US Patent 8,993,761 (Aripiprazole Hydrate A): Claim Scope, Patent Landscape, and US Competitive/Exclusivity Exposure
US Patent 8,993,761 is an aripiprazole hydrate polymorph/particle-size protection package. The claims are drafted around a defined thermal profile (TGA/DSC at a specified heating rate), defined crystallinity fingerprints (PXRD 2θ peak sets), defined IR absorption bands, and a particle-size envelope (mean size cutoffs and ranges) including a specific laser-diffraction measurement protocol. A second claim thread adds a controlled milling/atomization process to bring a defined hydrate precursor to the same particle-size targets. Scope is therefore primarily composition-by-characterization plus process-by-preparation that yields that composition.
What the patent protects in the US (core claim “hits”)
- Hydrate A of aripiprazole defined by DSC/TGA endothermic peak positions: first peak ~71°C and second peak ~60°C to 120°C (heating rate 5°C/min).
- Hydrous aripiprazole defined by (i) same DSC/TGA profile plus (ii) PXRD peak set (Cu Kα) and (iii) IR band set (KBr).
- The same materials further constrained to mean particle size: ≤50 μm, ≤20 μm, or 36–14 μm, with laser diffraction measurement requirements including a hexane/soy lecithin dispersion protocol.
- Milling/atomization processes that reduce a specific hydrate precursor (defined by PXRD + thermal profile) down to ≤50 μm (and dependent versions to ≤20 μm or 36–14 μm) using specified hardware/operating ranges (rpm and screen hole size).
Key business impact
- The claim set is narrow at the “identity” layer (Hydrate A fingerprint) and at the “manufacturing outcome” layer (particle-size distribution and measurement method). That structure can materially reduce risk to a generic if the ANDA product uses a different aripiprazole hydrate form or uses a different particle-size/measurement characterization approach.
- Conversely, if the generic uses the same hydrate form and controls particle size into the claimed ranges with equivalent characterization, 8,993,761 can create a direct infringement pathway, including for formulation manufacturing sites that perform the comminution step.
Estimated exclusivity window (US patent term)
- Patent numbers in the 8,9xx,xxx band typically issue around 2015–2017. With no PTA/term extension data provided in the prompt, the only actionable statement is: the patent term is age-based and is likely to be close to or past the early 2030s, subject to USPTO adjustments and any FDA-related term extensions. For litigation and launch planning, the practical levers are: (i) the exact issue date/expiration date from USPTO/Google Patents, (ii) PTA, and (iii) any pediatric extension, all of which are not specified in the prompt.
How do the claims define “Hydrate A of aripiprazole” in US 8,993,761?
Immediate scope (independent claim 1)
Claim 1 anchors “Hydrate A of aripiprazole” to a DSC/TGA endothermic curve:
- Heating rate: 5°C/min
- First endothermic peak: about 71°C
- Second endothermic peak: about 60°C to 120°C
- The claim is not expressly limited to a specific molar stoichiometry, but is functionally defined by the thermal behavior at a specified test condition.
Dependent layers (claims 2–4, 5–8)
These tighten scope by adding particle size and curve equivalence:
- Particle size mean ≤ 50 μm (claim 2); ≤ 20 μm (claim 3)
- Particle size mean 36–14 μm (claim 4)
- Claim 5 requires the endothermic curve to be substantially the same as FIG. 1 at the same heating rate
- Claims 6–8 repeat the particle-size limitations in the “FIG. 1 curve” context.
Key claim construction signals
- “About” and “substantially the same” introduce flexibility, but they also invite an expert test to map whether a defendant’s hydrate and test setup fall within the claimed boundaries.
- The explicit heating rate is a strong narrowing parameter; a generic arguing test condition differences may seek to de-emphasize “about” peak locations, but the claim’s test condition is fixed.
What makes the “hydrous aripiprazole” claims broader or different from Hydrate A alone?
Independent claim 11 reframes the identity layer as “hydrous aripiprazole” plus multi-modal characterization:
- Same DSC/TGA profile (heating rate 5°C/min, first peak ~71°C, second peak 60°C to 120°C)
- PXRD characteristic peaks (Cu Kα) at:
- 2θ = 12.6°, 15.4°, 17.3°, 18.0°, 18.6°, 22.5°, 24.8°
- IR (KBr) absorption bands at:
- 2951, 2822, 1692, 1577, 1447, 1378, 1187, 963, 784 cm−1
Dependent claims 12 and 13 lock PXRD and IR separately (only requiring the specified PXRD set or only requiring the specified IR band set, while still retaining the claim 11 base).
Claim 14 adds curve “substantially the same as FIG. 1” (parallel to claim 5).
Claims 15 (FIG. 3 PXRD), and 16–18 (particle size), and measurement method claims 19–24 (laser diffraction, including the hexane/soy lecithin protocol).
Practical interpretation
- Claim 11’s identity is “triply characterized.” This is often easier to enforce in infringement cases (multi-tech fingerprint matching) but can be harder for a generic to design around because it must avoid the same hydrate form or avoid matching the same PXRD/IR sets simultaneously.
How strong is the particle-size protection, and what exactly is claimed?
Mean particle size cutoffs and ranges
- ≤ 50 μm (claims 2, 6, 16, 24-series via dependencies)
- ≤ 20 μm (claims 3, 7, 17, etc.)
- 36–14 μm (claims 4, 8, 18, etc.)
Measurement method tightening
- Claims 9–10 and 22–24 specify laser diffraction measurement and a particular dispersion medium/protocol:
- 0.1 g sample in 20 mL n-hexane solution with 0.5 g soy lecithin
Infringement relevance
- A defendant can attempt to avoid literal infringement by showing:
- the hydrate form is not Hydrate A/hydrous aripiprazole as characterized; or
- the measured mean particle size falls outside the claimed ranges under the claimed dispersion/measurement protocol.
However, because many labs use similar laser diffraction workflows, a key litigation fact pattern often becomes whether a minor measurement-protocol difference is enough to change the mean value to “escape” ≤20 μm or 36–14 μm bands.
What process claims exist (milling/atomization), and how do they connect to the composition claims?
Claims 25–35 and 48–54 create a manufacturing pathway: milling/atomization a defined hydrate precursor to achieve the target particle size.
Process outcome claims tied to specific hydrate fingerprints
Equipment and parameter claims
Process measurement dependencies
- Claims 36–47 extend the process outcomes with the same laser diffraction measurement protocol and the same sample/solvent/soy lecithin amounts.
Core infringement mechanics
- For a generic manufacturer, the milling/atomization step that converts a particular aripiprazole hydrate precursor into the targeted particle-size distribution can be the infringement hook even if the end formulation is not separately claimed (depending on how downstream product claims are asserted in a given case).
Does the patent overlap with other aripiprazole hydrate and particle-size patents in the US?
What you can infer from the claim architecture
This patent’s structure matches a common category used across several brands/generics for oral solids:
- Identify a polymorph/hydrate by DSC/TGA + PXRD + IR
- Then lock particle size to reduce dissolution variability and bioavailability risk
- Then claim a comminution step to reach that size distribution.
That indicates the likely overlap is not with the “active ingredient” itself (aripiprazole base) but with:
- alternative hydrates/polymorphs of aripiprazole
- alternative processes for preparing hydrates
- alternative particle-size control approaches (including different milling methods or different dispersing media in laser diffraction)
- alternative measurement methods (D50 vs mean, alternative analyzers, alternative dispersants)
Key landscape variable
The presence of different PXRD peak sets across the claim families (claim 11 vs claim 25/26/27 vs claim 28’s FIG-based equivalents) suggests there may be multiple internal “defined hydrates” within the broader “hydrous aripiprazole/Hydrate A” umbrella. That increases the chance that related patents in the space partition protection by:
- different hydrate forms (different peak sets)
- different thermal transitions
- different particle size targets and measurement protocols.
Given the prompt does not include citations to related patents, assignees, application publication numbers, or the prosecution history, a complete US landscape map cannot be produced from the provided text.
What patents protect aripiprazole hydrate forms besides US 8,993,761? (US landscape mapping approach)
A full “how many patents cover aripiprazole Hydrate A” count requires Orange Book listings, ANDA filings, and a patent family search around:
- aripiprazole hydrate polymorphs (PXRD-defined)
- particle size and milling/atomization
- DSC/TGA-defined endothermic curves for hydrates
- IR fingerprint constraints
The prompt does not provide the assignee, publication number, priority dates, or related family members for 8,993,761, which are required to accurately identify the full US patent estate and competing families.
What generic entry risks exist for aripiprazole based on these claims?
Risk driver 1: manufacturing may be shaped to the claimed size
Many generic processes target a narrow particle size distribution for reproducibility. If the generic uses:
- the same hydrate form fingerprint, and
- a mean particle size ≤20 μm or within 36–14 μm,
- and uses laser diffraction under comparable dispersion conditions,
then US 8,993,761 can be a direct infringement risk.
Risk driver 2: multi-modal identity matching
Claim 11’s combined PXRD+IR+DSC creates an infringement pathway that can be hard to design around without switching hydrate form.
Risk driver 3: process claims
If the generic’s upstream step mills a “defined hydrate precursor” to the claimed mean size and does so using an atomizer within the parameter ranges, the process claims can be asserted.
Primary design-around levers
- Use a different aripiprazole hydrate or polymorph (avoid peak sets and thermal transitions).
- Maintain particle size outside the claimed envelopes under the claimed measurement protocol.
- Avoid the defined milling/atomization process parameters, though outcome-based claims can still create risk if the end material matches the composition claims.
When does US 8,993,761 lose exclusivity, and how does that affect Paragraph IV timing?
A precise “loss of exclusivity” date requires:
- issue date,
- USPTO patent term adjustment (PTA),
- any pediatric exclusivity adjustment,
- and any FDA-related extension (only relevant if the patent is eligible and tied to an approved product).
None of these are supplied in the prompt, so a compliant, accurate exclusivity timeline cannot be stated.
Key Takeaways
- US 8,993,761 protects aripiprazole Hydrate A / hydrous aripiprazole defined by DSC/TGA thermal peaks at 5°C/min, plus dependent layers locking PXRD and IR fingerprints and mean particle size cutoffs/ranges.
- The claims include both composition-by-characterization (thermal/PXRD/IR) and process-by-outcome (milling/atomization of a defined hydrate precursor to ≤50 μm and related particle-size targets).
- The patent’s enforceability depends heavily on whether an alleged infringer’s product matches the same hydrate fingerprint and whether its particle-size distribution falls within the claimed envelopes under the specified laser diffraction + hexane/soy lecithin protocol.
- Because the prompt does not include issue/expiration data, assignee, or related family search inputs, a complete US competitive and Orange Book/Paragraph IV landscape cannot be calculated from the information provided.
FAQs
1. What does “endothermic curve substantially the same” mean for aripiprazole hydrate infringement risk?
It is a comparative test claim requiring expert evaluation of DSC/TGA curves under specified conditions (5°C/min), typically focusing on whether peak positions and relative behavior match the claimed reference curve within accepted tolerance.
2. Does claim scope cover aripiprazole base (non-hydrated)?
No. The claims are limited to hydrated/hydrous aripiprazole identified by thermal and solid-state characterization.
3. Can a generic avoid infringement by measuring particle size differently?
A design-around depends on whether the generic avoids the claimed laser diffraction approach and especially the specific dispersion protocol (0.1 g in 20 mL n-hexane with 0.5 g soy lecithin) tied to certain claims.
4. Are the PXRD peak sets consistent across the entire patent?
No. The PXRD sets differ between claim families (for example, claim 11’s Cu Kα set differs from claim 25’s Cu Kα set), and additional claims use “substantially the same as FIG.” language.
5. Do the process claims require using the same atomizer hardware?
Some dependent process claims require an atomizer with specific operational parameters (rpm, feed rotation, screen hole size). Even so, litigation can also pivot to whether the produced hydrate product matches the composition claims.
References
No sources were provided in the prompt for US Patent 8,993,761 issue/expiration, assignee, prosecution history, or related patent families, so no external references can be cited under the given constraints.
