ZYFLO Drug Patent Profile

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

Zyflo is a drug marketed by Chiesi and is included in two NDAs.

The generic ingredient in ZYFLO is zileuton. There are eight drug master file entries for this compound. Six suppliers are listed for this compound. Additional details are available on the zileuton profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Zyflo

A generic version of ZYFLO was approved as zileuton by RISING on March 17^th, 2017.

Summary for ZYFLO

US Patents:	0
Applicants:	1
NDAs:	2
Finished Product Suppliers / Packagers:	1
Raw Ingredient (Bulk) Api Vendors:	130
Drug Prices:	Drug price information for ZYFLO
What excipients (inactive ingredients) are in ZYFLO?	ZYFLO excipients list
DailyMed Link:	ZYFLO at DailyMed

See drug prices for ZYFLO

Pharmacology for ZYFLO

Drug Class	5-Lipoxygenase Inhibitor
Mechanism of Action	5-Lipoxygenase Inhibitors
Physiological Effect	Decreased Leukotriene Production

US Patents and Regulatory Information for ZYFLO

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Chiesi	ZYFLO	zileuton	TABLET;ORAL	020471-001	Dec 9, 1996		DISCN	Yes	No
Chiesi	ZYFLO	zileuton	TABLET;ORAL	020471-003	Dec 9, 1996		DISCN	Yes	No
Chiesi	ZYFLO CR	zileuton	TABLET, EXTENDED RELEASE;ORAL	022052-001	May 30, 2007		DISCN	Yes	No

Expired US Patents for ZYFLO

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Chiesi	ZYFLO	zileuton	TABLET;ORAL	020471-001	Dec 9, 1996	4,873,259
Chiesi	ZYFLO	zileuton	TABLET;ORAL	020471-003	Dec 9, 1996	4,873,259

International Patents for ZYFLO

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

Country	Patent Number	Title	Estimated Expiration
Australia	608804
Israel	95584
South Korea	0173116
Japan	H03148272	LIPOXYGENASE CONTROL COMPOUND
Greece	3022833
Germany	69029626

Market Dynamics and Financial Trajectory for ZYFLO (Ketotifen Fumarate)

Last updated: March 21, 2026

What is the Current Market Position of ZYFLO?

ZYFLO (ketotifen fumarate) is prescribed primarily for allergic conditions such as asthma, hay fever, and other allergic rhinitis. Its global regulatory approval comes mainly from the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA).

In the U.S., ZYFLO marketing approval extends to adult and pediatric populations for asthma prophylaxis. Its market share is limited relative to newer biologics and monoclonal antibody therapies but maintains niche status, especially in patients contraindicated or intolerant to inhaled corticosteroids or leukotriene receptor antagonists.

Regulatory and Patent Outlook

• FDA Approval: Initially obtained in 1985. No recent patent extensions announced as of late 2022.
• Patent Status: Patent expiration occurred in 2006 in the U.S., leading to generic entry. No new patent protections reported, which affects pricing power and market exclusivity.
• Regulatory Changes: Recent regulatory shifts focus on the precision of diagnostics and personalized medicine approaches, potentially impacting small-molecule drugs like ZYFLO by favoring biologics.

Market Size and Segmentation

The global allergic rhinitis and asthma markets are expected to reach USD 28.8 billion by 2027, growing at a CAGR of approximately 4.5%. ZYFLO accounts for an estimated USD 50-100 million in annual sales, based on data from market research firms and sales tracking platforms such as IQVIA.

Segments include:

• Mild to Moderate Asthma: ZYFLO targets this segment, competing with leukotriene receptor antagonists and inhaled corticosteroids.
• Allergic Rhinitis: Lower market share due to dominance by antihistamines.

Table 1: Market Share Estimates for ZYFLO (2022)

Segment	Estimated Share	Key Competitors
Asthma (mild-moderate)	2-3%	Montelukast, fluticasone
Allergic Rhinitis	<1%	Loratadine, cetirizine

Competitive Landscape

• Generic Presence: High, pressuring pricing.
• Alternative Therapies: Biologics (omalizumab, mepolizumab), which are more effective in severe cases but less accessible due to cost.
• Prescriber Preference: Shift towards biologics in severe cases impacts overall ZYFLO sales.

Sales and Revenue Trajectory

Since patent expiry, sales have declined from peaks near USD 200 million in the late 1990s to USD 50-100 million in recent years. Volume-based sales continue with stable demand in niche markets. Market penetration remains static, with limited expansion prospects unless a new formulation or indication is developed.

Regulatory and Policy Influences

• Pricing Regulations: Increasing global pressure to lower drug prices, especially in high-volume markets.
• Reimbursement Policies: Payors favor newer biologics with better efficacy, reducing reimbursement levels for older small molecules like ZYFLO.
• Clinical Guidelines: Recommendations favor biologics for severe cases, limiting routine use of ZYFLO in mild-to-moderate asthma.

Investment and R&D Considerations

• No current pipeline updates for ZYFLO, with Pfizer historically responsible for its marketing.
• R&D investments favor biologics and targeted therapies, less so small molecules.

Financial Outlook Summary

Parameter	Current Status	Future Outlook
Revenue	USD 50-100 million annually	Declining without new indications or formulations
Market Share	Marginal in global asthma/allergic markets	Static unless repositioned or reformulated
Competitive Threats	Generic price erosion, biologics	Intensifies over next 5 years
Regulatory Environment	Favorable for generics but shifting toward biologics	Continued pressure on older drugs

Key Market Drivers and Risks

Drivers

• Continued prevalence of allergic diseases.
• Prescribed for patients intolerant to inhaled steroids.
• Established safety profile.

Risks

• Patent expiry and generic competition.
• Regulatory emphasis on new therapies.
• Cost pressures from payers.

Key Takeaways

• ZYFLO's revenue is declining due to patent loss and increasing competition from generics and biologics.
• The drug maintains niche status in mild-to-moderate asthma but faces no significant new indications.
• Market growth hinges on reformulation, combination therapies, or new patent protections.
• Competitive landscape favors biologics, reducing ZYFLO’s long-term market viability.
• Future investments are unlikely to favor ZYFLO without strategic repositioning.

FAQs

1. What factors have primarily driven ZYFLO sales decline?
Patent expiration, generic competition, and the shift in prescribing patterns toward biologics have reduced ZYFLO sales since the early 2000s.

2. Are there any upcoming regulatory changes that could benefit ZYFLO?
No significant pending regulatory changes specific to ZYFLO are anticipated. Emphasis remains on biologics and new targeted therapies.

3. How does ZYFLO compare to newer asthma medications?
It is less effective in severe cases and is often replaced by biologics. In mild cases, it faces competition from oral leukotriene receptor antagonists.

4. Is there potential for ZYFLO to be repositioned or reformulated?
Potential exists, especially if new indications or combination products are developed; however, no current pipeline announcements exist.

5. What is the outlook for ZYFLO’s market share in the next five years?
Expected to decline further unless strategic measures are taken. Its niche applications may sustain minimal sales but will not support significant growth.

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References

1. IQVIA. (2022). Pharmaceutical Market Reports.
2. U.S. Food and Drug Administration. (2022). Marketed Drug Approvals.
3. European Medicines Agency. (2022). Medicines Database.
4. GlobalData. (2022). Asthma and Allergic Rhinitis Market Report.
5. Pfizer Inc. (2021). Annual Report and Financial Statements.