United States Patent 8,247,425: Scope, Claim Architecture, and Enforceable Patent-Barrier Map
What is the core patented invention in US 8,247,425?
US 8,247,425 claims a prefilled syringe and related subcutaneous dosing method defined by a narrow, composition-and-contaminant control strategy:
- Active/identity constraint: the liquid composition contains a compound of formula III (and a specific variant of that family in claims 3, 5, 7, 9).
- Impurity constraint: the liquid composition contains a controlled low level of a compound of formula II (and, in broader total-impurity limits, also compound of formula IV).
- Equipment/contaminant constraint: the prefilled syringe is substantially free of tungsten, with explicit numeric limits in method claims.
- Dose/vehicle specificity in dependent claims: explicit mg-per-volume formulations for compound III-1 in 0.4 mL or 0.6 mL water with specific excipients.
The claims are not “composition broadly for any device.” They are device + liquid formulation + impurity spec + tungsten spec + (in method claims) indication. That combination creates both a tight infringement path and a clear design-around surface.
How is the claim set structured (independent claims vs layered dependencies)?
The independent claim set appears as:
- Claim 1: baseline prefilled syringe defined by formula III, tungsten-free limitation, and <190 ppm formula II.
- Claim 3: alternate independent thread using compound of formula III-1 and <190 ppm of formula II-1.
- Claim 9: method of providing and administering a tungsten-free prefilled syringe with 8 mg or 12 mg compound III-1 in 0.4 mL or 0.6 mL water, with <190 ppm II-1; subcutaneous injection; includes an indication dependent on claim 10.
All other claims layer numeric cutoffs (187, 185, 150, 125, 100, 25 ppm), and sum constraints (II + IV totals; II-1 + IV-1 totals), plus explicit excipient compositions and dose amounts.
What does claim 1 actually require to infringe?
Claim 1 requires all of the following:
- A prefilled syringe (device form factor).
- The syringe contains a liquid composition comprising:
- A compound of formula III (anion defined as “A− is a suitable anion”).
- The prefilled syringe is substantially free of tungsten.
- The liquid composition has:
- < about 190 ppm of a compound of formula II (anion “X− is a suitable anion”).
Key infringement levers in claim 1:
- If the accused product is not a prefilled syringe (for example, a manually filled syringe), literal claim 1 exposure changes.
- If the tungsten level fails “substantially free,” exposure increases under claim 11/12 (method) and indirectly under the base prefilled-syringe language.
- The impurity spec is a threshold: the claim is anchored to <190 ppm formula II.
How do claims 2 and 4 expand the impurity boundary?
Claim 2 adds a combined impurity ceiling:
- Liquid composition has < about 190 ppm total of:
- compound of formula II, plus
- compound of formula IV (with defined substituent set: R1 and R2 are each independently C1-6 aliphatic; and X− is a suitable anion).
Claim 4 is a corresponding “total impurity” dependent form tied to claim 3:
- Prefilled syringe of claim 3 with substantially free of tungsten and <190 ppm total of compound II-1 and compound IV-1.
In practice, claims 2 and 4 convert a single-impurity spec into a total impurity spec. A product that keeps formula II low but allows formula IV to drift upward can still violate these dependent claims if it exceeds the total ppm limit.
What changes when the claim set moves to compound III-1 (claims 3, 5, 7)?
Claim 3 replaces formula III with a more specific compound of formula III-1 and swaps the impurity definition to:
- liquid composition has < about 190 ppm of compound of formula II-1.
Claims 5 and 7 add hard dose and concentration structure:
- Claim 5: 8 mg of compound III-1 in 0.4 mL water, with II-1 at < about 190 ppm.
- Claim 7: 12 mg of compound III-1 in 0.6 mL water, with II-1 at < about 190 ppm.
These claims tightly map to a commercial dosing presentation: mg dose plus exact water volume.
What excipient package is locked in claims 6 and 8?
Claim 6 (dependent on claim 5) hardcodes:
- 2.6 mg sodium chloride
- 0.16 mg edetate calcium disodium
- 0.12 mg glycine hydrochloride
Claim 8 (dependent on claim 7) hardcodes:
- 3.9 mg sodium chloride
- 0.24 mg edetate calcium disodium
- 0.18 mg glycine hydrochloride
These are formulation-specific dependent claims. They matter most for infringement analysis when the accused formulation is known to contain these excipients at these exact amounts.
What is the method claim scope (claim 9) and what does it demand?
Claim 9 requires:
- Step (i): providing a prefilled syringe
- The syringe is:
- substantially free from tungsten
- containing unit dosage of liquid composition comprising:
- 8 mg or 12 mg compound III-1 in 0.4 mL or 0.6 mL water
- compound II-1 at < about 190 ppm
- Step (ii): administering the unit dosage to a subject via subcutaneous injection
The method claim is not only chemistry. It includes:
- unit dose identity and presentation,
- administration route (subcutaneous),
- and tungsten-avoidance.
Dependent claim 10 further narrows the method to:
- subject suffering from opioid induced constipation.
How do tungsten thresholds narrow claim exposure (claims 11 and 12)?
Claim 11: tungsten present in the prefilled syringe < 50 parts per billion.
Claim 12: tungsten present in the prefilled syringe < 12 parts per billion.
These numeric limits are high-value in enforcement. They create bright-line comparisons against elemental impurity testing results for device-contact materials, lubricants, seals, or metal components.
What impurity-spec ladder exists across claims 15 to 50?
The claim set repeatedly introduces narrower “less than” thresholds for both:
- formula II (claims 15-20),
- total II + IV (claims 21-26),
- formula II-1 (claims 27-32),
- total II-1 + IV-1 (claims 33-38),
- and corresponding conditional variants in claims 39-50.
Impurity threshold ladder (formula II only)
| Claim(s) |
Species |
Limit |
| 1 |
compound of formula II |
<190 ppm |
| 15 |
formula II |
<187 ppm |
| 16 |
formula II |
<185 ppm |
| 17 |
formula II |
<150 ppm |
| 18 |
formula II |
<125 ppm |
| 19 |
formula II |
<100 ppm |
| 20 |
formula II |
<25 ppm |
Total impurity ladder (formula II + formula IV)
| Claim(s) |
Species (total) |
Limit |
| 2 |
II + IV total |
<190 ppm |
| 21 |
II + IV total |
<187 ppm |
| 22 |
II + IV total |
<185 ppm |
| 23 |
II + IV total |
<150 ppm |
| 24 |
II + IV total |
<125 ppm |
| 25 |
II + IV total |
<100 ppm |
| 26 |
II + IV total |
<25 ppm |
Impurity threshold ladder (formula II-1 only)
| Claim(s) |
Species |
Limit |
| 3 |
II-1 |
<190 ppm |
| 27 |
II-1 |
<187 ppm |
| 28 |
II-1 |
<185 ppm |
| 29 |
II-1 |
<150 ppm |
| 30 |
II-1 |
<125 ppm |
| 31 |
II-1 |
<100 ppm |
| 32 |
II-1 |
<25 ppm |
Total impurity ladder (II-1 + IV-1)
| Claim(s) |
Species (total) |
Limit |
| 4 |
II-1 + IV-1 total |
<190 ppm |
| 33 |
II-1 + IV-1 total |
<187 ppm |
| 34 |
II-1 + IV-1 total |
<185 ppm |
| 35 |
II-1 + IV-1 total |
<150 ppm |
| 36 |
II-1 + IV-1 total |
<125 ppm |
| 37 |
II-1 + IV-1 total |
<100 ppm |
| 38 |
II-1 + IV-1 total |
<25 ppm |
Method-layer impurity thresholds (claims 45-50)
Dependent to claim 9 via claim 45:
- II-1: <187, <185, <150, <125, <100, <25 ppm across claims 45-50.
This is a classic “measurement armor” strategy: even if the accused product disputes precise impurity levels, the ladder provides multiple alternative metrology targets.
What is the enforceability posture created by this claim design?
This patent’s strongest enforcement posture comes from orthogonal constraints:
- Device + presentation: prefilled syringe.
- Chemical identity: compound III-1 / formula III family.
- Impurity control: II / II-1 and optionally IV / IV-1 with both single and total caps.
- Elemental contamination control: tungsten thresholds.
- Route and population (in method claims): subcutaneous injection and opioid induced constipation.
Any design-around must address at least one axis simultaneously:
- Change presentation (e.g., not prefilled; not water volumes tied to 0.4/0.6 mL; avoid 8 mg/12 mg unit doses).
- Increase impurity above relevant caps (risky for safety/stability).
- Introduce or increase tungsten above “substantially free” thresholds (also risky and detectable).
- Shift to a different route or indication (method claims remain relevant only where the asserted use is practiced).
Because the claims include both device and method, a competitor can’t always avoid exposure by changing manufacturing only; the final product must also comply with tungsten and impurity constraints.
How does this map to a likely patent landscape (what other claims typically collide with this one)?
Given the claim content, US 8,247,425 lives in the overlap zone of:
- formulation and impurity control patents (especially those built on ppm specifications for degradation-related species),
- device-material and extractables/leachables patents (tungsten as an elemental control marker),
- prefilled syringe container closure system patents (materials, coatings, contact surfaces),
- method-of-use patents for subcutaneous dosing in opioid-induced constipation populations.
Even without invoking specific external patents here, the internal claim categories indicate which patent families are most likely to surround it:
- Chemical entity + salt/formulation patents covering compound III-1 and related anion systems.
- Stability/impurity patents controlling degradation byproducts corresponding to “formula II / II-1” and “formula IV / IV-1.”
- Container closure + particulate/metal contamination patents that address tungsten leaching or contamination controls.
- Dosing regimen patents for subcutaneous injection of 8 mg and 12 mg unit doses in OIC patients.
This matters for freedom-to-operate planning because the claims are narrowly drafted yet likely to co-exist with other filings that cover adjacent aspects (the “compound,” the “device,” and the “indication”).
Where are the highest-risk infringement zones for a competitor?
Risk concentrates where the competitor’s product matches multiple claim elements:
1) Matches a prefilled syringe with tungsten-controlled formulation
- If the competitor uses a prefilled syringe and hits the “substantially free from tungsten” limitation, they remain in-bounds for claims 1, 3, 4, 14 (syringe limitation) and for method claim 9 (device provided).
2) Matches impurity ppm targets below 190 ppm (and especially below 125 or 100)
- If the competitor uses the same impurity profile management and achieves <190 ppm II-1, it may still infringe dependent claims if it also meets lower thresholds.
3) Matches the exact dose presentation
- 8 mg in 0.4 mL and 12 mg in 0.6 mL are high-signal because they directly track dependent claims 5 and 7.
- If the product is marketed in those unit dosages, the design-around window is smaller.
4) Matches excipient package amounts
- Inclusion of sodium chloride, edetate calcium disodium, and glycine hydrochloride at the disclosed mg levels can place the product inside dependent claims 6 and 8.
5) Method practice for opioid induced constipation
- For method claims (9-13), the competitor must show non-practice or a non-matching route/indication. If product use is within OIC and the administration is subcutaneous, method exposure stays live.
Key design-around surfaces implied by the claim language
Because the claims are threshold- and presentation-driven, the most practical design-around approaches are those that move the product outside at least one claimed boundary:
- Tungsten strategy: move tungsten above the “substantially free” threshold and above the numeric <50 ppb or <12 ppb levels. This is more likely to be unacceptable for product quality, but it is the direct claim escape hatch for tungsten subclauses.
- Impurity strategy: raise II / II-1 (and optionally total II + IV, II-1 + IV-1) above the asserted ppm thresholds. This risks stability and may be infeasible.
- Presentation strategy: avoid matching 8 mg in 0.4 mL or 12 mg in 0.6 mL water unit doses. If dose/volume is different, dependent claims 5 and 7 (and method claim 9 unit dose) become harder to read on the product.
- Route/indication strategy: avoid subcutaneous administration in the claimed OIC context for method claims 9-10, though product labeling and real-world use can still make exposure difficult to control.
What is the litigation-ready “claim map” a freedom-to-operate team should build?
A practical infringement check built directly from the claim structure looks like:
This maps to the same variables the patent itself uses for claim boundaries: device form, tungsten, ppm impurity, and dose/volume.
Key Takeaways
- US 8,247,425 is a prefilled-syringe and subcutaneous method patent built around three measurable constraints: compound identity (formula III / III-1), ppm impurity limits (formula II / II-1 and optional totals with formula IV / IV-1), and tungsten contamination limits.
- The claim set is structured for measurement armor: a single base limit (<190 ppm) expands into a ladder of lower thresholds down to <25 ppm, with parallel “single impurity” and “total impurity” claim forms.
- Enforcement leverage is highest where an accused product matches unit dose format (8 mg in 0.4 mL or 12 mg in 0.6 mL), uses a prefilled syringe, and practices the subcutaneous OIC method.
- Design-around is conceptually clear but operationally constrained: you generally must move at least one axis out of the claimed bounds (tungsten, impurity ppm, or presentation/route/indication).
FAQs
1) Does US 8,247,425 cover only the chemical compound, or also the container and manufacturing residue?
It covers a prefilled syringe device and explicitly includes a tungsten contamination limitation tied to the syringe.
2) Are impurity limits single-compound only, or do they include totals?
Both. The claims include caps on compound of formula II (or II-1) alone and caps on total impurities (II + IV or II-1 + IV-1).
3) What impurity targets matter most for narrowing risk?
The claims repeatedly recite thresholds at 190, 187, 185, 150, 125, 100, and 25 ppm, covering both single and total impurity definitions.
4) Do the method claims require opioid induced constipation?
The opioid induced constipation restriction is in dependent claim 10; claim 9 covers subcutaneous administration in general, but claim 10 adds the OIC patient context.
5) Is the tungsten threshold only qualitative or numeric?
Numeric. The method dependent claims specify tungsten <50 ppb and <12 ppb.
References
[1] US Patent 8,247,425. United States Patent and Trademark Office.
