US Patent 4,927,814: Scope of Claims and US Landscape
United States Patent US 4,927,814 claims a family of diphosphonate compounds defined by a Markush-type chemical formula, plus methods of use and pharmaceutical compositions for treating or preventing calcium metabolism disturbance or disease. The operative claim scope is concentrated in (i) the structural “diphosphonate” formula, (ii) specific N-alkylamino substitutions and salts, and (iii) administration (dose range expressed as mg P/kg) and composition claims for the same actives. The claim set is narrow at the disease-utility level (calcium metabolism disturbance) and narrow at the structural level (specific diphosphonate core with defined R substituents and N-substitution patterns).
What is the claim center of gravity?
1. Core product protection (Claims 1-5)
The patent’s product claims are structured as:
- Claim 1: A diphosphonate compound of a specified formula (the formula is redacted in the claim text you provided, but the claim is clearly a definitional Markush formula for the diphosphonate scaffold).
- Claims 2-5: Narrowing to particular embodiments:
- Claim 2: “wherein R1 is methyl.”
- Claims 3-5: Three specifically designated diphosphonic acids, plus physiologically active salts (claim 3 and claim 4 explicitly cover “and the physiologically active salt thereof”; claim 5 covers the salts as well, but the claim text you provided ends “and the physiologically active salt.”)
The three designated actives are:
- 1-hydroxy-3-(N-methyl-N-nonylamino)-propane-1,1-diphosphonic acid (+ physiologically active salt)
- 1-hydroxy-3-(N-methyl-N-pentylamino)-propane-1,1-diphosphonic acid (+ physiologically active salt)
- 1-hydroxy-3-(N-isobutyl-N-methylamino)-propane-1,1-diphosphonic acid (+ physiologically active salt)
These are all propane-1,1-diphosphonic acid derivatives with a 1-hydroxy group and an N-substituted 3-(N-alkylamino) side chain.
2. Use protection (Claims 6-9)
- Claim 6: A method for treating or preventing “calcium metabolism disturbance or disease” using a pharmaceutically effective amount of the compound of claim 1.
- Claim 7: Method of claim 6 with a dose range of 0.01-10 mg P/kg per day, where dosing is expressed as mg of phosphorus (P) from the diphosphonate.
- Claim 8: Method using at least one of the three designated compounds of Claims 3-5.
- Claim 9: Method of claim 8 with the same 0.01-10 mg P/kg per day dose range.
The practical effect: claims 6-9 cover both (i) the whole Markush genus in claim 1 and (ii) the named trio of embodiments, with the dose constraint acting as an additional limiting feature.
3. Composition protection (Claims 10-12)
- Claim 10: A pharmaceutical composition containing an effective amount of at least one compound of claim 1.
- Claim 11: Composition containing an effective amount of at least one compound of claim 2 (meaning, at least one embodiment consistent with R1 = methyl).
- Claim 12: Composition containing an effective amount of at least one of the three specifically designated compounds (Claims 3-5).
The composition claims are typical formulation claims: “in a pharmaceutically acceptable carrier,” without further limiting excipients in the claim text provided.
What exactly do the claims cover (and what they do not)?
Structural boundaries
Within the family, the patent’s claim logic is:
- Diphosphonate core is required (“diphosphonate compound” and “propane-1,1-diphosphonic acid” appears in the designated embodiments).
- A defined substitution pattern exists, with R1 taking at least the “methyl” value (claim 2).
- A defined side chain at the 3-position exists via N-substituted amines, with the patent naming:
- N-methyl-N-nonylamino
- N-methyl-N-pentylamino
- N-isobutyl-N-methylamino
- Physiologically active salts are explicitly within scope for the designated acids (Claims 3-5).
Out of scope based on the claim set you provided:
- Compounds not matching the diphosphonate formula (claim 1) are not covered by the genus claim.
- Non-specified R-groups beyond “R1 is methyl” (claim 2) and the explicitly named N-alkylamino substitutions (claims 3-5) are not explicitly captured in the text you supplied, unless they fall inside the claim 1 formula.
Use boundaries
- The utility is limited to treating or preventing “calcium metabolism disturbance or disease.”
- The claims do not enumerate specific diseases (for example, osteoporosis, Paget’s disease, bone metastases). The provided claim text does not list those.
- Dose limitation is only present in claims 7 and 9, not in claim 6 or claim 8 as provided.
Method-of-use boundary vs. compound genus boundary
There are two layers:
- Claim 6: uses the genus compound of claim 1 at a “pharmaceutically effective amount,” without a specific dose.
- Claim 7: further restricts the same method to a specific daily dosing band in mg P/kg.
- Claims 8-9: further restrict method use to at least one of the three named compounds, with the dose band again present in claim 9.
How broad is the patent: genus vs. specific embodiments?
Claim coverage map
| Claim |
Coverage type |
Structural scope |
Disease/utilization scope |
Dose/administration limits |
| 1 |
Product (genus) |
“diphosphonate compound of formula” |
Not stated (compound claim) |
None |
| 2 |
Product narrow |
claim 1 with R1 = methyl |
None |
None |
| 3-5 |
Product specific |
three named acids + salts |
None |
None |
| 6 |
Method (genus) |
compound of claim 1 |
treating/prophylaxis of “calcium metabolism disturbance or disease” |
None (generic effective amount) |
| 7 |
Method (genus + dose) |
compound of claim 1 |
same |
0.01-10 mg P/kg/day |
| 8 |
Method (specific) |
at least one named acid |
same |
None (effective amount) |
| 9 |
Method (specific + dose) |
at least one named acid |
same |
0.01-10 mg P/kg/day |
| 10 |
Composition (genus) |
at least one claim 1 compound |
same |
effective amount (no dose band) |
| 11 |
Composition (R1=methyl) |
at least one claim 2 compound |
same |
effective amount (no dose band) |
| 12 |
Composition (specific) |
at least one named acid |
same |
effective amount (no dose band) |
Practical breadth read
- Products: claim 1 is broad within its formula; claims 3-5 are narrow and directly enumerated.
- Uses: claim 6 and claim 8 are broader than claim 7 and 9 because they omit the dose band; dose-limited claims provide a secondary layer of enforceability around dosing practice.
- Compositions: claim 10-12 are enforceable against formulations using the claimed actives, but they do not add additional formulation mechanics in the provided text.
What are the key claim limitations to diligence competitors?
Dose expression is phosphorus-normalized
The method claims define dosing as mg P/kg/day. For competitor assessment, this means:
- dosing is tied to the phosphorus content of the diphosphonate, not just the weight of the drug salt or acid.
- a potential non-infringing approach could be to deviate outside 0.01-10 mg P/kg/day, but only if the competitor is practicing outside claim 7/9; claim 6/8 still exist for “effective amount” unless other factual limitations apply.
Disease term is generic
“Calcium metabolism disturbance or disease” is a broad functional utility phrase, but it still constrains to calcium-related indications. Competitors targeting unrelated indications may seek to avoid the utility claim coverage by treating outside that definition.
Salts are captured only as “physiologically active salts” for the designated acids
Claims 3-5 expressly include salts; claim 1’s formula claim likely covers compounds in general, but the text you supplied only explicitly mentions physiologically active salts for claims 3-5. Practical diligence should treat salts as within scope for the named acids at minimum, and potentially broader for claim 1 depending on the full spec.
US patent landscape: how to position this patent in freedom-to-operate
Claim strategy indicators
The patent uses a standard triad:
- Genus compound (claim 1)
- Specific named exemplars + salts (claims 3-5)
- Method + composition claims linked to the same actives
This means enforcement can be asserted across multiple infringement theories:
- direct compound infringement (product manufacture/import/sale)
- method infringement (administration)
- formulation infringement (pharmaceutical compositions)
Competitors seeking to design around should focus first on whether their molecules fall within the diphosphonate formula of claim 1 and whether their dosing falls within the P/kg band for claims 7 and 9.
Potential cluster of related assets
Based on the claim language alone, there are three “landscape nodes” that typically coexist in this chemical space:
- Diphosphonate scaffold families (generally older bone and calcium-modulation chemistries) that may lead to overlapping genus coverage disputes.
- Specific N-alkylamino substituted propane diphosphonates where enforcement often concentrates on a handful of exemplars, like the three named in claims 3-5.
- Dosing regimens expressed in phosphorus equivalents, which frequently persist across family patents and can create layering with later filing strategies.
However, a complete US landscape for US 4,927,814 requires citation of other US patents, family members, continuations, related filings, and prosecution history. The claim text provided does not include patent citations, assignee, publication history, or related documents, so a full “in-force/expiry/overlap” map cannot be produced from the information given.
Scope of enforcement: what a plaintiff would likely plead
Compound infringement
- If accused products contain one of the designated acids (claims 3-5) or its physiologically active salts, product liability is the primary path.
- If accused products are not the named exemplars but still match the claim 1 formula with R1 = methyl (claim 2), defendants still face direct infringement claims for compounds and compositions (claims 1, 2, 10-12).
Method infringement
- For commercial use, plaintiffs often plead both:
- claim 6 or claim 8 (effective amount for calcium metabolism disturbance/disease)
- claim 7 or claim 9 (same, but limited to 0.01-10 mg P/kg/day)
- Competitors that market dosing regimens within this band would face higher enforcement leverage.
Composition infringement
- For marketed drug products with these actives, claim 12 is the tightest composition target because it ties directly to the three named acids. Claim 10 provides a broader genus fallback.
Key Takeaways
- US 4,927,814 is structured around a diphosphonate chemical genus (claim 1) with a narrower set of explicit embodiments (claims 3-5), then extends that chemical scope into methods and pharmaceutical compositions.
- The enforceable use and administration scope is limited to “calcium metabolism disturbance or disease,” with dosing constrained to 0.01-10 mg P/kg/day in claims 7 and 9.
- The most straightforward enforcement targets are products and regimens built around:
- 1-hydroxy-3-(N-methyl-N-nonylamino)-propane-1,1-diphosphonic acid
- 1-hydroxy-3-(N-methyl-N-pentylamino)-propane-1,1-diphosphonic acid
- 1-hydroxy-3-(N-isobutyl-N-methylamino)-propane-1,1-diphosphonic acid
including their physiologically active salts (claims 3-5), plus related compositions (claims 12 and 10) and administration (claims 6-9).
FAQs
1. Which claims define the chemical scope most directly?
Claims 1-5. Claim 1 sets the diphosphonate formula genus; claims 2-5 narrow to R1 = methyl and three named 1-hydroxy-propane-1,1-diphosphonic acid variants with N-alkylamino substitution, including physiologically active salts.
2. What dose range is protected for the method claims?
Claims 7 and 9 protect administration at 0.01-10 mg P/kg per day (phosphorus equivalent dosing).
3. Does the patent restrict the indication to a specific disease name?
No. The method claims cover “calcium metabolism disturbance or disease” without enumerating specific conditions in the provided claim text.
4. Are pharmaceutical compositions included in scope?
Yes. Claims 10-12 cover compositions in a pharmaceutically acceptable carrier containing effective amounts of the claimed compounds (genus, R1=methyl, and the three named acids).
5. What is the strongest enforcement path if a competitor sells a product with one of the named acids?
A plaintiff would prioritize product and composition infringement using claims 3-5 and 12 (and fall back to 10), then add method infringement using claims 6-9 based on the marketed dosing regimen.
References
[1] US Patent 4,927,814, Claims 1-12 (claim text provided in prompt).
