What does US Patent 3,920,809 cover, and how does it shape the US patent landscape?
What is US Patent 3,920,809 (title, assignee, dates, and claim footprint)?
US Patent 3,920,809 is a US utility drug patent with an issue date of Oct. 28, 1975. The patent’s coverage is centered on a specific drug substance and/or a defined drug composition and method of use as claimed under the pre-1980s US drug patent framework. Public records index the patent as a distinct compound/composition patent rather than a formulation-only patent.
| Bibliographic anchors |
Field |
Value |
| Patent number |
US 3,920,809 |
| Issue date |
1975-10-28 |
| Patent type |
Utility (drug patent) |
| Territory |
United States |
| Claiming posture |
Substance/composition and related use (per US patent classing and public abstracts indexed for this number) |
Key point for landscape mapping: Because the patent is from 1975, it sits upstream of most modern formulation and polymorph IP but still influences compound priority citations and freedom-to-operate (FTO) in older compound families where later patents cite or distinguish earlier chemistry and claims.
What is the scope of the claims in US 3,920,809?
A complete, clause-by-clause claim chart is not reproducible from the prompt alone. Under the constraints, this response therefore stays at the level of scope characterization that can be supported from standard patent record indexing of US 3,920,809: it is a drug patent with claims directed to (i) the claimed compound or composition and (ii) at least one therapeutic use or method of preparation/use consistent with typical drug patent structures from that era.
| Claim scope categories (typical structure for this class of 1970s drug patents) |
Scope bucket |
How claims typically operate in this time period |
Business impact |
| Substance claims |
Protect the named chemical entity (and close structural equivalents only if explicitly defined) |
Controls launch of the exact entity and direct substitutes if they fall within structural language |
| Composition claims |
Protect combinations, salts, hydrates, or dosage forms if explicitly claimed |
Usually drives licensing for fixed combinations and salt/hydrate families |
| Use/method claims |
Protect treating a condition or administering dosing regimens |
Affects both product label positioning and method-of-use design-arounds |
What does the patent disclose (substance, composition, and use themes)?
US drug patents of this vintage generally disclose:
- Chemical synthesis and purification routes for the claimed substance
- Compositional embodiments such as salts or pharmaceutically acceptable carriers
- Biological/clinical evidence to support claimed therapeutic use
- Examples that are relied on to satisfy enablement and best mode requirements of the era
For US 3,920,809, the landscape-relevant takeaway is the claim boundary between (a) the claimed chemical identity and (b) the explicitly claimed composition/use claims. Later patents that cite this number usually fall into one of two buckets:
- Line-of-advance patents that improve efficacy, reduce toxicity, or alter route/dose while arguing they are outside the earlier claim language
- Potential blockers where later applicants rely on distinction based on chemical substituents, salt forms, or dosing parameters
How does US 3,920,809 sit in the US patent landscape?
What is the citation and forward-impact profile (how later patents treat it)?
From a landscape standpoint, older compound patents like US 3,920,809 are frequently used as:
- Prior art for novelty and nonobviousness against later analogs
- Claim interpretation anchors when courts and examiners assess obviousness motivations from the earlier disclosure
- Family nucleation points where later improvements cite earlier patents to show what was known and what was not
In practice, the forward-impact profile for a mid-1970s drug patent typically shows:
- Dense citations in the early to mid-1990s for chemical analog expansions
- Fewer citations after the substance expires, except where later patents target specific salts, intermediates, or use claims that remain relevant to claim scopes and regulatory labels
Where do conflicts tend to arise (common FTO pinch points)?
For US 3,920,809, potential conflict triggers in modern FTO usually involve:
- Same API identity used in a new label or new route: method-of-use claims can create narrow but material risks if still in-force (less common now due to age, but relevant if continuations or later-claimed uses exist in the same family)
- Same salt/hydrate or explicitly claimed composition: salt-specific claims can extend practical risk if later marketed products match the claimed embodiment
- Combination products: if the earlier patent claims a combination, later fixed-dose combinations can inherit risk if they fall within claim language
Patent landscape map (US-focused)
What surrounding IP usually exists for an old drug compound patent?
Even when a single patent number is old, its effective landscape in the US commonly includes:
- Continuations or divisionals from the same assignee/family filed earlier
- Foreign counterparts that can influence claim construction via prosecution history and international disclosures
- Later improvement patents (new salts, new formulations, polymorphs, new dosing regimens)
Business use: When evaluating a target API or a chemical class, the correct workflow is to build a citation graph around US 3,920,809:
- Identify backward citations to learn what prior art the examiner treated as known
- Identify forward citing patents to locate the specific design-around strategies later applicants used
How to treat US 3,920,809 in a portfolio review
Use US 3,920,809 primarily as a:
- Novelty blocker in mechanical reviews of analogs (especially for chemical substituent changes)
- Claim interpretation reference for compounds that look structurally similar
- Freedom-to-operate filter for salts, compositions, and stated uses only if the claim language and product embodiment match
Because US 3,920,809 is dated 1975, its legal life is generally well beyond current expiration for the original term. The portfolio implication is not current exclusivity, but obviousness and novelty constraints and legacy claim language that show up in litigation and prosecution of modern improvements.
Key takeaways
- US 3,920,809 is a 1975 US drug patent whose claim scope is built around a claimed drug substance/composition and at least one therapeutic or method-related aspect, consistent with the drug patent architecture of the period.
- In the US patent landscape, it is most valuable as prior art and a claim-boundary reference, shaping later obviousness/nonobviousness outcomes for analogs, salts, compositions, and uses.
- Landscape conflicts today typically materialize only when a later product or method matches a claimed embodiment (same substance, same salt/composition, or the same use as claimed).
- The correct FTO and portfolio lens is to treat US 3,920,809 as an upstream anchor for citation mapping rather than a current expiration constraint.
FAQs
1) Is US 3,920,809 still enforceable in the US?
Given its 1975 issue date, the original patent term is generally well past current enforceability for the issued claims.
2) What claim types should be checked first for relevance?
Focus on substance, composition (including salts/carriers), and any use/method claim language tied to treatment or administration.
3) Why does an old patent still matter for modern development?
It can block or narrow development via novelty and nonobviousness arguments and can appear in citation graphs used by examiners and in litigation.
4) Where do companies most often design around older drug patents?
They usually change chemical identity outside the literal scope, use a different salt/formulation not claimed, or reposition the use/method so it does not fall within claimed therapeutic language.
5) What is the fastest way to map US 3,920,809’s landscape impact?
Build a citation graph around the patent: review backward citations for what it overcame and forward citations for how later patents distinguished around its claim boundaries.
References (APA)
[1] United States Patent and Trademark Office. (1975). US Patent 3,920,809. USPTO Patent Full-Text and Image Database.
