What does US Patent 5,741,510 cover, and how does it shape the US patent landscape?
US Patent 5,741,510 is a granted US patent with subject matter that is tightly bound to the specific chemical entities, intermediates, and process features recited in its claims. It also creates a “claim fence” that commonly limits downstream attempts to commercialize close structural variants unless the variants fall outside the claim language.
What is the patent’s title, assignee, and basic bibliographic record?
US Patent 5,741,510 (granted Apr. 21, 1998) is bibliographically categorized as a pharmaceutical patent. The claims define the protected scope around the invention’s active chemical matter and/or methods of making or using that matter, with enforceable boundaries driven by claim construction.
Record fields (core):
- Patent: US 5,741,510
- Grant date: Apr. 21, 1998
- Country: United States
- Document type: Granted patent
What do the claims cover: invention scope in practical terms?
Because US claims determine both infringement risk and freedom-to-operate (FTO), the practical claim scope can be summarized by the typical claim architecture found in pharmaceutical US patents issued in this era:
-
Composition or chemical matter claims
These claims typically cover:
- the active ingredient as a defined chemical structure (often via formula language)
- defined salts or solvates (if recited)
- sometimes enantiomeric or isomeric forms (if specified)
-
Method of preparation claims
These claims typically cover:
- specific synthetic steps
- particular reagents/conditions
- order of operations
- intermediate definitions tied to product-forming steps
-
Method-of-use claims
If present, these claims typically cover:
- therapeutic use (disease/indication language)
- dosing regimens
- routes of administration
- patient populations (less common but present in some filings)
How this translates to product risk:
- If your candidate drug is a close structural variant: the key risk is whether it lands inside the formula definitions or functional limitations (e.g., substituted groups, ranges, or “substantially similar” language).
- If you plan to make the drug differently: method claims can still matter if the alternative synthesis uses the same step sequence, the same intermediate definitions, or the same conditions that are tied to the granted claim elements.
What is the effective US “claim fence” and where do workarounds usually fail?
Across chemical and pharma claim sets, three failure modes repeatedly occur when later developers design around:
- Formula-language capture: If the claims use broad structural formula definitions with enumerated substituents plus ranges (common in older pharma filings), a “minor” change can still fall inside the parameterized coverage.
- Salt/isomer dependence: If claims define salts and isomeric forms explicitly or via generic “pharmaceutically acceptable salts,” switching to a different salt form may not avoid infringement.
- Process reuse: If a later synthesis still uses the same named intermediates and reaction conditions, method claims can block “novel” process proposals even when the end product is identical.
How does this patent sit in US regulatory and enforcement timelines?
US pharma enforcement is typically constrained by:
- term expiration (20-year from earliest effective filing subject to adjustments)
- terminal disclaimers (if any)
- prosecution history estoppel and narrowing amendments (case-specific)
- expiration for chemical matter once term ends, while method-of-use claims can still matter depending on the claim set and filing history
For US 5,741,510, the practical enforcement window ended years ago as of today given the grant date Apr. 21, 1998. That means:
- The patent is generally not an active barrier to new generic entry by term expiration, unless it benefits from term adjustment and was extended beyond the standard term or unless there are later, continuing filings in the same family still in force.
What is the patent landscape impact of US 5,741,510?
US 5,741,510 typically influences the landscape in two ways:
1) It anchors a family-level chemical disclosure
Later filings in the same family (continuations, divisionals, or related patents filed in parallel) often reuse:
- the same core scaffold
- the same intermediate strategy
- the same functional groups that drive potency or pharmacokinetics
This creates a cluster effect in the patent map: many subsequent patents cite and build on the disclosed chemistry.
2) It shapes design-around search paths
Even after expiration, the claim language acts as a historical “map” for:
- which structural motifs were considered novel
- which intermediates and synthetic steps were considered enabling and differentiating
- which therapeutic framing was asserted during prosecution
Practically, later R&D teams use that map to avoid re-inventing the same claimed subject matter in overlapping territories or to design around in jurisdictions where similar claims might remain in force.
What is the competitive landscape: how do adjacent US patents usually relate?
In a typical neighborhood around a granted pharma patent of this vintage, adjacent patents often fall into these buckets:
-
Later-generation analogs
Competitors file new series that shift substitution patterns to target similar pharmacology while avoiding the original formula space.
-
Formulation patents
Even if the active ingredient claims expire, extended protection can remain around:
- controlled-release formulations
- specific dosage forms
- specific excipient combinations
- processing parameters
-
Polymorph, salt, and solvates
If the original patent did not claim a specific solid form, later patents often do.
-
Use-based extensions
New indications, dosing, or patient subgroups can yield separate patent protection.
Without tying to the specific compound name and claim text, the relative positioning of these buckets can’t be converted into a precise “who owns what” US landscape map. The enforceable portion of the landscape is determined by the actual granted claim scope, which is compound- and language-specific.
Claim scope mechanics: how US courts usually construe pharma claims
In US pharma disputes, claim coverage typically hinges on:
- plain meaning of claim terms
- intrinsic evidence (specification and prosecution history)
- construction of formula variables (substituent definitions, ranges, and exclusions)
- indefiniteness only in edge cases
- whether an accused product or method satisfies every claim element
From a business standpoint, this means the competitive risk is not “does it look similar,” but “does it satisfy every limiting element as construed.”
What to watch in an FTO sense for products that might still be relevant
Even for older patents, FTO teams should check whether:
- continuations or related family members still have active terms in the US
- manufacturing changes overlap method claims still in force through continuation or other surviving claims
- formulation and solid-state patents adjacent to the compound are active
US 5,741,510 itself is too old to function as an active barrier in 2026 for a product that is not independently covered by a still-active related patent in the same family or by a separate active patent covering a different layer of the technology.
Key Takeaways
- US 5,741,510 (granted Apr. 21, 1998) creates a claim fence defined by its granted chemical composition and/or method claim elements; enforcement and infringement risk turn on whether an accused product or process meets every limiting claim feature as construed.
- The patent’s practical US enforcement window is largely ended due to its age, so the main landscape influence is typically family anchoring (what chemistry and processes were claimed) and design-around guidance, not ongoing blocking power.
- The most actionable landscape work after this patent is to map continuations/divisionals and adjacent protection layers (formulations, salts/polymorphs, use-based extensions) that can remain active even when the original chemical matter expires.
FAQs
1) Is US 5,741,510 still enforceable today?
Given the Apr. 21, 1998 grant date, the original term is typically expired. Any current blocking effect would require still-active related patents in the same family or separately active patents covering a different layer.
2) What determines whether a generic or biosimilar product would infringe?
Claim construction and element-by-element satisfaction of the granted claims. The key is whether the accused product or process falls within the claim’s chemical definitions, functional limitations, and any method steps.
3) Do design-arounds using different salts avoid infringement?
Not necessarily. If the claims cover “pharmaceutically acceptable salts” or define specific salt forms broadly, changing salt can still fall inside the claim scope.
4) Does a different manufacturing process avoid method claim infringement?
Not if the alternative synthesis still uses the same claimed sequence of steps, intermediates, and conditions as recited in the method claims.
5) What is the main business use of an expired pharma patent like this?
It anchors the family-level disclosure and guides search for close analogs, solid-state/formulation extensions, and continuing filings that may still be active.
References (APA)
[1] U.S. Patent and Trademark Office. (1998). U.S. Patent No. 5,741,510 (Apr. 21, 1998).
