Details for Patent: 5,674,472

US Patent 5,674,472: What Is Claimed, What It Covers, and Where the Patent Landscape Tightens

United States Drug Patent 5,674,472 is a formulation-and-device claim set centered on a metered dose inhaler (MDI) canister that holds particulate fluticasone propionate (FP) (alone or in combination with selected bronchodilators), delivered from a canister using 1,1,1,2-tetrafluoroethane (HFA-134a) as the propellant, with tight constraints on particle size, surfactant level, and respirable fraction.

The strongest enforceable perimeter is the combination of:

• FP (or its physiologically acceptable solvate) + HFA-134a (core claims 1, 9, 31)
• “Consisting essentially of” language limiting other excipients by function, paired with a hard cap on surfactant (<0.0001% w/w based on medicament weight) (claims 1, 9, 31, 34, 16)
• Particle size <100 microns and low surfactant (claims 1, 9, 31, 34, 16)
• A device layer that turns the canister into an MDI via a metering valve and a channeling device (claims 26–29)

Below is a claim-by-claim scope dissection and a practical landscape read on what is likely protected and what is exposed.

1) What Is the Core Claim Scope (Claims 1, 9, 31)?

Claim 1 (core FP + HFA-134a particulate, low surfactant, low particle size)

A canister suitable for delivering a pharmaceutical aerosol formulation with:

• Container withstands vapor pressure of the propellant used
• Container is closed with a metering valve
• Contains a pharmaceutical aerosol formulation “consisting essentially of”:
  • Particulate medicament = fluticasone propionate or physiologically acceptable solvate
  • 1,1,1,2-tetrafluoroethane as propellant
• Formulation contains <0.0001% w/w surfactant based on the weight of the medicament
• Particulate medicament present at 0.005% to 5% w/w relative to total formulation
• Particles have particle size <100 microns

This claim is the conceptual “center of gravity”: it pins down a particulate FP/HFA-134a aerosol with extremely low surfactant and sub-100 micron particles, delivered via metering valve canister.

Claim 9 (same physics, but expressed as “consisting essentially of” with stricter recitation)

Claim 9 repeats the same essential structure as Claim 1 in slightly altered wording, still requiring:

• FP (or solvate)
• HFA-134a
• <0.0001% w/w surfactant
• 0.005% to 5% w/w medicament
• particle size <100 microns

Claim 31 (tightens medicament loading + explicit FP formulation)

Claim 31 narrows:

• FP only (no broader “solvate” wording in the provided text, but it still uses “fluticasone propionate” and HFA-134a)
• Surfactant <0.0001% w/w
• Medicament present at 0.01% to 1% w/w
• particle size <100 microns

This is the narrower “sweet spot” inside the broader Claim 1 range.

Implication for landscape: any competing product that moves away from particulate <100 microns and sub-0.0001% surfactant exits the strict wording quickly, even if the delivered active is still FP and the propellant is still HFA-134a.

2) What Additional Limitations Exist on Materials and Container Construction (Claims 2–7, 10–15, 18–23, 32–35)?

A second layer specifies canister container build:

• Plastics coated, lacquer-coated, or anodized (multiple dependents: claims 2, 10, 18, 30 plus others)
• Metal can (claims 3, 11, 19)
• Metal can plastics-coated (claims 4, 12, 20)
• Aluminum can (claims 5, 13, 21)
• Aluminum can plastics-coated (claims 6, 14, 22)
• Aluminum can plastics coated in the narrower FP-only formulation (claim 32)
• Combination analogs still use aluminum plastics-coated (claims 35)

These are not substitutes for the formulation limitations; they are narrower “implementation” windows.

Implication for landscape: if a third party uses a different can metallurgy or coating, it may still infringe the core formulation canister claim if their canister meets “container capable of withstanding vapor pressure” and is closed with a metering valve and contains the specified formulation. The coating claims add incremental scope only where the core formulation is otherwise met.

3) What Does “Consisting Essentially of” Do Here (And Why It Matters)?

The provided claim text repeatedly uses “consisting essentially of” for the formulation. Practically, that language limits what can be present while allowing minor amounts that do not materially affect the basic and novel characteristics. Here, the “basic and novel characteristics” are tightly operationalized by:

• Surfactant capped at <0.0001% w/w
• Particle size <100 microns
• Medicinal loading ranges
• Specific active(s) (FP and optional add-on bronchodilator actives)

Even where “surfactant” is not “free of,” the surfactant threshold is extremely low, which constrains excipient selection and manufacturing formulation choices.

4) How Are Combinations Claimed (Claims 16–17, 24–25, 34)?

Claim 16 (dual medicament: FP + selected add-on)

Claim 16 introduces a second particulate medicament selected from:

• salmeterol
• salbutamol
• beclomethasone dipropionate
• plus physiologically acceptable salts/solvates

It still requires:

• FP or physiologically acceptable solvate
• HFA-134a
• <0.0001% w/w surfactant based on medicament weight
• Total particulate medicament present at 0.005% to 5% w/w
• particle size <100 microns

So the claim is a combination aerosol canister delivering particulate FP with another selected bronchodilator or related corticosteroid, still with HFA-134a and low surfactant.

Claim 17 (same combination space but with stricter recitation form)

Claim 17 is another combination expression, with the same active set and constraints in the provided text.

Claim 24 (explicit “contains” language for dual actives)

Claim 24 is dependent on 16 or 17 and requires:

• FP plus salmeterol or salbutamol (or acceptable salts)

Claim 25 (specific salt/variant)

Claim 25 specifies:

• fluticasone propionate + salmeterol xinafoate

Claim 34 (explicit dual particulate: FP + salmeterol xinafoate)

Claim 34 requires:

• Formulation consists essentially of particulate medicaments:
  • fluticasone propionate
  • salmeterol xinafoate
• HFA-134a
• <0.0001% w/w surfactant
• medicament 0.01% to 1% w/w
• particle size <100 microns
• dependents add aluminum can plastics-coated (claim 35) and formulation free of surfactant (claim 36)

Implication for landscape: combinations that still satisfy HFA-134a, particulate <100 microns, and ultra-low surfactant are inside a relatively defined zone. The most targetable infringement hook is Claim 34/35/36 for FP + salmeterol xinafoate if their formulation is truly surfactant-free or below the surfactant threshold.

5) Respirability Is Claimed as a Quantitative Limitation (Claim 8, 30)

• Claim 8: formulation has respirable fraction of 20% or more by weight of the particulate medicament
• Claim 30: dependent similarly on Claim 16 or uses the same threshold

Implication for landscape: if an accused formulation meets all compositional constraints but fails on measured respirable fraction, it likely falls outside these respirability-specific dependents. Respirability measurement methods will govern infringement, but within the text, respirability is a real gating attribute.

6) Surfactant “Free” Dependents Tighten Further (Claims 33, 36, 37–38)

The portfolio includes both:

• explicit numerical cap (<0.0001% w/w) and
• explicit “free of surfactant” dependents:
  • Claim 33: free of surfactant (dependent on Claim 31)
  • Claim 36: free of surfactant (dependent on Claim 34)
  • Claim 37: free of surfactant (dependent on Claim 1)
  • Claim 38: free of surfactant (dependent on Claim 16)

Implication for landscape: “free of surfactant” likely captures formulations that omit surfactant entirely (or at least below detection/functional presence), but even if total surfactant is already <0.0001%, these dependents still matter for claim differentiation and for narrowing invalidation risks.

7) Device Scope: When Does a Canister Claim Become an MDI Claim (Claims 26–29)?

The device layer is straightforward:

• Claim 26: an MDI comprising a canister of Claim 1 fitted into a channeling device for nasal or oral inhalation
• Claim 27: same, but linked to Claim 9
• Claim 28: linked to Claim 16
• Claim 29: linked to Claim 17
• Claims 41–44: formulation in a form suitable for inhalation into the lungs (dependent language)

Implication for landscape: if a competitor’s aerosol product uses the same canister formulation constraints, the independent device argument becomes relevant because the claim ties an MDI to the specified canister. The “channeling device” is broad; infringement will hinge on whether the product uses the metering valve canister with the claimed formulation.

8) Practical Claim Coverage Map (What You Can Say the Patent Covers)

9) Patent Landscape Read: Where This Claim Set Likely Sits (Technology Buckets)

Without the remainder of the US patent family record, prosecution history, and the full bibliography of related art, the landscape can still be segmented into the technology buckets this patent explicitly occupies.

A. HFA-134a particulate MDI with FP

This patent is not just “FP + HFA-134a.” It requires:

• particulate medicament with particle size <100 microns
• very low surfactant (<0.0001% w/w)
• delivered through an MDI metering valve canister

That combination is narrow enough that many “FP/HFA” products that use different particle engineering or higher surfactant/excipient content fall outside.

B. Dual therapy: FP + salmeterol (or salbutamol) in a single canister

The combination claims explicitly name:

• salmeterol (including xinafoate)
• salbutamol and also include beclomethasone dipropionate in the “selected from” list.

Coverage tightens further in:

• Claim 25 (FP + salmeterol xinafoate)
• Claim 34 (explicit formulation and loading range)
• surfactant-free dependents (36)

C. Particle engineering and respirability

Claims 8 and 30 add a measurable performance attribute: respirable fraction ≥20%.

This creates a second exclusion path for competitors: even if they match composition and particle size, they must align with respirable performance.

D. Surfactant strategy

The surfactant threshold is exceptionally low. That suggests this patent targets formulation architectures designed to avoid typical aerosol stabilizers.

Competitors using standard surfactant systems are likely exposed on literal surfactant limits, unless their surfactant remains below the threshold and avoids detection or functional presence arguments.

10) Freedom-to-Operate Risk Signals Based on the Claim Language

This patent’s risk profile is driven by literal read, because multiple limitations are hard and numeric.

Higher-risk design-around targets

• Switching propellant away from HFA-134a (avoid the propellant limitation entirely)
• Increasing particle size above 100 microns
• Adding surfactant above 0.0001% w/w (or using functional surfactant that undermines “consisting essentially of”)
• Operating outside medicament loading ranges (0.005%–5% or 0.01%–1% in narrower dependent)
• Dropping respirable fraction below 20% (where that dependent matters)

Lower-risk areas (relative)

• Can construction changes (metal vs aluminum vs coating) alone will not avoid claims if formulation limitations remain met.
• Device channeling device design is broad in claim text; changing the channeling device does not by itself avoid the “MDI with metering valve canister” structure if the product otherwise uses the same claimed canister formulation.

Key Takeaways

• US 5,674,472 is a canister/MDI patent defined by particulate formulation constraints, not just by drug actives: FP (or FP + selected second actives) + HFA-134a plus particle size <100 microns and surfactant <0.0001% w/w (by medicament weight).
• Combination coverage is explicit for FP + salmeterol (including salmeterol xinafoate) and for FP + salbutamol, with tighter narrowing in Claim 34 and Claim 25.
• Respirable fraction ≥20% is a performance limiter in dependents, adding a measurable boundary to infringement.
• Device claims (26–29) generally follow the canister: if a product uses the same metering-valve canister formulation, it can fall into MDI claim scope despite channeling-device variations.
• Container metallurgy/coatings are mostly incremental, not primary escape routes, because the core enforceable boundary is the formulation.

FAQs

1. Does this patent cover only fluticasone propionate alone?
   No. It covers FP alone (Claims 1, 9, 31) and FP combinations with salmeterol, salbutamol, and beclomethasone dipropionate (Claims 16, 17, 24, 25, 34).

2. What exact surfactant limit drives the formulation boundary?
   Claims require less than 0.0001% w/w surfactant based on the weight of the medicament, with additional dependents requiring formulation free of surfactant.

3. How is particle size constrained?
   The claims require particle size of less than 100 microns for the particulate medicament.

4. Where do the MDI/device claims fit relative to the canister claims?
   Claims 26–29 turn the specified canister into a metered dose inhaler by requiring the canister fitted into a channeling device for nasal or oral inhalation.

5. Is respirable fraction part of the independent scope?
   No. Respirable fraction ≥20% appears in dependents (Claims 8 and 30), so it applies only when those dependent claim features are asserted.

References

[1] United States Patent 5,674,472.