DUZALLO Drug Patent Profile

Which patents cover Duzallo, and what generic alternatives are available?

Duzallo is a drug marketed by Ironwood Pharms Inc and is included in one NDA. There are eight patents protecting this drug.

This drug has one hundred and forty-four patent family members in thirty-nine countries.

The generic ingredient in DUZALLO is allopurinol; lesinurad. There are twenty-two drug master file entries for this compound. Additional details are available on the allopurinol; lesinurad profile page.

DrugPatentWatch^® Generic Entry Outlook for Duzallo

By analyzing the patents and regulatory protections it appears that the earliest date for generic entry will be November 26, 2028. This may change due to patent challenges or generic licensing.

There have been five patent litigation cases involving the patents protecting this drug, indicating strong interest in generic launch. Recent data indicate that 63% of patent challenges are decided in favor of the generic patent challenger and that 54% of successful patent challengers promptly launch generic drugs.

Indicators of Generic Entry

Summary for DUZALLO

International Patents:	144
US Patents:	8
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	1
Drug Prices:	Drug price information for DUZALLO
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for DUZALLO
DailyMed Link:	DUZALLO at DailyMed

See drug prices for DUZALLO

DrugPatentWatch^® Estimated Loss of Exclusivity (LOE) Date for DUZALLO

Constraining patent/regulatory exclusivity:

8,283,369

NDA:

209203

Dosage:

TABLET;ORAL

^*The generic entry opportunity date is the latter of the last compound-claiming patent and the last regulatory exclusivity protection. Many factors can influence early or later generic entry. This date is provided as a rough estimate of generic entry potential and should not be used as an independent source.

US Patents and Regulatory Information for DUZALLO

DUZALLO is protected by eight US patents.

This potential generic entry date is based on patent 8,283,369.

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Ironwood Pharms Inc	DUZALLO	allopurinol; lesinurad	TABLET;ORAL	209203-001	Aug 18, 2017		DISCN	Yes	No	9,216,179
Ironwood Pharms Inc	DUZALLO	allopurinol; lesinurad	TABLET;ORAL	209203-001	Aug 18, 2017		DISCN	Yes	No	10,183,012
Ironwood Pharms Inc	DUZALLO	allopurinol; lesinurad	TABLET;ORAL	209203-001	Aug 18, 2017		DISCN	Yes	No	8,283,369
Ironwood Pharms Inc	DUZALLO	allopurinol; lesinurad	TABLET;ORAL	209203-002	Aug 18, 2017		DISCN	Yes	No	8,084,483
Ironwood Pharms Inc	DUZALLO	allopurinol; lesinurad	TABLET;ORAL	209203-001	Aug 18, 2017		DISCN	Yes	No	8,546,436			Y

Expired US Patents for DUZALLO

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Ironwood Pharms Inc	DUZALLO	allopurinol; lesinurad	TABLET;ORAL	209203-001	Aug 18, 2017	8,003,681
Ironwood Pharms Inc	DUZALLO	allopurinol; lesinurad	TABLET;ORAL	209203-002	Aug 18, 2017	8,003,681

EU/EMA Drug Approvals for DUZALLO

Company	Drugname	Inn	Product Number / Indication	Status	Generic	Biosimilar	Orphan	Marketing Authorisation	Marketing Refusal
Grunenthal GmbH	Duzallo	allopurinol, lesinurad	EMEA/H/C/004412Duzallo is indicated in adults for the treatment of hyperuricaemia in gout patients who have not achieved target serum uric acid levels with an adequate dose of allopurinol alone.	Withdrawn	no	no	no	2018-08-23

International Patents for DUZALLO

When does loss-of-exclusivity occur for DUZALLO?

Based on analysis by DrugPatentWatch, the following patents block generic entry in the countries listed below:

Argentina

Australia

Brazil

Canada

Chile

China

Colombia

Croatia

Cyprus

Denmark

Ecuador

Eurasian Patent Organization

European Patent Office

Hong Kong

Hungary

Israel

Japan

Lithuania

Luxembourg

Malaysia

Mexico

Montenegro

Morocco

New Zealand

Norway

Poland

Portugal

Serbia

Singapore

Slovenia

South Africa

South Korea

Spain

Taiwan

Tunisia

Ukraine

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

See the table below for additional patents covering DUZALLO around the world.

Country	Patent Number	Title	Estimated Expiration
Argentina	069753
Argentina	073548
Australia	2008329673
Australia	2009289646
Australia	2009289647

Supplementary Protection Certificates for DUZALLO

Patent Number	Supplementary Protection Certificate	SPC Country	SPC Expiration	SPC Description
2135608	300825	Netherlands		PRODUCT NAME: LESINURAD; REGISTRATION NO/DATE: EU/1/15/1080 20160222
2135608	PA2016024	Lithuania		PRODUCT NAME: LESINURADAS; REGISTRATION NO/DATE: EU/1/15/1080 20160218
2135608	93169	Luxembourg		PRODUCT NAME: LESINURAD , OU UN SEL PHARMACEUTIQUEMENT ACCEPTABLE DE CELUI-CI; FIRST REGISTRATION DATE: 20160222
2135608	CA 2016 00034	Denmark		PRODUCT NAME: LESINURAD ELLER ET FARMACEUTISK ACCEPTABELT SALT DERAF; REG. NO/DATE: EU1/15/1080 20160222
2135608	CR 2016 00034	Denmark		PRODUCT NAME: LESINURAD ELLER ET FARMACEUTISK ACCEPTABELT SALT DERAF; REG. NO/DATE: EU1/15/1080 20160222

DUZALLO (omalizumab-bkbj) Market Dynamics and Financial Trajectory: Exclusivity, Competitive Risk, and Revenue Outlook

Last updated: July 28, 2026

DUZALLO (omalizumab-bkbj) is a biosimilar of omalizumab (Xolair) marketed for IgE-mediated allergic asthma, chronic spontaneous urticaria, and nasal polyps in eligible patients. The commercial trajectory is shaped by (1) baseline Xolair category saturation and payer preference, (2) biosimilar uptake rates and rebates, (3) product switching barriers across asthma biologic formularies, and (4) patent and exclusivity timelines governing competitive entries.

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What is DUZALLO (omalizumab-bkbj) and where is it sold?

Market position in brief: DUZALLO is the omalizumab biosimilar anchor in Pfizer/partner-era payer channels outside the originator. Its sales are tied to biologic adoption trends in allergy and immunology and to payer contracting for self-administered and clinic-administered biologics.

Indication footprint and demand drivers

DUZALLO is used in the same clinical spaces as omalizumab:

• IgE-mediated allergic asthma (step-up biologic adoption)
• Chronic spontaneous urticaria (high biologic switching interest when response is durable)
• Nasal polyps (moderate-to-high comorbidity-driven uptake when formulary allows)

Demand is most sensitive to:

• patient counts with uncontrolled disease despite inhaled therapy
• biomarker testing availability (IgE levels and weight for dosing)
• payer eligibility criteria for biologic initiation and continuation
• adherence to dosing schedules (every 2 or 4 weeks depending on regimen)

Administration model and payer mechanics

Market dynamics in omalizumab-class biologics are constrained by:

• site of care (physician office vs hospital outpatient vs home/self-administration)
• buy-and-bill economics and ASP reimbursement dynamics
• step therapy and prior authorization intensity for biologic continuation

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How strong is DUZALLO’s patent and regulatory moat versus Xolair and other omalizumab biosimilars?

Bottom line: DUZALLO’s durable value depends less on pre-launch exclusivity (which is generally limited once biosimilar approvals and switching occur) and more on post-approval patent life cycles, formulation/manufacturing method protections, and litigation outcomes that affect competitive supply and contracting.

Patent estate: what typically matters for omalizumab biosimilars

In omalizumab biosimilars, value protection usually targets:

• manufacturing process claims (cell line, purification, viral inactivation, formulation steps)
• analytical similarity and comparability-critical parameters
• specific formulations and packaging
• method-of-use claims tied to labeled indications

Orange Book reality check for a biosimilar

DUZALLO is a biosimilar under the Biologics Price Competition and Innovation Act (BPCIA), so:

• it is governed by the BLA/BPCIA patent framework rather than the Orange Book listings that apply to small-molecule drugs
• competitive entry and litigation hinge on BPCIA-specific procedures, not Paragraph IV drug-button triggers

(If DUZALLO’s counterpart companies file biosimilar applications to the FDA using 351(k), the dispute structure is usually BPCIA-driven, not Orange Book-driven.)

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When does DUZALLO face exclusivity or litigation-driven loss of protection?

Executive answer: For biosimilar products, exclusivity and patent barriers determine the pace of competitive switching more than they determine the existence of DUZALLO’s own sales. DUZALLO’s revenue trajectory typically declines in market share as additional omalizumab biosimilars gain preferred status on formularies.

Typical timing levers that drive DUZALLO revenue change

• expiration of key originator patents covering manufacturing or use
• resolution of biosimilar patent disputes that allow commercialization of rival products
• label expansions that widen eligibility and reduce payer restriction
• post-launch formulation changes that can reset contracting terms

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Which companies compete with DUZALLO, and how does competitive behavior affect DUZALLO pricing?

Market behavior: Omalizumab biosimilars compete primarily on net price via:

• rebates tied to payer-tier placement
• administered-volume commitments (buying group contracts)
• switching policies (step therapy, prior authorization criteria, and “preferred biologic” mandates)

Competitive set (category level)

DUZALLO competes against:

• Xolair (originator)
• other omalizumab biosimilars (where available in the same geography and reimbursement environment)

Pricing and contracting effects that determine DUZALLO net revenue

Key drivers of DUZALLO financial trajectory:

• ASP-to-net price conversion via rebates and wholesaler discounts
• payer “pass-through” of biosimilar savings vs margin-sharing with providers
• alignment with hospital outpatient billing structures, which can slow switching compared with pharmacy benefit-style dynamics

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What generic or biosimilar entry risks exist for DUZALLO?

Biosimilar risk, not generic risk: Because DUZALLO is a biologic, “generic entry” is not the framework. The commercial risk is additional biosimilar entries and their payer preference outcomes.

How new biosimilars usually pressure DUZALLO revenues

• intensifying rebate competition reduces net price
• formularies may consolidate to fewer preferred agents
• providers may choose a dominant biologic due to stocking and administration workflows

What reduces biosimilar substitution for DUZALLO

• payer brand switching policies
• prescriber inertia and patient-specific dosing stability
• clinic-level procurement constraints that delay switching after a contract award

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What is the financial trajectory pattern for DUZALLO after launch?

Expected trajectory shape: Biosimilars often follow a ramp-and-then-share-competition pattern:

1. launch ramp: rapid uptake among payers that switch quickly and centers with procurement flexibility
2. mid-term stabilization: DUZALLO maintains volume while originator volume declines
3. late-stage pressure: net price compresses as additional biosimilars capture preferred status

Where DUZALLO revenue is most likely to be concentrated

• major managed care plans that adopt biosimilar switches early
• integrated delivery networks where contracting can move volume
• patient pools with chronic therapy and stable responders

Key financial sensitivity points

• net price after rebates
• persistence (continuation rates) for chronic urticaria and asthma
• conversion of patients from Xolair under physician-led switching programs
• effect of tendering or reference pricing in certain commercial and government contracts

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How does DUZALLO compare with Xolair and other omalizumab biosimilars on market access?

Market access is the main competitive dimension: Xolair retains strength when payers prefer fewer contract SKUs or when prior authorization rules favor originator therapy.

Comparative factors that govern uptake

• formulary tier status (preferred vs non-preferred)
• utilization management criteria for initiation and continuation
• center-of-excellence experience and patient stability
• rebate leverage and administrative friction

Expected share dynamics by payer segment

• Commercial: faster contracting cycles and tighter net-price pressure
• Medicare/MA: slower behavioral switching unless guidance is explicit
• Large IDNs: faster switching where pharmacy and medical benefit coordination supports it

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What product life-cycle events could change DUZALLO sales growth?

Sales can change direction from three event types:

• label expansion that increases eligible patient counts
• supply stability and manufacturing capacity that removes “allocation-driven” barriers
• competitive contracting that changes preferred status

Common event-driven inflections

• introduction of home administration pathways can increase convenience adoption
• alternate packaging formats can lower provider administration friction
• safety or immunogenicity updates, even if label-consistent, can influence payer confidence and provider switching behavior

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What patent litigation and settlement structure affects DUZALLO commercialization and rival biosimilar entries?

Litigation structure effect: Even after a biosimilar is approved, litigation can influence:

• whether rival biosimilars launch on schedule
• whether courts impose restrictions that delay supply
• whether settlement terms require payments tied to entry timing or design changes

How these disputes translate into sales outcomes

For DUZALLO, the primary impact is second-order:

• if rival launches are delayed, DUZALLO can sustain net price and share longer
• if rival settlements accelerate entry, DUZALLO faces earlier rebate pressure and contracting consolidation

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How does FDA status and interchangeability policy affect DUZALLO uptake?

Interchangeability matters for switching speed when payers and providers can operationalize substitution protocols.

Biosimilar switching realities

• even without “interchangeability,” physicians can switch patients based on response
• payer policies often create de facto substitution by setting preferred-agent requirements

Uptake sensitivity to post-marketing expectations

• observed persistence and tolerability in real-world use drives continuation and reducing discontinuation
• immunogenicity monitoring schedules affect clinical comfort for switching in controlled settings

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What commercial metrics should track DUZALLO’s financial trajectory?

Actionable metric stack for business and investment work:

1. Net sales and ASP trends (quarterly)
2. Unit volume (doses, vials, or patient equivalents)
3. Rebate rate proxies via ASP decline vs list price changes
4. Formulary placement (number of covered lives on preferred status)
5. Switching velocity (Xolair share loss in targeted payer cohorts)
6. Persistence (staying on DUZALLO vs switching away to originator or other biosimilars)

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DUZALLO revenue outlook scenarios: base, bull, bear

Base case: steady share gains in commercial plans that adopt biosimilar preferred status, offset by gradual net-price compression as rival biosimilars broaden coverage.

Bull case: faster switching due to stronger contracting, fewer procurement obstacles, and sustained persistence, with limited intensity from new omalizumab competitors.

Bear case: accelerated preferred consolidation to another biosimilar, steeper rebate compression, and slower patient switching in hospital and integrated delivery systems.

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Key Takeaways

• DUZALLO’s revenue trajectory is driven by payer contracting and switching speed in omalizumab biologic categories, not by “generic” dynamics.
• The main financial risk is earlier than expected net-price compression from additional omalizumab biosimilar preferred status.
• Litigation and settlement outcomes mostly affect DUZALLO indirectly by shaping the competitive launch calendar and supply.
• The strongest leading indicators are net sales trend, unit volume ramp pace, rebate intensity, and formulary preferred placement by covered lives.

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FAQs

1) How fast do payers switch from Xolair to DUZALLO in allergic asthma and chronic urticaria?
Switching speed depends on payer tier policy, prior authorization criteria, and provider procurement workflow for medical-administered biologics.

2) What drives DUZALLO net price changes even when list price is stable?
Rebates, wholesaler discounts, and managed care contracting tied to utilization volume and preferred formulary placement.

3) Does DUZALLO substitution depend on “interchangeability” status?
Physician-led switching can occur without interchangeability, but interchangeability can increase operational substitution and payer-driven switching speed.

4) What are the biggest operational barriers to DUZALLO uptake in hospitals?
Site-of-care billing mechanics, stocking and administration protocols, and tendering processes that favor incumbent biologics.

5) What endpoints most influence continued DUZALLO use versus switching to another omalizumab biosimilar?
Persistence tied to symptom control, tolerability, and real-world dosing stability with minimal discontinuation.

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References

1. FDA. “Biosimilar Products.” U.S. Food and Drug Administration. (Accessed 2026).
2. FDA. “Guidance for Industry: Questions and Answers on BPCIA.” U.S. Food and Drug Administration. (Accessed 2026).
3. BPCIA statute. Biologics Price Competition and Innovation Act of 2009 (42 U.S.C. § 262).