RELENZA Drug Patent Profile

Which patents cover Relenza, and when can generic versions of Relenza launch?

Relenza is a drug marketed by Glaxosmithkline and is included in one NDA.

The generic ingredient in RELENZA is zanamivir. Two suppliers are listed for this compound. Additional details are available on the zanamivir profile page.

Summary for RELENZA

US Patents:	0
Applicants:	1
NDAs:	1
Finished Product Suppliers / Packagers:	2
Raw Ingredient (Bulk) Api Vendors:	73
Clinical Trials:	9
Patent Applications:	5,836
Drug Prices:	Drug price information for RELENZA
What excipients (inactive ingredients) are in RELENZA?	RELENZA excipients list
DailyMed Link:	RELENZA at DailyMed

See drug prices for RELENZA

Recent Clinical Trials for RELENZA

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
University of Oxford	Phase 2
Food and Health Bureau, Hong Kong	Phase 3
Chinese University of Hong Kong	Phase 3

See all RELENZA clinical trials

Pharmacology for RELENZA

Drug Class	Neuraminidase Inhibitor
Mechanism of Action	Neuraminidase Inhibitors

US Patents and Regulatory Information for RELENZA

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999		RX	Yes	Yes

Expired US Patents for RELENZA

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999	5,648,379
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999	4,627,432
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999	4,811,731

EU/EMA Drug Approvals for RELENZA

Company	Drugname	Inn	Product Number / Indication	Status	Generic	Biosimilar	Orphan	Marketing Authorisation	Marketing Refusal
GlaxoSmithKline Trading Services Limited	Dectova	Zanamivir	EMEA/H/C/004102Dectova is indicated for the treatment of complicated and potentially life-threatening influenza A or B virus infection in adult and paediatric patients (aged ≥6 months) when:The patient’s influenza virus is known or suspected to be resistant to anti-influenza medicinal products other than zanamivir, and/orOther anti-viral medicinal products for treatment of influenza, including inhaled zanamivir, are not suitable for the individual patient.Dectova should be used in accordance with official guidance.	Authorised	no	no	no	2019-04-26

International Patents for RELENZA

See the table below for patents covering RELENZA around the world.

Country	Patent Number	Title	Estimated Expiration
Austria	396333
Austria	A357683
Australia	1997783

Supplementary Protection Certificates for RELENZA

Patent Number	Supplementary Protection Certificate	SPC Country	SPC Expiration	SPC Description
0526543	C990030	Netherlands		PRODUCT NAME: ZANAMIVIRUM, DESGEWENST IN DE VORM VAN EEN FARMACEUTISCH AAN- VAARDBAAR ZOUT EN/OF VAN EEN FARMACEUTISCH AANVAARDBARE ESTER; NAT. REGISTRATION NO/DATE: RVG 24094 19990707; FIRST REGISTRATION: 14997 19990209
0526543	SPC/GB99/030	United Kingdom		PRODUCT NAME: ZANAMIVIR, OPTIONALLY IN THE FORM OF A PHARMACEUTICALLY ACCEPTABLE SALT OR DERIVATIVE; REGISTERED: SE 14997 19990209; UK PL10949/0327 19990625
0526543	990030	Netherlands		PRODUCT NAME: ZANAMIVIRUM, DESGEWENST IN DE VORM VAN EEN FARMACEUTISCH AAN- VAARDBAAR ZOUT EN/OF VAN EEN FARMACEUTISCH AANVAARDBARE ESTER; NATL. REGISTRATION NO/DATE: RVG 24094 19990707; FIRST REGISTRATION: SE 14997 19990209

Last updated: July 30, 2026

RELENZA market dynamics and financial trajectory (zanamivir) 2025 update

Executive summary: RELENZA (zanamivir) has transitioned from a core seasonal flu franchise to a lower-growth, niche influenza antiviral brand. The market is shaped by (1) heavy reliance on seasonal government and health-system purchasing, (2) competition from oseltamivir and newer influenza antivirals, and (3) diminishing payer and clinician preference as uptake has shifted toward orally dosed products. Financial trajectory trends are dominated by seasonal demand volatility and shrinking exclusivity-driven headroom in the US/major markets, with most future pricing power tied to contracting behavior and public-sector procurement cycles.

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How did RELENZA’s zanamivir sales evolve over time, and what drives the financial trajectory?

Short answer: RELENZA’s financial trajectory tracks seasonal influenza incidence, formulary position, and procurement channel mix (public vs private). It typically peaks in respiratory-virus-heavy winter periods and declines in off-season quarters, with additional sensitivity to substitution from oseltamivir and later-generation antivirals.

Key demand drivers

• Seasonality and severity of influenza seasons: Sales scale with the number of treated influenza patients and the willingness of health systems to pre-position antivirals.
• Guideline and clinician preference: Orally administered antivirals can be easier to prescribe and dispense at scale, shifting relative demand away from inhaled therapy.
• Public-sector procurement: Government stockpiling can smooth volumes but still creates lumpy quarter-to-quarter revenue.
• Substitution dynamics inside formularies: Once oseltamivir is secured, payer utilization management often limits inhaled alternatives unless specific subgroups or resistance patterns are cited.

Key financial mechanics

• Net price pressure: As patent/exclusivity headroom erodes and wholesalers carry competing stock, realized prices tend to compress versus list.
• Channel mix volatility: Sales booked through tenders, bulk hospital supply, and government contracts can materially alter gross-to-net ratios.
• Write-down risk in off-season inventory cycles: Distributor and customer destocking patterns can pull forward or postpone revenue recognition.

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What market dynamics shape the zanamivir inhaled influenza antiviral category?

Short answer: The category is dominated by seasonal demand, procurement-led volume swings, and competitive positioning versus cheaper or more convenient antivirals.

Competitive landscape structure

• Oseltamivir (oral): Usually the default first-line economic choice in many payers and health systems.
• Other influenza antivirals: Compete through administration route convenience, contracting terms, and clinician familiarity.
• Route-of-administration factor: RELENZA’s inhaled delivery adds friction for some settings, increasing the importance of device access, training, and patient selection.

Pricing and contracting patterns

• Seasonal contracting: Health systems frequently lock pricing before peak demand.
• Tender-based procurement: Public institutions buy by bid cycles, which can abruptly change market share.
• Payer formulary constraints: Managed care can narrow use to specific criteria even when clinicians are willing.

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When does RELENZA face exclusivity loss, and how does that affect revenue risk?

Short answer: RELENZA has already moved into the post-exclusivity era in most major markets, with revenue more exposed to generic/biosimilar-style substitution dynamics in general pharmacologic small-molecule antiviral categories and to increased procurement competition.

Exclusivity-to-revenue link

• Exclusivity expiration reduces pricing leverage: Lower pricing power typically follows as competitors enter or as buyers leverage switching.
• Channel inventory effects: Once competitive supply becomes routine, distribution networks optimize for lowest effective cost, shifting demand away from legacy brands.

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What patents protect RELENZA, and how does patent estate strength impact market position?

Short answer: The patent estate for zanamivir-based inhaled antiviral products has historically supported branded pricing and contracting strength. The current market posture is consistent with reduced exclusivity tailwinds and heightened competition.

Patent estate implications for market dynamics

• Formulation and device integration: Inhaled antivirals often have IP tied to formulation characteristics and delivery system specifics.
• Method-of-use and dosing regimens: Claims around dosing schedules and clinical use can delay certain substitution pathways.
• Process/mfg IP: Manufacturing know-how can create barriers to certain entrants even when core active ingredient competition expands.

(Note: No Orange Book patent-specific extraction is included here because the required drug listing and patent tables are not provided in the prompt.)

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What generic entry risks exist for RELENZA, and what would a generic launch scenario look like?

Short answer: The principal risk is substitution into inhaled zanamivir-equivalent supply channels through cheaper competing products and contract re-tendering, which can rapidly compress realized price even if total influenza antiviral demand stays stable.

Launch scenario mechanics

• Wholesaler shelf-share capture: Faster access through established distribution networks drives uptake.
• Tender recalibration: Health systems often re-bid quickly, particularly when there is a cost-reduction opportunity.
• Device and training barriers: Uptake can slow if competing products require different handling, but this often diminishes as hospitals standardize device protocols.

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How does RELENZA compare with oseltamivir and other influenza antivirals on adoption and contracting?

Short answer: Oseltamivir’s oral administration generally wins on convenience and operational simplicity. RELENZA can maintain use in settings where inhaled antivirals fit protocols, where specific patient factors support inhaled therapy, or where resistance or clinical pathway considerations favor it.

Comparison drivers by buyer type

• Hospitals: Prioritize administration workflow, drug availability, and procurement price.
• Clinics/urgent care: Prefer rapid prescribing and dispensing; oral regimens often dominate.
• Public health systems: Focus on contract value, stockpiling strategy, and administration capability.

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What is the Orange Book status of RELENZA, and how does it influence generic and Paragraph IV outcomes?

Short answer: Orange Book status is a direct input into generic timing and Paragraph IV strategy. The prompt does not include Orange Book listing identifiers or patent tables, so Orange Book status cannot be reliably stated here.

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Which companies compete against RELENZA in influenza antivirals, and how do their strategies affect RELENZA market share?

Short answer: Competitors generally win through lower effective cost, oral route preference, and contracting scale. Strategy differences show up in tender participation and formulary access rather than in claims of clinical superiority.

Competitive strategy patterns

• Low effective price via contracting: Re-tendering cycles can displace branded products.
• Manufacturing scale: Competitive supply reduces stock-out risk, which buyers value during peak weeks.
• Clinical pathway adoption: Formularies tighten usage, shaping relative demand.

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How are public-sector purchases and reimbursement policies changing RELENZA demand?

Short answer: Public-sector influenza antiviral demand is procurement-led. RELENZA’s volume sensitivity to tenders and stockpiling policies is high; shifts in contract specifications, device acceptance, or bundled purchasing can swing sales quickly.

Policy transmission channels

• Tender specifications: If procurement disqualifies certain routes or devices, brand demand falls even during severe seasons.
• Inventory management rules: Stock rotation schedules affect when inventory is purchased versus consumed.
• Reimbursement alignment: Even when clinical need exists, reimbursement rules can restrict inhaled antivirals to defined scenarios.

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What litigation or settlement activity affects RELENZA commercialization and entry timing?

Short answer: Patent litigation and settlements can affect launch timing and market share, but the prompt does not include any RELENZA-specific case list, docket numbers, or settlement terms. Without those data, litigation impact cannot be mapped.

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How does RELENZA’s financial performance vary by region, and what are the biggest geography-specific dynamics?

Short answer: Geography matters because procurement behavior, formulary design, and timing of exclusivity/patent events differ by country. Demand is generally stronger where inhaled antivirals are integrated into national or institutional influenza treatment protocols.

Regional demand patterns (framework)

• US: Contracting and managed care formularies can cap branded penetration post-exclusivity; seasonal volatility remains the biggest driver.
• EU/UK: Tender-based purchasing and national guideline adoption shape utilization; pricing pressure increases as alternatives consolidate.
• Other markets: Distribution capacity and health-system inventory policies can create episodic spikes around peak seasons.

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What is RELENZA’s revenue exposure profile under different influenza season scenarios?

Short answer: Revenue sensitivity is primarily driven by influenza incidence and health-system treatment intensity. Mild seasons reduce treated-case volume, while severe seasons can increase both usage and procurement stocking.

Scenario logic

• Mild season: Lower treated volume and slower inventory turnover reduce quarterly revenue; promotional/contracting adjustments may be needed to sustain share.
• Average season: Stable contracting flows dominate; market share depends on formulary positioning and device/protocol fit.
• Severe season: Emergency procurement and faster consumption can create revenue upside, but realized pricing may still compress if buyers switch to lower-cost competitors.

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Key Takeaways

• RELENZA’s market dynamics are dominated by seasonal influenza incidence, public-sector tender cycles, and substitution pressure from oral antivirals.
• Financial trajectory follows winter peak demand with quarterly volatility driven by procurement and inventory rotation.
• Post-exclusivity and contracting behavior shift the brand from exclusivity-led pricing toward effective-cost competition.
• Future revenue resilience depends on formulary/protocol fit for inhaled zanamivir and health-system device acceptance, not on category growth alone.
• Generic and patent-expiration risks primarily manifest through re-tendering, wholesaler shelf-share capture, and realized price compression rather than through demand collapse.

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FAQs

1. Why do inhaled influenza antivirals like RELENZA lose share to oral drugs during managed-care contracting?
2. How do public-sector influenza stockpiling policies change quarterly sales for antiviral brands like RELENZA?
3. What buyer criteria matter most for hospital tenders evaluating inhaled antivirals (device, usability, contract price)?
4. How does influenza resistance (neuraminidase inhibitor susceptibility) influence utilization of zanamivir products?
5. What factors determine whether a generic or competing inhaled zanamivir product captures shelf share in winter peaks?

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References

No sources were provided in the prompt, and no primary documents (FDA labels, Orange Book tables, annual reports, court dockets, or payer formularies) were included. Therefore, no citations can be accurately listed.

DrugChatter Q&A for RELENZA

Is relenza used as an inhaled powder?