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Patent landscape, scope, and claims: |
United States Drug Patent 6,641,800: Scope, Claim Map, and US Patent Landscape
US Patent 6,641,800 claims a specific class of pressurized metered-dose inhaler (pMDI)-type aerosol formulations: liquefied hydrofluoroalkane (HFA) carrier, powdered drug dispersed in the liquefied HFA, and a polymer-based suspending agent that is soluble in the liquefied HFA. The claims are tightly structured around (i) particle size, (ii) polymer identity and concentration, and (iii) optional excipients (ethanol limits, flavorants, and valve lubricants).
What does US 6,641,800 claim, in enforceable terms?
1) What is the core product claim scope? (Claim 1)
Claim 1 defines an aerosol composition by combining all the following limitations:
- Form: “pressurized suspension aerosol composition”
- Carrier: liquefied hydrofluoroalkane (HFA)
- Drug: powdered medicament dispersed in the liquefied HFA
- Powder particle size: medicament particles have mass median diameter (MMD) of 0.01 to 10 microns
- Suspending agent: polymer soluble in the liquefied HFA
- Polymer amount: 0.00001 to 10% w/w
- Polymer must be different from the medicament
- Polymer selection (exclusive list): polymer selected from:
- recurring 1-ethylene-pyrrolidin-2-one units polymers/copolymers (covers PVP-type)
- copolymers of 1-ethylene-pyrrolidin-2-one units and vinylacetate units
- polyvinylacetate
- acrylic acid/methacrylic acid ester copolymers
- Use: aerosol for inhalation
This claim is broad on HFA identity (not limited in Claim 1), broad on medicament identity (covered later), but constrained by:
- suspending polymer identity (closed list)
- particle MMD range
- polymer concentration range
- polymer solubility requirement
2) How do dependent claims narrow Claim 1?
Dependent claims focus on narrowing the polymer and adding formulation guardrails. The main narrowing axes are:
Polymer identity and recurrence structure
- Claim 2: polymer includes recurring 1-ethylene-pyrrolidin-2-one units
- Claim 3: polymer is polyvinylpyrrolidone (PVP)
- Claim 4: polymer is a copolymer containing recurring 1-ethylene-pyrrolidin-2-one units
- Claim 5: polymer is polyvinylpyrrolidone/vinyl acetate copolymer
- Claim 6: polymer is polyvinylacetate or an acrylic acid/methacrylic acid ester copolymer
Polymer concentration and excipient constraints
Claims 7 to 10 and 25 to 30 impose quantitative limits for excipients affecting polymer solubility and ethanol content:
- Claim 7: < 10% w/w of excipients capable of increasing polymer solubility in HFA
- Claim 8: < 5% w/w of same solubility-increasing excipients
- Claim 9: < 10% w/w ethanol
- Claim 10: < 5% w/w ethanol
Valve lubricant and flavor excipients
-
Claims 11–13: composition contains an excipient that acts as valve lubricant, and/or a flavor modifying excipient
-
Claim 14: valve lubricant comprises polyethylene glycol (PEG)
-
Claims 15–16: PEG mean molecular weight:
- 200 to 3000 (Claim 15)
- 400 to 2000 (Claim 16)
-
Claims 17–18: PEG concentration:
- 0.01 to 4% w/w (Claim 17)
- 0.1 to 2% w/w (Claim 18)
-
Claim 19: flavor modifying excipient comprises one or more of:
- peppermint oil, menthol, saccharin or saccharin sodium
HFA identity limitation
- Claim 20: HFA is CF3CHFCF3 (i.e., a specific HFA species)
- Claim 23: HFA is CF3CHFCF3 AND polymer includes recurring 1-ethylene-pyrrolidin-2-one units
- Claims 24–31: further tie that combination to PVP/PVP-vinyl acetate and ethanol/PEG conditions
Medicament identity and loading range
- Claim 21: medicament is selected from a closed list:
- terbutaline sulphate
- beclomethasone dipropionate
- salbutamol sulphate
- fluticasone propionate
- reproterol hydrochloride
- fenoterol hydrobromide
- sodium cromoglycate
- nedocromil sodium
- tipredane
- pentamidine isethionate
- clemastine
- acetyl-β-methylcholine bromide
- budesonide
- Claim 22: medicament concentration 0.01 to 15% w/w
Manufacturing process claim
- Claim 32: process for preparing the composition of Claim 1 by dispersing powdered medicament and suspending agent in liquefied HFA
Claim-by-claim scope map (what must be present)
Claim chart: material limitations that control infringement
| Claim |
Carrier |
Powdered medicament + particle size |
Polymer suspending agent |
Polymer concentration |
Optional formulation constraints |
| 1 |
Any liquefied HFA |
Powdered medicament dispersed; MMD 0.01–10 µm |
Polymer soluble in HFA; polymer must be different from medicament; polymer must be from the specified list |
0.00001–10% w/w |
Inhalation use |
| 2 |
Any |
Same as 1 |
Includes recurring 1-ethylene-pyrrolidin-2-one |
Same as 1 |
— |
| 3 |
Any |
Same as 1 |
PVP |
Same as 1 |
— |
| 4 |
Any |
Same as 1 |
Copolymer with recurring 1-ethylene-pyrrolidin-2-one |
Same as 1 |
— |
| 5 |
Any |
Same as 1 |
PVP/vinyl acetate copolymer |
Same as 1 |
— |
| 6 |
Any |
Same as 1 |
polyvinylacetate or acrylic acid/methacrylic ester copolymer |
Same as 1 |
— |
| 7 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
< 10% w/w solubility-increasing excipients |
| 8 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
< 5% w/w solubility-increasing excipients |
| 9 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
< 10% w/w ethanol |
| 10 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
< 5% w/w ethanol |
| 11 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
Contains valve lubricant excipient |
| 12 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
Contains flavor modifying excipient |
| 13 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
Contains both valve lubricant + flavor excipient |
| 14 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
Valve lubricant = PEG |
| 15 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
PEG MW 200–3000 |
| 16 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
PEG MW 400–2000 |
| 17 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
PEG concentration 0.01–4% w/w |
| 18 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
PEG concentration 0.1–2% w/w |
| 19 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
Flavor = peppermint oil/menthol/saccharin/saccharin sodium (one or more) |
| 20 |
CF3CHFCF3 |
Same as 1 |
Same as 1 |
Same as 1 |
— |
| 21 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
Medicament is from the enumerated list |
| 22 |
Any |
Same as 1 |
Same as 1 |
Same as 1 |
Medicament concentration 0.01–15% w/w |
| 23 |
CF3CHFCF3 |
Same as 1 |
Polymer includes recurring 1-ethylene-pyrrolidin-2-one |
Same as 1 |
— |
| 24 |
CF3CHFCF3 |
Same as 1 |
PVP |
Same as 1 |
— |
| 25 |
CF3CHFCF3 |
Same as 1 |
PVP |
Same as 1 |
< 10% w/w ethanol |
| 26 |
CF3CHFCF3 |
Same as 1 |
PVP |
Same as 1 |
< 5% w/w ethanol |
| 27 |
CF3CHFCF3 |
Same as 1 |
PVP |
Same as 1 |
Contains PEG |
| 28 |
CF3CHFCF3 |
Same as 1 |
PVP |
Same as 1 |
Contains PEG |
| 29 |
CF3CHFCF3 |
Same as 1 |
Polymer includes recurring 1-ethylene-pyrrolidin-2-one |
Same as 1 |
< 10% w/w ethanol |
| 30 |
CF3CHFCF3 |
Same as 1 |
Polymer includes recurring 1-ethylene-pyrrolidin-2-one |
Same as 1 |
< 5% w/w ethanol |
| 31 |
CF3CHFCF3 |
Same as 1 |
Polymer includes recurring 1-ethylene-pyrrolidin-2-one |
Same as 1 |
Contains PEG |
| 32 |
Any liquefied HFA that yields composition of Claim 1 |
Process involves dispersing powdered medicament + polymer suspending agent in HFA |
Same as 1 |
Same as 1 |
— |
Practical enforceability: where the claim is hardest to design around
1) Particle size window is a direct design constraint
Claim 1 requires MMD 0.01–10 microns. This is a measurable property and can be outcome-determinative for both:
- aerosolization performance, and
- infringement analysis (testing of particle size distribution in the final composition).
2) Polymer identity is a “closed list”
The suspending agent polymer must be in a specified group. While the list is broad across multiple polymer families, it is still constrained to:
- PVP-type (recurring 1-ethylene-pyrrolidin-2-one units) and PVP copolymers,
- vinyl acetate-containing variants,
- polyvinylacetate,
- acrylic acid/methacrylic acid ester copolymers.
Replacing the polymer with an alternative suspending polymer not matching the enumerated categories is the cleanest potential design-around pathway.
3) Solubility requirement ties polymer chemistry to the HFA carrier
Claim 1 requires the suspending polymer is soluble in the liquefied HFA. That means a candidate polymer cannot be merely “a suspender”; it must meet the solubility condition in the specific liquefied HFA.
4) Ethanol, solubility aid excipients, PEG valve lubricant are layered narrowing features
Claims 7–10 and 25–30 limit ethanol and solubility-increasing excipients. Claims 11–19 and 27–31 add excipient-specific narrowing when products include PEG valve lubricant and/or flavorants.
From an IP mapping standpoint:
- If the product includes PEG valve lubrication and/or the listed flavorants, it can fall quickly into narrower dependent claim territory.
- If it avoids ethanol within specified limits, it may still infringe Claim 1 unless Claim 1 itself requires ethanol limits (it does not).
Patent landscape: where this patent sits in the US HFA/pMDI formulation space
What 6,641,800 represents
US 6,641,800 is positioned at the intersection of three technology buckets:
- HFA pressurized suspension aerosols
- powder drug with controlled particle size (MMD 0.01–10 µm)
- polymer-based suspending agents soluble in the HFA, with a defined polymer family scope (PVP and close relatives, vinyl acetate and acrylic/methacrylic ester copolymers)
That combination narrows the landscape relative to broader “HFA propellant + drug + micronized powder” prior art. It also narrows relative to generic suspending systems because of:
- the polymer enumerated group,
- the solubility requirement,
- particle size window,
- concentration window of the polymer.
How competing formulations typically differ to reduce overlap
Common divergence points in this formulation space (relevant for freedom-to-operate):
- use of suspending agents outside the enumerated polymer families,
- adjustment of powder particle size distribution outside 0.01–10 µm,
- use of alternative solubility profiles or carriers, or
- avoidance of PEG valve-lubricant or flavorants that match dependent claims.
Claim coverage summary by product element (what to diligence)
Powdered medicament dispersion in liquid HFA
- Ensure the product is truly a suspension aerosol with powder dispersed in liquefied HFA, not a dissolved formulation or an emulsion system with different structural claims.
Mass median diameter measurement
- Validate whether the product’s medicament particle size meets the final composition MMD 0.01–10 µm requirement.
Polymer suspending agent
- Identify polymer identity and its structural class:
- PVP (polyvinylpyrrolidone),
- PVP/vinyl acetate,
- polyvinylacetate,
- acrylic acid/methacrylic ester copolymers,
- or other polymers with recurring 1-ethylene-pyrrolidin-2-one units and the specified copolymer arrangements.
- Confirm polymer concentration falls within 0.00001–10% w/w.
Excipients affecting solubility and ethanol
- Check:
- whether ethanol is included and at what level,
- whether “excipients capable of increasing the solubility of the polymer in the hydrofluoroalkane” are present and at what weight percent.
PEG valve lubricant and flavor modifying excipients
- If PEG is used as valve lubricant:
- check PEG molecular weight (200–3000; or tighter 400–2000),
- check PEG concentration (0.01–4%; or 0.1–2%).
- If minty or sweetener flavors are used:
- check peppermint oil, menthol, saccharin, saccharin sodium.
Key Takeaways
- US 6,641,800 Claim 1 is defined by four hard constraints: liquefied HFA carrier, powdered medicament dispersed with MMD 0.01–10 µm, HFA-soluble polymer suspending agent from a closed enumerated set, and polymer level 0.00001–10% w/w.
- Dependent claims add layered limits: PVP/PVP-vinyl acetate/vinyl acetate and acrylic/methacrylic ester copolymer embodiments, ethanol thresholds, limits on solubility-increasing excipients, PEG valve lubrication parameters, and specific flavorants.
- The patent landscape in this subspace is best attacked by product-dossier differentiation around polymer identity, solubility behavior, and powder MMD in the final formulation, then secondarily around ethanol/PEG/flavor features.
FAQs
-
Does Claim 1 require the HFA to be CF3CHFCF3?
No. Claim 1 is not limited to a specific HFA; CF3CHFCF3 is introduced in dependent claims (e.g., Claim 20, Claim 23).
-
Is ethanol required for infringement of Claim 1?
No. Ethanol limits appear only in dependent claims (Claims 9–10 and related dependent claims), while Claim 1 itself does not impose ethanol content limits.
-
What polymer families does the patent allow as suspending agents?
The polymer must be soluble in the HFA and is selected from enumerated families including recurring 1-ethylene-pyrrolidin-2-one unit polymers and close copolymers, polyvinylacetate, and acrylic acid/methacrylic acid ester copolymers.
-
What particle size metric is required in the claims?
The medicament particles must have mass median diameter (MMD) of 0.01 to 10 microns.
-
Is there a process claim, or is it only composition coverage?
There is a process claim: Claim 32 covers preparing the composition of Claim 1 by dispersing powdered medicament and the suspending agent in liquefied HFA.
References
- US Patent 6,641,800 (claims as provided).
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