United States Drug Patent 7,575,757: Claim Scope, Expiration, Orange Book Status, and Generic Risk

U.S. Patent No. 7,575,757 protects aqueous, stable liquid formulations of alpha-adrenergic receptor antagonists, with the commercial focus on phentolamine mesylate used in dental anesthesia reversal. The broadest issued claims require a low-dose alpha-adrenergic antagonist, an aqueous solvent, a pH-control buffer, and a metal chelator. Dependent claims narrow the formulation to phentolamine mesylate, EDTA, acetate buffer, d-mannitol, specified pH ranges, and single-dose containers.

The patent issued on August 18, 2009, from an application claiming priority to January 23, 2004. Its ordinary U.S. patent term therefore ran to approximately January 23, 2024, subject to any patent-term adjustment, disclaimer, or maintenance-fee event recorded by the USPTO. The patent no longer represents a forward-looking blocking right against new U.S. generic entry if its term has ended.

What drug and formulation does U.S. Patent 7,575,757 protect?

The patent protects stable liquid formulations containing an alpha-adrenergic receptor antagonist. The claims identify multiple possible active ingredients but concentrate commercially on phentolamine mesylate.

Claim element	Scope
Active ingredient	Alpha-adrenergic receptor antagonist
Broad active amount	About 0.02 mg to about 0.43 mg
Concentration limitation	About 0.01 mg/mL to about 1 mg/mL in claim 4
Solvent	Aqueous solvent, specifically water in claim 5
pH control	Buffer; claim 1 requires pH about 2.0 to 6.0
Metal chelator	Required by claim 1
Optional excipients	Tonicity modifier, antioxidant, complexing agent
Preferred antagonist	Phentolamine mesylate
Preferred chelator	EDTA
Preferred pH	About 3.5 to 4.5
Preferred buffer	10 to 50 mM acetate buffer or methanesulfonic acid
Preferred container	Ampule, dental cartridge, or prefilled sterile syringe
Preferred fill volume	About 1.6 to 1.8 mL

The claim architecture is formulation-centered. It does not broadly claim phentolamine mesylate as a molecule, its general therapeutic use, or every injectable composition. Infringement requires the accused product to satisfy the required formulation elements, either literally or under an applicable doctrine of equivalents.

How do the independent claims differ?

Claims 1, 26, and 27 are the principal independent formulation claims. Claims 23 and 24 extend protection to a container holding the formulation.

Claim 1

Claim 1 is the most technically specific broad formulation claim. It requires:

About 0.02 mg to about 0.43 mg of an alpha-adrenergic receptor antagonist.
A buffer for maintaining pH.
An aqueous solvent.
A metal chelator.
A formulation pH of about 2.0 to 6.0.
Optional tonicity modifier, antioxidant, and complexing agent.

The phrase “consisting essentially of” is important. It generally permits components that do not materially affect the basic and novel characteristics of the formulation, while potentially excluding additional ingredients that materially alter stability or function. The precise scope depends on the patent specification, prosecution history, and claim construction.

Claim 26

Claim 26 repeats the core composition but omits the express pH limitation. It requires the active ingredient, buffer, aqueous solvent, and metal chelator, with the same optional excipients.

This claim is potentially broader than claim 1 with respect to pH. Claim 27 narrows claim 26 by adding a pH range of about 2.0 to 7.0.

Claims 23 to 25

These claims cover a container containing a single dosage form of the claimed stable liquid formulation. Claim 24 identifies an ampule, dental cartridge, or prefilled sterile syringe. Claim 25 narrows the volume to approximately 1.6 to 1.8 mL.

These container claims were commercially relevant to dental cartridges containing phentolamine mesylate. They do not independently protect a container filled with any formulation. The formulation must first fall within the scope of claim 1 or claim 26.

What are the narrowest commercially important claims?

The commercially important chain is claims 3, 7, 8, 9, 10, 11, 14, 15, 22, and 25.

Claim	Commercial limitation
3	Phentolamine mesylate
7	EDTA at about 0.5 to 1.0 mg/mL
8	Phentolamine mesylate plus claim 7
9	pH about 3.5 to 4.5
10	10 to 50 mM acetate buffer or methanesulfonic acid
11	Phentolamine mesylate plus claim 10
14	d-Mannitol at 4% to 5%
15	Phentolamine mesylate plus claim 14
22	0.5 mg/mL EDTA, 5% d-mannitol, 16.6 mM acetate buffer, pH 3.8 to 4.2
25	Single-dose container with approximately 1.6 to 1.8 mL

Claim 22 is the most formulation-specific claim and appears designed around the commercial product configuration. A product that falls outside the exact excipient concentration or pH limitations could avoid claim 22 while still implicating broader claims, particularly claims 1 or 26.

Does the patent cover OraVerse or phentolamine mesylate dental cartridges?

The patent is closely associated with the formulation technology used for OraVerse, a phentolamine mesylate dental injection marketed by Novalar Pharmaceuticals and later commercialized by Septodont. FDA labeling identifies OraVerse as a 0.4 mg/2 mL product, equivalent to 0.2 mg/mL phentolamine mesylate. That concentration falls within claim 4’s range of about 0.01 mg/mL to about 1 mg/mL, assuming the other required elements are present.[1]

The claims also cover the relevant unit-dose format if the product is supplied in a dental cartridge with a fill volume of approximately 1.6 to 1.8 mL. A 2 mL labeled presentation, however, does not automatically satisfy the narrower 1.6 to 1.8 mL limitation in claim 25. The actual filled volume, not merely the nominal container capacity, would control that analysis.

The patent’s commercial relevance depends on the full inactive-ingredient profile. A phentolamine mesylate injection without the claimed metal chelator would not literally meet claim 1 or claim 26. A product with a different buffer, pH, or tonicity modifier could avoid narrower dependent claims while remaining within an independent claim.

What formulations are specifically protected?

The principal protected formulation combinations are:

Phentolamine mesylate with EDTA

Claims 7, 8, and 22 identify EDTA as the preferred metal chelator. Claim 22 requires 0.5 mg/mL EDTA. A formulation using another chelator, such as citric acid or diethylenetriamine pentaacetic acid, could fall within claim 6 if all parent limitations are met, but would not fall within the EDTA-specific claims.

Phentolamine mesylate with d-mannitol

Claims 12 through 15 cover formulations containing a tonicity modifier, with claim 14 specifying d-mannitol at 4% to 5%. This is a narrower formulation path than the broad claims because the tonicity modifier is optional in claim 1.

Acetate-buffered formulations

Claims 9 through 11 focus on pH about 3.5 to 4.5 and a 10 to 50 mM acetate buffer or methanesulfonic acid. Claim 22 narrows the acetate buffer to 16.6 mM and pH 3.8 to 4.2.

Antioxidant and complexing-agent formulations

Claims 16 through 21 cover optional antioxidants and complexing agents. The listed antioxidants are ascorbic acid, sodium metabisulfite, butylated hydroxyanisole, and butylated hydroxytoluene. The listed complexing agents are alpha-cyclodextrin and niacinamide.

These claims create formulation design-around routes because the antioxidant and complexing-agent components are not required by the independent claims.

How broad is the patent’s claim scope?

The patent has moderate historical breadth but limited present-day blocking value because its ordinary term has ended.

Its strongest scope was against a liquid phentolamine mesylate product containing:

An aqueous vehicle;
A buffer;
A metal chelator;
A pH between approximately 2.0 and 6.0;
A low unit dose within the claimed amount range.

The patent is weaker against:

Solid dosage forms;
Lyophilized products reconstituted before administration;
Products lacking a metal chelator;
Products using a materially different stabilization system;
Products with a concentration or unit dose outside the claimed ranges;
Products administered in containers outside the specified format.

The “about” language creates potential claim-construction disputes at the boundaries of dose, concentration, pH, buffer strength, and fill volume. The word “stable” may also require reference to the specification’s stability testing and acceptance criteria. A formulation is not necessarily covered merely because it contains the listed ingredients.

When did U.S. Patent 7,575,757 expire?

The patent’s priority date was January 23, 2004. Under the 20-year term applicable to the relevant application, the expected term ran to January 23, 2024, adjusted for any USPTO patent-term adjustment or terminal disclaimer.[2]

The issued patent date, August 18, 2009, does not determine the expiration date. For applications filed after June 8, 1995, the term generally runs from the earliest effective nonprovisional filing date, not from issuance.[3]

The patent’s maintenance-fee and legal-status records should be read together with the term calculation. A lapse for nonpayment of maintenance fees can end enforceability earlier, but a later expiration date does not revive a patent whose term has ended.

What is the Orange Book status of Patent 7,575,757?

Patent 7,575,757 was associated with the OraVerse product and its formulation protection. The FDA Orange Book is the operative source for listed patents and expiration information for approved small-molecule drug products.[4]

The patent was not a patent on the phentolamine molecule itself. Its relevance to an abbreviated new drug application depended on whether the listed patent remained active and whether the generic product’s formulation met the claimed limitations.

After expiration, the patent should not create an active Paragraph IV litigation risk based solely on the patent’s formulation claims. FDA approval timing can still be affected by other listed patents, statutory exclusivity, product-specific requirements, and regulatory review.

Did the patent create Paragraph IV or generic-entry risk?

A Paragraph IV certification would have been relevant while the patent remained listed and unexpired. An ANDA applicant could assert that the patent was invalid, unenforceable, or would not be infringed. The patent’s formulation-specific structure would have supported a noninfringement strategy based on:

Omitting the metal chelator;
Using a different stabilizer;
Selecting a pH outside the asserted range;
Changing the buffer system;
Altering the unit-dose amount;
Using a different container or fill volume.

A generic applicant could also challenge validity based on anticipation, obviousness, indefiniteness, written description, enablement, or claim construction. The central validity question would likely concern whether the claimed combination of low-dose alpha-adrenergic antagonist, aqueous buffer, chelator, pH range, and optional excipients was predictable from earlier injectable formulations and stability disclosures.

No active U.S. Paragraph IV threat should be inferred from the patent number alone after the patent’s expected January 2024 expiration.

What patent litigation affected the product?

The principal litigation risk associated with U.S. Patent 7,575,757 was expected to arise from an ANDA or other commercial product that reproduced the claimed phentolamine mesylate formulation. Public FDA and USPTO records, rather than the patent text, control whether a particular ANDA triggered a notice letter, a 30-month stay, or district-court litigation.

The patent should be analyzed separately from:

Any patent covering the phentolamine mesylate active ingredient;
Any later patent covering OraVerse manufacturing;
Any formulation patent with a different expiration date;
Trade-secret protection for manufacturing parameters;
Trademark rights in the OraVerse name;
Regulatory exclusivity under the Federal Food, Drug, and Cosmetic Act.

A settlement agreement, if any, would not extend the patent term beyond its statutory expiration. It could affect the timing of an authorized generic or other commercial entry only during the settlement period and only under the agreement’s terms.

Are biosimilar risks relevant to Patent 7,575,757?

No. Phentolamine mesylate is a chemically synthesized small-molecule drug, not a biologic. The relevant competitive pathway is an ANDA for a generic drug, not a biosimilar application under the Public Health Service Act.

The relevant barriers are formulation equivalence, injectable-product quality, container closure, sterility, stability, manufacturing validation, and any remaining Orange Book-listed patents. FDA approval would generally require the generic product to demonstrate pharmaceutical equivalence and bioequivalence or satisfy an applicable waiver or alternative equivalence approach.[5]

How does the patent compare with other possible barriers?

Barrier	Relevance to phentolamine mesylate dental products
U.S. Patent 7,575,757	Historical formulation protection; expected term ended around January 2024
Active-ingredient patent	Generally unlikely to be a current barrier for an established salt and drug product
Method-of-use patent	Could matter only if separately listed and unexpired
Manufacturing patent	Could restrict a process even after formulation-patent expiry
Trade secret	May affect manufacturing know-how but is not listed in the Orange Book
Regulatory exclusivity	Separate from patent term and depends on FDA designation
Sterile injectable requirements	Practical development barrier independent of patent rights
Trademark	OraVerse branding remains distinct from generic formulation rights

What generic launch scenarios exist?

The principal scenarios are:

A formulation that reproduces the historical product, launched after patent expiration if FDA requirements are satisfied.
A design-around formulation that omits EDTA or uses a different chelator.
A formulation using a different buffer or pH while retaining phentolamine mesylate.
A product supplied in a vial or prefilled syringe rather than the claimed dental-cartridge configuration.
An authorized generic or licensed product using the incumbent manufacturer’s formulation and manufacturing process.

The lowest technical risk may come from reproducing the approved product after expiry. The lowest patent risk may come from a formulation that avoids the required metal-chelator limitation, but that approach can create new stability, compatibility, or regulatory risks.

What is the commercial exposure?

OraVerse is used to reverse soft-tissue anesthesia and reduce the duration of numbness after dental procedures. Its commercial value is tied to dental-office adoption, cartridge compatibility, reimbursement, and the availability of competing anesthetic-reversal products.

The patent did not protect the entire clinical market for phentolamine mesylate. It protected specific liquid formulations and container presentations. Revenue exposure therefore depended on whether a competing product used the claimed excipient system rather than merely whether it contained phentolamine mesylate.

Key Takeaways

U.S. Patent 7,575,757 is a formulation patent focused on stable aqueous alpha-adrenergic antagonist products.
Phentolamine mesylate is the central commercial embodiment.
The broadest claims require a buffer, aqueous solvent, metal chelator, and low-dose active ingredient.
EDTA, d-mannitol, acetate buffer, pH 3.8 to 4.2, and a 1.6 to 1.8 mL unit dose are covered by narrower claims.
The patent does not broadly claim phentolamine mesylate, dental anesthesia reversal, or every injectable formulation.
The ordinary patent term ran approximately to January 23, 2024, subject to USPTO term adjustments and legal-status records.
Biosimilar analysis is irrelevant because phentolamine mesylate is a small-molecule drug.
Current generic risk is primarily regulatory and manufacturing-related unless another unexpired patent remains listed or enforceable.
A formulation design-around can avoid the narrowest claims by changing the chelator, buffer, pH, concentration, or container format.

FAQs About U.S. Patent 7,575,757

Does Patent 7,575,757 cover all phentolamine mesylate injections?

No. It covers only formulations satisfying the required claim elements, including a buffer, aqueous solvent, and metal chelator in the independent claims.

Is EDTA mandatory in every asserted claim?

No. EDTA is required only in EDTA-specific dependent claims. The independent claims require a metal chelator, which can include other listed agents.

Does a 2 mL vial infringe the container claims?

Not necessarily. Claim 25 requires a volume of approximately 1.6 to 1.8 mL. A nominal 2 mL container may fall outside that limitation, although the formulation claims could still be relevant.

Is OraVerse protected by a method-of-use claim in this patent?

No. The claims provided are directed to formulations and containers. They do not claim the therapeutic method of reversing dental anesthesia.

Can a generic launch occur after the patent expiration date?

Potentially, subject to FDA approval, any other unexpired listed patents, regulatory exclusivity, sterile manufacturing requirements, and compliance with the approved product’s formulation and quality standards.

References

U.S. Food and Drug Administration. (n.d.). OraVerse (phentolamine mesylate) injection prescribing information.
United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term calculation resources.
United States Code. (2023). 35 U.S.C. § 154: Contents and term of patent; provisional rights.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (n.d.). ANDA submissions: Product-specific guidance and abbreviated new drug application requirements.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2003247568	⤷ Start Trial
Brazil	0311965	⤷ Start Trial
Brazil	PI0311965	⤷ Start Trial
Canada	2489526	⤷ Start Trial
China	100391460	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,575,757

Summary for Patent: 7,575,757