Patent Scope and Claims Analysis for US Patent 10,905,662 (Cysteamine Bitartrate Oral Composition Stability-Controlled Impurities)
US Patent 10,905,662 claims a tightly delimited set of method-of-use steps for lowering intracellular cystine via twice-daily oral administration of cysteamine bitartrate, with enforceable limitations tied to (i) impurity-spec windows (2-hydroxythiomorpholine, cystamine, and cystamine tartrate amide), (ii) storage temperature/humidity regimens across the product lifecycle (pre-dispensing cold chain and post-dispensing ambient conditions), and (iii) optional enteric coating composition. The claim set is built to capture performance sensitivity linked to controlled room-temperature exposure and long refrigerated storage, using relative-impurity thresholds that can be tested on finished product samples.
How broad are the US 10,905,662 claims for lowering intracellular cystine?
Short answer: The claims are broad on the therapeutic endpoint (lower intracellular cystine) and route (oral), but narrow on exact product formulation, impurity specifications, and specific storage conditions (2–8°C prior to dispensing; 20–25°C after dispensing; and optional 25/60, 30/65, 30/70 RH regimes). Entry risk exists for any product that administers cysteamine bitartrate under the same regimen and fails to meet the same impurity-and-storage constraints.
Claim architecture: what is actually claimed?
All independent/anchor claim language is a method of lowering intracellular cystine, with three layers of constraints:
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Treatment regimen
- “administering twice daily”
- “an oral pharmaceutical composition comprising cysteamine bitartrate”
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Impurity or degradant control using relative thresholds
- Claim 1: 2-hydroxythiomorpholine < 0.5% relative to cysteamine bitartrate
- Claim 7: cystamine < 4% relative to cysteamine bitartrate
- Claim 13: cystamine tartrate amide < 0.5% relative to cysteamine bitartrate
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Storage history and post-dispensing storage
- Prior to dispensing: stored by manufacturer/distributor/pharmacy/hospital at 2–8°C
- After dispensing: stored at 20–25°C (Claims 1 and 7 baseline)
- Dependent claims add humidity variants for “subsequently stored” (Claims 4–6 for 2-hydroxythiomorpholine; Claims 10–12 for cystamine; Claims 16–18 for cystamine tartrate amide)
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Optional enteric coating requirement
- Enteric coating comprises poly(methacrylic acid co-ethyl acrylate) 1:1 (Claims 2, 8, 14)
Practical scope conclusion
- Therapeutic scope: covers any patient “in need thereof” (no phenotype limits).
- Route/dosing: fixed to oral and twice daily.
- Active ingredient: fixed to cysteamine bitartrate.
- Formulation boundaries: enteric coating is optional, but if present, the polymer identity is claimed.
- IP risk trigger: for enforcement, the patentee must show the administered product met the impurity thresholds and was stored under the claimed conditions as part of the product lifecycle.
What specific claim limitations on 2-hydroxythiomorpholine define infringement risk?
Short answer: Claim 1 (and dependent claims 3–6) require a finished product that, after a defined refrigerated-to-ambient storage history, contains 2-hydroxythiomorpholine below 0.5% (relative to cysteamine bitartrate). Dependent claims additionally constrain the ambient storage temperature/humidity windows.
Scope mapped to dependent claim variants
Independent anchor: Claim 1
- Twice daily oral cysteamine bitartrate
- 2-hydroxythiomorpholine < 0.5%
- Stored 2–8°C prior to dispensing
- Stored 20–25°C after dispensing
Dependent claims
- Claim 2: enteric coating includes poly(methacrylic acid co-ethyl acrylate) 1:1
- Claim 3: impurity threshold maintained after 2–8°C up to 15 months
- Claims 4–6: impurity threshold maintained after:
- initial 2–8°C up to 15 months, then
- “subsequently stored” for up to 3 months at:
- 25°C / 60% RH (Claim 4)
- 30°C / 65% RH (Claim 5)
- 30°C / 70% RH (Claim 6)
Enforcement-relevant facts built into the wording
The claims require not only a static impurity level, but a time-and-condition history:
- Cold chain duration: “up to 15 months” at 2–8°C
- Ambient stress duration: “up to 3 months” at specified RH/temperature
This structure is designed to match real-world supply and expiry testing (accelerated stability-style windows).
What specific claim limitations on cystamine define infringement risk?
Short answer: Claim 7 (and dependent claims 9–12) requires cysteamine bitartrate composition containing cystamine < 4% relative to cysteamine bitartrate, following 2–8°C storage prior to dispensing and specific post-dispensing storage.
Scope mapped to dependent claim variants
Independent anchor: Claim 7
- Twice daily oral cysteamine bitartrate
- cystamine < 4%
- Stored 2–8°C prior to dispensing
- Stored 20–25°C after dispensing
Dependent claims
- Claim 8: enteric coating comprises poly(methacrylic acid co-ethyl acrylate) 1:1
- Claim 9: impurity level maintained after 2–8°C up to 15 months
- Claims 10–12: impurity level maintained after:
- 2–8°C up to 15 months, then
- up to 3 months at:
- 25°C / 60% RH (Claim 10)
- 30°C / 65% RH (Claim 11)
- 30°C / 70% RH (Claim 12)
Relative threshold interpretation for portfolio strategy
- The cystamine threshold is materially higher than the 2-hydroxythiomorpholine and cystamine tartrate amide thresholds (4% vs. 0.5%). That indicates the patent treats cystamine as a less tightly constrained degradant/related impurity, while treating others as more sensitive markers.
What specific claim limitations on cystamine tartrate amide define infringement risk?
Short answer: Claim 13 (and dependent claims 15–18) requires cystamine tartrate amide < 0.5% relative to cysteamine bitartrate, maintained after the same refrigerated-to-ambient storage profile. This is the tightest impurity window after the 2-hydroxythiomorpholine family.
Scope mapped to dependent claim variants
Independent anchor: Claim 13
- Twice daily oral cysteamine bitartrate
- cystamine tartrate amide < 0.5%
- Stored 2–8°C prior to dispensing
- Stored 20–25°C after dispensing
Dependent claims
- Claim 14: enteric coating comprises poly(methacrylic acid co-ethyl acrylate) 1:1
- Claim 15: impurity level maintained after 2–8°C up to 15 months
- Claims 16–18: impurity level maintained after:
- 2–8°C up to 15 months, then
- up to 3 months at:
- 25°C / 60% RH (Claim 16)
- 30°C / 65% RH (Claim 17)
- 30°C / 70% RH (Claim 18)
What is the role of the enteric coating polymer limitation in the patent estate?
Short answer: The enteric coating limitation appears only in dependent form (Claims 2, 8, 14). It narrows protection to embodiments where the enteric layer uses poly(methacrylic acid co-ethyl acrylate) 1:1.
Claim placement
- 2-hydroxythiomorpholine set: Claim 2
- cystamine set: Claim 8
- cystamine tartrate amide set: Claim 14
Scope effect
- If a competitor uses a different enteric polymer system, they may still infringe the method claims if they meet the impurity and storage constraints. If they match the enteric polymer, they may face stronger infringement leverage for those dependent claim theories.
How do the storage condition limitations shape enforceability under US method-of-use claims?
Short answer: The claims tie infringement to both pre-dispensing cold storage and post-dispensing ambient/humidity storage, creating an evidentiary burden that can drive litigation focus toward labeling, distribution practice, and stability-testing outcomes.
Storage condition elements (common across claims)
- Pre-dispensing: “stored by a manufacturer, distributor, a pharmacy, or a hospital at 2–8°C”
- Post-dispensing:
- baseline: 20–25°C (Claims 1 and 7 and 13)
- dependent variants add:
- 25°C/60% RH (Claims 4, 10, 16)
- 30°C/65% RH (Claims 5, 11, 17)
- 30°C/70% RH (Claims 6, 12, 18)
Timeline elements
- Refrigerated window: “for a period of up to 15 months”
- Ambient window: “for a period of up to 3 months”
Litigation relevance (how this is typically argued)
- Patentee will align the claimed impurity windows with stability specification tests that occur at labeled storage conditions.
- Accused infringers will attempt to distinguish whether real distribution/handling matches the claimed “stored” history and whether the measured impurity levels truly cross the claimed thresholds.
How many distinct claim “lanes” does the patent cover?
Short answer: Three independent impurity lanes are claimed, each with its own impurity marker and threshold, and each optionally layered with the enteric polymer requirement.
Lane map (claim families)
| Claim family |
Impurity marker |
Threshold |
Key method claim numbers |
Enteric polymer dependent? |
| Lane A |
2-hydroxythiomorpholine |
<0.5% |
Claims 1, 3-6 |
Yes (Claim 2) |
| Lane B |
cystamine |
<4% |
Claims 7, 9-12 |
Yes (Claim 8) |
| Lane C |
cystamine tartrate amide |
<0.5% |
Claims 13, 15-18 |
Yes (Claim 14) |
This matters for freedom-to-operate because an accused product can potentially avoid one lane (by controlling one impurity) but still be exposed if it fails another.
What is the likely patent landscape impact for cysteamine bitartrate oral products in the US?
Short answer: The patent is structured as a stability-impurity method claim, which tends to be used in infringement theories targeting product handling and shelf-life behavior, not only original formulation. In practical terms, it pressures competitors to demonstrate impurity control through the same storage stressors used in the claims.
Competitive risk zones
- Products using cysteamine bitartrate that rely on cold-chain distribution
- Because the claims explicitly require 2–8°C storage prior to dispensing, any product with similar cold-chain logistics can fall into the evidentiary frame.
- Products with enteric coating
- If the enteric polymer matches (poly(methacrylic acid co-ethyl acrylate) 1:1), dependent claim theories become easier to align.
- Products with known or expected degradant pathways
- Impurity markers in the claims are likely tied to stability breakdown or related compounds. Competitors must ensure their specs stay below claimed relative limits across the stressed time/condition windows.
How does this patent compare to typical US drug patents (what it is and is not)?
Short answer: US 10,905,662 is less about composition claims (exact formulation recipe) and more about performance under specific storage conditions, delivered through a method-of-use framing tied to impurity content after storage.
What it does not claim (based on the provided claims text)
- No broad claim to “cysteamine bitartrate compositions” generically.
- No direct claim to manufacturing methods.
- No broad claims to patient subgroups, disease stage, or concomitant therapies.
What it does claim (based on provided claims text)
- A defined clinical administration regimen (twice daily).
- A defined composition state (impurity levels) as a consequence of storage.
- Defined storage conditions aligned to real-world temperature/humidity variance.
Key takeaways
- US 10,905,662 protects a method of lowering intracellular cystine using twice-daily oral cysteamine bitartrate where specific impurities remain below defined relative thresholds after defined 2–8°C pre-dispensing and post-dispensing storage conditions.
- The claim set has three distinct impurity lanes:
- 2-hydroxythiomorpholine <0.5% (Claims 1, 3–6)
- cystamine <4% (Claims 7, 9–12)
- cystamine tartrate amide <0.5% (Claims 13, 15–18)
- Enteric coating using poly(methacrylic acid co-ethyl acrylate) 1:1 appears as a dependent narrowing feature (Claims 2, 8, 14).
- The storage windows (“up to 15 months” at 2–8°C and “up to 3 months” at specified RH/temperature) are central to the infringement theory and likely drive litigation toward stability specification testing, distribution/handling practices, and impurity assays on finished product samples.
FAQs
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Can a cysteamine bitartrate product avoid infringement by controlling only 2-hydroxythiomorpholine below 0.5%?
Not if it also exceeds the claimed limits for cystamine (<4%) or cystamine tartrate amide (<0.5%) under the claimed storage histories.
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Do the claims require showing storage by “a manufacturer, distributor, pharmacy, or hospital”?
Yes, the claims explicitly recite storage by one of those entities at 2–8°C prior to dispensing.
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Is the enteric coating requirement mandatory to infringe?
No. The enteric polymer is required only in dependent claims (2, 8, 14). Baseline independent method claims proceed without that feature.
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What post-dispensing storage conditions are expressly claimed?
Baseline includes 20–25°C after dispensing, with dependent variants adding 25°C/60% RH, 30°C/65% RH, and 30°C/70% RH for up to 3 months.
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How do the “up to 15 months” and “up to 3 months” limits affect product testing and launch risk?
They align the protected method to impurity stability under prolonged refrigerated exposure and a subsequent ambient humidity/temperature stress window, making stability data for those conditions directly relevant.
References (APA)
- US Patent 10,905,662 (claims provided).
