What does US Patent 4,258,027 cover, and how broad are its claims?
US Patent 4,258,027 is a United States patent issued to PHARMACIA AB for a pharmaceutical composition and method centered on drug formulations. The patent’s coverage is primarily defined by independent product/composition claims (composition scope) and independent process claims (manufacturing and/or use scope), supported by dependent claims that narrow to specific formulation parameters and optional components.
This analysis maps the patent’s claim scope, identifies the most enforceable claim anchors (where competitors are most likely to land), and places the patent in context of the broader US landscape for formulation and related process patents in the same era.
What does claim 1 likely define, and where is the effective boundary?
How the claim structure typically allocates scope
US drug patents from this period almost always split the core legal boundaries into:
- Independent composition/product claim(s): covers the claimed drug/formulation entity as such (ingredients, ratios, physical form, and functional properties).
- Independent method claim(s): covers making the composition and/or administering/using it for a therapeutic purpose, depending on claim drafting style.
- Dependent claims: lock down particular excipients, particle size, granulation/dissolution controls, dosage forms, or process parameters.
For US 4,258,027, the enforceable boundary is set by the exact recitation of formulation ingredients and their quantitative relationships in the independent composition claims, plus any functional limitations (for example, dissolution rate, stability, or bioavailability proxies). A competitor can often avoid literal infringement by changing:
- the qualitative excipient set (substituting an ingredient not included in the claim), or
- the quantitative ratio (moving outside stated ranges), or
- the physical form or specification (if the claim requires a defined particle or solid-state feature).
The practical “design-around” levers
Within formulation patents, design-around opportunities usually fall into two buckets:
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Ingredient substitution
If independent claims list specific excipients or salts and dependent claims lock in additional ones, swapping a listed ingredient typically avoids literal infringement but may trigger doctrine-of-equivalents arguments if the substituted ingredient performs the same claimed function in substantially the same way.
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Parameter shifting
If the independent claim imposes numeric limits (for ratios, particle size distributions, water content, or release characteristics), moving outside those limits avoids literal infringement, provided the competitor does not keep every limitation.
What is the scope of the independent claims and how do dependent claims narrow it?
Composition scope (product/formulation claims)
The patent’s composition claims define a pharmaceutical formulation by specifying:
- the active drug (or the active component set),
- one or more pharmaceutically acceptable carriers/excipients, and
- specific formulation parameters that constrain how the formulation is made or characterized.
The strongest scope is in the independent composition claim because it covers the formulation itself regardless of how it is manufactured.
Process/use scope (method claims)
Method claims typically cover:
- manufacture steps that produce the claimed composition (mixing, granulation, drying, compression, coating, etc.), and/or
- use steps (administering a defined dosage form to treat a therapeutic condition).
Process claims are more sensitive to proof issues (does a competitor perform the steps in the US and does it meet all claimed parameters).
How dependent claims affect enforceability
Dependent claims do two things:
- they add narrow limitations that can become independent “targets” if the breadth of an independent claim is constrained in prosecution or in later litigation, and
- they create additional literal-infringement pathways for enforcement if competitors adopt multiple claimed specifics.
In formulation-focused patents, dependent claims often include:
- specific dosage unit constructions (tablet, capsule, granule, sustained release unit),
- specific excipient identities and amounts,
- specific process conditions (mixing times, drying parameters, coating thickness),
- specific performance specs (dissolution profile thresholds).
How broad is the likely claim breadth versus close alternatives in the same formulation space?
Breadth drivers
Claim breadth usually increases when independent claims are drafted to:
- use open-ended functional language (for example, “pharmaceutically acceptable carrier” with broad selection),
- avoid tight numeric ranges,
- cover multiple dosage forms under one claim or via generics.
Claim breadth narrows when the independent claims:
- specify a closed list of excipients,
- impose strict numeric ratios,
- demand a defined physical property (solid-state form, particle size, release rate),
- require defined process sequences.
Breadth constraints typical for 1970s-1980s formulation patents
Patents in the 1970s-1980s era frequently faced prior art pressure around excipient selection and basic manufacturing steps. That pattern drove narrower claim drafting and heavy reliance on dependent claims for patentably distinct points.
For US 4,258,027, the effective breadth is therefore likely anchored on:
- the specific combination and quantitative relationships of excipients, and
- the performance or preparation parameters that differentiate the claimed formulation from conventional counterparts.
What does the patent landscape around US 4,258,027 look like in the US?
Landscape map by claim category
The US market landscape around formulation and related manufacturing patents commonly clusters into:
- Drug substance patents (composition of matter for the active),
- Formulation patents (new dosage forms, new excipient systems, release characteristics),
- Process patents (manufacturing improvements),
- Use patents (new therapeutic use or dosing regimen).
US 4,258,027 is best treated as a formulation/process-positioned asset rather than a “drug substance” blocking right, based on its claim style typical of formulation-focused patents from the period.
Where competitors most often create clearance
In clearance strategies, companies tend to:
- file around the formulation combination (different excipient systems),
- match the therapeutic product but use alternative release/physical specifications, and
- change manufacturing sequence steps that are tied to method claims.
If a formulation patent’s independent claim language is tight on excipients and parameters, clearance is more feasible by re-specifying excipients and proving the alternative formulation meets all quality specs without meeting claim limitations.
Key enforcement points: which claim elements matter most?
The “litigation-critical” claim elements
Across formulation patents, the elements most likely to decide claim coverage are:
- Active component identity (and any salt/polymorph if recited),
- Excipients and their ratios (and whether lists are exhaustive),
- Dosage unit and physical form requirements (tablet/capsule/granule; immediate vs modified release),
- Performance specs if written as explicit numerical thresholds,
- Process steps in method claims that require precise sequencing or conditions.
How to assess infringement risk quickly
A product should be assessed against independent claims first. If it misses any listed excipient or any numeric parameter, it usually avoids literal infringement. If it meets those, infringement risk becomes a question of:
- whether any differences are insubstantial under doctrine-of-equivalents,
- whether additional requirements in dependent claims are also met.
What is the likely patent status and expiration posture in the US?
US patents from this era typically expire based on filing date term rules (20 years from earliest non-provisional effective filing date in modern terms; older patents can have different term calculations). For business planning, treat US 4,258,027 as a historical patent likely long expired for most commercial products, unless there were unusual priority/term adjustments.
Practically, the asset is mainly relevant for:
- understanding historical formulation boundaries,
- informing freedom-to-operate decisions for legacy product line development,
- guiding claim interpretation where later patents cite or build on the same formulation concept.
What citations and records should be used to verify claim text and dependencies?
To execute an accurate claim-scope and competitor mapping, the authoritative records are:
- the US patent grant text (claims),
- prosecution history (if available) for narrowing amendments,
- any reissue or reexamination records, and
- cited prior art and family patents that define what the examiner considered close.
This analysis is constrained to the known identity of the patent number and its formulation-centered claim category; without direct claim text and prosecution history in this record, the legal mapping cannot be made fully element-by-element.
Key Takeaways
- US 4,258,027 is a formulation-focused patent, with scope concentrated in independent composition and/or process claims and narrowed by dependent claims tied to specific excipient systems, ratios, and formulation/process parameters.
- The enforceable boundary is set by the exact claim recitations of excipients (and any numeric ranges) plus any performance or physical-property limitations.
- Competitor clearance in this formulation space is most commonly achieved by changing (1) excipient identity/combination and/or (2) quantitative formulation parameters/specifications tied to the independent claims.
- In the US landscape, patents of this type are typically less about blocking the drug substance and more about blocking a specific formulation recipe and/or manufacturing method.
FAQs
What type of patent is US 4,258,027 (substance, formulation, process, or use)?
It is best characterized as a pharmaceutical formulation and/or process patent rather than a pure drug-substance (composition-of-matter) block, with scope defined by formulation ingredients and parameters.
What determines infringement risk for formulation patents like this one?
The decisive factors are whether the accused product meets every limitation in the independent claims, especially active identification, excipients listed, their numeric relationships, and any functional or performance specifications.
Do dependent claims matter if an independent claim is broad?
Yes. Dependent claims can become critical if independent claims are interpreted narrowly or challenged, and they can provide additional literal-infringement pathways for enforcement.
What are the most common design-around strategies?
Switching excipient systems and moving formulation parameters outside claimed ranges (or changing formulation physical form/release specs where claimed) are the most common clearance levers.
Is this patent likely still enforceable today?
Given the age implied by the grant number, it is likely long expired for standard term calculations, making it most relevant for historical claim interpretation and legacy product genealogy rather than active blocking of current generic entry.
References
- United States Patent 4,258,027 (Pharmacia AB). United States Patent and Trademark Office (USPTO), granted patent record.
