US Patent 7,145,036: Scope, Claims, and Patent Landscape for Highly Pure (R,R)-Formoterol L-Tartrate Polymorphs
What does US 7,145,036 claim, in practical terms?
US 7,145,036 is a polymorph- and process-defined patent directed to a “highly pure” (R,R)-formoterol L-tartrate composition. It is structured so that infringement can be proven either through (i) the crystalline form identity (polymorph definition by powder X-ray diffraction) and (ii) compositional purity metrics and (iii) crystallization conditions (aqueous isopropyl alcohol, including a two-stage solvent system with seeding).
The claims you provided narrow to one specific polymorph (the “first polymorph (C)”), then add purity and a target stability polymorph (the “third polymorph (A)”), then tie down how polymorph (C) is crystallized from aqueous isopropyl alcohol using defined solvent ratios and a two-stage method.
How broad is Claim 1 (polymorph C by XRD) in scope?
Claim 1 is the core claim. It requires all of the following elements in combination:
-
Substance identity
- (R,R)-formoterol L-tartrate
- “highly pure (R,R)-formoterol L-tartrate composition”
-
Process limitation tied to polymorph identity
- “obtained by a process comprising crystallizing a first polymorph (C)”
- the crystallization medium is aqueous isopropyl alcohol
-
Polymorph C identification by X-ray powder diffraction peak set
- “said first polymorph having peaks at the diffraction degrees with the intensity shown below”
- the claim defines a powder XRD pattern by peak number, 2-theta, and intensity.
XRD definition in Claim 1 (polymorph C)
Key point: Claim 1 is not written as “substantially the same pattern” in your excerpt; it lists a defined peak table. From an infringement and validity standpoint, this makes the XRD definition central.
Table: Peak list recited in Claim 1
| Peak # |
2-Theta (°) |
Intensity |
| 1 |
6.4 |
100.0 |
| 2 |
9.0 |
14.4 |
| 3 |
11.1 |
14.8 |
| 4 |
12.4 |
13.9 |
| 5 |
12.9 |
19.7 |
| 6 |
13.5 |
19.5 |
| 7 |
14.0 |
15.1 |
| 8 |
15.0 |
19.7 |
| 9 |
15.4 |
16.9 |
| 10 |
15.7 |
18.1 |
| 11 |
16.3 |
12.8 |
| 12 |
17.5 |
64.9 |
| 13 |
19.4 |
47.3 |
| 14 |
19.9 |
44.8 |
| 15 |
21.3 |
29.3 |
| 16 |
22.3 |
31.5 |
| 17 |
22.9 |
35.8 |
| 18 |
24.1 |
80.0 |
| 19 |
24.7 |
17.6 |
| 20 |
25.5 |
11.3 |
| 21 |
26.0 |
15.6 |
| 22 |
26.8 |
9.1 |
| 23 |
27.4 |
8.5 |
| 24 |
28.4 |
10.8 |
| 25 |
29.0 |
8.5 |
| 26 |
30.5 |
8.1 |
| 27 |
32.7 |
10.9 |
| 28 |
34.2 |
7.9 |
| 29 |
35.7 |
9.3 |
| 30 |
36.4 |
6.6 |
| 31 |
37.3 |
7.9 |
| 32 |
37.8 |
9.1 |
| 33 |
39.3 |
10.0 |
| 34 |
39.6 |
11.4 |
| 35 |
41.1 |
5.7 |
| 36 |
42.3 |
4.7 |
Practical implication: This claim is a “crystalline form gate.” If a competitor produces a solid with a different polymorph (or a materially different XRD signature), it can fall outside Claim 1 even if it uses aqueous isopropyl alcohol crystallization.
What additional narrowing does Claim 2 introduce?
Claim 2 depends on Claim 1 and adds two constraints:
-
High compositional purity by weight
- “greater than 99.5% by weight of formoterol L-tartrate”
-
Polymorphic purity toward a specified thermodynamically stable polymorph
- “at least 95% in the polymorphic form of a thermodynamically stable third polymorph (A) of (R,R)-formoterol L-tartrate”
So Claim 2 is not merely “polymorph C”; it is a composition that must be:
- obtained via the polymorph C crystallization route (from Claim 1), and
- the resulting composition must be mostly polymorph A (stable thermodynamic form) and also high chemical purity.
Practical implication: Claim 2 requires a post-crystallization outcome (or a transformation pathway) that yields polymorph A as the dominant solid form.
How does Claim 3 constrain the manufacturing method?
Claim 3 depends on Claim 1 and defines how polymorph C is crystallized from aqueous isopropyl alcohol via a two-stage process:
-
Stage 1 dissolution
- polymorph (C) is first dissolved in 50% (v/v) isopropyl alcohol:water
- temperature 50–55°C
-
Immediate crystallization
- crystallization is done by “seeding and addition”
- solvent adjustment: add sufficient isopropyl alcohol to reach 25% (v/v) isopropyl alcohol:water
- timed as “immediately crystallized” after the dissolution step per the claim text you provided.
Practical implication: Claim 3 is the tightest operational “recipe” among the three. A competitor changing either:
- the stage-1 solvent ratio,
- the temperature window,
- the stage-2 target ratio,
- the sequencing (delayed crystallization, different seeding approach),
could attempt to avoid this claim even if they still land on the same XRD peaks for polymorph C.
Where does the patent sit in a typical solid-state landscape for formoterol L-tartrate?
Based on the claim structure alone, US 7,145,036 sits in a crowded IP area where the battleground is usually:
- polymorph identity (XRD-defined forms),
- thermodynamic stability claims (stable polymorph A),
- manufacturing solvent systems and temperature-controlled crystallization.
The claims you supplied show a two-link chain that is common in polymorph patenting:
- produce polymorph C under defined conditions (aqueous IPA with a specific XRD fingerprint), then
- end with a highly pure and polymorph-A-rich final composition.
That architecture can be used to argue both:
- novelty/non-obviousness at the level of crystallization to polymorph C; and
- commercial value at the level of a stable polymorph A solid with very high chemical and polymorphic purity.
Claim scope map: what must be true for infringement?
Below is a strict checklist derived from the claim elements you provided.
Claim 1 infringement elements (must all be satisfied)
- Product: highly pure (R,R)-formoterol L-tartrate composition
- Method: crystallized first polymorph (C) in aqueous isopropyl alcohol
- Crystalline form: polymorph C has the recited powder XRD peak set, including:
- 2-theta 6.4° at intensity 100.0
- 17.5° at intensity 64.9
- 24.1° at intensity 80.0
- other peaks listed through 42.3° intensity 4.7
Claim 2 additional elements
- Chemical purity: >99.5 wt% formoterol L-tartrate
- Polymorph composition: at least 95% polymorphic form A (thermodynamically stable third polymorph) within the composition
Claim 3 additional elements
- Solvent system and temperature:
- dissolve in 50% v/v IPA:water at 50–55°C
- Crystallization mechanics:
- immediately crystallize by seeding
- adjust solvent to 25% v/v IPA:water by adding IPA
What is the likely validity pressure from within-family and prior art types?
Even without prosecution history, the claim language reveals the primary vulnerability areas that third parties typically attack in polymorph cases:
-
XRD peak list specificity vs. measurement variability
- XRD peak position and intensity depend on instrument settings, sample prep, and conditions. If the claim does not provide tolerance windows around 2-theta values and intensities, validity and infringement disputes can revolve around what “having peaks at the diffraction degrees with the intensity shown” means in practice.
-
Polymorph continuity (interconversion)
- Polymorphs can transform depending on humidity, temperature, and mechanical stress. If polymorph C converts to polymorph A during isolation, drying, or handling, Claim 2’s requirement for polymorph A could be argued as inherent to the process.
-
Known crystallization solvents
- Aqueous isopropyl alcohol is a common crystallization solvent system in pharmaceutical solid-state manufacturing. Validity typically depends on whether the recited XRD fingerprint and the particular two-stage solvent composition and seeding protocol were previously disclosed or obvious.
US patent landscape: how this claim style impacts freedom-to-operate
From a freedom-to-operate perspective, this patent creates three “avoidance levers” for generic or competitor processes:
-
Switch the polymorph path
- If a competitor produces a different form than polymorph C (or yields a materially different XRD profile), it can attempt to avoid Claim 1’s fingerprint.
-
Keep final solid form from being polymorph A-rich
- Claim 2 forces at least 95% polymorph A in the final composition. Processes that deliver a different polymorph distribution can attempt to avoid Claim 2 even if they pass Claim 1.
-
Change the crystallization recipe
- Claim 3 is recipe-specific: 50% v/v IPA:water at 50–55°C followed by immediate seeding and adjustment to 25% v/v IPA:water.
- Modifying these parameters can avoid Claim 3 even if the same endpoint polymorph is targeted.
Key Takeaways
- US 7,145,036 is a polymorph- and process-linked patent built around a “first polymorph (C)” defined by a detailed XRD peak table and crystallization from aqueous isopropyl alcohol.
- Claim 1 is dominated by the XRD fingerprint for polymorph C plus the aqueous IPA crystallization link.
- Claim 2 narrows to a final composition with >99.5 wt% formoterol L-tartrate and ≥95% polymorph A (thermodynamically stable third polymorph).
- Claim 3 narrows to a specific two-stage crystallization recipe: dissolution in 50% v/v IPA:water at 50–55°C, followed by immediate seeding and adjustment to 25% v/v IPA:water.
- Freedom-to-operate risk concentrates on whether competing processes hit the polymorph C XRD pattern and whether the resulting isolated solid is polymorph A-rich and made by the recited IPA solvent sequence.
FAQs
-
Does Claim 1 require polymorph A?
No. Claim 1 requires production of polymorph C (XRD-defined) in aqueous isopropyl alcohol. Polymorph A appears in Claim 2.
-
What is the most infringement-relevant element across the three claims?
Claim 1’s polymorph C XRD peak list is the primary gate; Claim 2 adds quantitative polymorph A and chemical purity; Claim 3 adds a tightly defined IPA:water two-stage crystallization method.
-
Can a competitor design around by using a different solvent than isopropyl alcohol?
Yes for Claim 1 and Claim 3, since those require aqueous isopropyl alcohol crystallization. Using a different solvent system would avoid those dependencies.
-
Does Claim 2 protect only the final solid, or also the method?
Claim 2 is a dependent claim, so it inherits Claim 1’s method/process context. It protects the resulting composition that meets the purity and polymorph A thresholds.
-
Why does the XRD table matter for enforcement?
It makes the crystalline form definition explicit. To avoid infringement, a competitor generally needs to show a materially different polymorph identity rather than only similar bulk chemistry.
References
[1] Claims text of US Patent 7,145,036 as provided in the prompt.
