Details for Patent: 6,429,210

United States Patent 6,429,210 (Clopidogrel Hydrogen Sulfate Polymorph Form 2): Claims Scope and US Patent Landscape

What does US 6,429,210 claim in scope and how broad is it?

US Patent 6,429,210 is a polymorph and formulation IP position built around a single crystalline form: (+)-(S) clopidogrel hydrogen sulfate Form 2. The patent claims both (i) the material defined by analytical fingerprints (XRPD and IR), and (ii) compositions using that polymorph.

Core claim set: Form 2 identified by XRPD, IR, and melting point

The independent claim (Claim 1) defines the polymorph by an XRPD peak set at specific interplanar distances:

• ~4.11; 6.86; 3.60; 5.01; 3.74; 6.49; 5.66 Å (XRPD characteristic peaks)

Claim 2 defines the same Form 2 by IR absorption bands in cm−1 with approximate transmittance percentages:

• 2551 (43%); 1497 (63.7%); 1189 (18%); 1029 (33.2%)

Claim 3 defines Form 2 by melting behavior:

• 176 ± 3 °C

Claims 4–6 are dependent-style coverage that repeats the analytical definitions tied to figures:

• XRPD spectrum match to FIG. 2
• IR spectrum match to FIG. 3
• combined XRPD + IR constraints

Claim 7 moves from the solid form into downstream infringement exposure for products:

• A pharmaceutical composition containing an effective amount of Form 2 with excipients.

Additional material claims expand the XRPD “single-peak” footprint

Claims 8–14 broaden the “clopidogrel hydrogen sulfate (Form 2)” framing by allowing narrower XRPD feature assertions. The claims specify that the solid has a pattern with certain characteristic peaks. Key points:

• Claim 8: includes a ~4.11 Å characteristic peak
• Claim 9: includes a ~6.86 Å characteristic peak
• Claim 10: includes a ~3.60 Å characteristic peak
• Claim 11: includes a peak at ~3.87 Å
• Claims 12–14 add layered peak requirements:
  • Claim 12: ~6.86 Å and additionally ~6.86? (text indicates further shows ~6.86, which in practice implies “still includes” that peak plus another; Claim 12 also lists ~6.86 plus further ~3.60 depending on the claim text you provided)
  • Claim 13: includes ~6.86 Å and additionally ~3.60 Å
  • Claim 14: includes ~3.60 Å as additional to Claim 9’s condition

These dependents matter because they can create infringement theories that do not require the full seven-peak list in Claim 1, depending on claim construction and how the court treats “exhibiting a characteristic peak” versus “showing the XRPD diffractogram of FIG. 2.”

Thermodynamic characterization claim

Claim 15 adds another orthogonal material descriptor:

• enthalpy of fusion ~87 J/g

How is “Form 2” likely to be enforced in practice? (Claim-to-testing mapping)

The patent’s enforcement path is test-driven. Each independent/major material definition correlates to a standard analytical method:

What is the likely infringement boundary vs. other clopidogrel hydrogen sulfate forms?

The claims are anchored to clopidogrel hydrogen sulfate that matches Form 2 fingerprints. That creates a typical boundary:

• Infringement likelihood increases if the manufactured solid is predominantly Form 2 and retains its XRPD/IR signature in the tested material.
• Risk decreases if the product uses another polymorph (Form 1, hydrates, amorphous material) or if manufacturing produces a mixture where Form 2 is absent below the “effective amount” threshold or below the detectable fingerprint threshold.

However, Claims 8–14 potentially enlarge exposure even when only a subset of peaks is present. The legal question becomes whether those narrower claims still require the polymorph to be Form 2, or whether they capture broader materials that show single characteristic peaks.

What does the composition claim cover, and how far does it extend?

Claim 7 covers:

• A pharmaceutical composition comprising an effective amount of Form 2 polymorph plus at least one excipient.

That is standard “drug product” coverage, but it is not a use claim limited to a specific indication. The scope is instead tied to the solid-state API form present in the composition. If a dosage form contains Form 2 at manufacturing and remains Form 2 at relevant testing points, it can fall within the claim.

Where does this patent sit in the broader US clopidogrel polymorph landscape?

Context: clopidogrel is a settled commercial drug, but polymorph IP remains a recurring strategy

Clopidogrel hydrogen sulfate has had multiple crystalline forms reported historically. US patent families often claim:

• specific crystalline forms by XRPD/IR/DSC,
• processes for making those forms,
• and product/formulation compositions containing those forms.

In that landscape, US 6,429,210 is best viewed as:

• a materials claim (Form 2 fingerprinted),
• plus a composition claim (use in pharmaceutical formulations),
• with additional claim coverage using partial peak assertions (Claims 8–14) and thermodynamics (Claim 15).

Practical implication for portfolio mapping

For business and litigation purposes, your competitive “freedom-to-operate” map for solid-state clopidogrel should treat 6,429,210 as a Form 2 gatekeeper:

• If a competitor’s API is made or isolated in a different form, the XRPD/IR mismatch reduces risk.
• If it uses Form 2 deliberately or if Form 2 is the inevitable solid-state outcome of a shared process, the patent is directly relevant.

Which other claim features drive licensing/settlement leverage?

The combination of analytical definitions and composition coverage creates stronger leverage than a “process-only” patent:

• Material fingerprint claims can attach to both API and finished products.
• Composition claim reduces the need to prove manufacturing steps, focusing instead on what the product contains.
• Multiple orthogonal descriptors (XRPD + IR + melting + enthalpy) reduces the chance that a simple analytical dispute defeats infringement.

Claim-by-claim scope table (what each claim protects)

How does the patent’s “partial peak” claim structure affect landscape risk?

Claims 1–6 are tight: they require either a full multi-peak XRPD set and/or the full IR fingerprint. Claims 8–14 are looser because they only enumerate one or a subset of peaks.

In a practical risk model:

• If a competitor’s solid shows only one fingerprint peak due to coincidence (e.g., background or overlap with another form), the tighter claims (1/2/6/4/5) are less likely to be infringed.
• But the presence of single peaks can still create litigation leverage depending on how the court construes whether “exhibiting a characteristic peak” inherently means “Form 2.”

Key takeaways

What US 6,429,210 most strongly covers

• A single crystalline form: (+)-(S) clopidogrel hydrogen sulfate Form 2.
• Material identification by XRPD peak set (Claim 1) and IR absorption set (Claim 2).
• Product-level coverage via a pharmaceutical composition claim using Form 2 (Claim 7).

Where the enforcement threat is highest

• API batches and finished products that test as Form 2 by the specified XRPD/IR fingerprints and thermal behavior.
• Manufacturers who adopt crystallization/isolation conditions that consistently yield Form 2.

Where the threat is more nuanced

• If a product uses Form 2 only transiently during processing but converts before testing.
• If products show only partial XRPD peak presence captured by Claims 8–14 without the full fingerprint required for Claims 1–6.

FAQs

1. Is Claim 7 limited to a particular therapeutic use?
   No. It is a composition claim covering an effective amount of Form 2 with excipients.

2. Which claim set is most stringent for XRPD matching?
   Claims 1, 4, and 6 because they tie Form 2 to a multi-peak set and/or a figure-defined XRPD pattern.

3. Which claim set can be infringed with fewer XRPD features?
   Claims 8–14 because they specify single or paired characteristic peaks.

4. What thermal property is explicitly required?
   Claim 3 requires a melting point 176 ± 3 °C, and Claim 15 requires enthalpy of fusion ~87 J/g.

5. Does the patent cover both API and finished drug products?
   Yes. It covers the crystalline polymorph itself (material claims) and also pharmaceutical compositions containing that polymorph (Claim 7).

References

[1] US Patent 6,429,210 (claims reproduced in user-provided text).