administration profile, it can win formulary share even if efficacy is comparable.

What patent litigation affects ecallantide or plasma kallikrein inhibitor development?

Featured snippet answer: Patent litigation risk is concentrated in disputes over infringement and validity of protein-related formulation/manufacturing and method claims.

Typical litigation themes in this class

Claim construction for biologic process and formulation patents.
Non-infringement based on manufacturing step differences.
Validity challenges under anticipation and obviousness.
Settlement agreements that often include:
- Launch date covenants.
- Royalty or license payments.
- Confidential “carve-outs” for new indications or formulations.

(Complete, accurate case listings with docket numbers and settlement terms require docket-level and FDA listing mapping not provided in the input; no case table is produced.)

Do generic or biosimilar versions exist, and what generic entry risks exist for plasma kallikrein inhibitors?

Featured snippet answer: For ecallantide-like biologics, the relevant entry risk is follow-on biologics, not generic substitution.

Generic vs biosimilar reality for this class

Small-molecule generic frameworks do not apply because the active is a biologic protein.
Follow-on biologic pathways require:
- Demonstrated similarity in analytical, functional, and clinical measures.
- Managed IP risk around listed patents.

Practical entry barriers

Patent barriers: listed patents and remaining exclusivity.
Technical barriers: manufacturing control to avoid aggregation and maintain functional inhibition.
Clinical barriers: label and bridging data requirements.

How does plasma kallikrein inhibition compare with competing HAE therapies in market uptake and IP risk?

Featured snippet answer: Alternative HAE mechanisms often compete on administration convenience and home-use readiness; IP risk for plasma kallikrein inhibitors is mostly tied to biologic-specific product and process claims.

Comparative adoption drivers

Acute treatment time-to-effect.
Route feasibility and site requirements.
Payer preference based on total cost of care and patient setting.
Safety handling and patient training burden.

IP and lifecycle differences across HAE modalities

Small molecule bradykinin-pathway agents can face generic substitution timelines that move faster than biologics.
Biologics often extend market duration through:
- Product-specific exclusivity.
- Formulation/manufacturing and process-dependent patents.
- Expansion patents where permitted.

What formulations are protected for plasma kallikrein inhibitors like ecallantide?

Featured snippet answer: Formulation protection typically covers excipient composition, concentration ranges, stabilization strategy, and container closure/handling parameters.

Formulation patent categories to expect

Stabilizing agents and pH buffers.
Surfactants to reduce surface adsorption and aggregation.
Osmolality control.
Packaging-related patents that define closure system constraints and shelf-life.

How formulation patents affect competitive strategy

Follow-on products must prove equivalence in stability profiles.
Design-around is possible only if claims are narrow and the entrant’s formulation avoids literal infringement.
If claims are functional and broad, reliance on process differences can still trigger infringement risk.

What method-of-use patents for plasma kallikrein inhibitors could deter entry?

Featured snippet answer: Method-of-use claims can deter entry when they cover dosing schedules, patient subgroups, or attack-onset treatment windows.

How method-of-use differs from formulation risk

Method patents can be navigated by:
- Different dosing.
- Different timing recommendations.
- Different labeled indications or physician guidance.
If claims are broad and tied to the approved labeling language, entry timelines can extend through settlement.

What is the regulatory pathway for follow-on biological entrants in this class?

Featured snippet answer: Follow-on entrants for biologics in the US generally use biosimilar pathways (if reference product is eligible), with patent listing and challenge frameworks that can delay commercialization.

Regulatory timing mechanics that matter for IP execution

Filing of abbreviated biosimilar applications can be timed to trigger patent challenge timelines.
Launch depends on:
- Remaining patent protections that are not carved out by settlement.
- Exclusivity that is still active.
- FDA approval timing.

Key Takeaways

Ecallantide is the primary marketed plasma kallikrein inhibitor in HAE, and its commercial outlook is shaped by biologic-specific IP and regulatory timing rather than generic substitution.
Patent estates for biologic kallikrein inhibitors typically concentrate in protein identity, formulation stability, and manufacturing process controls, which are harder for follow-on entrants to design around than simple indication-only claims.
Competitive dynamics are dominated by other HAE modalities competing on administration convenience and safety handling; direct follow-on biologic competition hinges on remaining listed patents and biologics exclusivity windows.
Entry risk is best framed as follow-on biologic launch delay rather than generic entry, with litigation and settlements usually determining the actual commercialization date.

FAQs

1) What are the main remaining patent risk areas for follow-on products targeting plasma kallikrein in HAE?
Formulation stability, manufacturing/process controls, and method-of-use language tied to dosing and onset timing.

2) Does expiration of biologics exclusivity automatically allow biosimilar entry for plasma kallikrein inhibitors?
No. Launch is constrained by remaining patents listed against the reference product and any stay or settlement obligations.

3) Can a competitor avoid patent infringement for a kallikrein inhibitor by using a different formulation?
Only if formulation claims are narrow and the competitor’s excipient and stability strategy falls outside literal and functional infringement under claim construction.

4) Which HAE therapy classes most directly erode market share of plasma kallikrein inhibitors?
C1 esterase inhibitor replacements and bradykinin-pathway agents, depending on payer coverage and administration convenience.

5) How do settlement agreements typically affect biosimilar timing in this therapeutic area?
They often create launch covenants tied to patent expiry calendars and can include royalty or license arrangements.

References

No citations are provided because the input does not include FDA labels, Orange Book/biosimilar listing exports, patent numbers, docket-level litigation records, or company portfolio sources needed to produce an evidence-backed, patent-specific landscape.