Details for Patent: 5,439,670
Summary for Patent: 5,439,670
| Title: | Medicinal aerosol formulations | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | A self-propelling aerosol formulation which may be free from CFC's which comprises a medicament, 1,1,1,2-tetrafluoroethane, a surface active agent and at least one compound having a higher polarity than 1,1,1,2-tetrafluoroethane. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Tarlochan S. Purewal, David J. Greenleaf | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | 3M Innovative Properties Co | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US08/086,820 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Patent Claim Types: see list of patent claims | Formulation; Compound; | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | US Drug Patent 5,439,670: Claim Scope, Expiration, Litigation and HFA Inhaler Patent LandscapeU.S. Patent No. 5,439,670 covers hydrofluoroalkane-based aerosol formulations that use 1,1,1,2-tetrafluoroethane, commonly known as HFA-134a, with a surface-active agent and a more polar co-compound. The patent is directed primarily to metered-dose inhaler formulations replacing chlorofluorocarbon propellants. The patent’s practical exclusivity has ended. Its principal commercial value was the formulation technology used during the transition from CFC-containing inhalers to HFA inhalers. It does not create a current blocking right against ordinary HFA-134a inhalers because the patent term expired in 2012, absent an unusual term adjustment or restoration. What does US Patent 5,439,670 protect?The patent protects pharmaceutical aerosol formulations containing four core elements:
Claims 1 and 15 are the principal independent claims. Claim 29 is a separate independent formulation claim focused on isopropyl myristate.
The claims use the term “comprising.” That is legally significant. A formulation can contain additional excipients, propellants, stabilizers, cosolvents, or processing aids and still fall within the literal scope if it contains all required claim elements. When did US 5,439,670 expire?The patent’s statutory term expired in approximately November 2012, based on the relevant early-1990s filing and priority chronology. No current enforceable patent term is generally associated with U.S. Patent 5,439,670.
The patent issued before the Uruguay Round Agreements Act changed the standard U.S. patent term to 20 years from the earliest effective filing date. Accordingly, the issuance date is not the controlling expiration benchmark. Patent term adjustment, if any, would have to be confirmed in the USPTO prosecution record. The ordinary commercial conclusion remains unchanged: the patent no longer blocks launch. How are claims 1 through 14 structured?Claims 1 through 14 form a dependent-claim chain built on claim 1. Claim 1: broad formulation architectureClaim 1 requires:
The claim does not require inhalation, a particular dosage strength, a specific drug, a particular canister, or a particular valve. Those limitations appear in dependent claims. The “higher polarity” requirement is defined functionally by Kauri-butanol value rather than by a single chemical class. This gives the claim a broader conceptual reach than a claim limited only to ethanol or propylene glycol, although the specification and prosecution history would control how the term is construed in litigation. Claims 2 and 11: ingredient listsClaim 2 identifies permissible higher-polarity compounds, including:
Claim 11 identifies a long list of surface-active agents, including:
These lists are limiting for the specific dependent claims, but they do not necessarily limit claim 1 to those listed substances. A formulation may infringe claim 1 with a different qualifying compound if it satisfies the functional and compositional limitations. Claims 3 through 5: route and physical stateClaim 3 limits the formulation to oral or nasal inhalation. Claim 4 requires medicament particles with a median particle size below 10 microns. This limitation is relevant to suspension products in which micronized drug particles are dispersed in the propellant system. Claim 5 covers drug in solution. The patent therefore reaches both major pMDI formulation architectures:
The distinction matters because a solution product may avoid claim 4 but can still fall within claims 1, 3, 5, 6-14, or the corresponding claim 15 chain. What formulation concentrations and ratios are claimed?Claims 6 through 10 and 20 through 24 define quantitative HFA-134a and co-compound ranges.
The ratio claims are nested. A formulation with an HFA-134a-to-ethanol ratio of 10:1, for example, would fall within all three ratio ranges, assuming the other elements are present. Claim 14 and claim 28 require medicament content of 0.01% to 5% by weight. That is a broad range covering many therapeutic aerosol products, although commercial products may be characterized by dose per actuation rather than total formulation weight. Claim 12 and claim 26 require a surface-active-agent-to-medicament weight ratio of 1:100 to 10:1. This range is unusually broad and can cover formulations with very low surfactant loading as well as formulations in which surfactant is present at a substantial multiple of the drug weight. Which drugs are expressly covered?Claims 13 and 27 identify the following medicaments:
The express drug list is commercially important because it maps onto bronchodilator, corticosteroid, mast-cell stabilizer, and anticholinergic inhaler products. The list does not necessarily define the full scope of claim 1 or claim 15. Those independent claims recite “a medicament” without limiting the drug to the named compounds. A competitor using a different active ingredient could still implicate the independent claims if the formulation satisfies the remaining limitations. What is the scope of claim 15’s CFC-free limitation?Claim 15 requires that the formulation be free of chlorofluorocarbons. It otherwise tracks claim 1:
The claim is directed to the regulatory and technical shift away from CFC propellants under the Montreal Protocol and U.S. ozone-depletion controls. The phrase “free of chlorofluorocarbons” is narrower than a general “environmentally acceptable” limitation. HFA-134a itself is a hydrofluoroalkane, not a chlorofluorocarbon. Claims 15 through 28 largely duplicate claims 1 through 14 while adding the CFC-free limitation. For claim-chart purposes, the patent can be analyzed as two parallel claim families:
What does claim 29 add?Claim 29 requires isopropyl myristate. It is independently drafted and does not depend on claim 1 by reference. Its required elements are:
Because claim 29 uses “comprising,” isopropyl myristate must be present, but other surfactants or excipients may also be present. The claim may cover isopropyl myristate as a co-surfactant, dispersing aid, or formulation stabilizer, depending on the specification’s disclosure and the product composition. A product containing ethanol, oleic acid, HFA-134a, and isopropyl myristate would be a close historical claim-chart candidate. The patent’s expiration eliminates current infringement exposure, but the formulation architecture remains relevant for prior-art and freedom-to-operate analysis involving later patents. What patent landscape surrounded HFA-134a inhalers?The patent landscape developed around four technical problems:
U.S. Patent 5,439,670 occupies the formulation-composition segment. It is less focused on:
Those adjacent rights often determined commercial freedom to operate after the basic HFA formulation patents expired. Representative competing formulation approaches
The critical claim boundary is HFA-134a. A formulation using only HFA-227ea and no HFA-134a would ordinarily fall outside these claims, subject to any equivalents analysis and the actual product composition. What is the Orange Book status of US 5,439,670?U.S. Patent 5,439,670 is not a current Orange Book exclusivity barrier. The Orange Book lists patents submitted by sponsors for approved drug products, but the presence or absence of a patent in the Orange Book does not determine whether a formulation patent is valid or enforceable in all circumstances. The patent has expired and therefore cannot support a current Paragraph IV blocking strategy. The relevant regulatory pathways for products using the claimed formulation technology are:
A biosimilar analysis is not relevant because the claimed products contain conventional small-molecule drugs, not biologic active ingredients. Regulatory competition would proceed through ANDA or 505(b)(2) pathways rather than the biosimilar pathway. Which companies were exposed to the patent’s formulation scope?The patent’s technical scope was relevant to companies commercializing CFC-transition inhalers, including major respiratory-product manufacturers such as:
The patent itself does not establish that each company infringed, licensed, challenged, or settled the patent. Product-level analysis requires the formulation composition, manufacturing date, and relevant patent-family records. Commercial products such as albuterol HFA, beclomethasone HFA, fluticasone HFA, and combination inhalers illustrate the broader market transition, but product inclusion alone does not prove coverage by U.S. Patent 5,439,670. Were there Paragraph IV challenges or litigation?No current Paragraph IV risk exists for U.S. Patent 5,439,670 because the patent has expired. A historical Paragraph IV challenge would have required an ANDA applicant to certify that the patent was invalid, unenforceable, or not infringed. The statutory framework is under the Hatch-Waxman Act, 21 U.S.C. § 355(j)(2)(A)(vii)(IV). Because the patent is no longer enforceable, a later ANDA applicant would not need to use the patent as a launch-blocking litigation target. No widely reported, currently operative settlement agreement, injunction, or exclusion order is associated with this patent. Patent-specific litigation should be checked against PACER and USPTO Patent Center records rather than inferred from litigation involving later HFA inhaler patents. How strong was the patent estate?Historical strengthThe patent had meaningful historical value because it claimed a broad formulation combination at a time when the industry was replacing CFC propellants. Its strengths included:
WeaknessesThe main vulnerabilities were:
The patent’s current strength is zero as an exclusionary right because it is expired. Its residual value is evidentiary: it may be cited as prior art against later claims directed to similar HFA-134a, ethanol, surfactant, or isopropyl-myristate formulations. What generic launch scenarios exist?Current launch scenarios are not constrained by this patent. A generic or follow-on manufacturer can generally pursue:
The remaining commercial barriers are more likely to involve:
Does the patent create manufacturing or geographic barriers?No current geographic barrier exists in the United States from U.S. Patent 5,439,670. A U.S. patent has no direct exclusionary effect in Europe, Canada, Japan, China, or other jurisdictions. International risk would depend on counterpart patents in the same family and their individual expiration dates. The formulation technology may also have been protected by national counterparts, continuation applications, or related patents directed to specific drugs, devices, or manufacturing methods. Manufacturing processes can remain protected separately even after a composition patent expires. Relevant process questions include:
Those issues are outside the literal composition scope of the claims supplied. Key Takeaways
Frequently Asked QuestionsCan an HFA-134a inhaler still infringe US 5,439,670?The patent is expired, so an HFA-134a inhaler cannot generate current liability under that patent. The formulation may still be relevant to later, unexpired patents. Does ethanol in an inhaler automatically trigger US 5,439,670?No. Ethanol is one listed higher-polarity compound, but all required elements, including HFA-134a, a medicament, and a surface-active agent, must be present for literal coverage. Is isopropyl myristate required for all claims?No. Isopropyl myristate is specifically required by claim 29 and is listed as a surfactant in claim 11 and claim 25. It is not required by independent claims 1 or 15. Are dry-powder inhalers covered by this patent?Ordinary dry-powder inhalers do not contain the claimed HFA-134a propellant system and therefore fall outside the literal aerosol-composition claims. Can later patents still block an HFA inhaler after this patent expired?Yes. Later patents may cover a specific drug formulation, device, valve, actuator, canister coating, dose counter, manufacturing process, or combination product even though U.S. Patent 5,439,670 has expired. References
More… ↓ |
Drugs Protected by US Patent 5,439,670
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Patented / Exclusive Use | Submissiondate |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| >Applicant | >Tradename | >Generic Name | >Dosage | >NDA | >Approval Date | >TE | >Type | >RLD | >RS | >Patent No. | >Patent Expiration | >Product | >Substance | >Delist Req. | >Patented / Exclusive Use | >Submissiondate |
International Family Members for US Patent 5,439,670
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
|---|---|---|---|---|---|
| Australia | 4595689 | ⤷ Start Trial | |||
| Australia | 631155 | ⤷ Start Trial | |||
| Canada | 2004598 | ⤷ Start Trial | |||
| >Country | >Patent Number | >Estimated Expiration | >Supplementary Protection Certificate | >SPC Country | >SPC Expiration |
