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Patent landscape, scope, and claims: |
US Patent 9,271,968: Rifaximin polymorph X-ray diffraction scope, claim coverage, and landscape
What is US 9,271,968 protecting?
US Patent 9,271,968 protects solid pharmaceutical compositions that contain rifaximin with specific crystal forms defined by X-ray powder diffraction (XRPD) peak positions (2θ, ±0.2° tolerance), optionally coupled with water-content and standard solid-form/excipient limitations.
The claims split into two XRPD “fingerprints” (Claims 1-11 and 12-18) that cover different rifaximin crystalline signatures. Both sets include coverage broad to formulation types (granules/tablets/capsules/powders in sealed packets) and conventional excipient classes.
How are the claims structured and what do they require?
The patent is composition-centric and claim elements are, in practice, three buckets:
- Drug identity and role: “therapeutically effective amount of rifaximin together with excipients”
- XRPD-based solid-state definition: specific rifaximin peak sets at defined 2θ angles
- Formulation qualifiers (some dependent claims): water content, excipient classes, and solid dosage presentation
Independent claim set (XRPD-constrained compositions)
- Claim 1: composition with rifaximin having XRPD peaks at about
5.7°±0.2, 6.7°±0.2, 8.0°±0.2 (2θ)
Plus excipients (broad).
- Claim 12: composition with rifaximin having XRPD peaks at about
7.3°±0.2, 8.2°±0.2, 10.3°±0.2 (2θ)
Plus excipients (broad).
Dependent expansion of the XRPD fingerprint
For Claim 1, the dependent claims progressively add additional peaks. For Claim 12, the dependent claims progressively add additional peaks.
Claim 1 XRPD fingerprint expansions (Claims 2-11, 16)
- Claim 2 adds a peak at 7.1°±0.2
- Claim 3 adds 10.4°±0.2
- Claim 4 adds 11.3°±0.2
- Claim 5 adds 7.1°±0.2 and 10.8°±0.2
- Claim 6 adds 12.1°±0.2
- Claim 7 specifies a multi-peak addition: 7.1°±0.2, 8.7°±0.2, 10.4°±0.2
- Claim 8 provides a full explicit set of peaks at:
5.7, 6.7, 7.1, 8.0, 8.7, 10.4, 11.3, 12.1, 17.0, 17.3, 17.5, 18.5, 18.8, 19.1, 21.0, 21.5 (all ±0.2°; 2θ)
- Claim 9 limits water content to 2.5% to 6.0%
- Claim 10 limits excipients to categories: diluting, binding, lubricating, disintegrating, coloring, flavoring
- Claim 11 limits dosage form: granules, tablets, capsules, powders in sealed packets
- Claim 16 repeats the long peak set from Claim 8 (same list and tolerances)
Claim 12 XRPD fingerprint expansions (Claims 13-18)
- Claim 13 adds 7.0°±0.2 and 11.1°±0.2
- Claim 14 adds 12.4°±0.2, 8.7°±0.2, 11.7°±0.2
- Claim 15 adds 17.5°±0.2 and 21.5°±0.2
- Claim 16 (cross-referenced in your excerpt as a “composition according to claim 11”) restates the larger peak set for the Claim 1-family fingerprint, not the Claim 12-family fingerprint (as written, this portion is internally inconsistent because Claim 11 is not the Claim 12 family). Still, operationally, the long peak set itself is clearly specified.
- Claim 17 limits excipients to the same category list
- Claim 18 limits dosage form to the same set (granules/tablets/capsules/powders in sealed packets)
What is the practical claim scope (what would infringe vs avoid)?
What is required to land inside the claims
A practicing entity would generally need to show, for at least one claim path:
- The formulation contains rifaximin in a crystalline form whose XRPD 2θ peaks match the specified values within ±0.2°.
- The formulation includes excipients (no restriction on identity except in dependent claims).
- For dependent coverage, it must also satisfy:
- water content: 2.5% to 6.0% (Claim 9)
- excipient type categories (Claim 10/17)
- solid form type (Claim 11/18)
Because the independent claims are already XRPD-defined, the core value is the polymorph identification by peak positions rather than a specific manufacturing method.
How broad is the “excipient” and “form” coverage?
- Excipient language is broad at the independent level (“together with excipients”). Dependent claims narrow only by excipient class, not by exact composition.
- Solid dosage formats are covered: granules, tablets, capsules, and powders in sealed packets. Liquid is not within these written dependent claims as stated.
How tight is the XRPD match?
The XRPD definition uses “about X°±0.2” for each listed peak. That is a narrow numerical window, but it also means:
- A competitor could potentially use the same general crystal form while shifting peak positions within instrumentation- and preparation-related variability, but the claim terms explicitly allow ±0.2° around each target.
- In practice, infringement risk rises when the competitor’s material shows the same peak set (especially the longer explicit lists like Claim 8 and the “full” set repeated in Claim 16).
Claim-by-claim XRPD coverage map (what peaks are claimed)
Rifaximin XRPD peak sets under the Claim 1 family
Minimum explicitly recited in Claim 1:
- 5.7°±0.2, 6.7°±0.2, 8.0°±0.2
Expanded peak requirements appear in dependent claims including:
- 7.1°±0.2 (Claims 2, 5, 7, and in the full list)
- 10.4°±0.2 (Claims 3, 7, and in full list)
- 11.3°±0.2 (Claim 4, and in full list)
- 10.8°±0.2 (Claim 5 only)
- 12.1°±0.2 (Claim 6, and in full list)
- 8.7°±0.2 and 17.0, 17.3, 17.5, 18.5, 18.8, 19.1, 21.0, 21.5 appear in the full list (Claim 8/16)
Rifaximin XRPD peak sets under the Claim 12 family
Minimum explicitly recited in Claim 12:
- 7.3°±0.2, 8.2°±0.2, 10.3°±0.2
Dependent claim peak expansions include:
- 7.0°±0.2 and 11.1°±0.2 (Claim 13)
- 12.4°±0.2, 8.7°±0.2, 11.7°±0.2 (Claim 14)
- 17.5°±0.2 and 21.5°±0.2 (Claim 15)
What does this mean for design-around strategies?
At a high level, design-around must move one of the claim pillars:
-
Use a rifaximin crystalline form whose XRPD does not match the claimed peak positions within ±0.2°.
The strongest pivot is the peak set rather than the composition formulation.
-
For dependent claims, move on water content, excipient categories, or dosage form.
- Water content: to avoid Claim 9, target outside 2.5% to 6.0%.
- Excipient classes: Claim 10 and 17 only list standard categories; a formulation that uses atypical excipient roles could be positioned outside those dependent limitations (while still meeting independent claim XRPD elements).
- Solid form: avoid the specified forms if those dependent claims are used for enforcement; however, independent claims still cover “pharmaceutical composition” broadly and do not state form restrictions.
Net: the dominant risk lever is XRPD congruence.
Patent landscape positioning (based on claim content)
What this patent sits between in the rifaximin ecosystem
Based on claim language, US 9,271,968 is in the “solid-state and polymorph/formulation” layer:
- It does not claim a new dosing regimen in your excerpt.
- It does not claim a specific synthesis route.
- It does claim a specific solid-state definition using XRPD peaks and tolerances, along with common formulation attributes.
That placement matters commercially:
- It tends to protect product-relevant material specifications (the polymorph used in drug substance or a stable form in drug product).
- It can complicate generic entry if the generic’s rifaximin form matches the XRPD peak list and the formulation fits the stated solid form and excipient framing.
Where enforcement leverage typically concentrates
Given the XRPD-defined claims, enforcement leverage typically concentrates on:
- Material characterization (XRPD testing methods and sample prep)
- Comparability of peak positions and peak sets
- Whether the accused rifaximin matches the full explicit peak list (Claim 8/16) or the minimal three-peak set (Claim 1 or 12)
Scope summary table
| Claim group |
Core requirement |
Additional dependent qualifiers (examples) |
Practical enforcement target |
| 1 (independent) |
XRPD peaks at 5.7, 6.7, 8.0 (±0.2), 2θ |
Expanded peaks in Claims 2-8, plus water/excipient/form in Claims 9-11 |
Verify accused XRPD peak set matches within ±0.2 |
| 12 (independent) |
XRPD peaks at 7.3, 8.2, 10.3 (±0.2), 2θ |
Expanded peaks in Claims 13-15; excipient and form in Claims 17-18 |
Compare accused XRPD fingerprint for the Claim 12 family |
| 8 / 16 |
Full explicit multi-peak list (Claim 1 family) |
Water and other dependent limits apply only where claimed |
Strongest “fingerprint” subset for claim matching |
| 9 |
XRPD match + water content 2.5% to 6.0% |
Dependent on Claim 1 |
Moisture/spec control in drug product |
Key Takeaways
- US 9,271,968 protects rifaximin-containing solid pharmaceutical compositions defined by XRPD peak positions with ±0.2° tolerance.
- Claim scope is built around two independent XRPD fingerprints: (5.7, 6.7, 8.0) (Claim 1 family) and (7.3, 8.2, 10.3) (Claim 12 family).
- Dependent claims broaden coverage through additional peaks, and narrow in areas that matter for formulation: water content (2.5% to 6.0%), excipient class, and solid dosage format (granules/tablets/capsules/powders in sealed packets).
- The main infringement and design-around lever is whether the accused rifaximin crystalline form matches the claimed XRPD peaks and peak sets within the stated tolerance, not the excipient identity or general dosage form.
FAQs
1) Do the claims cover liquid formulations?
The provided claim set targets solid dosage presentations in dependent claims (granules, tablets, capsules, powders in sealed packets). The independent claims as excerpted are “pharmaceutical composition” without explicit form limits, but the solid-form dependent claims do not extend to liquids.
2) What is the tightest claim element numerically?
The XRPD angles: each listed peak is specified “about X°±0.2” at 2θ. The full explicit peak list (Claim 8/16 for the Claim 1 family) is the most restrictive formulation of the XRPD fingerprint.
3) Can a generic avoid infringement by changing excipients only?
Changing excipients alone likely does not avoid the independent claims if the rifaximin XRPD fingerprint still matches the claimed peaks. Excipient swaps only matter for dependent claims that restrict excipient categories.
4) Is water content only relevant for Claim 9?
Yes. Water content appears in Claim 9 as 2.5% to 6.0%. Other dependent claims in your excerpt do not impose a water-content limit.
5) Which claim is the strongest “fingerprint”?
For the Claim 1 family, the most explicit fingerprint is the multi-peak list in Claim 8 (and repeated in Claim 16), which enumerates many additional peaks beyond the minimal three required in Claim 1.
References
[1] United States Patent 9,271,968 (claims as provided in the prompt).
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