Kappa Opioid Receptor Agonist Drug Class List

Drugs in Drug Class: Kappa Opioid Receptor Agonist

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Vifor Intl	KORSUVA	difelikefalin acetate	SOLUTION;INTRAVENOUS	214916-001	Aug 23, 2021		RX	Yes	Yes	8,236,766
Vifor Intl	KORSUVA	difelikefalin acetate	SOLUTION;INTRAVENOUS	214916-001	Aug 23, 2021		RX	Yes	Yes	8,217,007
Vifor Intl	KORSUVA	difelikefalin acetate	SOLUTION;INTRAVENOUS	214916-001	Aug 23, 2021		RX	Yes	Yes	10,793,596		Y	Y
Vifor Intl	KORSUVA	difelikefalin acetate	SOLUTION;INTRAVENOUS	214916-001	Aug 23, 2021		RX	Yes	Yes	7,727,963		Y	Y
Vifor Intl	KORSUVA	difelikefalin acetate	SOLUTION;INTRAVENOUS	214916-001	Aug 23, 2021		RX	Yes	Yes	10,138,270
Vifor Intl	KORSUVA	difelikefalin acetate	SOLUTION;INTRAVENOUS	214916-001	Aug 23, 2021		RX	Yes	Yes	7,713,937		Y	Y
Vifor Intl	KORSUVA	difelikefalin acetate	SOLUTION;INTRAVENOUS	214916-001	Aug 23, 2021		RX	Yes	Yes	10,017,536			Y

Last updated: July 11, 2026

Kappa Opioid Receptor Agonist Drugs: Market Dynamics and Patent Landscape (Exclusivity, Litigation, and Generic/Biosimilar Risk)

Kappa opioid receptor agonists remain a small but heavily IP-dependent segment. Most in-market and late-stage programs trace to a limited set of chemotypes and target product profiles designed to separate analgesia and/or anti-pruritic activity from mu-opioid–mediated risks. Patent estates typically concentrate in (1) lead-scaffold composition of matter, (2) specific substitution patterns that define kappa potency and selectivity windows, and (3) formulation and dosing regimens that support commercial differentiation. Competitive risk comes less from rapid generic substitution and more from long tails of method-of-use and formulation patents combined with tight regulatory and clinical-enrollment barriers for new entrants.

This market is shaped by:

• Low addressable population for specific indications (for example, pruritus subtypes and pain subsets).
• Safety-driven differentiation versus mu agonists.
• Clinical endpoints that gate reimbursement (ITCH scales, neuropathic pain measures, opioid-sparing claims).
• Regulatory fragmentation (different indication approvals across jurisdictions and label-specific exclusivity).

A complete, accurate patent landscape cannot be produced without identifying the specific kappa receptor agonist drugs (brand/generic names), their FDA marketing applications, and their Orange Book and patent lists, because different members of the class have materially different expiration schedules and litigation histories.

Which kappa opioid receptor agonists are on the market and how do their patents drive competition?

Featured snippet answer: Competition is driven by each product’s specific Orange Book patent clusters (composition, method-of-use, formulation) and the presence or absence of Paragraph IV litigation for kappa agonists, rather than by a class-wide patent moat.

What matters most in kappa agonist patent estates?

1. Composition of matter (CoM) that covers the core scaffold
   • Typically defined by a specific kappa agonist chemical structure or narrow substitution range.
2. Selectivity and potency-defined analogs
   • Claims often focus on chemical variants that preserve kappa efficacy while reducing off-target binding.
3. Method-of-use claims tied to clinical endpoints/indications
   • Particularly common where efficacy is measured by pruritus scales or neuropathic pain outcomes.
4. Formulation and route claims
   • Oral extended release, transdermal delivery, intranasal formulations, and depot technologies can extend exclusivity beyond CoM.
5. Manufacturing/process claims
   • Less frequently decisive but relevant in litigation where generic synthesis design-arounds exist.

Which companies tend to hold the dominant IP positions in this class?

The class is characterized by fewer lead holders than typical small-molecule markets. Dominant positions usually track:

• originator pharmas and biotech licensees of kappa agonist chemotypes, and
• contract developers of platform synthesis and dosing technologies.

A class-level answer without drug identification would be incomplete.

When do kappa opioid receptor agonists lose exclusivity and patent protection?

Featured snippet answer: Exclusivity and patent loss timelines are drug-specific; the practical launch window is often governed by the last-to-expire formulation or method-of-use patent rather than the earliest composition-of-matter expiry.

Typical exclusivity stack for kappa agonists

• Patent CoM expiry (scaffold claims)
• Patent term adjustments and exclusivity extensions (where applicable)
• Method-of-use patents (indication labeling or dosing regimen)
• Formulation patents (release profile, excipients, device integration)
• Data exclusivity and marketing exclusivity depending on FDA approval pathway

How to model the “generic launch window” for kappa agonists

The window usually opens only after all three layers are cleared:

1. Regulatory: ANDA pathway availability (or 505(b)(2) for reformulations), plus label/indication fit.
2. Patent: last Orange Book-listed blocking patent for the intended label.
3. Litigation: Paragraph IV timing and potential settlements can push entry.

Class-level scheduling is not actionable without mapping the specific drugs.

What patents protect kappa opioid receptor agonists (composition, methods, formulations)?

Featured snippet answer: For kappa agonists, composition-of-matter patents dominate the estate, while method-of-use and formulation patents determine the remaining bottleneck after CoM expiry.

Composition-of-matter (CoM) claim patterns

Common patterns include:

• Claims that define the exact kappa agonist structure
• Dependent claims that narrow to specific ring substitutions and stereochemistry
• Coverage for salt forms, prodrugs, and isomeric variants

Method-of-use claim patterns

Method claims often appear as:

• Treatment of pruritus (including disease-context formulations)
• Treatment of neuropathic pain or defined chronic pain categories
• Treatment using defined dose ranges and titration schedules

Formulation and device claim patterns

Formulation patents cover:

• Extended-release oral constructs
• Depot or implantable systems (where used)
• Combination formulations with excipients engineered for release control

Which Orange Book patents and FDA exclusivities affect kappa opioid agonists?

Featured snippet answer: Orange Book status is the governing dataset for US generic entry risk; for kappa agonists, the critical set is the subset of listed patents tied to the intended strength/dosage form and labeled indication.

Orange Book risk model

For any specific kappa agonist product:

• Identify listed patents by type (drug substance, drug product, method of use)
• Link each to blocking vs non-blocking patent status relative to the applicant’s proposed ANDA label
• Assess if any patents are recently added via patent listing updates, which can alter timing

Class-level Orange Book analysis requires drug identification.

What Paragraph IV challenges and patent litigation have targeted kappa opioid receptor agonists?

Featured snippet answer: Litigation activity for kappa agonists is episodic and usually tied to specific products where patent life overlaps with a viable ANDA 505(b)(2) route.

How litigation changes market dynamics

• Sustained injunction risk can delay first generic entry.
• Settlement agreements often trade early entry for royalty, delayed launch date, or partial carve-outs to label.
• Design-around pressure can raise generic manufacturing costs if the key differentiator is formulation or stereochemistry.

A class-level answer would be speculative without naming the specific asserted patents and venues.

What settlement agreements govern generic entry risk for kappa opioid agonists?

Featured snippet answer: Settlements are typically structured around delayed launch dates and/or carve-outs to labeled indications rather than eliminating all patent exposure.

Common settlement structures

• Delayed entry until a specific patent expiry date
• Design-around constraints (for example, different salt form or different release technology)
• Limited label entry aligned to non-infringed claims
• Royalty or payment-for-delay arrangements (where permitted by law and evidence)

Settlement details are drug-specific.

How do biosimilar risks apply to kappa opioid receptor agonists?

Featured snippet answer: Biosimilar risk is largely irrelevant for most small-molecule kappa agonists because biosimilars apply to biologics, not small molecules.

When biosimilar risk could matter

• If the kappa program is a biologic (for example, engineered proteins that modulate kappa pathways) rather than a receptor agonist small molecule.
• If the product is a monoclonal antibody or other biologic modality that targets the kappa axis.

Without naming candidate drugs, a biosimilar assessment cannot be completed.

How does kappa opioid agonist IP compare with mu-opioid and delta-opioid agonists?

Featured snippet answer: Kappa agonist estates tend to be narrower in commercial volume but deeper in claim segmentation (selectivity, indication, dosing), while mu-opioid markets often have longer-standing generic pathways and larger realized generic penetration after major method patents fall.

Key comparison dimensions

• Market size: kappa programs can be indication-constrained; mu opioids are broader.
• IP depth: kappa estates often emphasize selectivity-driven analogs and label-specific use claims.
• Regulatory leverage: endpoint-linked dosing can preserve method claims post CoM expiry.

Which dosage forms and routes are most protected in kappa agonists?

Featured snippet answer: The most protected commercial differentiation usually aligns with the approved route and release profile.

Common protected commercial formats

• Oral immediate and extended-release
• Depot or parenteral formats where they exist
• Specialty delivery technologies (where they create a clinical advantage that supports labeling)

Drug-specific patent mapping is required to confirm exact coverage.

What generic entry risks exist for kappa opioid receptor agonists?

Featured snippet answer: Entry risks depend on whether the generic applicant can carve around (1) method-of-use claims tied to the label and (2) formulation patents tied to strength/dosage form, not just CoM expiry.

High-risk patent categories

• Method-of-use tied to approved indications
• Formulation tied to extended-release profiles or excipient systems
• Stereochemical and salt-form dependencies where courts treat them as infringement-defining

Where is commercial revenue exposure concentrated for kappa opioid agonists?

Featured snippet answer: Revenue exposure is typically concentrated in the smallest number of labeled indications that can support payer adoption, and in the product(s) with the cleanest IP pathway relative to the development pipeline.

Determinants of revenue durability

• Payer coverage for pruritus or chronic pain subgroups
• Patient adherence for dosing schedules
• Safety/tolerability profile that affects continuation rates
• Degree of label differentiation vs off-label alternatives

A precise revenue-exposure map needs identified products.

Key Takeaways

• Kappa opioid receptor agonist markets are IP-governed; generic entry is typically blocked by the latest Orange Book-listed patents in method-of-use and formulation categories.
• Competition is episodic and product-specific, with Paragraph IV challenges and settlements dictating real launch timing.
• Class-wide patent and exclusivity conclusions are not actionable without mapping each drug’s FDA listing and patent set.

FAQs

1. Which Orange Book patent types most often block ANDA entry for kappa opioid receptor agonists?
2. Do kappa opioid agonists face method-of-use patent barriers even after composition-of-matter expiry?
3. How do formulation patents (extended-release, depot, salts) affect design-arounds for generic kappa agonists?
4. What regulatory exclusivities (data exclusivity, marketing exclusivity) materially extend kappa agonist commercialization?
5. Are any kappa opioid receptor agonists biologic modalities with biosimilar pathways?

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References (APA)

No sources were cited because specific kappa opioid receptor agonist products, their FDA Orange Book entries, and litigation dockets were not provided.