Scope and claims analysis for US Patent 9,687,506 (sodium nitrite with ultra-low impurities for injectable cyanide antidote use)
US 9,687,506 is drafted as a high-purity sodium nitrite composition and related sterile solutions and kits, with claim scope anchored to specific impurity ceilings (carbonate, nitrate, heavy metals, halides, endotoxin, microbial counts, residual solvents) and delivery-system coverage across multiple parenteral routes. The strongest, most infringement-relevant elements are (i) the composition-quality specification set and (ii) the combination/sequential treatment for cyanide poisoning with sodium thiosulfate pentahydrate in a defined kit or sequential IM method.
What patents protect sodium nitrite pharmaceutical compositions for intravenous and other injection routes under US 9,687,506?
Independent claim 1 scope: composition specification controls “what” is protected
Claim 1 protects a pharmaceutical composition comprising sodium nitrite plus pharmaceutically acceptable carriers/excipients, where the sodium nitrite meets a long list of quantitative purity and impurity thresholds, and where the formulation is intended for multiple injection routes.
Core infringement trigger: a product that is sodium nitrite-based and meets the entire impurity and quality parameter set recited in claim 1, plus is formulated for one or more of the recited parenteral administrations.
A. Sodium nitrite impurity and quality ceilings (claim 1)
Key quantitative limits (all must be met as claimed):
- Sodium carbonate: ≤ 0.02% by weight
- Anti-caking agent: ≤ 10 ppm
- Loss on drying: ≤ 0.25% by weight
- Water content: ≤ 0.5% by weight
- Heavy metals: ≤ 10 ppm
- Sodium nitrate: ≤ 0.4% by weight
- Insoluble matter: ≤ 0.005% by weight
- Chloride: ≤ 0.005% by weight
- Sulfate: ≤ 0.01% by weight
- Iron: ≤ 0.001% by weight
- Calcium: ≤ 0.01% by weight
- Potassium: ≤ 0.005% by weight
- Mercury: ≤ 0.05 ppm
- Aluminum: ≤ 2 ppm
- Arsenic: ≤ 3 ppm
- Selenium: ≤ 0.003% by weight
- Ethanol: ≤ 5000 ppm
- Methanol: ≤ 3000 ppm
- Total non-volatile organic carbon: ≤ 10 ppm
- Bacterial endotoxins: ≤ 0.25 EU/mg
- Solids are formulated for: IV, intraarterial, intraperitoneal, intrathecal, intraventricular, intraurethral, intrasternal, intracranial, intramuscular, intrasynovial, intravesical, or subcutaneous administration.
B. Formulation requirement: route-of-administration tail
Claim 1 uses “wherein the pharmaceutical composition is formulated for” a defined set of parenteral routes. That means scope is not limited to cyanide use in claim 1, but the route language still ties enforceability to injectable-ready products.
C. Practical claim construction for infringement
The claim reads like a finished injectable sodium nitrite specification claim: it is both composition-level (sodium nitrite purity/impurities) and product-level (formulated for injection routes, and endotoxin). Any competitive sodium nitrite bulk that is not tightened to these injectable-grade thresholds is outside scope even if it is used in a “pharmaceutical composition” with excipients.
How does US 9,687,506 narrow with dependent claims (2–34)?
Claims 2–6: content grade and physical/solution performance
- Claim 2: sodium nitrite ≥ about 98% by weight
- Claim 3: sodium nitrite ≥ about 99.8% by weight (by ion chromatography)
- Claim 4: sodium nitrite is a white solid
- Claim 5: a 10% aqueous solution at 25°C has pH 8 to 9
- Claim 6: microbial load caps: aerobic ≤ 100 CFU/g; yeast+mold ≤ 20 CFU/g
These claims layer additional narrowing; they are most relevant for products that already meet the impurity ceiling in claim 1 but differ in assay purity, physical form, or pH and bioburden.
Claims 7–12: dosage form and sterile aqueous intent
- Claim 7: composition is a single dosage form
- Claim 8: excipient is water
- Claim 9–10: includes pH adjusting agents and isotonic agents
- Claims 11–12: formulated for intravenous; and as a sterile aqueous solution for IV injection, infusion, or implantation
Claims 13–34: route-specific sterile aqueous solution dependent claims
Claims 13–34 repeat the same claim 1 structure for each route, each specifying sterile aqueous solution intended for injection/infusion/implantation for:
- intraarterial (13–14)
- intraperitoneal (15–16)
- intrathecal (17–18)
- intraventricular (19–20)
- intraurethral (21–22)
- intrasternal (23–24)
- intracranial (25–26)
- intramuscular (27–28)
- intrasynovial (29–30)
- intravesical (31–32)
- subcutaneous (33–34)
From an enforcement perspective, these dependent claims matter because they reduce design-around space based on route-of-administration claims: a defendant cannot freely argue “we are not using it IV” if the product is otherwise within claim 1 and the route matches one of the dependent claims.
What does the cyanide poisoning treatment claim add (claim 35)?
Claim 35: sequential IM sodium nitrite + sodium thiosulfate regimen
Claim 35 adds a method for treating cyanide poisoning via sequential intramuscular administration to a subject:
- a therapeutically effective amount of the sterile aqueous solution comprising the pharmaceutical composition of claim 1, then
- a therapeutically effective amount of pharmaceutical grade sodium thiosulfate pentahydrate.
Impact on patent landscape: claim 35 is not only a composition claim. It is a regimen claim with a specific sequence and route (intramuscular). It can be asserted even if the defendant uses the same sodium nitrite quality but administers it in a different sequence, or even the same sequence but different administration route, depending on claim construction.
What does the kit claim protect (claim 36)?
Claim 36: kit-level infringement risk is high
Claim 36 protects a kit with:
- a single unit dosage form containing pharmaceutical grade sodium nitrite meeting the same extensive impurity thresholds as claim 1; and
- a single unit dosage form containing sodium thiosulfate pentahydrate meeting its own defined quality profile, including:
- non-purgeable organic carbon ≤ 8 ppm
- mercury ≤ 0.05 ppm, aluminum ≤ 2 ppm
- selenium ≤ 0.003% by weight
- sodium thiosulfate content ≥ 98% on anhydrous basis
- water content 32% to 37%
- heavy metals ≤ 10 ppm
- chloride ≤ 200 ppm
- sulfide ≤ 0.001% by weight
- iron ≤ 0.002% by weight
- calcium ≤ 0.01% by weight
- potassium ≤ 0.005% by weight
- sulfite ≤ 0.1%
- sulfate ≤ 0.5%
- arsenic ≤ 3 ppm
- lead ≤ 0.001% by weight
- microbial load caps: aerobic ≤ 100 CFU/g, yeast+mold ≤ 20 CFU/g
- bacterial endotoxins ≤ 0.02 EU/mg
- nitrogen compounds ≤ 0.002%
- insoluble matter ≤ 0.005%
- residual anti-caking agent ≤ 0.01%
- organic volatile impurities within ICH Q3C (R3) limits
- physical solution properties: 10% aqueous solution is colorless, pH 6.0–8.0, solid is odorless crystals
Practical enforcement angle: kits are typically distributed to hospitals and EMS systems as packaged therapy. If a competitor sells a two-component kit with both components meeting their respective impurity specifications, claim 36 provides a direct infringement pathway. If the competitor sells components separately, kit claim coverage depends on “kit” interpretation and packaging/marketing facts.
How strong is the patent estate for US 9,687,506 based on claim drafting style (composition purity + route + regimen)?
Claim strength indicators
- Tight numeric thresholds: the extensive impurity list increases the likelihood that non-infringing products differ materially in specifications and analytics rather than merely in inactive ingredients.
- Multiple dependent route claims: reduces escape by changing route.
- Regimen and kit claims: extends coverage beyond “what it is” into “how it’s used” and “how it’s packaged.”
Where weakness can exist (based on claim form)
- Breadth is conditional: claim scope is broad in “route coverage,” but narrow in “quality requirements.” A generic entrant can avoid infringement by manufacturing sodium nitrite outside any one threshold while still meeting pharmacopoeial acceptance for injectable use, if the threshold is not functionally required for safety/efficacy and if they can justify different specs.
- Proof burden is analytics-heavy: infringement is likely to turn on lab test reports (COAs) across multiple impurities and endotoxin. Litigation will hinge on whether testing methods match claimed concepts (eg, “total non-volatile organic carbon,” endotoxin units, “anti-caking agent” identification).
What generic entry risks exist for sodium nitrite injectable products referencing US 9,687,506?
Risk profile by product strategy
High risk of infringement
- Branded or generic products that use sodium nitrite with impurity levels engineered to meet these exact ceilings, and are formulated as sterile aqueous solutions for one of the listed parenteral routes.
- Cyanide antidote kits combining sodium nitrite and sodium thiosulfate pentahydrate with matching quality profiles.
Lower risk via spec divergence
- Sodium nitrite injectable products that are otherwise acceptable but do not hit the specific impurity ceilings, especially endotoxins (EU/mg), carbonate (wt%), nitrate (wt%), heavy metals, and volatile organics caps.
- Different regimen and kit configurations: different sequence from claim 35, different administration route from claim 35, or omission of the kit pairing from claim 36.
What patents protect cyanide antidote combinations beyond US 9,687,506?
No complete landscape can be produced from the provided information alone because the question requires identifying other US patents in the same family and/or related sodium nitrite + sodium thiosulfate antidote patents, plus their claims, expiration dates, and litigation/Orange Book status. The content provided is limited to the claim set of US 9,687,506 and does not include family data, assignee, prosecution history, or referenced documents needed to map the broader US patent estate.
When does exclusivity end for US 9,687,506 / what are the relevant expiration dates?
No expiration timetable can be generated from the claim set alone. A definitive exclusivity/expiration analysis requires priority dates, filing and publication timelines, and jurisdictional term rules; none are provided.
Key Takeaways
- US 9,687,506 is primarily a composition-quality patent: it protects sodium nitrite-based injectable compositions that meet an unusually detailed set of impurity and quality specifications.
- Coverage extends across multiple parenteral routes through dependent claims tied to sterile aqueous solutions and “formulated for” language.
- The patent adds meaningful enforcement hooks for cyanide poisoning (claim 35) via a sequential IM regimen with sodium thiosulfate pentahydrate.
- The kit claim (36) creates a direct infringement pathway for two-component distribution where both sodium nitrite and sodium thiosulfate pentahydrate meet the claimed impurity specifications.
FAQs
- Does claim 1 require endotoxin limits in the sodium nitrite itself or the finished injectable?
- If a product meets the impurity ceilings but uses a different administration route than listed, does claim coverage fall away?
- Can a competitor avoid claim 36 by selling sodium thiosulfate pentahydrate separately rather than as a kit?
- How do dependent claims 2–6 affect infringement strategy for sodium nitrite assay and pH controls?
- What analytics are most likely to be disputed in enforcement of the numeric impurity limits (eg, endotoxin, TOC, heavy metals)?
References (APA)
- United States Patent No. 9,687,506.
