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Patent landscape, scope, and claims: |
US Patent 8,877,938 Landscape: What Claims Cover for a Specific Crystalline Trisodium Tetrazolyl Biphenyl Propionate Salt Hydrate (and What’s Left to Design Around)
What does US Patent 8,877,938 claim exactly for the crystalline trisodium hydrate?
Core subject matter. US 8,877,938 is directed to a narrowly defined, solid-state form of a specific trisodium salt of a tetrazolyl biphenyl-containing propionate/butyrate molecule, specifically in a crystalline hemipentahydrate form with enumerated structural, spectroscopic, and crystallographic identifiers. The independent claim is essentially “the compound in crystalline form” with subsequent claims locking down the hydrate stoichiometry and property tests.
Independent claim scope (Claim 1)
Claim 1: “Trisodium [3-((1S,3R)-1-biphenyl-4-ylmethyl-3-ethoxycarbonyl-1-butylcarbamoyl)propionate-(S)-3′-methyl-2′-(pentanoyl{2″-(tetrazol-5-ylate)biphenyl-4′-ylmethyl}amino)butyrate] hemipentahydrate in crystalline form.”
Practical reading: Claim 1 is not merely the chemical entity. It is limited to:
- the exact trisodium salt form (3 Na),
- the hemipentahydrate (non-integer hydrate language in the title, but Claim 2 resolves it as 2.5 H2O),
- and a crystalline form (not amorphous, not solvated with different stoichiometry).
Species reinforcement (Claim 2)
Claim 2: The compound has sum formula C48H55N6O8Na3 ● 2.5 H2O, and the asymmetric unit comprises six such formula units.
This “locks” the hydrate stoichiometry to 2.5 waters per formula unit and sets an internal crystallographic asymmetry unit count. For design-around, that usually forces challengers to move to a different hydrate/solvate stoichiometry or a different solid-state polymorph with different asymmetric unit composition.
Spectral identity claims (Claims 3-4)
- Claim 3: ATR-FTIR absorption bands at: 1711 (±2), 1637 (±2), 1597 (±2), 1401 (±2) cm−1.
- Claim 4: A more extensive ATR-FTIR band set (multiple peaks with “w/m/st” intensity tags) including 2956, 1711, 1637, 1597, 1488, 1459, 1401, 1357, 1295, 1266, 1176, 1085, 1010, 942, 907, 862, 763, 742, 698, 533 cm−1 (each with ±2 cm−1 where indicated).
Practical reading: These are testable “identity” claims. If a generic developer produces a solid that fails the ATR-FTIR band presence/positions within the tolerances, it can attempt to avoid literal infringement of these dependent claims (though Claim 1 could still be asserted depending on whether the product is still the same crystalline hydrate).
Powder XRD identity claims (Claim 5-6)
- Claim 5: XRPD interlattice plane intervals d (Å) within ±0.1 Å at:
21.2(s), 17.0(w), 7.1(s), 5.2(w), 4.7(w), 4.6(w), 4.2(w), 3.5(w), 3.3(w).
- Claim 6: 2θ list for the Scintag XDS2000 including:
4.5, 5.5, 5.6, 9.9, 12.8, 15.7, 17.0, 17.1, 17.2, 18.3, 18.5, 19.8, 21.5, 21.7, 23.2, 23.3, 24.9, 25.3, 27.4, 27.9, 28.0, 30.2 (degrees).
Practical reading: These are classic polymorph-locking claims. A generic can try to select a different polymorph or different hydrate/solvate that yields a different XRPD pattern and does not include the enumerated reflections at the same positions/intensities within measurement variance.
Crystallography “hard lock” claims (Claims 7-10)
- Claim 7: monoclinic unit cell with cell content comprising twelve formula units of C48H55N6O8Na3 ● 2.5 H2O.
- Claim 8: monoclinic unit cell where cell content comprises two asymmetric units on two-fold positions.
- Claim 9: P2i space group.
- Claim 10: a full set of cell parameters and properties:
Molecular mass 957.99, color/shape descriptors, crystal system monoclinic, space group P21,
a = 20.344 Å, b = 42.018 Å, c = 20.374 Å, β = 119.29°, volume 15190.03 ų, Z (as provided), density 1.26845 g/cm³.
Practical reading: This section narrows Claim 1 to a specific crystallographic form. A manufacturer who makes the same chemical salt but crystallizes it into another form likely avoids these dependent claims.
Formulation composition coverage (Claims 11-14)
- Claim 11: A pharmaceutical composition with an effective amount of the compound of Claim 1 and at least one pharmaceutically acceptable additive.
- Claim 12: Further comprising a therapeutic agent selected from anti-diabetic, hypolipidemic, anti-obesity, anti-hypertensive agents.
- Claim 13: Therapeutic agent is amlodipine besylate.
- Claim 14: Therapeutic agent is hydrochlorothiazide.
Practical reading: This is a combination formulation “parasitic” claim that depends on the protected solid form. If a competitor avoids Claim 1’s crystalline hemipentahydrate, these dependent combination claims typically become harder to reach. If the competitor uses the protected solid form and simply changes the co-ingredient, these claims can be leverage points for licensing or enforcement.
How broad is the patent estate from the claim structure: molecule vs. solid form vs. co-formulation?
US 8,877,938 is primarily a solid-state form patent. The majority of claim language is crystallographic, spectroscopic, and XRPD-based. That tends to create three infringement paths:
- Literal product form match: the competitor sells the same trisodium hemipentahydrate crystalline solid.
- Identity-test match: competitor’s material shows the same ATR-FTIR/XRPD peak sets within tolerances.
- Downstream formulation match: competitor uses the protected solid form inside a drug product composition.
What it does not do (based on the claim text provided):
- It does not read on “any hydrate” or “any crystalline polymorph” of the compound.
- It does not claim a general method of making the solid form (nothing in the provided claims indicates manufacturing steps).
- It does not claim broad dosage regimens or broad combination therapy indications; it claims combinations only by listing co-therapeutic agents (amlodipine besylate, hydrochlorothiazide) under composition claims.
What is the claim “design-around surface area” for a generic: hydrate, polymorph, and analytical fingerprint
A design-around strategy for a crystalline-form patent usually targets one of these elements.
1) Change hydrate/solvate stoichiometry
Claim 1 ties to “hemipentahydrate,” and Claim 2 fixes the formula to C48H55N6O8Na3 ● 2.5 H2O. A competitor who crystallizes a different stoichiometry (e.g., different number of waters) is structurally moving outside the claim-defined species.
2) Switch polymorph or unit cell
Claims 7–10 set monoclinic system attributes, space group (P2i / P21 language appears in the claim set you provided), and specific cell parameters. A different polymorph or a different crystalline lattice typically changes XRPD and ATR-FTIR fingerprints.
3) Ensure ATR-FTIR band set failure
Claims 3–4 include ±2 cm−1 windows for key bands and a full band panel. A competitor would validate that its solid form does not generate the same set at the specified positions within tolerance.
4) Ensure XRPD reflections do not match within measurement bounds
Claim 5 has ±0.1 Å on d-spacings. Claim 6 lists 2θ peaks for a specific diffractometer setup. A competitor would aim to produce a solid form whose XRPD pattern does not match those peak locations.
5) Avoid downstream formulation dependency
Even if the API avoids Claim 1, a combination formulation claim still requires using the compound of Claim 1 “as an ingredient.” If Claim 1 is avoided at the API solid-form level, Claims 11–14 typically become non-infringing.
What patent scope is created by the composition claims with amlodipine and hydrochlorothiazide?
Claims 12–14 create a conditional combination coverage:
- If a product contains the protected trisodium crystalline hemipentahydrate compound of Claim 1, and the co-therapeutic agent is amlodipine besylate or hydrochlorothiazide, then Claims 13 or 14 can be asserted.
- Claim 12’s broader “therapeutic agent selected from” list gives an additional hook for other classes, but it is still dependent on Claim 11 (which depends on Claim 1).
Commercial implication: Even if a generic intends to launch a monotherapy, enforcement risk shifts if it intends a fixed-dose combination involving those listed agents. For licensing, these combination claims can expand the settlement umbrella beyond simple API supply.
How many distinct protected “things” are in US 8,877,938 based on the claim dependencies?
Based strictly on the provided claim set, the patent protects at least four distinct “layers”:
- Crystalline hemipentahydrate trisodium salt (Claim 1).
- Specific hydrate stoichiometry and asymmetric unit content (Claim 2).
- Spectroscopic identity via ATR-FTIR peak panels (Claims 3–4).
- Crystallographic identity via XRPD peaks and unit cell/space group parameters (Claims 5–10).
- Downstream compositions with permitted co-therapeutic agents (Claims 11–14).
This is a typical fortress pattern: chemical identity plus analytical identity plus crystallography identity.
What litigation, Orange Book status, and FDA exclusivity does the claim set imply?
No Orange Book listing status, FDA approval dates, or exclusivity windows are provided with US 8,877,938 in the material here. Without such data, there is no reliable basis to map:
- FDA application numbers,
- listed patents and reference products,
- paragraph IV use codes,
- Orange Book expiration or pediatric exclusivity impacts.
Which generic entry risks exist for the protected crystalline hemipentahydrate?
Risk is high for generic API that is empirically the same crystalline form. The combination of XRPD and ATR-FTIR identity claims reduces plausible “form drift” arguments where the solid ends up matching the protected lattice.
Risk is lower, but still non-zero, for polymorph/hydrate-switch strategies, because:
- crystallization can revert to the thermodynamically stable protected form,
- commercial solid-state processes can be contaminated with trace of the protected polymorph that still yields matching peaks,
- and downstream formulation conditions can induce solid-state transformation.
How long could the patent remain enforceable in the US (expiration mechanics)?
US patent term mechanics depend on filing/priority dates and any terminal disclaimers or PTA, none of which are included here. The claim text alone does not provide enforceability timing.
Key Takeaways
- US 8,877,938 is a crystalline solid-state form patent focused on a trisodium hemipentahydrate with fixed hydrate stoichiometry (C48H55N6O8Na3 ● 2.5 H2O) and a defined crystalline identity.
- The claims stack chemical identity (trisodium hemipentahydrate) with analytical identity (ATR-FTIR band sets, XRPD peak positions) and crystallography identity (monoclinic unit cell, space group, and cell parameters).
- Design-around is most feasible via changing hydrate/solvate stoichiometry or selecting a different polymorph that fails the defined ATR-FTIR and XRPD fingerprints.
- Downstream combination formulation coverage exists if the protected crystalline solid form is used with amlodipine besylate or hydrochlorothiazide (Claims 13 and 14).
- The claim structure increases the odds that “different process, same solid” outcomes will still land within infringement risk.
FAQs
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Can a different hydrate avoid infringement of US 8,877,938 if the chemical moiety is the same?
Avoidance is most plausible when the alternate solid form does not match the claim-defined 2.5 H2O stoichiometry and fails the ATR-FTIR and XRPD identity constraints.
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Do the ATR-FTIR and XRPD dependent claims create separate infringement theories?
Yes. They provide additional identity-based pathways tethered to the protected compound, increasing enforcement leverage if the product’s analytical profile matches.
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If a generic uses a different polymorph, can the formulation claims still be asserted?
Formulation claims are dependent on “the compound of Claim 1.” If the competitor avoids Claim 1’s crystalline identity, dependent formulation claims should be harder to reach.
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How do space-group and unit-cell claims affect solid-state design-around?
They target the specific lattice. A different crystalline form typically changes unit-cell metrics and XRPD reflections, weakening literal identity.
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What co-therapeutic agents are explicitly covered in composition claims?
Amlodipine besylate and hydrochlorothiazide are explicitly named in dependent claims 13 and 14, respectively.
References
- Provided claim text for US Patent 8,877,938 (user-supplied).
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