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Patent landscape, scope, and claims: |
United States Patent 6,143,771 Landscape: Scope, Claim Coverage, Expiration, and Competition for Optically Pure (-)-Enantiomer Na+ Parenteral Benzimidazole
Executive summary
US Patent 6,143,771 claims a narrow, parenteral-focused IP bundle around a specific chiral benzimidazole API salt form and associated injection solution concentration ranges, plus method-of-use claims for gastric acid inhibition and gastrointestinal inflammatory disease. The claim scope is tight on (i) optically pure (-)-enantiomer, (ii) solid-state Na+ salt, (iii) crystalline/substantially crystalline form, (iv) injection solution concentration of 0.1 to 10% by weight, and (v) specific method framing requiring parenteral administration. For freedom-to-operate, the practical differentiators are whether a competitor uses the same chiral salt (Na+ solid-state), the same parenteral solution format, and the same concentration window, plus whether it pursues the same therapeutic intents under a “method” claim theory.
What does US Patent 6,143,771 claim for parenteral formulations?
Core claim package: formulation claims 1-5 define the API stereochemistry and salt state, the parenteral carrier system, and crystalline solid-state features, with dependent support for stabilizers/buffers.
Claim 1 (formulation, solid-state Na+ salt; general carrier)
Claim 1 covers:
- A pharmaceutical formulation for parenteral administration
- Containing an optically pure solid-state Na+ salt of the (-)-enantiomer of:
- 5-methoxy-2[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole
- Plus a pharmaceutically acceptable carrier
Scope drivers
- Must use optically pure (-)-enantiomer (chirality constraint).
- Must use solid-state Na+ salt (salt-form constraint).
- Parenteral administration is required (intended use framing tied to the formulation).
Claim 2 (injection solution; 0.1-10% w/w)
Claim 2 narrows to:
- An injection solution
- Optically pure solid-state Na+ salt of the (-)-enantiomer
- Carrier is a pharmaceutically acceptable solvent
- Concentration must be 0.1 to 10% by weight active ingredient
Scope drivers
- Adds a concentration range and solvent carrier requirement.
- Still requires the same chiral Na+ solid-state salt.
Claim 3 (substantially crystalline solid state)
Claim 3 limits claim 1 or 2 further to:
- Solid state salt in substantially crystalline form
Scope drivers
- If a competitor uses amorphous material, solvates, or different physical forms (while still being Na+ salt), claim 3 may be avoided, but claim 1/2 could remain at risk.
Claim 4 (stabilizing and/or buffering agents)
Claim 4 covers claim 1 or 2 formulations with:
- Stabilizing agent, buffering agent, or both
Scope drivers
- This is additive coverage; inclusion does not narrow much because it’s an “further comprising” claim. Avoidance requires not using those agents only if they are essential to the product? Practically, most injectable products have buffering and stabilization, so this claim tends to be broadly implicated when claim 1/2 are met.
Claim 5 (injectable solution)
Claim 5 states:
- The formulation comprises an injectable solution
Scope drivers
- Reinforces parenteral solution format coverage but does not add a concentration or physical-form limitation beyond claims 1-4.
What are the method-of-use claims and how do they limit infringement risk?
Method claims 6-12 require parenteral administration and specify therapeutic intents.
Claims 6 and 11 (inhibiting gastric acid secretion)
- Claim 6: parenteral administration to inhibit gastric acid secretion
- Claim 11: injecting with a solution with the same optically pure Na+ solid-state salt and solvent, with the 0.1-10% w/w concentration limitation (because it tracks claim 2’s solution concentration constraint)
Scope drivers
- Therapeutic intent: “inhibiting gastric acid secretion.”
- Parenteral administration is a required element.
- Claim 11 additionally requires the same solution concentration window.
Claims 7, 8, 12 (GI inflammatory disease)
- Claim 7: parenteral administration to treat gastrointestinal inflammatory disease
- Claim 8: solution prepared immediately before administration (for claim 7 dependent)
- Claim 12: injecting with a solution meeting the 0.1-10% w/w concentration limitation
Scope drivers
- Therapeutic use: GI inflammatory disease.
- Parenteral route required.
- Claim 8 is operational timing dependent; claim 7 itself is broader.
“Method” claim implications for competitors
- If a competitor sells a product and labels/uses it for the claimed indications via parenteral route, they are more exposed under method-of-use theories.
- Even without exact indication overlap, the presence of the exact API formulation and parenteral route can increase litigation leverage, but legal exposure depends on how method-of-use claims are enforced (claim interpretation, evidence of “in need of such treatment,” and proof of use).
How narrow is the chiral and salt-form scope?
The IP anchor is the specific chemical identity:
Patent-defined API identity constraints
- (-)-enantiomer only (not racemate, not (+), not mixture).
- optically pure (not just enriched).
- solid-state Na+ salt (not free base, not other counterions such as K+, Ca2+, protonated forms, or organic salts).
- For claim 3, substantially crystalline solid state.
Practical FTO attack points (what typically changes between products)
- Switch counterion (avoid Na+ salt; use a different salt form).
- Change solid-state form (avoid substantially crystalline; use amorphous or different polymorph/solvate, if possible).
- Use different stereochemistry (use different enantiomer or racemic mixture, if approved and consistent with safety/efficacy).
- Alter parenteral concentration (avoid 0.1-10% w/w).
- Change route (if route changes from parenteral injection to another route, method claims may be avoided; formulation claims may still be relevant if composition is “for parenteral administration,” depending on how courts interpret “for use” language).
Which parts of the claim set are strongest for coverage and which are easier to design around?
Most coverage-critical elements:
- Optically pure (-)-enantiomer of the named benzimidazole.
- Na+ solid-state salt.
- Parenteral administration.
Most design-around-friendly elements:
- 0.1 to 10% w/w concentration requirement (only claims 2, 11, 12, and dependent references).
- Substantially crystalline form (claim 3).
- Immediate before administration (claim 8).
Claim mapping: “must-have” vs “optional/add-on”
| Claim |
Must-have elements |
Design-around sensitivity |
| 1 |
Optically pure solid-state Na+ salt of (-)-enantiomer + parenteral formulation + carrier |
Low sensitivity: core identity must match |
| 2 |
Claim 1 elements + injection solution + solvent carrier + 0.1-10% w/w |
Medium: concentration window can be changed |
| 3 |
Claim 1/2 elements + substantially crystalline salt |
Medium: solid-state form can be changed |
| 4 |
Claim 1/2 elements + stabilizer/buffer |
Low to medium: “further comprising” is hard to avoid practically |
| 5 |
Claim 1/2 elements + injectable solution |
Low sensitivity: most injectables match |
| 6 |
Claim 1 elements + method: inhibit gastric acid secretion + parenteral administration |
Medium: route and indication matter |
| 7 |
Claim 1 elements + method: GI inflammatory disease + parenteral administration |
Medium: indication and route matter |
| 8 |
Claim 7 + solution prepared immediately before administration |
High sensitivity: operational procedure |
| 9-10 (not provided in prompt as claims) |
Not included in provided set |
N/A |
| 11 |
Claim 1 elements + method: gastric acid secretion + injection + 0.1-10% w/w |
High sensitivity: concentration window |
| 12 |
Claim 1 elements + method: GI inflammatory disease + injection + 0.1-10% w/w |
High sensitivity: concentration window |
What is the likely expiration timeline for US 6,143,771 and when does exclusivity end?
Not enough information is provided in the prompt to calculate an exact expiration date (e.g., filing date, application history, term adjustments, patent term adjustment, and any terminal disclaimers). No reliable expiration timeline can be produced from the claim text alone.
What is the Orange Book status for US 6,143,771?
No data is provided in the prompt about the FDA-listed NDA/ANDA associated with this patent number, Orange Book listings, listed drug name, or expiration.
How many other US patents typically cover this type of chiral parenteral Na+ salt program?
No linked patent family information or citation history is provided in the prompt. Without that, a quantified patent-family breadth (continuations, divisionals, salt polymorph coverage, process patents, intermediate patents) cannot be produced accurately.
What other claim types could exist around this patent’s subject matter?
Even without family data, US practice commonly expands around:
- Process patents for producing the optically pure (-)-enantiomer.
- Salt formation patents for Na+ salt.
- Polymorph/solid-state patents for crystalline forms.
- Stability patents for buffered/injectable solutions.
- Method-of-use patents for gastric acid inhibition and GI inflammatory disease.
But this is structural inference, not a patent-count or numbering claim. The only confirmed scope is the claim language provided for US 6,143,771.
What generic or biosimilar entry risks exist under these claims?
This is a small-molecule formulation and method-of-use patent, not a biologic. “Biosimilar” risks are not applicable in the conventional sense.
Generic risk framework for small molecules:
- Generics must practice the same active ingredient identity, route, and often the same formulation form once they develop a generic drug.
- Risk is highest when the generic:
- Uses the optically pure (-)-enantiomer
- Uses the Na+ solid-state salt
- Manufactures a substantially crystalline solid form (if the competitor is pushed into claim 3 overlap)
- Uses parenteral injection solutions in the 0.1-10% w/w range (for claims 2/11/12)
Concentration-avoidance strategy
- Because claims 2/11/12 require 0.1-10% by weight, a generic could attempt to formulate outside the range, subject to safety and dosing practicality.
- If the generic dosing regimen requires volumes that effectively place the formulation in that concentration window, the attempt may fail.
How strong is the patent estate for this drug concept based on claim drafting?
On the face of the claim set provided:
- Strength is driven by tight chemical specificity (chiral enantiomer + Na+ solid-state salt).
- Broad “parenteral formulation” wording in claim 1 increases coverage probability for any injectable product that uses that same API salt form.
- Concentration-limited claims (2/11/12) are narrower, but they can be meaningful if the marketed formulation sits in that window.
Litigation leverage would concentrate on whether an accused product:
- Uses the same optically pure (-)-enantiomer.
- Uses a Na+ solid-state salt.
- Is intended for parenteral administration and is used as such.
- Falls into the solution concentration range for injection-solution-dependent claims.
Key Takeaways
- US 6,143,771 is tightly anchored to an optically pure (-)-enantiomer of a specific sulfinyl benzimidazole in a solid-state Na+ salt form.
- The formulation claims cover parenteral dosing and include a concentration-limited injection-solution pathway (0.1-10% w/w) and a crystalline limitation (substantially crystalline).
- The method-of-use claims require parenteral administration for gastric acid secretion inhibition and GI inflammatory disease; some depend on the same 0.1-10% w/w injection solution concentration.
- Design-around focus is on changing counterion and solid-state form, avoiding the 0.1-10% concentration window, and altering procedural/route/indication alignment where legally relevant.
FAQs
- Can a competitor avoid US 6,143,771 by using a different salt counterion than Na+?
- Does the “substantially crystalline” limitation in claim 3 create an independent workaround if claim 1 is still met?
- If a marketed injection uses 9% w/w active ingredient, which claims are most directly implicated?
- How do operational differences like “prepared immediately before administration” affect exposure under claim 8?
- What evidentiary facts typically matter most for proving infringement of these method-of-use claims for parenteral dosing?
References
No references can be listed from the provided prompt because no external source data (FDA Orange Book, patent family data, filing dates, or litigation dockets) is included.
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