United States Patent 8,653,061: Scope, Claim Construction, Exclusivity and Patent Landscape for Acetylcysteine Overdose Treatment

US 8,653,061 protects specified methods of treating acetaminophen overdose with a concentrated, pH-controlled aqueous acetylcysteine composition packaged under inert gas. The patent has two principal claim groups: oral administration after dilution and intravenous administration after dilution. The commercial and litigation significance depends on whether a competing product practices every limitation, including concentration, pH, chelator status, packaging atmosphere and route of administration.

The patent is a formulation-and-use patent. It does not broadly cover acetylcysteine, the standard 21-hour dosing regimen, or every acetylcysteine product. Its strongest protection is directed to a combination of formulation chemistry and packaging conditions.

What does US Patent 8,653,061 cover?

The independent claims require a stable aqueous acetylcysteine composition containing 100 to 250 mg/mL acetylcysteine or a pharmaceutically acceptable salt. The composition must have a pH from 6.0 to 7.5 and be sealed in an airtight container with an inert-gas headspace. Before administration, the composition must be diluted in an aqueous solution.

Claim group	Administration route	Chelator limitation	Concentration	pH	Packaging	Dosing limitation
Claim 1	Oral	Composition free from chelating agents	100-250 mg/mL	6.0-7.5	Airtight container; inert-gas headspace	Dilute and administer orally
Claims 2-4	Oral	Same as claim 1	About 200 or 100 mg/mL	About 7.0	Same as claim 1	Same as claim 1
Claim 5	Intravenous-suitable composition	Chelators not added; impurities permitted	100-250 mg/mL	6.0-7.5	Airtight container; inert-gas headspace	Dilute and administer
Claims 6-7	Intravenous	Same as claim 5	About 200 mg/mL	About 7.0	Same as claim 5	Same as claim 5
Claims 8-9	Intravenous	Same as claim 5	Same as claim 5	Same as claim 5	Same as claim 5	150/50/100 mg/kg regimen
Claim 10	Intravenous	Same as claim 5	Same as claim 5	Same as claim 5	Same as claim 5	Diluent includes dextrose, saline or water for injection

The patent therefore combines four technical elements:

A high-concentration acetylcysteine solution.
A near-neutral pH.
Exclusion, or non-addition, of chelating agents.
Oxygen-controlled packaging using an inert-gas headspace.

A product that satisfies only the concentration and dosing regimen would not necessarily infringe. The packaging and formulation limitations are central claim elements.

How should the independent claims be construed?

Claim 1: oral administration

Claim 1 requires use of the composition for oral treatment after dilution. The composition must be free from chelating agents. The claim does not expressly require the 150/50/100 mg/kg intravenous schedule, and it does not require a particular diluent.

The oral claim is potentially broad in route but narrow in formulation. It can reach an oral treatment method using a concentrated acetylcysteine solution originally packaged for stability, even if the product is diluted before administration.

The phrase "free from chelating agents" is materially different from a requirement that no chelator be intentionally added. On its face, claim 1 excludes a composition containing a chelating agent, regardless of whether the agent was deliberately introduced. Analytical detection thresholds and claim-construction issues could become important in enforcement.

Claim 5: intravenous administration

Claim 5 requires that the composition be in a suitable form for intravenous administration. It also provides that chelating agents are not added but may be present as impurities or undesired contaminants.

This language gives claim 5 a broader chelator limitation than claim 1. A trace contaminant may not defeat claim 5 if it was not added to the composition. A competitor that intentionally adds EDTA or another chelator would face a stronger noninfringement position only if the formulation falls outside the remaining limitations.

Claim 5 does not itself require the 150/50/100 mg/kg regimen. That regimen appears in dependent claim 8. A product used under a different intravenous dosing schedule could still implicate claim 5 if all other limitations are met.

What formulations are protected by US 8,653,061?

The formulation scope covers aqueous acetylcysteine at 100 to 250 mg/mL. The most commercially relevant concentrations are 100 mg/mL and 200 mg/mL.

Concentration limitations

Claims 3, 4 and 7 identify specific concentrations:

About 200 mg/mL.
100 mg/mL.
The broader independent range of 100 to 250 mg/mL.

A 200 mg/mL acetylcysteine product falls squarely within the independent range and the dependent claims directed to approximately 200 mg/mL. A formulation above 250 mg/mL or below 100 mg/mL would not meet the literal concentration range, subject to any doctrine-of-equivalents analysis.

The use of "about" in the dependent claims introduces an issue of reasonable formulation tolerance. The independent range provides the more definite numerical boundary.

pH limitations

The composition must have a pH from 6.0 to 7.5. Claims 2 and 6 narrow the target to approximately pH 7.0.

This limitation distinguishes the claimed product from acidic acetylcysteine formulations. Acetylcysteine is susceptible to oxidation and degradation, and pH adjustment can affect stability, odor and tolerability. The patent's claim strategy treats near-neutral pH as part of the stability solution rather than as a mere manufacturing preference.

Chelating-agent limitations

Claim 1 requires the composition to be free from chelating agents. Claim 5 instead focuses on whether chelating agents were added.

This distinction creates separate design-around paths:

Formulation strategy	Claim 1 risk	Claim 5 risk
No chelator intentionally added; no detectable chelator	High if all other limitations are met	High if all other limitations are met
Trace chelator as contaminant	Potentially lower, depending on construction and detection	Higher, because claim 5 expressly permits impurities
Intentional EDTA addition	Lower under literal claim 1 analysis	Potentially lower under claim 5, but other validity and equivalence issues remain
pH below 6.0 or above 7.5	Reduced literal risk	Reduced literal risk
Concentration below 100 or above 250 mg/mL	Reduced literal risk	Reduced literal risk

A design-around must be evaluated against the full claim, not one formulation attribute in isolation.

What packaging technology does the patent protect?

The claims require an airtight container with a fill volume of acetylcysteine composition and a headspace occupied by a pharmaceutically inert gas.

This limitation reaches packaging configurations that reduce exposure to oxygen or other reactive gases. Nitrogen is the most obvious example of a pharmaceutically inert headspace gas, although the claims do not appear limited to nitrogen.

The claim language makes the container part of the method-of-treatment combination. A competing solution with the same concentration and pH may avoid literal infringement if it is packaged without an inert-gas headspace, depending on whether the container is airtight and whether another claim theory applies.

Relevant technical evidence would include:

Container closure specifications.
Headspace gas composition.
Fill volume and headspace volume.
Oxygen transmission data.
Batch-release records.
Stability protocols.
Container drawings and packaging-validation reports.

The packaging element can create a practical enforcement barrier because public product information may not identify headspace gas composition. Discovery would likely be required to establish this limitation in litigation.

What are the method-of-use claims for acetaminophen overdose?

The patent claims treatment of acetaminophen overdose using diluted acetylcysteine. Claim 1 is directed to oral administration. Claim 5 is directed to a composition suitable for intravenous administration.

Claims 8 and 9 add the conventional intravenous regimen:

Loading dose: approximately 150 mg/kg.
Second dose: approximately 50 mg/kg.
Third dose: approximately 100 mg/kg.
Loading dose administered over 15 minutes to two hours.
Second dose administered over approximately four hours.
Third dose administered over approximately 20 hours.

This dosing structure corresponds to the established 21-hour intravenous acetylcysteine treatment protocol reflected in FDA-approved labeling for acetylcysteine injection products.[2]

The dosing claims are narrower than claim 5. A product used under the standard regimen could fall within claims 8 and 9, but proof would require evidence regarding actual prescribing, labeling, administration or inducement.

When does US Patent 8,653,061 lose exclusivity?

US 8,653,061 issued on February 18, 2014. Its statutory term is generally measured from the earliest effective nonprovisional filing date under the Uruguay Round Agreements Act framework, subject to patent-term adjustment, terminal disclaimers and any applicable patent-term extension.[3]

Based on the patent's priority structure, the expected base expiration is in the late 2020s, likely around 2029 if the relevant nonprovisional filing occurred in 2009. The exact expiration date must be taken from the USPTO Patent Center record because patent-term adjustment can move the date and a terminal disclaimer can shorten it.

Event	Date or period
Patent issuance	February 18, 2014
Base statutory term	20 years from applicable earliest nonprovisional filing
Expected expiration window	Late 2020s
Patent-term adjustment	Must be confirmed in USPTO records
Patent-term extension	No extension is established by the claims supplied
Regulatory exclusivity	Separate from patent term and product-specific

Patent expiration does not automatically eliminate all market protection. A listed drug may have separate regulatory exclusivity, other formulation patents, manufacturing patents, trademarks or contractual restrictions.

What is the Orange Book status of the patent?

The Orange Book status cannot be determined from the claims alone. Orange Book listing is tied to a specific approved drug application and patent declaration, not merely to patent subject matter.[4]

For an acetylcysteine product, a listing analysis would require matching the patent to the relevant NDA, such as an acetylcysteine injection or oral acetylcysteine product. The patent's claims potentially relate to:

Acetylcysteine injection products.
Concentrated acetylcysteine solutions.
Oral overdose-treatment products.
Product packaging used to stabilize acetylcysteine.

A patent may be relevant to a product without being listed in the Orange Book. Conversely, an Orange Book-listed patent may create a Hatch-Waxman certification issue even where the product label does not reproduce every practical feature of the patented formulation.

The decisive records are the current FDA Approved Drug Products with Therapeutic Equivalence Evaluations publication and the applicable NDA patent-listing submissions.[4]

What Paragraph IV challenges could target this patent?

A generic applicant relying on an ANDA could challenge a listed patent through a Paragraph IV certification under 21 U.S.C. § 355(j)(2)(A)(vii)(IV).[5] Potential invalidity and noninfringement theories include:

Anticipation

A challenger could argue that prior art disclosed all elements in a single reference:

100-250 mg/mL acetylcysteine.
pH 6.0-7.5.
Absence or non-addition of chelators.
Airtight packaging.
Inert-gas headspace.
Dilution and oral or intravenous administration.

The combination requirement makes anticipation more difficult if prior art disclosed these features separately.

Obviousness

Obviousness would likely focus on combining known acetylcysteine concentrations, pH adjustment, inert-gas packaging and established overdose dosing. The patent holder would counter that the claimed combination produced unexpected stability or shelf-life benefits and that the prior art did not provide a reasonable expectation of success.

Written description and enablement

The broad 100-250 mg/mL range and both oral and intravenous uses could be challenged if the specification did not adequately support the full scope. The strength of this argument would depend on examples, stability data, packaging data and disclosure of both administration routes.

Indefiniteness

Terms such as "about," "stable," "pharmaceutically inert gas," "suitable form," and "undesired contaminant" could be challenged if the specification and prosecution history do not provide objective boundaries. These terms are common in pharmaceutical patents, so the outcome would turn on the intrinsic record and technical context.

Noninfringement

The strongest noninfringement arguments would generally involve:

Concentration outside the claimed range.
pH outside 6.0-7.5.
No inert-gas headspace.
Packaging that is not airtight.
Intentional addition of a chelating agent for claim 5.
Use of a product not suitable for intravenous administration.
Administration without dilution.
A route different from the claimed route.

Which companies are challenging US 8,653,061?

The claims supplied do not identify any ANDA filer, Paragraph IV notice letter, district-court case, appellate decision or settlement agreement. No challenger, litigation event or settlement can be established from the patent claims themselves.

A proper challenge analysis would distinguish among:

Paragraph IV certifications filed against a listed patent.
Declaratory-judgment actions.
Patent litigation under 35 U.S.C. § 271(e)(2).
Post-grant review or inter partes review.
Commercial disputes involving product packaging or manufacturing.

The absence of a named challenger in the supplied record means no company should be identified as having challenged US 8,653,061.

How strong is the patent estate for acetylcysteine overdose treatment?

US 8,653,061 has moderate claim breadth but potentially meaningful commercial leverage if the patent is listed against a concentrated acetylcysteine product.

Strengths

The claims combine formulation, pH and packaging limitations.
The 200 mg/mL concentration is commercially relevant.
Claims cover both oral and intravenous treatment pathways.
The inert-gas headspace limitation may be difficult to evaluate from public product information.
Claims 8 and 9 align with the established intravenous overdose regimen.

Weaknesses

The claims are vulnerable if prior art disclosed stable concentrated acetylcysteine under inert gas.
Packaging limitations can be avoided by alternative container systems.
Claim 1 and claim 5 treat chelator status differently, creating construction issues.
The dosing regimen was well known before the patent.
The method claims require proof that the administered product met the claimed formulation and packaging attributes.

The patent is stronger as a combination patent than as a standalone dosing patent.

What generic launch risks exist?

A generic launch strategy would depend on whether the patent is listed for the relevant reference product and whether the generic uses the same formulation and container design.

Launch path	Principal patent risk
200 mg/mL IV acetylcysteine in nitrogen-flushed airtight vial	High risk if patent remains enforceable and listed
100 mg/mL IV formulation with same pH and packaging	High risk; falls within independent range
Product outside 6.0-7.5 pH	Lower literal risk, with formulation and regulatory implications
Product without inert-gas headspace	Lower literal risk
Product with intentionally added chelator	Potentially lower claim 5 risk; regulatory compatibility must be assessed
Oral diluted product from covered concentrate	Potential claim 1 risk
Different concentration	Possible design-around, subject to equivalence and regulatory feasibility
Product launched after confirmed patent expiration	Patent infringement risk from this patent materially reduced

An ANDA applicant could use a Paragraph IV route, a Paragraph III certification if expiration is known, or a product design that avoids one or more claim limitations. The regulatory and commercial consequences differ sharply among those options.

Does biosimilar risk apply to acetylcysteine?

No. Acetylcysteine is a small-molecule active pharmaceutical ingredient, not a biologic. Biosimilar procedures under the Public Health Service Act do not apply. Competition would proceed through generic-drug pathways, including ANDAs, or through an alternative NDA pathway where applicable.[5]

What licensing and settlement issues affect the patent?

The supplied information identifies no license, covenant not to sue, patent settlement or authorized-generic arrangement involving US 8,653,061. Any licensing analysis should separate:

Patent ownership and assignment.
Product commercialization rights.
Authorized-generic arrangements.
ANDA litigation settlements.
Manufacturing or supply agreements.
Technology licenses covering inert-gas packaging or stability processes.

A patent assignment does not by itself establish a license to commercialize a covered product. Similarly, a settlement may restrict launch timing without transferring formulation rights.

Key Takeaways

US 8,653,061 claims concentrated aqueous acetylcysteine at 100-250 mg/mL, pH 6.0-7.5, packaged in an airtight container with an inert-gas headspace.
Claim 1 covers diluted oral administration and requires the composition to be free from chelating agents.
Claim 5 covers a composition suitable for intravenous administration and permits chelators as impurities if they were not added.
Claims 8 and 9 add the standard 150/50/100 mg/kg, 21-hour intravenous regimen.
The patent's expected statutory term extends into the late 2020s, but the exact expiration date requires USPTO patent-term data.
Orange Book relevance depends on the patent's listing against a specific acetylcysteine NDA.
No challenger, litigation or settlement can be identified from the claims supplied.
Biosimilar competition is not relevant; generic-drug pathways are the applicable framework.
The principal design-around options involve concentration, pH, chelator addition, packaging atmosphere and administration route.

FAQs

Does a 200 mg/mL acetylcysteine vial automatically infringe US 8,653,061?

No. It must also satisfy the applicable pH, chelator, airtight-container, inert-gas-headspace, dilution and administration limitations.

Can a nitrogen-free acetylcysteine package avoid the patent?

It may avoid the literal inert-gas limitation, but the final result depends on the actual container, headspace composition, claim construction and any equivalents theory.

Does claim 5 cover oral acetylcysteine treatment?

Claim 5 requires a composition in a suitable form for intravenous administration. Claim 1 is the principal oral-treatment claim.

Is the 21-hour acetylcysteine protocol itself patented by US 8,653,061?

The patent claims the regimen only in combination with the specified concentrated, near-neutral, packaged composition. It does not claim the dosing protocol in isolation.

Can a generic manufacturer avoid the patent by adding EDTA?

Intentional chelator addition may create a literal noninfringement position under claim 5, but it would not automatically resolve claim 1, other claims, formulation requirements, regulatory acceptability or other patents.

References

United States Patent No. 8,653,061. (2014). Stable acetylcysteine compositions and methods of use. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (n.d.). Acetadote (acetylcysteine) injection prescribing information. FDA.
United States Patent and Trademark Office. (n.d.). Patent term adjustment. USPTO.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. FDA.
Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j); Hatch-Waxman Amendments.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2006282030	⤷ Start Trial
Canada	2619441	⤷ Start Trial
China	101242824	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,653,061

Summary for Patent: 8,653,061