Details for Patent: 11,510,941

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Which drugs does patent 11,510,941 protect, and when does it expire?

Patent 11,510,941 protects ELCYS and NOURESS and is included in two NDAs.

Summary for Patent: 11,510,941

Title:	Stable, highly pure L-cysteine compositions for injection and methods of use
Abstract:	The subject matter described herein is directed to stable L-cysteine compositions for injection, comprising: L-cysteine or a pharmaceutically acceptable salt thereof and/or hydrate thereof in an amount from about 10 mg/mL to about 100 mg/mL; Aluminum in an amount from about 1.0 parts per billion (ppb) to about 250 ppb; cystine in an amount from about 0.01 wt % to about 2 wt % relative to L-cysteine; pyruvic acid in an amount from about 0.01 wt % to about 2 wt % relative to L-cysteine; a pharmaceutically acceptable carrier, comprising water; headspace O2 that is less than 1.0%; dissolved oxygen present in the carrier in an amount from about 0.01 parts per million (ppm) to about 1 ppm, wherein the composition is enclosed in a single-use container having a volume of from 10 mL to 100 mL. Also described are compositions for a total parenteral nutrition regimen and methods for their use.
Inventor(s):	John Maloney, Aruna Koganti, Phanesh Koneru
Assignee:	Exela Pharma Sciences LLC
Application Number:	US17/164,263
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 11,510,941
Patent Claim Types: see list of patent claims	Use; Composition; Formulation;

United States Patent 11,510,941: L-Cysteine Parenteral Nutrition Solution Patent Scope and Landscape

United States Patent 11,510,941 protects low-aluminum, low-cystine L-cysteine solutions intended for use as parenteral nutrition additives. The broadest composition claim requires a specific combination of concentration, aluminum limit, cystine limit, acidic pH, particulate control, pharmaceutical carrier, and suitability for parenteral nutrition. The patent also covers a manufacturing process using low-oxygen carrier solution, oxygen-reduced headspace, and sealed single-use containers.

The patent is directed to the formulation and manufacturing quality profile of injectable L-cysteine, rather than to the L-cysteine molecule itself. A competing product may avoid infringement by changing one required parameter, but commercial design-around options are constrained by the need to maintain injectable quality, stability, and parenteral nutrition compatibility.

What does United States Patent 11,510,941 protect?

The patent contains two principal claim groups:

1. Composition claims covering L-cysteine solutions.
2. A process claim covering preparation and packaging of the solution.

Claim 1 is the primary composition claim. It requires all of the following:

Claim element	Required limitation
Active ingredient	L-cysteine, a pharmaceutically acceptable salt, and/or hydrate
Concentration	About 10 mg/mL to about 100 mg/mL
Aluminum	No more than 200 ppb for at least six months from manufacture
Cystine	No more than 2.0% relative to L-cysteine
Carrier	Pharmaceutically acceptable carrier
pH	About 1.0 to about 2.5
Visual quality	Substantially free of visually detectable particulate matter
Intended use	Suitable as an additive in a parenteral nutrition composition

Every limitation must generally be met for literal infringement. A solution containing 50 mg/mL L-cysteine, for example, does not infringe claim 1 solely because it has the same concentration. It must also satisfy the aluminum, cystine, pH, particulate, carrier, and intended-use limitations.

How broad is independent claim 1?

Claim 1 is broad in concentration but narrow in quality attributes. Its concentration range spans approximately 10-fold, from 10 mg/mL to 100 mg/mL. The claim does not require a specific salt, hydrate, container material, sterilization method, or excipient beyond a pharmaceutically acceptable carrier.

The principal limiting features are:

• Aluminum content capped at 200 ppb for at least six months.
• Cystine limited to 2.0% relative to L-cysteine.
• pH limited to 1.0-2.5.
• Absence of visually detectable particulate matter.
• Suitability for parenteral nutrition use.

The aluminum limitation is temporal. It is not merely a measurement at release. The claimed solution must remain at or below the specified aluminum level for the stated period after manufacture. Evidence relevant to this limitation may include stability protocols, validated analytical methods, container-closure studies, and batch-specific testing.

The claim does not expressly require dissolved oxygen below a specified level. That feature appears only in claims 11, 12, 15, 16, and 17.

What do claims 2 through 14 add?

Claims 2 through 14 narrow claim 1 through concentration, impurity, oxygen, carrier, and stability limitations.

Claim	Added limitation	Commercial significance
2	20-80 mg/mL L-cysteine	Removes low and high concentration embodiments
3	30-70 mg/mL	Covers common mid-range formulations
4	40-60 mg/mL	Narrows toward a 50 mg/mL product
5	About 50 mg/mL	Directly targets a 50 mg/mL formulation
6	No more than 150 ppb aluminum for 12 months	Adds longer-term aluminum control
7	No more than 120 ppb aluminum for 12 months	More restrictive aluminum specification
8	No more than 100 ppb aluminum for 12 months	Stronger low-aluminum limitation
9	No more than 80 ppb aluminum for 12 months	Narrowest aluminum threshold in this group
10	No more than 1.0% cystine	More restrictive degradation-product limit
11	Dissolved oxygen below 2 ppm	Adds oxygen-control requirement
12	Dissolved oxygen below 1 ppm	More restrictive oxygen specification
13	Aqueous carrier	Limits the carrier to an aqueous system
14	No more than 200 ppb aluminum for 12 months	Extends claim 1's aluminum period

Claims 5, 10, and 12 are commercially important because they collectively define a narrow profile centered on:

• Approximately 50 mg/mL L-cysteine.
• No more than 1.0% cystine.
• Dissolved oxygen below 1 ppm.

A product that falls outside claim 1 may still fall within one of the narrower claims only if it meets the relevant dependent-claim limitations and all limitations incorporated from claim 1. The dependent claims cannot broaden claim 1.

What does claim 15 protect?

Claim 15 is an independent composition claim with a substantially narrower formulation profile:

• About 50 mg/mL L-cysteine.
• No more than 120 ppb aluminum for at least six months.
• No more than 1.0% cystine.
• pH of about 1.0-2.5.
• Dissolved oxygen below 1 ppm.
• No visually detectable particulate matter.
• Pharmaceutically acceptable carrier.
• Suitability as a parenteral nutrition additive.

Claim 15 is narrower than claim 1 in concentration, aluminum, cystine, and oxygen requirements. Its value is claim specificity. It may be more difficult to invalidate based on broad prior art directed generally to cysteine solutions, but infringement requires proof of the tighter specifications.

The claim's 120 ppb aluminum threshold applies for six months, while dependent claims 6-9 and 14 address 12-month aluminum control in the claim 1 branch. A product with 50 mg/mL L-cysteine, 100 ppb aluminum, 0.5% cystine, and dissolved oxygen below 1 ppm could potentially implicate both claim 15 and narrower claims depending on the remaining limitations.

What does the manufacturing method in claim 16 cover?

Claim 16 covers a process requiring:

1. Preparation of a mixture containing:
   • A pharmaceutically acceptable carrier with less than about 1 ppm dissolved oxygen; and
   • L-cysteine, a salt, and/or hydrate.
2. Adjustment of pH to approximately 1.0-2.5.
3. Transfer into a single-use container.
4. Reduction of headspace oxygen.
5. Sealing of the container.

The resulting solution must also meet the composition and quality requirements recited in the claim.

This is a product-by-process-style method claim, but it is drafted as a method of preparing a solution. The process does not cover every L-cysteine solution meeting the final specifications. It requires the specified sequence or performance of process steps.

The method claim creates several infringement questions:

• Whether the carrier contains less than about 1 ppm dissolved oxygen before mixing.
• Whether the pH is adjusted after or during mixture preparation.
• Whether the container is single-use.
• Whether headspace oxygen is actively reduced.
• Whether the final container is sealed.
• Whether the final solution satisfies the aluminum, cystine, concentration, pH, and particulate requirements.

A manufacturer using pre-deoxygenated water but not reducing headspace oxygen may avoid literal infringement of claim 16 while potentially remaining exposed under composition claims 1 or 15.

What does claim 17 add to the manufacturing method?

Claim 17 narrows claim 16 to a formulation with:

• About 50 mg/mL L-cysteine.
• No more than 120 ppb aluminum for at least six months.
• No more than 1.0% cystine.
• pH of approximately 1.0-2.5.
• Dissolved oxygen below 1 ppm.
• No visually detectable particulate matter.
• Parenteral nutrition suitability.

Claim 17 is the process counterpart to the narrow product profile in claim 15. It is likely to be most relevant to manufacturers using controlled oxygen management, low-oxygen compounding, and single-use packaging.

What formulation and manufacturing features are protected?

The patent's technical scope can be divided into five protection layers.

Chemical composition

The claims cover L-cysteine and its pharmaceutically acceptable salts or hydrates. The claim language does not limit the active ingredient to one specific salt form.

Degradation control

Cystine is the principal expressly limited degradation-related impurity. Claim 1 permits no more than 2.0% cystine relative to L-cysteine. Claims 10, 15, and 17 reduce that threshold to 1.0%.

Elemental impurity control

The patent claims aluminum limits of:

• 200 ppb for six months.
• 150 ppb for 12 months.
• 120 ppb for six or 12 months, depending on the claim.
• 100 ppb for 12 months.
• 80 ppb for 12 months.

These limitations may implicate the entire manufacturing system, including raw materials, water, compounding equipment, filters, tubing, storage vessels, container components, and closure systems.

Oxygen control

The claims separately address:

• Carrier dissolved oxygen below 1 ppm in the process claim.
• Finished-solution dissolved oxygen below 2 ppm.
• Finished-solution dissolved oxygen below 1 ppm.
• Reduced container headspace oxygen.

This creates a potential distinction between the oxygen condition of the carrier, the finished solution, and the sealed container headspace.

Injectable product quality

The claims require a solution substantially free of visually detectable particulate matter and suitable for use as a parenteral nutrition additive. These limitations align the patent with injectable-product manufacturing and quality-control requirements rather than oral or topical cysteine products.

When does United States Patent 11,510,941 lose exclusivity?

The claims provided do not establish the patent's filing date, priority chain, terminal disclaimer, patent-term adjustment, patent-term extension, maintenance-fee status, reexamination history, or disclaimer record. Those factors determine the enforceable expiration date under 35 U.S.C. §§ 154 and 156.

The patent number and claim text alone therefore do not establish a reliable expiration date. A patent's expected term generally runs 20 years from the earliest effective nonprovisional filing date, subject to statutory adjustments and terminal disclaimers. FDA regulatory exclusivity is separate from patent exclusivity.

What is the Orange Book status of the patent?

The claims themselves do not establish Orange Book listing status.

A patent may be listed in the FDA's Orange Book only if it satisfies the applicable statutory and regulatory requirements for patents claiming a drug substance, drug product, or approved method of use. Composition and manufacturing claims do not automatically qualify for listing. The relevant FDA framework is 21 C.F.R. § 314.53 and the applicable provisions of the Hatch-Waxman statute.

For a parenteral L-cysteine product, Orange Book relevance would depend on the approved product, NDA holder, approved labeling, patent type, and whether the patent claims the approved drug or an approved method of use. A formulation or manufacturing patent may have limited or no effect on an abbreviated new drug application if it is not properly listed or does not claim the approved product.

What Paragraph IV challenge risks exist?

A generic applicant could use a Paragraph IV certification against an Orange Book-listed patent. The principal challenge theories would likely focus on:

• Lack of novelty based on prior L-cysteine solutions.
• Obviousness based on known cysteine oxidation, aluminum contamination, oxygen reduction, acidic pH, or parenteral nutrition practices.
• Indefiniteness of terms such as “about,” “substantially free,” and “suitable for use.”
• Written-description or enablement issues concerning the full aluminum and stability ranges.
• Failure to prove that the claimed aluminum threshold remains satisfied for the stated period.
• Noninfringement based on concentration, cystine, dissolved oxygen, headspace, carrier, or container differences.

The strongest litigation position may arise from claims 15 and 17 if the patent specification provides robust experimental support for the combined 50 mg/mL, sub-120-ppb aluminum, sub-1% cystine, and sub-1-ppm oxygen profile. The broader claim 1 presents a larger potential market but generally exposes more validity attack surface.

How strong is the patent estate based on the supplied claims?

The claim set has moderate commercial breadth and meaningful technical specificity.

Strength factor	Assessment
Product concentration coverage	Broad, 10-100 mg/mL
Coverage of common 50 mg/mL product	Directly addressed by claims 5 and 15
Aluminum control	Repeated across six- and 12-month periods
Oxidation control	Addressed through cystine and dissolved oxygen limits
Manufacturing coverage	Includes low-oxygen carrier and headspace reduction
Excipient flexibility	Broad pharmaceutically acceptable carrier language
Container coverage	Single-use container required in method claims
Design-around potential	Moderate, because composition claims require multiple measurable attributes
Invalidation exposure	Depends heavily on cited prior art and specification support
Regulatory leverage	Depends on NDA approval and Orange Book listing

The estate is stronger against products deliberately engineered to match the claimed stability profile. It is weaker against products using a different concentration, higher cystine specification, different oxygen profile, alternative packaging process, or a formulation not suitable for parenteral nutrition.

What generic launch scenarios are commercially plausible?

Scenario 1: Same 50 mg/mL formulation

A generic using approximately 50 mg/mL L-cysteine, acidic pH, low aluminum, low cystine, low dissolved oxygen, and visually clear single-use packaging faces the highest infringement risk.

Scenario 2: Different concentration

A product below 10 mg/mL or above 100 mg/mL would fall outside the literal concentration range of claim 1, subject to any applicable doctrine-of-equivalents analysis. A product within 10-100 mg/mL remains exposed if the other elements are met.

Scenario 3: Higher cystine specification

A product with more than 2.0% cystine relative to L-cysteine would not literally meet claim 1. It may, however, face regulatory or commercial barriers if the higher impurity level affects injectable quality.

Scenario 4: Higher aluminum specification

Exceeding 200 ppb aluminum during the claimed period would avoid the aluminum limitation in claim 1. This approach may conflict with applicable limits for aluminum exposure in parenteral nutrition products under FDA requirements.

Scenario 5: Different oxygen-control process

A manufacturer may avoid claim 16 by using a process without less-than-1-ppm carrier oxygen, without headspace oxygen reduction, or without single-use containers. Composition claims 1 and 15 could still apply if the finished product meets their limitations.

What biosimilar risk applies to L-cysteine products?

Biosimilar risk is not the primary issue. L-cysteine is a small-molecule amino acid, not a biologic. Competitive entry would generally occur through an ANDA or another small-molecule pathway rather than a biosimilar application under the Public Health Service Act.

The key competitive risks are generic substitution, 505(b)(2) development, formulation replication, and competing parenteral nutrition products. Patent analysis should focus on Orange Book listing, Paragraph IV certifications, ANDA litigation, and regulatory exclusivity rather than biosimilar interchangeability.

What litigation and settlement information is established by the claims?

The supplied claims do not identify:

• Patent owner or assignee.
• Inventors.
• Priority applications.
• Related continuation or divisional patents.
• Patent-term adjustment.
• Orange Book listing.
• ANDA applicant.
• Paragraph IV notice.
• District-court litigation.
• Federal Circuit proceedings.
• Settlement or license agreements.

Those events cannot be inferred from the claim language. The claims establish technical scope, not litigation status or licensing history.

Key Takeaways

• U.S. Patent 11,510,941 targets injectable L-cysteine solutions for parenteral nutrition.
• Claim 1 covers 10-100 mg/mL solutions with pH 1.0-2.5, aluminum no higher than 200 ppb for six months, cystine no higher than 2.0%, and no visually detectable particulate matter.
• Claims 5 and 15 directly target a 50 mg/mL formulation.
• Claims 15 and 17 add a more restrictive profile: no more than 120 ppb aluminum, no more than 1.0% cystine, and dissolved oxygen below 1 ppm.
• Claim 16 protects low-oxygen compounding, headspace oxygen reduction, single-use filling, and sealing.
• The patent protects formulation quality and manufacturing controls, not L-cysteine as a chemical entity.
• Generic risk is highest for products matching the 50 mg/mL, low-aluminum, low-cystine, low-oxygen profile.
• Orange Book status, patent expiration, ownership, litigation, and settlements are not established by the supplied claims.

Frequently Asked Questions

Does Patent 11,510,941 cover all L-cysteine injections?

No. It covers only solutions meeting the claimed concentration, aluminum, cystine, pH, carrier, particulate, and parenteral nutrition limitations.

Does a 50 mg/mL L-cysteine product automatically infringe?

No. The product must also meet the applicable aluminum, cystine, oxygen, pH, particulate, carrier, and intended-use limitations.

Can a manufacturer avoid the patent by using a different container?

Potentially. A different container may avoid the single-use-container and headspace-reduction limitations in the method claims, but it would not necessarily avoid the composition claims.

Is L-cysteine subject to biosimilar competition?

No. L-cysteine is a small-molecule active ingredient. Generic and 505(b)(2) pathways are more relevant than biosimilar approval.

Does a low-aluminum formulation necessarily require an FDA-approved drug product?

No. Aluminum control is a product-quality attribute. FDA approval depends on the drug application, manufacturing controls, labeling, and applicable regulatory requirements.

References

1. United States Patent No. 11,510,941, claims 1-17. U.S. Patent and Trademark Office.

2. United States Code, Title 35, §§ 154 and 156. Patent term and patent-term extension provisions.

3. Code of Federal Regulations, Title 21, § 314.53. FDA patent submission and listing requirements.

4. Code of Federal Regulations, Title 21, § 314.101. FDA application filing and regulatory pathway provisions.

Drugs Protected by US Patent 11,510,941

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Exela Pharma	ELCYS	cysteine hydrochloride	SOLUTION;INTRAVENOUS	210660-001	Apr 16, 2019		RX	Yes	Yes			Y
Baxter Hlthcare Corp	NOURESS	cysteine hydrochloride	SOLUTION;INTRAVENOUS	212535-001	Dec 13, 2019		RX	Yes	Yes			Y