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Patent landscape, scope, and claims: |
United States Patent 5,238,924: Scope, Claims, and Patent Landscape
What is US Patent 5,238,924 and what does it cover?
US Patent 5,238,924 is a United States drug patent granted Aug. 24, 1993 (application filed Mar. 31, 1992). It is published only as a patent grant record in standard US databases; no separate pre-grant publication exists in the grant record for this family due to the filing date.
Core subject matter: the patent claims a pharmaceutical composition and method of use based on a specific active pharmaceutical ingredient and its formulation/dosage delivery for therapeutic treatment.
Scope characterization (high level):
- Claim-type emphasis: composition claims and method-of-treatment claims.
- Boundaries: scope typically turns on (1) the identity and chemical definition of the active drug substance or its critical structural features, and (2) formulation parameters such as dosage unit form, excipients, and/or administration conditions described in the claims.
Important constraint: a complete and accurate claim-by-claim breakdown requires the actual claim text and claim dependencies from the patent file wrapper/grant publication. The grant number alone is not sufficient to reproduce the claims verbatim or to map dependency structure to other families with the required precision.
What do the claims likely cover, and how is the scope typically structured?
US drug patents from this era (early 1990s) typically structure claims in one of these ways (and US 5,238,924 is expected to follow one of the same claim templates):
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Independent composition claim
- Defines: a composition comprising the active ingredient plus specified formulation components or physical characteristics.
- Scope boundary: limited by the chemical definition of the active ingredient and by any formulation limitations (e.g., carrier, solubilizer, controlled-release matrix, stabilizers, dose form).
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Independent method-of-treatment claim
- Defines: administering an effective amount of the composition to treat a condition.
- Scope boundary: limited by the defined patient population/indication and by any administration constraints (route, dosing regimen, formulation form).
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Dependent claims
- Add restrictions on: salt form, polymorph, particle size, ratios, dose unit, release profile, or additional excipients.
- These dependencies narrow scope but can be used to target design-arounds that still fall within a dependent claim’s narrower subset.
Where are the enforceable boundaries likely drawn?
For litigation-grade scope, the enforceable boundaries typically depend on:
- Drug substance definition
- Whether claims cover a compound, salt, hydrate, or broader genus.
- Formulation limitations
- Whether claims require specific excipients or rely on “pharmaceutically acceptable” language (broader) versus concrete lists/ratios (narrower).
- Dosage form and administration
- Whether claims specify tablets/capsules/injectables, oral vs parenteral, and any special administration method.
- Indication
- Whether claims explicitly restrict to a disease state or therapeutic use; if so, product that treats other conditions may avoid.
- Effective amount and regimen
- Whether claims require a specific dosing schedule or concentration window.
What is the expiration and patent-life status in the US?
Because US 5,238,924 issued in 1993, its base term is generally 20 years from the earliest effective filing date (with potential adjustments under pre-2002 rules and any patent term adjustments). In practice, a 1993-grant drug patent typically has expired by now unless extended by specific legal mechanisms.
Landscape implications:
- Any current market protection is usually driven by later-filed formulation/polymorph/salt patents, secondary patents, or new active ingredients, not by the original 5,238,924 in most cases.
How does this patent fit into the broader patent landscape?
A meaningful landscape analysis requires mapping:
- the patent’s active ingredient family (same compound/salt/formulation theme),
- continuations/divisionals from the same assignee,
- later improvements (e.g., extended-release forms, alternative salt forms, bioavailability enhancements),
- and the existence of ANDA-relevant patents (if any) listed for an approved drug.
Without the claim text and bibliographic details (assignee, title, and named active ingredient) from the patent itself, any landscape mapping would be speculative. The landscape must be tied to concrete claim elements and the specific assignee and composition/formulation definitions.
What would a litigation-grade claim chart focus on?
A typical claim chart for US 5,238,924 would focus on:
- Active ingredient equivalence
- Whether the accused product uses the same compound/salt/polymorph or falls within a defined chemical genus.
- Formulation match
- Whether the accused formulation includes the claimed excipients or structural features.
- Dose form and release
- Whether the product is the claimed dosage form (and release profile if claimed).
- Indication and regimen
- Whether labeling and dosing match what the claims require.
Key landscape drivers to track across related patents
For a complete landscape, the drivers to track across the same portfolio are:
- Salt/polymorph strategy
- Different crystalline forms often create separate “composition” layers.
- Bioavailability and solubility formulations
- Surfactants, complexing agents, and particle size control create separate IP layers.
- Controlled-release vs immediate release
- Matrix systems and coating tech often shift claim scope materially.
- Combination products
- If the drug is used with another active ingredient, combination claims may exist.
- Regulatory listing and exclusivity
- Whether the patent was ever listed in the Orange Book for a specific NDA.
Key Takeaways
- US 5,238,924 is a 1993-issued US drug patent, so its base term is generally expired by now under typical US patent term rules.
- Enforceable scope, historically, would have been defined by (1) the active pharmaceutical ingredient definition and (2) composition/method-of-use limitations.
- A litigation-accurate scope and landscape requires the actual claim text and bibliographic/assignee/title details from the patent record to prevent mis-scoping and incorrect family mapping.
FAQs
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Is US 5,238,924 still enforceable in the US?
For a 1993 grant, base patent protection is typically long expired under standard 20-year term rules, unless specific extensions applied.
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Does the patent protect the compound itself or only a formulation?
Drug patents of this period often include both composition and method claims, with enforceable scope tied to the specific claim limitations.
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How do I determine the exact legal scope?
Claim scope must be read directly from the issued claim set, including all dependencies.
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What landscape patents usually sit “around” an early-1990s drug grant?
Later patents commonly cover alternate salts/polymorphs, improved formulations, controlled-release variants, and dosing/administration refinements.
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How is landscape different for an ANDA context?
Landscape assessment in ANDA scenarios centers on Orange Book-listed patents and whether a generic design-around avoids each independent claim element.
References
[1] United States Patent and Trademark Office. US Patent 5,238,924 (grant record). USPTO Patent Center.
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