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. One supplier is 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:	1
Raw Ingredient (Bulk) Api Vendors:	73
Clinical Trials:	9
Patent Applications:	5,124
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
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999
Glaxosmithkline	RELENZA	zanamivir	POWDER;INHALATION	021036-001	Jul 26, 1999

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
South Korea	840006441
Japan	S5988158	APPARATUS FOR DOSING DRUG TO PATIENT AND PACK USED THEREFOR
Romania	114792
Hungary	9203180
Hungary	221971	Kristályos N-acetil-neuraminsav-származékok, ezeket tartalmazó gyógyszerkészítmények és eljárások a kristályok előállítására (CRYSTALLINE N-ACETYL NEURAMINIC ACID DERIVATIVES PHARMACEUTICAL COMPNS. CONTG. THEM AND PROCESSES FOR THE CRISTALS PREPARATION)
Canada	2291994	DERIVES ET ANALOGUES DE L'ACIDE 2-DESOXY-2,3-DIDESHYDRO-N-ACETYLNEURAMINIQUE; LEUR UTILISATION COMME AGENTS ANTIVIRAUX (DERIVATIVES AND ANALOGUES OF 2-DEOXY-2,3-DIDEHYDRO-N-ACETYL NEURAMINIC ACID AND THEIR USE AS ANTIVIRAL AGENTS)
Poland	186384

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	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
0526543	34/1999	Austria		PRODUCT NAME: ''ZANAMIVIR'' GEGEBENENFALLS IN FORM EINES PHARMAZEUTISCH ANNEHMBAREN SALZES ODER DERIVATS; NAT. REGISTRATION NO/DATE: 1-23120 19990702; FIRST REGISTRATION: SE 14997 19990209
0208846	99C0032	Belgium		PRODUCT NAME: ZANAMIVIR; NAT. REGISTRATION NO/DATE: NL 24 551 19990726; FIRST REGISTRATION: SE - 14 997 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	99C0042	Belgium		PRODUCT NAME: ZANAMIVIR; NAT. REGISTRATION NO/DATE: 725 IS 380 F 11 19990906; FIRST REGISTRATION: SE 14997 19990209

Market Dynamics and Financial Trajectory for RELENZA

Last updated: July 29, 2025

Introduction

RELENZA (zanamivir) is aneurally administered neuraminidase inhibitor developed for the treatment and prophylaxis of influenza. Since its approval by the U.S. Food and Drug Administration (FDA) in 1999, RELENZA has played a notable role in influenza management. This analysis examines the current market dynamics affecting RELENZA and projects its financial trajectory amidst evolving healthcare landscapes, competitive pressures, and regulatory considerations.

Market Landscape and Key Drivers

Influenza Epidemiology and Treatment Demand

Influenza remains a persistent global public health challenge, with seasonal epidemics causing significant morbidity and mortality. According to the World Health Organization (WHO), annual influenza epidemics result in approximately 3 to 5 million severe cases and up to 650,000 respiratory deaths globally [1]. The demand for antiviral drugs like RELENZA correlates directly with influenza prevalence, especially during peak seasons.

Therapeutic Profile and Competitive Positioning

RELENZA, administered via inhalation, offers rapid symptom alleviation when given early in infection. Its mechanism targets viral neuraminidase, inhibiting viral replication. However, the emergence of oral neuraminidase inhibitors like oseltamivir (Tamiflu) and newer antivirals such as baloxavir marboxil (Xofluza) has intensified competition.

Advantages of RELENZA:

• Reduced systemic side effects owing to localized delivery
• Efficacy in both treatment and prophylaxis

Limitations:

• Inhalation delivery complicates administration, requiring patient education
• Limited data on efficacy against resistant strains [2]

Given these factors, RELENZA's market share appears constrained relative to oral antivirals, especially in outpatient settings.

Regulatory Environment

The regulatory landscape influences market access and profitability. Recent regulatory developments, including emergency use authorizations during influenza pandemics and coronavirus outbreaks, occasionally expand or restrict antiviral indications. Although RELENZA has maintained its approval, antimicrobial stewardship initiatives and resistance monitoring could impact its future use.

Manufacturing and Supply Chain Considerations

Global production capacity and supply chain resilience are critical. Influenza antivirals face manufacturing constraints during pandemic surges, as observed during the H1N1 outbreak in 2009 and COVID-19. Ensuring steady supply influences revenue stability.

Market Dynamics Shaping RELENZA's Financial Trajectory

Patent Status and Lifecycle

Relenzal retains method-of-use patents in various jurisdictions, with some expirations approaching. Patent cliffs typically lead to generic entry, reducing prices and market share.

Pricing Strategies and Reimbursement

Pricing is contingent on healthcare systems' reimbursement policies. In the United States, antiviral coverage varies, but government programs like Medicare and Medicaid influence distribution channels. Market penetration depends on negotiated pricing and formulary inclusion.

Pipeline Developments and Future Innovations

Research into novel delivery mechanisms (such as dry powder inhalers) and combination therapies could influence RELENZA's relevance. Additionally, development of resistance strains necessitates continuous innovation and surveillance.

Impact of Pandemics and Outbreaks

Pandemic scenarios elevate demand for effective antivirals. RELENZA’s inhaled form might face challenges during such events due to infection control concerns. Conversely, heightened awareness and stockpiling can temporarily boost sales.

Competitive Landscape

Major competitors include:

• Oseltamivir (Tamiflu, Roche/Genentech)
• Zanamivir (RELENZA, GlaxoSmithKline)
• Baloxavir marboxil (Xofluza, Shionogi/AbbVie)

Emerging agents targeting different viral mechanisms or longer-acting formulations threaten RELENZA’s market position. Market entrants with easier administration routes and broader efficacy profiles might displace RELENZA in certain segments.

Financial Trajectory Projections

Revenue Prospects

Projections for RELENZA’s revenue suggest a gradual decline over the next five years, driven by patent expirations, competitive pressures, and evolving treatment guidelines. Several industry analysts estimate that sales could decrease by 10-15% annually post-patent expiry, barring new approvals or significant pandemic-driven demand.

However, during influenza outbreaks or pandemics, short-term revenue spikes could occur, contingent on stockpiling and emergency use authorizations. The ability to capitalize on such events depends heavily on manufacturing agility and regulatory agility.

Market Penetration Strategies

To sustain revenues, manufacturers may pursue strategies such as:

• Diversifying indications, including prophylactic applications for high-risk populations
• Partnering with public health agencies for stockpiling contracts
• Developing novel formulations that improve administration convenience

Cost Management and Profitability

Relenza’s production costs are relatively stable, but margins are under pressure as generic competitors emerge. Companies must optimize manufacturing efficiencies and negotiate favorable reimbursement terms to maintain profitability.

Long-Term Outlook

In the long term, RELENZA’s market share is predicted to diminish unless offset by clinical innovations or strategic positioning in pandemic preparedness. Firms focusing on personalized antivirals or combination therapies could influence the competitive landscape, emphasizing the need for continued R&D investment.

Implication of Regulatory and Market Trends for Stakeholders

Stakeholders, including pharmaceutical companies, healthcare providers, and investors, should remain vigilant to:

• Patent expirations and impending generic entrants
• Regulatory shifts favoring new antiviral agents
• Emerging resistance patterns necessitating new drug development
• Public health policies prioritizing mass vaccination over antiviral stockpiling

Collaboration between industry and health agencies can facilitate the development of next-generation antivirals or delivery mechanisms, securing future revenue streams.

Key Takeaways

• RELENZA maintains a niche position in influenza management, primarily used where inhalation delivery is preferred.
• The competitive landscape increasingly favors oral antivirals with ease of administration and broader efficacy profiles.
• Patent expirations and rising generic competition will likely lead to revenue erosion over time.
• Pandemic scenarios and public health initiatives may offer short-term revenue opportunities but are unpredictable in the long term.
• Strategic innovation, including novel formulations and indications, is essential for sustained financial performance.

Conclusion

The future financial trajectory of RELENZA hinges on a complex interplay of epidemiological trends, regulatory policies, competitive dynamics, and technological innovation. While current market conditions suggest gradual revenue decline amid intensifying competition, targeted strategic efforts can prolong its relevance. Stakeholders must adopt a forward-looking approach, emphasizing diversification, pipeline development, and collaborations to navigate an evolving influenza antiviral market.

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Sources:

[1] World Health Organization. Influenza (Seasonal). 2022.
[2] Centers for Disease Control and Prevention. Antiviral Drugs for Seasonal Influenza. 2021.