United States Patent 7,198,796: Anidulafungin Formulation Claims, Patent Scope, and Generic-Entry Risk

US Patent 7,198,796 protects selected parenteral anidulafungin formulations that use ethanol-containing aqueous vehicles and require the active pharmaceutical ingredient to have been stored in solid form for more than nine months before formulation. The patent is formulation-focused rather than compound-focused. Its commercial relevance depends on whether an anidulafungin injectable product uses the claimed ethanol concentration, excipient combinations, and solid-storage history.

The broadest independent claim is claim 1. Claims 2 through 23 narrow the formulation by specifying solvents, ethanol levels, excipients, concentration ranges, and a longer solid-storage period.

What does US Patent 7,198,796 protect?

The patent claims a pharmaceutically acceptable parenteral formulation containing:

Anidulafungin;
An aqueous solvent;
About 5% to about 50% w/v ethanol; and
Anidulafungin stored in solid form for more than nine months before the formulation is prepared.

The storage condition is a claim limitation. A formulation containing the same ingredients may avoid literal infringement if the anidulafungin was not stored in solid form for more than nine months. That limitation also creates an evidentiary issue because infringement analysis may require manufacturing, inventory, stability, and batch-history records.

Claim architecture

Claim group	Subject matter	Commercial significance
Claim 1	Core ethanol-containing parenteral formulation and greater-than-nine-month solid storage	Broadest claim
Claim 2	Water or saline as aqueous solvent	Covers ordinary injectable vehicles
Claims 3-5	Ethanol and anidulafungin concentration ranges	Targets practical formulation concentrations
Claims 6 and 22	Propylene glycol or polyethylene glycol	Covers cosolvent systems
Claims 7-10	Stabilizers and bulking agents	Covers lyophilized or stability-oriented compositions
Claims 11-13	Solubilizers, including polysorbate 80	Relevant to poorly water-soluble anidulafungin
Claims 14-15	Buffers, including tartaric acid	Covers pH-control systems
Claims 16-17	Tonicity agents	Relevant to injectable tolerability
Claims 18-19	Antioxidants	Covers oxidative-stability approaches
Claims 20-21	Multi-excipient formulations with defined ranges	Narrow composition claims
Claim 23	Greater-than-12-month solid storage	Narrower storage limitation

How broad is claim 1 of US 7,198,796?

Claim 1 is composition-based, but it is narrower than a conventional formulation claim because it includes a manufacturing and storage-history requirement.

A product must satisfy all claim 1 elements for literal infringement. The principal limitations are:

The dosage form must be parenteral.
The formulation must be pharmaceutically acceptable.
Anidulafungin must be present.
The formulation must contain an aqueous solvent.
Ethanol must be present at approximately 5% to 50% w/v.
The anidulafungin must have been stored in solid form for more than nine months before formulation.

The claim does not require a particular stabilizer, buffer, surfactant, bulking agent, tonicity agent, or antioxidant. Those features appear in dependent claims.

The claim also does not require a lyophilized final product. It requires prior storage of anidulafungin in solid form. A liquid formulation made from a previously stored solid active ingredient may fall within the claim if the other limitations are met.

What formulations are protected by claims 20, 21, and 23?

Claims 20 and 21 are narrower, multi-component formulation claims. Claim 23 narrows the storage period.

Claim 20

Claim 20 covers a formulation containing:

5.0% to 30% w/v ethanol;
0.1% to 2.0% w/v anidulafungin;
0.1% to 1.0% w/v stabilizing agent;
0.1% to 10.0% w/v bulking agent;
0.01% to 5.0% w/v buffer; and
0.1% to 5.0% w/v solubilizing agent.

The supplied text contains a typographical defect in the bulking-agent range, written as "0.1–1 0.0%." The surrounding formulation structure indicates a likely intended range of 0.1% to 10.0%, but claim construction must rely on the issued patent text and any certificate of correction.

Claim 21

Claim 21 specifies:

5.0% to 30% w/v ethanol;
0.1% to 2.0% w/v anidulafungin;
0.1% to 1.0% w/v fructose;
0.1% to 10.0% w/v mannitol;
0.01% to 5.0% w/v tartaric acid; and
0.1% to 5.0% w/v polysorbate 80.

This is the most formulation-specific claim in the set. A competing product using a different buffer, omitting fructose, replacing mannitol, or using a non-polysorbate solubilizer may reduce literal infringement risk, although the doctrine of equivalents could remain relevant.

Claim 23

Claim 23 requires solid storage for more than 12 months rather than more than nine months. It remains subject to the formulation limitations of claim 1.

The difference between nine and 12 months is commercially important. A manufacturer with validated solid-state storage below the claimed period may have a non-infringement position, but the relevant period may be established by batch records, stability protocols, release documentation, and the date on which the material was converted into the injectable formulation.

How does US 7,198,796 differ from anidulafungin compound patents?

US 7,198,796 is directed to a formulation and storage strategy. It does not broadly claim the anidulafungin molecule itself.

Patent category	Typical protected subject matter	Relevance to generic entry
Compound patent	Anidulafungin chemical structure and analogs	May block manufacture or sale of the active ingredient during its term
Formulation patent	Ethanol-containing injectable compositions and excipient systems	May block a particular finished dosage form
Method-of-use patent	Treatment of candidemia, invasive candidiasis, or related infections	May create labeling or induced-infringement issues
Manufacturing patent	Synthesis, purification, crystallization, or solid-state handling	May restrict API sourcing or production
Regulatory exclusivity	FDA orphan, new chemical entity, or pediatric exclusivity	Operates independently from patent claims

The practical distinction is that expiration of a compound patent does not necessarily eliminate risk under an unexpired formulation patent. Conversely, an unexpired formulation patent may have limited commercial value if a generic manufacturer can design around the claimed ethanol and excipient parameters.

When does US Patent 7,198,796 expire?

A precise expiration date cannot be calculated from the patent number or issue date alone. For a post-June 8, 1995 US utility patent, the ordinary term is generally 20 years from the earliest effective nonprovisional filing date, subject to terminal disclaimers, patent-term adjustment, and any patent-term extension under 35 U.S.C. §156 [USPTO, 2024a; 35 U.S.C. §§154, 156].

The relevant dates are:

Event	Date or rule
US patent issue	April 3, 2007
Ordinary statutory term	20 years from the applicable earliest nonprovisional filing date
Patent-term adjustment	May extend the term for qualifying USPTO delay
Patent-term extension	May apply only if statutory requirements are satisfied
Terminal disclaimer	Could shorten the term if filed during prosecution

The issue date is not the expiration date. A current freedom-to-operate analysis must use the USPTO Patent Center record, the front-page term data, any terminal disclaimer, maintenance-fee status, and any certificate of correction.

What is the Orange Book status of US 7,198,796?

The Orange Book is the controlling FDA source for patents submitted by an NDA holder for a listed drug. The relevant reference product is Eraxis, anidulafungin for injection, associated with NDA 021632 [FDA, 2024a].

An Orange Book listing does not establish that every claim of the patent covers every anidulafungin product. It identifies patent information submitted for the reference listed drug and determines whether an ANDA applicant must make a patent certification under 21 U.S.C. §355(j)(2)(A)(vii).

For an ANDA applicant, the principal possibilities are:

Paragraph I: no patent information is listed;
Paragraph II: the listed patent has expired;
Paragraph III: the applicant will wait until expiration;
Paragraph IV: the patent is invalid, unenforceable, or not infringed;
A section viii statement: the applicant omits a patented method of use from its labeling.

A formulation patent such as US 7,198,796 is more likely to generate a Paragraph IV analysis than a section viii carve-out if the patent is directed to the composition rather than a treatment indication.

Which companies are challenging Eraxis and anidulafungin patents?

A reliable list of challengers requires current FDA Orange Book records, ANDA litigation dockets, and district-court filings. The supplied claim text does not identify an ANDA applicant, litigation party, settlement, or court decision.

The relevant litigation trigger is service of a Paragraph IV notice letter. Under the Hatch-Waxman framework, the NDA holder and patent owner generally have 45 days to file an infringement action. A timely action can trigger a 30-month stay of ANDA approval under 21 U.S.C. §355(j)(5)(B)(iii), subject to statutory exceptions and court decisions.

A Paragraph IV challenge would likely focus on:

Whether the accused product contains 5% to 50% w/v ethanol;
Whether the aqueous vehicle falls within claim 2;
Whether the active was stored in solid form for more than nine or 12 months;
Whether claim 20 or claim 21 ranges are met;
Whether the patent claims are anticipated or obvious over prior anidulafungin formulations;
Whether the storage limitation is definite and adequately supported; and
Whether the patent remains enforceable and has not been terminally disclaimed.

How strong is the patent estate for anidulafungin?

US 7,198,796 has moderate formulation-blocking strength but limited molecule-level exclusivity.

Strengths

Claim 1 covers a broad ethanol range, from approximately 5% to 50% w/v.
The claim reaches the formulation process history through solid-state storage.
Dependent claims cover common injectable excipients, including polysorbate 80, mannitol, buffers, and glycols.
Claims 20 and 21 provide fallback positions around defined commercial formulations.
The claims can apply even where the final product is not itself stored as a solid.

Weaknesses

The greater-than-nine-month storage limitation may be difficult to prove without access to supply-chain records.
Ethanol-containing injectable formulations may be vulnerable to prior-art attacks if the cited art discloses similar solvent systems.
The claim ranges permit design-around opportunities.
Claims 20 and 21 require multiple excipients and numerical ranges, reducing their coverage.
The patent does not independently control anidulafungin manufacture if compound and process rights have expired.
A generic may source API late in the manufacturing cycle or formulate from material that has not met the claimed storage period.

What generic launch scenarios exist for anidulafungin?

Launch route	Patent strategy	Main exposure
Paragraph III ANDA	Await listed-patent expiration	Delayed launch but lower litigation exposure
Paragraph IV ANDA	Assert invalidity, unenforceability, or non-infringement	Hatch-Waxman litigation and possible 30-month stay
Formulation design-around	Use ethanol outside the claimed range or a different vehicle	Requires stability, solubility, and injectable-safety validation
Storage-history design-around	Avoid solid storage beyond the claimed period	Requires controlled API-to-product manufacturing logistics
Label carve-out	Omit patented use, if an eligible method-of-use patent applies	Limited relevance to a pure formulation patent
505(b)(2) application	Rely partly on reference-drug data while proposing formulation differences	Regulatory and patent strategy depends on the proposed product

The most commercially practical design-around is likely a formulation that avoids the claimed ethanol range or uses a materially different solvent and excipient system. That option may create technical problems because anidulafungin has limited aqueous solubility and requires a formulation capable of maintaining potency, clarity, sterility, and acceptable administration characteristics.

What manufacturing and IP barriers remain after patent expiration?

Patent expiration does not remove all barriers to market entry. A generic or follow-on applicant still must establish:

API identity, purity, and impurity control;
Injectable sterility assurance;
Stability through the proposed shelf life;
Compatibility with the container-closure system;
Control of particulate matter;
Reconstitution or dilution performance, where applicable;
Bioequivalence or appropriate clinical-bridging evidence;
Compliance with current FDA manufacturing requirements.

Anidulafungin is a complex echinocandin active ingredient. Process know-how may remain commercially relevant even after compound or formulation patents expire. Solid-state handling, impurity clearance, and formulation stability can create practical barriers that are not visible from the patent claims.

What licensing deals and settlement agreements affect US 7,198,796?

The patent number and claims do not establish a license, covenant not to sue, authorized-generic arrangement, or Hatch-Waxman settlement. Such agreements may be confidential or reported in FTC reviews, SEC filings, court orders, or FDA-related litigation records.

The commercial effect of a settlement depends on:

The agreed launch date;
Whether the agreement permits an authorized generic;
The scope of any license;
Supply obligations;
Restrictions on API sourcing;
Payment or reverse-payment provisions;
Treatment of later ANDA applicants; and
Whether the agreement covers only US rights or broader geographic territories.

No settlement terms should be inferred solely from the existence of US 7,198,796.

How does the patent apply geographically?

US 7,198,796 has territorial effect in the United States. It does not directly block manufacture, use, or sale outside the United States.

International risk depends on corresponding national patents and their legal status. Relevant jurisdictions for anidulafungin commercial planning may include:

European Patent Convention states;
Canada;
Japan;
China;
Australia;
South Korea; and
Other markets where Eraxis or generic anidulafungin is sold.

A US formulation claim does not establish the scope or enforceability of foreign family members. Each jurisdiction requires separate review of national claims, translations, maintenance fees, supplementary protection certificates, and local litigation.

Key Takeaways

US 7,198,796 is a formulation patent, not a broad anidulafungin compound patent.
Claim 1 requires ethanol at approximately 5% to 50% w/v and solid-state storage of anidulafungin for more than nine months.
Claim 23 extends the storage limitation to more than 12 months.
Claims 20 and 21 target defined multi-excipient formulations, including fructose, mannitol, tartaric acid, and polysorbate 80.
The storage-history limitations may create substantial proof issues in litigation.
A generic may pursue a Paragraph IV challenge or design around the ethanol, excipient, concentration, or storage-period limitations.
The patent’s exact expiration date requires review of the prosecution record, terminal disclaimers, patent-term adjustment, and any patent-term extension.
Orange Book listing status must be confirmed against the current FDA records for Eraxis NDA 021632.
Patent expiration would not eliminate regulatory, manufacturing, stability, or API-sourcing barriers.

FAQs

Does US 7,198,796 cover all anidulafungin injections?

No. It covers formulations that satisfy the claimed ethanol, aqueous-solvent, parenteral, and solid-storage limitations. An anidulafungin product using a different formulation or storage history may fall outside the literal claims.

Can a manufacturer avoid claim 1 by storing anidulafungin as a liquid?

Potentially, if the product genuinely avoids the requirement that anidulafungin be stored in solid form for more than nine months. The full manufacturing record and claim construction would determine the result.

Is polysorbate 80 required by the broadest claim?

No. Polysorbate 80 appears in claims 12, 13, and 21. Claim 1 does not require a solubilizer or polysorbate.

Does an expired compound patent eliminate infringement risk under US 7,198,796?

No. Compound, formulation, manufacturing, and method-of-use patents are separate rights. An expired compound patent does not by itself establish that the formulation claims are expired or invalid.

Can an ANDA applicant omit anidulafungin formulation patents through a section viii statement?

Usually not when the patent claims the composition itself. Section viii statements are designed primarily for patented methods of use that can be omitted from labeling, not for composition claims that cover the proposed product.

References

U.S. Patent No. 7,198,796. (2007). United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2024a). Drugs@FDA: Eraxis (anidulafungin) NDA 021632. https://www.accessdata.fda.gov/scripts/cder/daf/
U.S. Food and Drug Administration. (2024b). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
United States Code. 35 U.S.C. §§ 154, 156.
United States Code. 21 U.S.C. § 355(j).
U.S. Patent and Trademark Office. (2024a). Patent term adjustment and patent term calculation guidance. https://www.uspto.gov/patents/laws/patent-term-calculator
U.S. Patent and Trademark Office. (2024b). Patent Center: Patent application and prosecution records. https://patentcenter.uspto.gov/

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	040226	⤷ Start Trial
Australia	2003248692	⤷ Start Trial
Canada	2488872	⤷ Start Trial
European Patent Office	1511378	⤷ Start Trial
Israel	165720	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,198,796

Summary for Patent: 7,198,796