US Drug Patent 6,120,752: Claim Scope, Inhaler Technology, Exclusivity and Patent-Landscape Analysis

US Patent 6,120,752 protects a combination inhaler product rather than the claimed chemical compound in isolation. Its independent claim requires a dissolved compound within a defined Markush formula, an HFA propellant, a cosolvent, an aerosol vial and a dispensing valve. The dependent claims progressively narrow protection to a metered-dose valve, a specific adapter and tightly defined nozzle dimensions. The patent is therefore most relevant to HFA metered-dose inhaler products using one of the covered compounds and the claimed delivery architecture.

The supplied text omits the chemical structure identified as “##STR4##.” That omission prevents a complete identification of the covered active ingredients, marketed drug, Orange Book relevance, licensing history, or product-specific litigation exposure.

What does US Patent 6,120,752 protect?

The patent protects an aerosol product with five principal technical components:

A vial or canister equipped with a dispensing valve.
A pharmaceutical aerosol formulation suitable for oral or nasal inhalation.
A therapeutically effective amount of a dissolved compound within formula (I).
A propellant consisting of HFA-134a, HFA-227, or a mixture.
A cosolvent sufficient to dissolve the compound, with surfactant use permitted but not required.

The claim is a combination claim. It does not claim the compound by itself, a pharmaceutical composition without the delivery system, or every formulation containing the active ingredient.

What compounds fall within the Markush definition?

Based on the text supplied, formula (I) allows:

Variable	Permitted substituents
R1	1-butyl, 2-butyl, cyclohexyl or phenyl
R2	acetyl or isobutanoyl

The disclosed substitution pattern creates up to eight R1/R2 combinations, assuming every combination is chemically valid within the omitted core structure.

The scope cannot be determined solely from the R1 and R2 definitions because the central chemical structure is missing. The difference is material. The same R1 and R2 variables could define a broad class of corticosteroids, bronchodilators, anti-inflammatory agents, or another inhaled pharmaceutical class depending on the omitted scaffold.

How broad is independent claim 1?

Claim 1 is commercially narrower than a compound patent but potentially broad across product configurations.

Formulation requirements

The active compound must be dissolved, not merely suspended. A formulation using undissolved particles would present a substantial non-infringement position against the express “dissolved compound” limitation.

The formulation must contain a cosolvent in an amount effective to solubilize the compound. The claim does not specify:

A particular cosolvent;
A concentration range;
A particular vial material;
A particular valve supplier;
A particular surfactant;
A particular dose;
A particular particle-size distribution; or
A particular vapor pressure.

The claim expressly permits, but does not require, a surfactant. A formulation without a surfactant can still fall within claim 1 if the remaining limitations are satisfied.

Propellant requirements

The claim is limited to:

1,1,1,2-tetrafluoroethane, commonly HFA-134a;
1,1,1,2,3,3,3-heptafluoropropane, commonly HFA-227; or
A mixture of those propellants.

A product using a different propellant is outside the literal scope of this limitation. The restriction is important because the claim does not cover every hydrofluoroalkane, compressed gas or future low-global-warming propellant.

Oral and nasal delivery

The language “suitable for oral or nasal inhalation” establishes the intended delivery route. The claim can potentially cover an inhaler used through a mouthpiece or a nasal adapter, provided the formulation and device limitations are met.

The claim does not expressly require treatment of asthma, chronic obstructive pulmonary disease, allergic rhinitis or another named indication. “Therapeutically effective amount” is functional language that may create claim-construction and enablement issues if applied to compounds or dosing conditions not supported by the specification.

What additional limitations appear in claims 2 through 8?

The dependent claims create a nested series of device-specific positions.

Claim	Additional limitation	Practical effect
2	Metered-dose dispensing valve	Excludes non-metered aerosol valves
3	Detailed ferrule, metering tank, valve stem and bottle-emptier structure	Narrows protection to a particular valve architecture
4	Adapter with body, nozzle block and mouthpiece	Requires an integrated inhaler adapter
5	Exit-orifice diameter of 0.20 to 0.33 mm	Adds a dimensional nozzle limitation
6	Exit-orifice diameter of about 0.28 mm	Narrows claim 5 to a target dimension
7	Jet length of 0.30 to 0.60 mm	Adds a second nozzle dimension
8	Jet length of 0.50 mm	Narrows claim 7 to a target dimension

How important is claim 3?

Claim 3 is a detailed mechanical claim. It requires:

A valve ferrule with a rim, gasket and aperture;
A metering tank with an internal metering chamber;
An inlet orifice;
An elongate valve stem;
A filling channel and discharge orifice;
Sealing engagement between specified components;
A bottle emptier surrounding the metering tank and valve stem; and
Two operating positions, including an extended closed position and a compressed open position.

The claim is likely difficult to prove against a competing inhaler without physical teardown, supplier drawings, engineering specifications or discovery. Small differences in the valve’s internal geometry could avoid literal infringement.

Claim 3 also creates a potential design-around path. A competitor could use a different metering-valve arrangement, alter the location of the inlet orifice, modify the stem and chamber relationship, or employ a distinct actuator and dose-metering system.

How important are claims 5 through 8?

Claims 5 through 8 protect the outlet nozzle and jet geometry. Their commercial value depends on whether the dimensions are necessary for the claimed aerosol performance.

Claim 8 is the narrowest position. It requires the approximate 0.28 mm exit diameter from claim 6 and the 0.50 mm jet length from claim 7. A product outside those dimensions may avoid claim 8 while still implicating claim 5 or claim 7.

The use of “about” in claim 6 introduces a range-of-equivalents issue. The permissible deviation depends on the specification, prosecution history, measurement method and whether the patent disclosed an accepted tolerance.

What is the likely infringement test for a competing inhaler?

A competing product would generally need to satisfy every limitation of at least one asserted claim. The most relevant claim-by-claim analysis is:

Claim 1

A product is exposed if it uses:

A covered formula (I) compound;
Dissolution rather than suspension;
HFA-134a, HFA-227 or their mixture;
A solubilizing cosolvent;
An aerosol vial; and
A dispensing valve.

A product using the covered active compound in a dry-powder inhaler, nebulizer, tablet, nasal spray pump or suspension formulation would not literally satisfy all claim 1 elements.

Claim 2

The product must use a metered-dose valve. A conventional aerosol canister with a continuous spray valve would present a strong non-infringement argument.

Claim 3

The internal valve structure must correspond to the detailed architecture. The presence of a metering valve alone is not enough.

Claims 4 through 8

The product must have the specified adapter, mouthpiece, nozzle-block configuration and dimensional characteristics. These claims are more technically narrow and likely more vulnerable to design-around.

When does US Patent 6,120,752 lose exclusivity?

The issue date of US Patent 6,120,752 was September 19, 2000. Its enforceable expiration date cannot be calculated from the claims supplied. The controlling date depends on the application’s earliest effective nonprovisional filing date, continuity, patent-term adjustment and any terminal disclaimer. Under 35 U.S.C. § 154, utility patents generally expire 20 years from the earliest effective U.S. nonprovisional filing date, subject to statutory adjustments and disclaimers.

The patent’s issue date alone does not establish its expiration date. A patent issued in 2000 could have expired before, on or after the corresponding 20-year anniversary of its relevant filing date depending on priority and continuity data.

Exclusivity issue	Relevance to this patent
Patent term	Requires USPTO continuity and PTA review
Patent-term extension	Potentially relevant only if statutory drug-product conditions were met
Patent-term adjustment	Could extend the ordinary term
Terminal disclaimer	Could shorten the term
Regulatory exclusivity	Separate from patent rights
Orange Book listing	Requires identification of the NDA and active ingredient

A patent that has expired cannot support a new infringement action for future conduct, although historical litigation, settlement obligations and damages periods may still require separate analysis.

Is US Patent 6,120,752 an Orange Book patent?

The supplied claim text does not establish Orange Book listing. Orange Book listing is product-specific and depends on whether the patent was submitted by an NDA holder and whether it claims the drug substance, drug product or approved method of use under FDA listing standards (FDA, 2024).

The patent appears, from the claims provided, to focus on:

Aerosol formulation;
Valve construction;
Adapter design; and
Nozzle geometry.

Those categories do not automatically qualify for Orange Book listing. A formulation claim may qualify in some circumstances, but a stand-alone device claim generally requires analysis under FDA’s patent-listing rules and the relevant NDA record.

Because the claimed chemical structure and associated drug are not identified, no reliable conclusion can be made about:

Whether the patent was listed in the Orange Book;
Whether an ANDA applicant would have had to address it;
Whether a Paragraph IV certification was possible;
Whether a 30-month stay was triggered; or
Whether the patent had a listed pediatric or regulatory exclusivity period.

What Paragraph IV risks exist?

Paragraph IV exposure depends on Orange Book status, patent expiration and the ANDA’s proposed product.

If listed, claim 1 could be relevant to an ANDA for a solution-based HFA inhaler containing a covered compound. The applicant would need to evaluate:

Whether the active ingredient falls within formula (I);
Whether the formulation is a solution;
Whether the product uses HFA-134a, HFA-227 or both;
Whether the product uses a cosolvent;
Whether the canister and valve satisfy the claim; and
Whether the patent is expired or remains enforceable.

Claims 3 through 8 would be less likely to create a broad generic barrier because they require particular internal valve and nozzle characteristics. A generic applicant could potentially avoid those claims through a different actuator, valve supplier, metering mechanism or nozzle specification.

A Paragraph IV certification does not arise merely because a patent exists. The patent must be listed or otherwise become relevant through the applicable regulatory pathway, and the drug product must fall within the patent’s scope.

What generic launch scenarios exist?

Scenario 1: Same active compound, different formulation state

A suspension formulation may avoid the “dissolved compound” requirement of claim 1. The feasibility of that approach depends on dose uniformity, particle engineering, valve compatibility and FDA product-specific expectations.

Scenario 2: Same active compound, different propellant

A product using a propellant outside the closed HFA-134a/HFA-227 definition could avoid literal infringement of claim 1. Regulatory comparability and device performance would remain separate issues.

Scenario 3: Same formulation, different valve

A competing product could use a metered valve with internal geometry that does not meet claim 3. This would be a principal design-around route.

Scenario 4: Same valve, different nozzle geometry

Changing the exit diameter or jet length could avoid claims 5 through 8, subject to aerosol performance requirements.

Scenario 5: Alternative delivery platform

A dry-powder inhaler, nebulizer or nasal pump would generally fall outside the supplied combination claims because the claims require an aerosol vial and propellant-based formulation.

How strong is the patent estate?

On the supplied claims, the estate has a mixed profile.

Estate component	Relative strength
Covered chemical compound in isolation	None shown
HFA solution formulation	Moderate, if the active and all formulation elements are present
Metered-dose valve architecture	Narrow to moderate
Adapter and mouthpiece	Narrow
Nozzle dimensions	Narrow and readily measurable
Alternative inhaler platforms	Little apparent coverage
Broad regulatory blocking power	Cannot be established without Orange Book data

The strongest commercial position is claim 1 because it covers the full product combination without requiring the detailed valve and nozzle dimensions. Its weakness is that every limitation must be present, including dissolution, specified HFA propellant and a covered compound.

The strongest technical evidence would be formulation composition records, canister and valve specifications, actuator drawings, nozzle metrology and the identity of formula (I). Without the omitted structure, active-ingredient mapping is unavailable.

What litigation, licensing and biosimilar risks affect the patent?

No litigation, settlement, licensing or biosimilar conclusion can be drawn from the supplied claims. Biosimilar risk is generally not the relevant pathway because the patent claims a small-molecule aerosol product, not a biologic. The principal competitive pathway would be an ANDA or, depending on the product, another abbreviated small-molecule pathway.

Patent litigation risk would depend on:

Current enforceability;
Patent listing status;
The identity of the covered active;
Commercial sales of an accused HFA solution;
The accused valve’s internal structure; and
Any prosecution-history disclaimer.

A settlement agreement could impose restrictions beyond the patent’s statutory scope, but no settlement terms are identified in the supplied material.

What geographic coverage does the patent provide?

US Patent 6,120,752 provides rights only in the United States. Equivalent foreign rights would require separate national or regional patents. The supplied claims do not establish coverage in:

Europe;
Canada;
Japan;
China;
Australia; or
Any other jurisdiction.

Foreign patent families may differ in claim scope, prosecution history, term and legal status. A US claim to a specific HFA formulation does not create worldwide exclusivity.

Key Takeaways

US Patent 6,120,752 is a combination patent for an HFA aerosol product.
Claim 1 requires a dissolved formula (I) compound, HFA-134a and/or HFA-227, a solubilizing cosolvent, an aerosol vial and a dispensing valve.
The patent does not, on the supplied text, claim the active compound independently.
Claims 3 through 8 add narrow valve, adapter and nozzle limitations.
The omitted “STR4” chemical structure prevents identification of the covered drug and product-specific patent landscape.
Orange Book status, Paragraph IV exposure, litigation, licensing and revenue exposure cannot be established from the claims alone.
A generic design-around could use a suspension, different propellant, different valve architecture, different nozzle dimensions or a non-aerosol delivery platform.
US rights do not establish foreign coverage.
Patent expiration requires USPTO continuity, filing-date, PTA and terminal-disclaimer data.

FAQs

Does US Patent 6,120,752 claim a specific inhaled drug?

The supplied text does not identify the drug because the chemical structure for formula (I) is omitted. The claim covers compounds defined by the missing structure and the stated R1 and R2 substituents.

Would a dry-powder inhaler infringe these claims?

A dry-powder inhaler would generally not satisfy the aerosol vial and propellant limitations in claim 1.

Can a formulation use a surfactant and remain within claim 1?

Yes. Surfactant use is optional under claim 1. The formulation must still contain the required dissolved compound, specified propellant and effective cosolvent.

Does changing the mouthpiece automatically avoid the patent?

No. Claim 1 does not require the adapter and mouthpiece limitations found in claims 4 through 8. Changing the mouthpiece may avoid a dependent claim but would not necessarily avoid claim 1.

Is a Paragraph IV certification required for every generic product containing the covered compound?

No. Paragraph IV analysis depends on Orange Book listing, the relevant NDA, patent status and whether the proposed generic product falls within the listed patent claims.

References

United States Patent No. 6,120,752. (2000, September 19). Aerosol pharmaceutical product claims 1-8. United States Patent and Trademark Office.
United States Code, 35 U.S.C. § 154. (2024). Contents and term of patent; provisional rights.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
U.S. Food and Drug Administration. (2024). 21 C.F.R. § 314.53: Submission of patent information. Electronic Code of Federal Regulations.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	9710496	May 21, 1997
United Kingdom	9803990	Feb 25, 1998

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0983058	⤷ Start Trial	CA 2005 00036	Denmark	⤷ Start Trial
European Patent Office	0983058	⤷ Start Trial	PA2005006	Lithuania	⤷ Start Trial
European Patent Office	0983058	⤷ Start Trial	PA2005006,C0983058	Lithuania	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,120,752

Summary for Patent: 6,120,752