United States Patent 11,510,984: Sodium Thiosulfate Composition Claims, Scope, and Patent Landscape

U.S. Patent No. 11,510,984 protects a narrow pharmaceutical formulation of aqueous anhydrous sodium thiosulfate. The independent claim requires approximately 0.5 M sodium thiosulfate and borate ions below 0.05%. Dependent claims add a 100 mL presentation, hydrochloric acid, sodium hydroxide, and specified pH ranges. The claims target formulation composition rather than sodium thiosulfate’s therapeutic use, manufacturing process, or delivery device.

The commercial risk is highest for an injectable product that contains approximately 12.4 to 12.5 g of sodium thiosulfate per 100 mL, includes a low level of borate, and has a pH near 8.6 to 8.8. A competing product could reduce risk by changing the sodium thiosulfate concentration, eliminating borate, using a different buffering system, or moving outside the claimed pH and volume limitations.

What does U.S. Patent 11,510,984 cover?

The patent covers a pharmaceutical composition with four core limitations:

Claim element	Requirement
Active ingredient	Aqueous anhydrous sodium thiosulfate
Concentration	About 0.5 M
Borate	Borate ions present at less than 0.05%
Product type	Pharmaceutical composition

The claim is composition-based. It does not require:

A particular patient population
Treatment of ototoxicity
Treatment of cisplatin-induced hearing loss
Intravenous administration
Pediatric use
A specific container
A specific manufacturing method
A particular sodium thiosulfate source
A particular brand or trade name

A product can infringe the independent claim without using the same manufacturing process or labeling the same indication, provided the accused composition contains each required element.

How should claim 1 be construed?

Claim 1 is the controlling claim because claims 2 through 6 depend on it. A product must satisfy all of the following limitations to create a strong literal-infringement case:

It is a pharmaceutical composition.
Sodium thiosulfate is present in aqueous form.
The sodium thiosulfate is described as anhydrous sodium thiosulfate.
The concentration is about 0.5 M.
Borate ions are present.
The borate-ion concentration is less than 0.05%.

The phrase "comprising" makes the claim open-ended. A formulation can contain additional active or inactive ingredients and still fall within claim 1. The presence of hydrochloric acid, sodium hydroxide, preservatives, or other excipients does not avoid the independent claim unless the total formulation no longer satisfies a required limitation.

What does "aqueous anhydrous sodium thiosulfate" mean?

The claim distinguishes the sodium thiosulfate used to prepare the solution from sodium thiosulfate pentahydrate or another hydrated raw material. The formulation is aqueous, but the claimed sodium thiosulfate is identified as anhydrous.

This distinction can create a technical dispute in infringement analysis. Testing the final liquid may establish total sodium thiosulfate concentration but may not, by itself, prove whether the starting material was anhydrous or hydrated. Documentation concerning raw materials, certificates of analysis, manufacturing records, and water content may therefore become relevant.

The patent language also creates a potential claim-construction issue because sodium thiosulfate can exist in different solid-state forms, while the final product is an aqueous solution. The practical question is whether "anhydrous" describes the starting material, the sodium thiosulfate species in the composition, or a formulation characteristic preserved after dissolution.

What does "about 0.5 M" cover?

"About" gives the claim flexibility around the stated concentration. The precise boundary cannot be determined from the claim text alone. Courts generally assess the term in view of the specification, examples, prosecution history, technical measurement tolerances, and whether the boundary provides reasonable certainty.

A formulation nominally labeled 0.5 M presents the clearest risk. A product at 0.48 M or 0.52 M could also be within the claim, depending on the patent record and the relevant manufacturing tolerances. A materially lower or higher concentration creates a stronger non-infringement position, but the claim does not state a fixed numerical cutoff.

For anhydrous sodium thiosulfate, 0.5 M corresponds to approximately 79 g/L, or approximately 7.9 g per 100 mL, based on a molecular weight of about 158.11 g/mol. If a product is formulated using sodium thiosulfate pentahydrate, the equivalent mass is approximately 124 g/L, or 12.4 g per 100 mL, based on a molecular weight of about 248.18 g/mol. This distinction matters when comparing molarity, mass concentration, and product labeling.

What do claims 2 through 6 add?

Claim	Additional limitation	Commercial significance
2	Total volume of about 100 mL	Targets a standard vial or injectable presentation
3	Hydrochloric acid	Captures acid adjustment or pH-control formulations
4	Sodium hydroxide	Captures alkaline adjustment or pH-control formulations
5	pH between about 5 and about 9.5	Broad pH-dependent formulation claim
6	pH between about 8.6 and about 8.8	Narrow claim directed to a specific alkaline range

Claims 3 and 4 are separate dependent claims. Claim 3 does not require sodium hydroxide, and claim 4 does not require hydrochloric acid. Each incorporates every limitation of claim 1 and adds one specified ingredient.

Claim 6 is narrower than claim 5. A product with a pH of about 8.7 could potentially satisfy both claims. A product at pH 7.0 could fall within claim 5 but not claim 6. A product at pH 9.7 would be outside the express range of claim 5, subject to interpretation of "about" and any doctrine-of-equivalents analysis.

Which formulation characteristics create the greatest infringement risk?

The highest-risk profile is a sterile sodium thiosulfate injection with the following attributes:

Characteristic	Risk level
Approximately 0.5 M sodium thiosulfate	High
Borate ions below 0.05%	High
Approximately 100 mL fill volume	High for claim 2
pH of approximately 8.6 to 8.8	High for claim 6
Hydrochloric acid present	High for claim 3
Sodium hydroxide present	High for claim 4
pH between approximately 5 and 9.5	High for claim 5

The claim does not require all of these dependent limitations simultaneously. A product may infringe claim 1 while avoiding claims 2 through 6. Conversely, a product that satisfies the 100 mL volume and pH limitations but lacks borate ions would not satisfy claim 1 or any dependent claim.

What formulation design-arounds are available?

Potential design-around paths include:

Changing sodium thiosulfate concentration

A developer could formulate materially above or below approximately 0.5 M. This is the most direct design-around because concentration is a central limitation of claim 1. The commercial and clinical consequences would include changes in dose volume, osmolarity, stability, and administration logistics.

Eliminating borate ions

A composition containing no borate ions is a direct candidate for avoiding claim 1. The wording "further comprising borate ions" indicates that some borate must be present. Trace boron contamination, however, may generate an analytical dispute. The relevant issue is whether the detected species are borate ions and whether the concentration is intentional, measurable, and within the claim.

Substituting a non-borate buffer

Phosphate, citrate, acetate, or another buffering system could avoid the express borate limitation. Such a substitution would require separate evaluation of stability, compatibility, pH control, container interaction, and regulatory comparability.

Changing pH

A pH outside approximately 8.6 to 8.8 would provide a stronger position against claim 6. A pH outside approximately 5 to 9.5 would also avoid claim 5 if the product remains outside the scope of "about." This strategy does not avoid claim 1 unless the pH change also affects another required limitation.

Changing the fill volume

A product materially different from approximately 100 mL may avoid claim 2 while remaining exposed to claim 1. Volume is therefore a limited design-around unless combined with changes to concentration or borate content.

Using a different sodium thiosulfate solid form

Use of sodium thiosulfate pentahydrate instead of anhydrous sodium thiosulfate could create a non-infringement argument. Its strength depends on how the court construes the term "aqueous anhydrous sodium thiosulfate" and whether the accused product is treated as containing the claimed chemical entity after dissolution.

What is the patent's likely relevance to sodium thiosulfate products?

The formulation is commercially relevant to products using sodium thiosulfate as an injectable pharmaceutical. Sodium thiosulfate has applications in cyanide poisoning, calciphylaxis, and prevention of cisplatin-associated ototoxicity. The patent claims do not themselves limit the composition to any one indication.

The formulation concentration can be compared with the approximate composition of a 100 mL sodium thiosulfate injection containing 12.5 g of sodium thiosulfate pentahydrate. That quantity is approximately 0.50 M when calculated using the pentahydrate molecular weight. The comparison is formulation-specific and does not establish infringement without confirming the precise API form, borate content, pH, and other claim elements.

What is the FDA status of the relevant sodium thiosulfate product?

The FDA approved Pedmark, a sodium thiosulfate injection marketed by Fennec Pharmaceuticals, for reduction of the risk of ototoxicity associated with cisplatin in pediatric patients 1 month of age and older with localized, nonmetastatic solid tumors.[2] The approval was granted under an NDA, not an abbreviated new drug application.

The FDA-approved product is a finished injectable formulation. Its regulatory status makes formulation patents commercially important because an ANDA applicant seeking approval for a therapeutically equivalent product would need to address applicable listed patents and exclusivity.

Sodium thiosulfate products approved for unrelated indications may have different formulations, concentrations, pH values, labeling, and patent exposure. FDA approval of sodium thiosulfate as an active ingredient does not establish freedom to operate for a particular formulation.

What is the Orange Book status of U.S. Patent 11,510,984?

A patent number alone does not establish whether the patent is listed in the FDA Orange Book, whether it is listed against a specific NDA, or whether a particular claim is eligible for listing. Orange Book listing is a regulatory submission and publication issue separate from patent validity and enforceability.

For an ANDA applicant, the relevant diligence questions are:

Issue	Significance
Whether the patent is listed against the relevant NDA	Determines whether a statutory patent certification is required
Whether the listed claims cover the approved drug product	Determines listing relevance
Patent expiration date	Determines the potential statutory stay and launch timing
Whether pediatric exclusivity applies	Can add six months to listed patent or exclusivity periods
Whether the patent has been delisted or corrected	Changes the ANDA certification analysis

The product-specific Orange Book record and the patent’s front-page term information should be used for the operative expiration and listing analysis. The claim text supplied here does not establish those facts.

When does U.S. Patent 11,510,984 expire?

The patent’s enforceable term is generally calculated as 20 years from the earliest effective U.S. nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and any applicable regulatory extension.[3] The issue date, November 29, 2022, does not determine the expiration date.

A reliable term calculation must account for:

The earliest priority and nonprovisional filing dates
Continuation or divisional relationships
Patent-term adjustment
Terminal disclaimer records
Patent-term extension under 35 U.S.C. § 156
Any pediatric exclusivity associated with the approved product

The patent expiration date should therefore be taken from the USPTO patent-term data and the applicable Orange Book entry rather than inferred from the grant date.

Are there Paragraph IV challenges to this patent?

A Paragraph IV challenge would arise if an ANDA applicant certifies that a listed patent is invalid, unenforceable, or not infringed. The patent claims create several potential challenge points:

Written description and enablement

The challenger could examine whether the specification supports the full scope of:

All compositions at approximately 0.5 M
All borate concentrations below 0.05%
All pH values from approximately 5 to 9.5
Both hydrochloric acid and sodium hydroxide embodiments
The interpretation of anhydrous sodium thiosulfate in an aqueous solution

Definiteness

Potential issues include the boundaries of:

"About 0.5 M"
"About 100 mL"
"Less than 0.05%"
"About 5" and "about 9.5"
"About 8.6" and "about 8.8"

The specification and prosecution history are central to assessing whether these terms have objective boundaries.

Anticipation and obviousness

Prior art could include sodium thiosulfate injections, aqueous sodium thiosulfate formulations, borate-buffered pharmaceutical compositions, pH-adjusted injectable solutions, and formulations used in ototoxicity studies. A challenger would need to show either that a single reference discloses every limitation or that a skilled person would have combined the relevant teachings with a reasonable expectation of success.

The most difficult limitation for a prior-art reference may be the combination of approximately 0.5 M anhydrous sodium thiosulfate with borate ions below 0.05%, particularly if the reference does not identify the borate concentration.

How strong is the patent estate?

The supplied claims indicate a focused formulation estate rather than a broad sodium thiosulfate monopoly.

Estate dimension	Assessment
Active ingredient	Narrowly focused on sodium thiosulfate
Therapeutic indication	Not required by the claims
Formulation	Central subject matter
Concentration	Specific, with "about" flexibility
Buffer system	Borate is required
pH	Broad claim 5 and narrow claim 6
Container volume	Addressed only in dependent claim 2
Manufacturing process	Not claimed in the supplied claims
Delivery device	Not claimed
Geographic scope	United States only for this patent
Biosimilar protection	Not relevant because sodium thiosulfate is a small molecule

The patent can create meaningful blocking risk for a close formulation, but it does not prevent all sodium thiosulfate products. A competitor that uses a different concentration and non-borate buffer may have a credible design-around route.

Patent strength is likely highest against a product intentionally matched to the claimed formulation. It is weaker against products that differ in borate content, solid-state source, concentration, or pH.

What patent litigation and settlement issues should companies monitor?

Relevant disputes would likely concern:

Whether the approved product contains the claimed borate concentration
Whether an ANDA product contains borate ions
Whether sodium thiosulfate pentahydrate satisfies the anhydrous limitation
The meaning of "about 0.5 M"
Whether the patent is properly listed in the Orange Book
Whether the patent claims are invalid for obviousness or indefiniteness
Whether a settlement permits a licensed generic launch before patent expiration

A patent settlement involving a sodium thiosulfate product would normally be assessed under the Hatch-Waxman framework. The commercially material terms would include launch date, authorized-generic rights, supply arrangements, restrictions on formulation changes, and any license covering patents beyond U.S. Patent 11,510,984.

No settlement conclusion follows from the claim text alone. A litigation docket, ANDA notice, or settlement filing would be required to establish an active Paragraph IV dispute.

How does this patent compare with method-of-use and manufacturing patents?

U.S. Patent 11,510,984 is materially different from other common pharmaceutical patent categories.

Patent category	What it protects	Relevance here
Composition patent	Ingredients and physical parameters	Directly relevant
Method-of-use patent	Treatment method or patient population	Not present in supplied claims
Manufacturing patent	Production or sterilization process	Not present in supplied claims
Container or device patent	Vial, syringe, infusion system, or packaging	Not present in supplied claims
Salt or solid-state patent	Crystal form or chemical form	Potentially separate from this patent
Regulatory exclusivity	FDA approval-based market protection	Separate from patent rights

A competitor can avoid a composition claim while still infringing a separate method-of-use or manufacturing patent. Conversely, a product can avoid method-of-use infringement if it is sold with a non-overlapping label, while remaining exposed to a composition patent.

What generic launch scenarios exist?

Launch after patent expiry

This is the lowest-risk route if no other patent or exclusivity remains in force. The applicant does not need to rely on a successful Paragraph IV challenge.

Paragraph III certification

An ANDA applicant may acknowledge the patent and defer approval until the patent expires. This preserves the ability to seek approval without immediately contesting validity or infringement.

Paragraph IV certification

The applicant may assert that the patent is invalid, unenforceable, or not infringed. If the patent is listed, the certification can trigger patent litigation and a potential 30-month FDA approval stay under the Hatch-Waxman statute.[4]

Non-infringing formulation

A generic applicant may develop a product outside the claimed formulation, for example by excluding borate or using a materially different concentration. The applicant would still need to address bioequivalence, pharmaceutical equivalence, quality, sterility, stability, and any other listed patents.

Key Takeaways

U.S. Patent 11,510,984 is a narrow composition patent focused on aqueous anhydrous sodium thiosulfate.
Claim 1 requires approximately 0.5 M sodium thiosulfate and borate ions below 0.05%.
Claims 2 through 6 add a 100 mL volume, hydrochloric acid, sodium hydroxide, and pH limitations.
The strongest infringement exposure concerns an injectable formulation closely matching the claimed concentration, borate content, and pH.
Eliminating borate or materially changing the sodium thiosulfate concentration offers the clearest design-around strategy.
The patent does not claim a therapeutic indication, manufacturing process, delivery device, or all sodium thiosulfate products.
Orange Book listing, patent-term adjustment, terminal disclaimers, pediatric exclusivity, and any patent-term extension must be evaluated separately from the claim language.
Biosimilar analysis is not applicable because sodium thiosulfate is a small-molecule active ingredient.
A Paragraph IV strategy would likely focus on claim construction, definiteness, obviousness, and whether the accused product contains the claimed borate and anhydrous sodium thiosulfate limitations.

FAQs About U.S. Patent 11,510,984

Does a sodium thiosulfate product without borate infringe claim 1?

On the supplied claim language, a product without borate ions would not literally satisfy the borate limitation. The product could remain exposed to other patents, including separate method-of-use or manufacturing patents.

Does a 12.5 g/100 mL sodium thiosulfate injection necessarily infringe?

No. Mass concentration alone is insufficient. The analysis must determine the sodium thiosulfate solid form, molarity, borate content, pH, and whether the composition satisfies the other limitations.

Does claim 6 cover every sodium thiosulfate injection with an alkaline pH?

No. Claim 6 is limited to a pH of about 8.6 to about 8.8 and also incorporates every limitation of claim 1.

Can a product with sodium thiosulfate pentahydrate avoid the patent?

It may create a non-infringement argument, but the result depends on construction of the "aqueous anhydrous sodium thiosulfate" limitation and the evidence concerning the final composition and manufacturing process.

Does FDA approval make a sodium thiosulfate product non-infringing?

No. FDA approval and patent rights are separate. A product may receive regulatory approval while remaining subject to patent infringement risk or a Paragraph IV dispute.

References

United States Patent and Trademark Office. (2022). U.S. Patent No. 11,510,984. Washington, DC: U.S. Department of Commerce.
U.S. Food and Drug Administration. (2022). Pedmark (sodium thiosulfate injection) prescribing information. Silver Spring, MD: FDA.
United States Code. 35 U.S.C. §§ 154, 156.
United States Code. 21 U.S.C. § 355(j).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Fennec Pharms Inc	PEDMARK	sodium thiosulfate	SOLUTION;INTRAVENOUS	212937-001	Sep 20, 2022		RX	Yes	Yes	11,510,984	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2019299216	⤷ Start Trial
Australia	2019299217	⤷ Start Trial
Australia	2025204721	⤷ Start Trial
Brazil	112021000021	⤷ Start Trial
Brazil	112021000022	⤷ Start Trial
Canada	3103982	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 11,510,984