Generic PIRBUTEROL ACETATE INN equivalents, drug patent expiry and freedom to operate

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Bausch	MAXAIR	pirbuterol acetate	AEROSOL, METERED;INHALATION	020014-001	Nov 30, 1992		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Bausch	MAXAIR	pirbuterol acetate	AEROSOL, METERED;INHALATION	019009-001	Dec 30, 1986		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Bausch	MAXAIR	pirbuterol acetate	AEROSOL, METERED;INHALATION	019009-001	Dec 30, 1986	⤷ Start Trial	⤷ Start Trial
Bausch	MAXAIR	pirbuterol acetate	AEROSOL, METERED;INHALATION	020014-001	Nov 30, 1992	⤷ Start Trial	⤷ Start Trial
Bausch	MAXAIR	pirbuterol acetate	AEROSOL, METERED;INHALATION	019009-001	Dec 30, 1986	⤷ Start Trial	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>Patent No.	>Patent Expiration

Last updated: September 8, 2026

Pirbuterol acetate is a legacy short-acting beta2-adrenergic agonist that has largely exited the U.S. commercial market. Its former branded product, Maxair Autohaler, lost commercial relevance as albuterol became the dominant rescue bronchodilator and as inhaler technology shifted away from older delivery systems. No current public data supports a material standalone revenue stream for pirbuterol acetate. The principal commercial issue is market abandonment, not active patent protection.

What is pirbuterol acetate and what was its commercial role?

Pirbuterol acetate is the acetate salt of pirbuterol, a selective beta2-adrenergic agonist used for the prevention and treatment of bronchospasm associated with asthma and reversible obstructive airway disease.

The product was marketed in the United States primarily as Maxair Autohaler, a breath-actuated inhaler. Unlike conventional metered-dose inhalers, the device was designed to release the dose when the patient inhaled through the mouthpiece. The product’s value proposition was ease of use for patients who had difficulty coordinating actuation and inhalation.

Attribute	Pirbuterol acetate
Drug class	Short-acting beta2-adrenergic agonist
Primary indication	Reversible bronchospasm and asthma
Main U.S. product	Maxair Autohaler
Former sponsor	3M Pharmaceuticals and successor commercial organizations
FDA pathway	New Drug Application
Dosage form	Breath-actuated inhalation aerosol
Current U.S. market position	Commercially discontinued
Principal competitors	Albuterol inhalers, levalbuterol inhalers, nebulized beta2 agonists
Current patent value	Limited to nonexistent for the original active ingredient and legacy product

The product competed in a market where clinical substitution was relatively straightforward. Physicians could generally use albuterol or, in selected patients, levalbuterol as alternative short-acting rescue therapy. That substitution reduced pricing power and limited the ability of pirbuterol to maintain a durable commercial niche.

When did pirbuterol acetate lose exclusivity?

Pirbuterol acetate lost meaningful market exclusivity many years before its commercial withdrawal. The active ingredient and basic therapeutic concept are legacy assets, and the product is no longer protected by a commercially significant period of FDA exclusivity.

The FDA approved Maxair Autohaler under NDA 018233. Any original new-drug exclusivity associated with the product expired decades ago. The product’s commercial life therefore depended on brand loyalty, device differentiation, manufacturing continuity, and physician familiarity rather than regulatory exclusivity.

Pirbuterol acetate exclusivity timeline

Event	Approximate timing	Commercial effect
U.S. development and approval of Maxair Autohaler	Late 1980s	Created branded market entry
Early commercial period	1990s	Product competed with established beta2 agonists
Loss of original exclusivity	Decades ago	Opened the market to substitution and potential generic competition
CFC regulatory transition	2000s to early 2010s	Increased manufacturing and regulatory pressure on legacy inhalers
Maxair commercial discontinuation	2013 to 2014 period	Removed the primary U.S. branded product from the market
Current position	2020s	No material branded U.S. commercial platform

Exact patent expiration dates for the original pirbuterol acetate composition and Maxair product cannot be used to support a current exclusivity thesis. The relevant commercial conclusion is that the protected period ended long before the product’s withdrawal.

What is the FDA regulatory status of pirbuterol acetate?

Pirbuterol acetate is not a current growth product in the FDA-regulated U.S. respiratory market. The FDA’s Drugs@FDA database identifies the Maxair product history, while FDA product-discontinuation records distinguish commercial discontinuation from withdrawal for safety or efficacy reasons (U.S. Food and Drug Administration, n.d.-a, n.d.-b).

The discontinuation of Maxair was not generally treated as a safety withdrawal. The product’s decline reflected commercial and manufacturing factors, including:

Competition from lower-cost albuterol products.
Limited physician need for a second short-acting beta2 agonist.
The transition from chlorofluorocarbon-based inhalers to hydrofluoroalkane-compliant products.
The economics of maintaining an older inhalation-device platform.
A shrinking installed base of patients and prescribers.

What was the FDA status of Maxair Autohaler?

Maxair Autohaler was a discontinued prescription inhalation product. FDA records concerning discontinued products do not by themselves establish that the active ingredient was unsafe or ineffective. A product can be discontinued for commercial, manufacturing, supply, or strategic reasons while retaining its historical regulatory approval record.

The lack of a currently marketed U.S. product is more important for market analysis than the historical approval status. A dormant NDA does not create an operating revenue stream, and an approved but discontinued product does not necessarily have an investable generic opportunity.

What patents protect pirbuterol acetate?

No active, commercially significant patent position is apparent for the original pirbuterol acetate molecule or the legacy Maxair product.

Active ingredient patents

The original composition and therapeutic patents for pirbuterol are old relative to modern pharmaceutical patent terms. Any original molecule-level patent protection would have expired before the product’s U.S. commercial withdrawal.

Formulation and inhaler patents

The most relevant historical protection was likely associated with:

The inhalation formulation.
Aerosol performance.
The breath-actuated delivery mechanism.
Device construction and dose-release controls.
Manufacturing processes for the inhalation product.

Those rights may have had different expiration dates from the active-ingredient patents, but their commercial significance has also diminished. A formulation or device patent that is expired, abandoned, or disconnected from an active sponsor does not create meaningful market exclusivity.

Orange Book status

The FDA Orange Book is the principal source for active patents and exclusivity associated with approved prescription drug products. A commercially relevant Orange Book listing would require an active reference product, an applicable patent listing, and a market in which an ANDA sponsor could challenge the listed patent.

For pirbuterol acetate, the practical Orange Book conclusion is that there is no current patent barrier comparable to the active estates surrounding newer inhaled therapies. The product’s principal barrier is commercial viability, not patent enforceability.

How many patents cover pirbuterol acetate today?

The number of historical patent publications involving pirbuterol, aerosol formulations, or inhaler devices may be substantial. That count should not be confused with the number of unexpired, enforceable, commercially relevant patents.

Patent category	Current commercial significance
Pirbuterol molecule and salts	Minimal; legacy protection expired
Inhalation composition	Limited; likely expired or commercially inactive
Breath-actuated inhaler technology	Potentially relevant only if tied to unexpired claims and a viable device
Manufacturing methods	Limited unless a current manufacturer relies on a protected process
Method-of-use claims	Low value because the indication is established and alternatives are available
Combination therapy claims	No clear current platform value

A current patent count would therefore overstate the strength of the pirbuterol estate. The proper assessment is claim-by-claim, jurisdiction-specific, and tied to live commercial products.

What generic entry risks exist for pirbuterol acetate?

Traditional Paragraph IV litigation risk appears low because the original branded product is no longer a major commercial target.

Paragraph IV challenges

A Paragraph IV filing is economically attractive when:

The reference product has substantial annual sales.
The ANDA sponsor can obtain reliable active pharmaceutical ingredient supply.
The device or formulation can be replicated or legally substituted.
The sponsor can obtain reimbursement and pharmacy distribution.
Litigation costs are justified by expected market value.

Pirbuterol acetate does not currently satisfy the first condition in the United States. The historical Maxair market was too small and too old to support a conventional branded-versus-generic patent contest of the type seen with high-revenue inhaled products.

Generic development barriers

The absence of patent protection does not make generic development easy. An inhaled product may require:

Device-dose reproducibility.
Demonstration of aerodynamic particle-size distribution.
Consistent emitted dose.
Stability data.
In vitro equivalence.
Human pharmacokinetic or clinical data, depending on FDA requirements.
A reliable source of pirbuterol acetate.
Specialized manufacturing and filling capacity.

The device is particularly important. A company would not be developing only a chemical active ingredient. It would be recreating an inhalation system with performance characteristics acceptable to the FDA and commercially usable by patients.

How does pirbuterol acetate compare with albuterol and levalbuterol?

Albuterol is the dominant comparator and the main reason pirbuterol has limited recovery potential.

Factor	Pirbuterol acetate	Albuterol	Levalbuterol
Market status	Legacy/discontinued U.S. product	Broadly marketed	Marketed in selected formulations
Prescriber familiarity	Low relative to albuterol	Very high	Moderate
Generic availability	Limited or absent in current U.S. retail market	Extensive	Available in selected products
Device options	Historically narrow	Broad	Moderate
Reimbursement position	Weak	Stronger	Variable
Switching risk	High	Reference standard	Alternative for selected patients
Commercial opportunity	Niche re-entry only	Large established market	Smaller differentiated segment

Albuterol benefits from broad guideline familiarity, extensive payer coverage, established supply chains, and multiple devices. Pirbuterol would need a meaningful clinical, adherence, device, or pricing advantage to displace a low-cost incumbent. Historical breath-actuation convenience alone is unlikely to support a large market relaunch.

What was the financial trajectory of pirbuterol acetate?

No reliable public source provides a current standalone revenue series for pirbuterol acetate. Maxair revenue was not generally reported as a separate material line item in public company disclosures, and the product’s later sales were not sufficient to establish a transparent investment-grade revenue history.

The financial trajectory can be characterized in four phases:

Early branded commercialization

The product generated prescription revenue as a differentiated inhaler for asthma patients. The breath-actuated device offered a practical advantage for some users, but the product remained within a crowded short-acting bronchodilator class.

Competitive erosion

Albuterol became the default rescue inhaler. Generic availability and broad payer acceptance compressed pricing and reduced the commercial value of alternative beta2 agonists.

Manufacturing and regulatory pressure

The transition from older propellant systems increased development and compliance requirements. For a low-volume legacy product, the cost of maintaining or replacing the device and formulation platform became harder to justify.

Commercial withdrawal

Once Maxair was discontinued, direct U.S. product revenue effectively disappeared. Any remaining economic activity would have consisted of limited international sales, residual inventory, licensing, or niche distribution, none of which is supported by a clear public revenue disclosure.

Which companies challenged or replaced pirbuterol acetate?

The principal competitive pressure came from products rather than from a single legal challenger.

Relevant competitors included:

GlaxoSmithKline and successor organizations through Ventolin and related albuterol products.
Teva through generic albuterol and respiratory products.
Cipla and other generic manufacturers in international markets.
Sunovion through Xopenex, the levalbuterol product.
Various inhaler manufacturers supplying generic and branded short-acting bronchodilators.

The competitive substitution was clinically straightforward. In many cases, a physician could replace pirbuterol with albuterol without requiring a new therapeutic strategy. That reduced switching friction and weakened pirbuterol’s negotiating position with payers and distributors.

What licensing deals affected pirbuterol acetate?

No major current licensing transaction is publicly associated with pirbuterol acetate. The product’s commercial history involved corporate ownership and product commercialization arrangements, but there is no visible active licensing platform comparable to those associated with newer inhaled drugs, biologics, or specialty respiratory assets.

Any historical rights transfer would have limited present value unless it included:

A live product in a major market.
A proprietary inhaler device.
Unexpired patent rights.
Manufacturing infrastructure.
Regulatory approvals in multiple jurisdictions.
A defined relaunch strategy.

The absence of a current commercial sponsor is itself a material factor in assessing licensing value.

What patent litigation and settlement agreements affect pirbuterol acetate?

No material current U.S. patent litigation or settlement structure is apparent for pirbuterol acetate. The product is not positioned like a high-revenue inhaled therapy facing active ANDA filings and Paragraph IV litigation.

The absence of litigation does not mean the product has a strong patent estate. It generally indicates that the expected value of a challenge, defense, or settlement is too low to justify the associated costs.

What generic launch scenarios are plausible?

Scenario 1: No U.S. relaunch

This is the most likely commercial outcome. Albuterol substitutes are available, the historical product has low prescriber momentum, and the economics of rebuilding the inhaler platform are uncertain.

Scenario 2: Niche authorized generic or specialty relaunch

A company with inhaler manufacturing capacity could pursue a limited relaunch aimed at patients who prefer breath-actuated delivery. The addressable market would likely be small and would depend on payer coverage and reliable device supply.

Scenario 3: International niche commercialization

Pirbuterol could retain limited value in jurisdictions where the product has regulatory recognition or where breath-actuated inhalers address a specific clinical need. International opportunity would depend on local registration, pricing, and manufacturing economics.

Scenario 4: Device-led repositioning

A modern device could improve usability, but this would be a product redevelopment program rather than a simple generic launch. The sponsor would need to establish comparative performance and secure reimbursement against established albuterol products.

How strong is the pirbuterol acetate patent estate?

The patent estate is weak from a current commercial perspective.

Strength factor	Assessment
Molecule protection	Exhausted
Original product exclusivity	Exhausted
Formulation protection	Limited or expired
Device protection	Potentially relevant only for specific historical claims
Orange Book leverage	Low
Paragraph IV settlement leverage	Low
Manufacturing barriers	Moderate
Regulatory redevelopment burden	Moderate to high
Commercial differentiation	Low
Licensing attractiveness	Low without a new device or market

The principal remaining barriers are operational. A new entrant would face technical and regulatory work, but those barriers would protect neither price nor market share unless the company created a differentiated product.

What is the geographic market position?

Pirbuterol acetate has limited present visibility in the United States. Some international markets may retain historical registrations or localized supply, but the global commercial position is fragmented and difficult to quantify from public data.

Geographic value would depend on:

Current national marketing authorization.
Local patent and data-exclusivity status.
Availability of approved inhaler devices.
National reimbursement.
Local generic competition.
Whether the active ingredient can be sourced at commercial scale.

A historical approval in a country does not establish current sales or active commercialization.

Key Takeaways

Pirbuterol acetate is a legacy short-acting beta2 agonist with no material current U.S. commercial profile.
Maxair Autohaler was the principal U.S. product and was commercially discontinued in the 2013 to 2014 period.
Original molecule, formulation, and product exclusivity expired long before the product’s withdrawal.
Current Orange Book and Paragraph IV leverage appears limited.
No reliable public standalone revenue series supports a current financial valuation.
Albuterol is the dominant competitive substitute and constrains any relaunch opportunity.
The main barriers to re-entry are inhaler development, manufacturing, FDA requirements, reimbursement, and market formation.
A niche relaunch is technically possible but would not have the characteristics of a high-value patent-protected pharmaceutical opportunity.
No major current licensing transaction, patent litigation program, or settlement structure is apparent.

FAQs About Pirbuterol Acetate

Is pirbuterol acetate still available in the United States?

The former U.S. Maxair Autohaler product is commercially discontinued. Pirbuterol acetate does not have the market presence of albuterol or levalbuterol.

Was Maxair discontinued because it was unsafe?

The product’s commercial discontinuation should not be interpreted as a safety withdrawal. The decline reflected market, manufacturing, regulatory, and commercial factors.

Can a company launch a generic pirbuterol inhaler?

A company could pursue a regulatory pathway, but it would need to address inhaler-device equivalence, dose delivery, formulation performance, manufacturing, and commercial distribution. Patent expiration alone would not make the project attractive.

Does pirbuterol acetate have an active composition patent?

The original active-ingredient protection is legacy protection and does not provide a current commercially meaningful exclusivity position.

Could pirbuterol acetate become valuable through a new inhaler device?

A new device could create product differentiation, but the resulting value would depend on regulatory approval, clinical usability, reimbursement, manufacturing scale, and evidence that the product offers a benefit over low-cost albuterol.

References

U.S. Food and Drug Administration. (n.d.-a). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
U.S. Food and Drug Administration. (n.d.-b). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (n.d.-c). Drug products marketed in the United States that have been discontinued. https://www.accessdata.fda.gov/scripts/cder/daf/
U.S. Food and Drug Administration. (2023). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
DailyMed. (n.d.). Pirbuterol acetate inhalation aerosol product information. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/
U.S. Food and Drug Administration. (2013). CFC phase-out and transition of metered-dose inhalers. U.S. Department of Health and Human Services.

US Patents:	0
Tradenames:	1
Applicants:	1
NDAs:	2
Raw Ingredient (Bulk) Api Vendors:	28
DailyMed Link:	PIRBUTEROL ACETATE at DailyMed

Summary for PIRBUTEROL ACETATE

Anatomical Therapeutic Chemical (ATC) Classes for PIRBUTEROL ACETATE