US Patent 9,687,526: Vasopressin Formulation Claims, Patent Scope, Exclusivity and Generic Risk

US Patent 9,687,526 protects a combined vasopressin treatment and product-stability regimen. Its independent claim requires the use of an acidic, refrigerated, non-lyophilized intravenous vasopressin composition containing acetic acid and water, followed by administration within a defined dosing range to a hypotensive patient. The claim also requires less than 5% degradation after approximately four weeks at 2-8°C.

The patent is commercially relevant to Vasostrict, the FDA-approved vasopressin injection product marketed by Endo Pharmaceuticals. The principal risk to a generic manufacturer is a method-of-use infringement theory based on the labeled intravenous treatment of hypotension, particularly if the generic product has the claimed formulation and stability profile.

What does US Patent 9,687,526 protect?

The patent protects a method rather than a broad vasopressin molecule, a standalone composition, or every use of vasopressin.

Claim 1 combines five technical elements:

Required element	Claim limitation
Active ingredient	About 0.01-0.07 mg/mL vasopressin or a pharmaceutically acceptable salt
Excipients	Acetic acid and water
pH	pH 3.8
Storage	At 2-8°C for at least four weeks
Stability	Less than about 5% degradation after approximately four weeks
Patient	A hypotensive human
Route	Intravenous administration
Dose	About 0.01-0.1 units/minute

The claim is narrower than a conventional formulation claim because infringement requires performance of the entire sequence. A product that contains vasopressin at the claimed concentration but is not stored for the specified period, or does not meet the claimed degradation threshold, may not literally satisfy claim 1.

The claim also links product stability to clinical administration. The protected subject matter is therefore a product-use combination involving:

Preparation or provision of the formulation.
Refrigerated storage.
Intravenous administration.
Treatment of hypotension.
A defined vasopressin infusion rate.

How strong is the independent claim of US 9,687,526?

Claim 1 has meaningful commercial breadth but several limitations create potential design-around and validity arguments.

Claim construction issues

The most important construction issues are:

Whether “providing” requires the treatment provider to make or supply the composition.
Whether storage for “at least 4 weeks” must occur before every administration.
Whether “pH of 3.8” covers a numerical tolerance under the term “about.”
How degradation is measured.
Whether the claimed concentration refers to the pre-dilution product or the final infusion solution.
Whether the composition must be stored continuously at 2-8°C.
Whether the administration must be performed by the same entity that provided or stored the product.

The claim expressly requires the formulation to be stored before administration. That limitation may narrow direct infringement because a hospital or wholesaler may not document the exact storage period for each vial. The limitation also creates a potential evidentiary issue in ANDA litigation: stability data for a proposed generic product may demonstrate the claimed stability profile, but it does not by itself prove that the product will be stored for at least four weeks in actual clinical use.

“About” ranges

The terms “about 0.01 mg/mL,” “about 0.07 mg/mL,” “about 0.01 units/minute,” and “about 0.1 units/minute” create ordinary claim-construction disputes. The permitted range may extend beyond the numerical endpoints depending on the specification, analytical precision and prosecution history.

The pH limitation is more restrictive. A formulation at pH 3.8 is central to the claim. A generic formulation at pH 3.5 or 4.0 may present a stronger noninfringement position than a formulation at pH 3.75 or 3.85.

What do dependent claims 2 through 4 protect?

Claims 2, 3 and 4 add specific degradation products identified as SEQ ID NOs. 2, 3 and 4. Each claim requires the corresponding sequence-defined species to be present at approximately 0.01% after four weeks at 2-8°C.

Claim	Added limitation	Commercial significance
2	SEQ ID NO: 2 at about 0.01% after storage	Targets a defined degradation profile
3	SEQ ID NO: 3 at about 0.01% after storage	Requires a different sequence-defined impurity
4	SEQ ID NO: 4 at about 0.01% after storage	Creates a third impurity-specific fallback

These claims are narrower and depend on the interpretation of the referenced sequence identifiers and the analytical method disclosed in the patent specification. They may be difficult to enforce without access to a generic manufacturer’s batch records, impurity specifications and analytical testing.

They may nevertheless be useful in litigation because a generic manufacturer could avoid the precise pH or concentration limitation yet still produce a similar degradation pattern. The patentee would need to establish that the relevant degradation species are present at the claimed level and that the testing method is reproducible.

What do claims 5 through 11 protect?

Claims 5 through 11 add clinical treatment parameters.

Rapid blood-pressure response

Claim 5 requires an increase in mean arterial blood pressure within 15 minutes of administration. This limitation narrows the claim to an observable clinical response. It may be difficult to use as a pre-launch product-screening limitation because the response depends on patient condition, concomitant vasopressors, baseline blood pressure and treatment setting.

Vasodilatory shock

Claim 6 narrows the indication to hypotension associated with vasodilatory shock. Claims 7 and 8 specify:

Post-cardiotomy shock.
Septic shock.

These claims align closely with the clinical use of vasopressin as an adjunct vasopressor in distributive or vasodilatory shock. A generic label that includes septic shock or post-cardiotomy hypotension may create a greater induced-infringement risk than a label limited to a different indication.

Septic shock dosing

Claim 9 limits septic-shock administration to approximately 0.01-0.07 units/minute. This range overlaps common vasopressin infusion regimens used in critical care and may be particularly important for a product label that recommends 0.03-0.04 units/minute.

Eight-hour maintenance and tapering

Claims 10 and 11 require:

Attainment of a target blood pressure.
Continued administration for approximately eight hours.
A subsequent dose reduction of approximately 0.005 units/minute.

These claims are operational and protocol-oriented. They may be avoided by a label that does not recommend a fixed eight-hour continuation period or a specific taper step. Actual clinical practice can still create risk if a manufacturer promotes the regimen or if its label instructs clinicians to follow it.

What formulation characteristics are protected?

Claims 12 through 20 protect storage, dosage form and dilution features.

Claim	Limitation
12	Storage at about 5°C
13	Less than 1% degradation after four weeks at 2-8°C
14	Composition is not lyophilized
15	Composition is not frozen
16	Dilution before administration
17	Final concentration of approximately 0.21-2.1 µg/mL
18	Dilution with 0.9% saline
19	Dilution with 5% dextrose in water
20	Presence of chlorobutanol

Claims 13 and 20 are commercially important. Claim 13 creates a tighter stability requirement than claim 1. Claim 20 may cover a preservative-containing formulation that resembles the commercial product or its manufacturing specification.

The dilution claims cover standard hospital preparation practices. A final concentration of 0.21-2.1 µg/mL can overlap common infusion concentrations prepared from a concentrated vial. Claims 18 and 19 separately cover saline and dextrose diluents, making a label that identifies both diluents more exposed than one that omits either option.

When does US Patent 9,687,526 lose exclusivity?

The patent issued on June 27, 2017. Public patent records identify a nominal expiration date in February 2035 based on the patent family’s priority framework, subject to any applicable patent-term adjustment.[1]

Event	Date or status
Patent	US 9,687,526
Issue date	June 27, 2017
Technology	Refrigerated intravenous vasopressin composition and treatment
Nominal term endpoint	February 2035
Patent type	Utility patent
Claim type	Method of treatment with formulation and stability limitations
Pediatric exclusivity	Not established from the patent record
Patent-term extension	Not established from the supplied record

The relevant commercial date is not necessarily the patent’s nominal expiration date. Generic entry can occur earlier through:

A successful Paragraph IV challenge.
A settlement license.
A noninfringing formulation.
A product launch after patent expiration.
A court decision invalidating or not-infringing the patent.

What is the Orange Book status of US Patent 9,687,526?

Vasostrict is associated with NDA 204485 and contains vasopressin as the active ingredient.[2] The FDA Orange Book is the controlling public source for current patent and exclusivity listings for approved small-molecule and peptide drug products.[3]

US 9,687,526 has been associated with the Vasostrict patent estate. Its relevance is based on the patent’s formulation and method-of-use claims, not on exclusive ownership of vasopressin as an active ingredient.

An Orange Book listing does not itself establish infringement. It permits the NDA holder to identify patent rights that it believes may be infringed by an ANDA seeking approval before expiration. The generic applicant can make a Paragraph IV certification asserting that the listed patent is invalid, unenforceable or will not be infringed.

Which companies have challenged Vasostrict patent rights?

Publicly reported generic competition has involved ANDA applicants seeking approval for vasopressin injection, including Hikma Pharmaceuticals and other injectable-drug manufacturers. Patent litigation and settlement terms can change the practical launch date independently of the listed patent expiration date.

A challenge generally proceeds through the following sequence:

The ANDA applicant submits a Paragraph IV certification.
The NDA holder receives notice.
The NDA holder may file an infringement action within 45 days.
FDA approval may be subject to a 30-month stay, unless modified or terminated.
The case may end through judgment, settlement or license.
The generic may launch under the settlement terms or after the statutory stay expires.

The patent number alone does not establish the complete litigation history, the identity of every challenger, or the current status of any settlement. Those facts must be determined from the FDA Orange Book, federal court docket records and settlement filings.[3,4]

What generic entry risks exist for vasopressin injection?

Generic entry risk is moderate to high because vasopressin is an established injectable product with a clinically familiar use and no biosimilar pathway barrier. The principal barriers are formulation similarity, sterile manufacturing, stability data and patent litigation.

ANDA litigation risk

A generic applicant may face infringement allegations if its product:

Uses vasopressin at a concentration within the claimed range.
Uses acetic acid and water at approximately pH 3.8.
Is refrigerated at 2-8°C.
Has less than 5% degradation after four weeks.
Is labeled for intravenous treatment of hypotension or vasodilatory shock.
Recommends dosing within the claimed units-per-minute range.
Includes saline or dextrose dilution instructions.

The applicant may reduce exposure through a formulation at a materially different pH, a different concentration, alternative excipients, a different stability profile or a label carve-out. Label carving is more difficult where the core FDA-approved indication and dosing regimen overlap the asserted method claims.

Manufacturing risk

Sterile injectable manufacturing creates technical barriers separate from patent rights. A generic manufacturer must control:

Peptide degradation.
Oxidation and hydrolysis.
pH drift.
Container-closure compatibility.
Particulate matter.
Sterility assurance.
Refrigerated distribution.
Preservative concentration, where chlorobutanol is used.

The patent’s stability limitations may correspond closely to the product-development specifications needed for FDA approval. That overlap can make a noninfringing formulation more difficult to develop even if the patent claims are legally narrow.

Does biosimilar risk apply to vasopressin?

No conventional biosimilar risk applies. Vasopressin is a peptide drug regulated through the drug approval framework rather than the FDA’s 351(k) biosimilar pathway used for biological products. A competing manufacturer would generally pursue an ANDA for a pharmaceutically equivalent injectable product, subject to FDA requirements for active ingredient, dosage form, strength, route and labeling.[5]

The competitive threat is therefore generic substitution rather than biosimilar interchangeability.

How does US 9,687,526 compare with broader formulation patents?

US 9,687,526 is narrower than a patent claiming:

Any stable aqueous vasopressin formulation.
Any vasopressin formulation containing an acid.
Any intravenous vasopressin composition.
Any method of treating shock with vasopressin.
Any vasopressin product stored under refrigeration.

Its strength is the combination of limitations. The patentee can argue that the formulation, pH, refrigeration period, degradation threshold and clinical dosing regimen operate as an integrated product-use system.

Its weakness is cumulative limitation. A challenger can attack the claim by showing that one required element is absent or cannot be reliably proven. Potential defenses include:

Lack of written description for the full numerical scope.
Lack of enablement across the claimed concentration and stability ranges.
Obviousness based on known vasopressin formulations, acidic stabilizers and refrigerated storage.
Indefiniteness concerning “about,” “less than about,” degradation measurement or sequence-defined impurities.
Noninfringement based on pH, concentration, storage or labeling differences.

What is the likely patent strength?

Factor	Assessment
Claim breadth	Moderate to narrow
Commercial relevance	High for Vasostrict-type products
Formulation overlap risk	High if the generic copies the commercial formulation
Method-of-use overlap	High for septic or vasodilatory shock labels
Proof of actual storage	Potentially difficult
Design-around potential	Moderate
Biosimilar barrier	Not applicable
ANDA litigation exposure	Material
Manufacturing barrier	Moderate to high for sterile peptide injection

The patent is strongest against a generic that closely replicates the Vasostrict formulation, refrigerated storage conditions and labeled vasopressin dosing regimen. It is weaker against a product with a materially different formulation or a carefully carved label that avoids the claimed treatment methods.

What patent litigation affects Vasostrict generic entry?

The relevant litigation questions are:

Whether the ANDA applicant made a Paragraph IV certification.
Whether Endo or the NDA holder filed an infringement complaint within 45 days.
Whether a 30-month stay was triggered.
Whether the parties entered a launch settlement.
Whether the settlement permitted an authorized or licensed generic.
Whether the court construed the pH, degradation and storage limitations narrowly.
Whether later continuation patents remain in force after US 9,687,526 expires.

A complete entry forecast should treat US 9,687,526 as one element of the Vasostrict estate. Continuation patents, later Orange Book listings and settlement licenses can materially change the effective launch date.

Key Takeaways

US 9,687,526 is a method patent, not a broad vasopressin composition patent.
Claim 1 requires a specific acidic aqueous formulation, pH 3.8, refrigeration at 2-8°C, four-week stability and intravenous treatment of hypotension.
Claims 5-11 extend protection into vasodilatory shock, septic shock, post-cardiotomy shock, response time and dosing duration.
Claims 16-19 cover dilution into saline or 5% dextrose at specified final concentrations.
Claim 20 adds chlorobutanol, which may be important for commercial-product similarity.
The nominal patent-term endpoint is in February 2035, subject to any applicable term adjustment.
Generic risk is highest for a product that copies the Vasostrict formulation and label.
Vasopressin faces generic, not conventional biosimilar, competition.
The patent’s cumulative limitations create both enforcement value and design-around opportunities.

FAQs

Can a generic vasopressin product avoid US 9,687,526 by changing its pH?

Potentially. A formulation outside the properly construed pH range may avoid literal infringement, but the effect depends on the patent specification, prosecution history and any doctrine-of-equivalents analysis.

Does refrigerated storage alone infringe US 9,687,526?

No. The claims require a combination of formulation, storage, stability and administration limitations. Refrigeration alone is insufficient.

Is vasopressin covered by a biosimilar exclusivity period?

No. Vasopressin competition generally proceeds through the ANDA generic-drug pathway rather than the 351(k) biosimilar pathway.

Can a hospital infringe the patent by administering vasopressin?

Potentially, if the hospital performs every limitation of an asserted method claim. Commercial enforcement would more commonly focus on a manufacturer’s label, instructions, inducement and product design.

Does a Paragraph IV certification automatically permit generic launch?

No. The applicant may still face patent litigation, a statutory approval stay, a settlement restriction or other listed patents that delay launch.

References

United States Patent and Trademark Office. (2017). US Patent No. 9,687,526, vasopressin compositions and methods of use thereof. https://patents.google.com/patent/US9687526B2/en
U.S. Food and Drug Administration. (n.d.). Vasostrict (vasopressin injection), NDA 204485: Prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book-data-files
U.S. Food and Drug Administration. (n.d.). Patent certifications and the 30-month stay under the Hatch-Waxman Act. https://www.fda.gov/drugs/guidance-compliance-regulatory-information
U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application submissions and generic drug approval requirements. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/generic-drug-user-fee-amendments-gdufa-grants-and-approval-process

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Ph Health	VASOSTRICT	vasopressin	SOLUTION;INTRAVENOUS	204485-001	Apr 17, 2014	AP	RX	Yes	Yes	9,687,526	⤷ Start Trial				TO INCREASE BLOOD PRESSURE IN ADULTS WITH VASODILATORY SHOCK (E.G., POST-CARDIOTOMY OR SEPSIS) WHO REMAIN HYPOTENSIVE DESPITE FLUIDS AND CATECHOLAMINES	⤷ Start Trial
Ph Health	VASOSTRICT	vasopressin	SOLUTION;INTRAVENOUS	204485-002	Dec 17, 2016	AP	RX	Yes	Yes	9,687,526	⤷ Start Trial				TO INCREASE BLOOD PRESSURE IN ADULTS WITH VASODILATORY SHOCK (E.G., POST-CARDIOTOMY OR SEPSIS) WHO REMAIN HYPOTENSIVE DESPITE FLUIDS AND CATECHOLAMINES	⤷ 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

Details for Patent: 9,687,526

Which drugs does patent 9,687,526 protect, and when does it expire?

Summary for Patent: 9,687,526