US Patent 9,968,649: Vasopressin Formulation Claims, Patent Scope, and Generic Entry Risk

US Patent 9,968,649 protects a narrow but commercially relevant method of administering vasopressin to hypotensive human patients. The patent does not broadly claim vasopressin, vasopressin injection, or every vasopressin formulation. Its principal limitation is a specific combination of concentration, acidic pH, acetate buffer, dextrose, defined peptide impurities, minimum storage time, intravenous administration rate, and treatment of hypotension.

The strongest infringement risk is for a ready-to-use vasopressin product that matches the claimed impurity profile and is administered intravenously for vasodilatory shock. The principal invalidity and noninfringement issues are claim construction, inherent presence of the specified impurities, enablement of the sequence-homology limitations, and whether a generic product’s labeling induces the claimed method.

What patent is US 9,968,649 and what does it protect?

US 9,968,649 is directed to vasopressin formulations and methods of using those formulations to increase blood pressure in hypotensive humans. The patent issued May 15, 2018. Based on the patent’s priority and filing structure, its nominal expiration is expected to fall in 2035, subject to patent-term adjustment, terminal disclaimers, and any applicable regulatory exclusivity. The patent record and USPTO Patent Center should control the operative expiration date. (U.S. Patent No. 9,968,649, 2018; 35 U.S.C. § 154.)

Claim 1 is the only independent claim. It is a method claim requiring the accused party or an actor subject to liability to satisfy every material limitation.

Claim element	Scope of requirement
Patient	Human who is hypotensive
Therapeutic objective	Increasing blood pressure
Dosage form	Unit dosage form
Active ingredient	Vasopressin or pharmaceutically acceptable salt
Concentration	About 0.1 to about 1 unit/mL
pH	3.6 to 3.9
Excipients	Dextrose and approximately 1 to 10 mM acetate buffer
Impurities	0.9% to 1.7% total, with 85% to 100% sequence homology to SEQ ID NO. 1
Storage	At least approximately 24 hours at the stated vasopressin concentration
Administration	Intravenous
Dose rate	Approximately 0.01 to 0.1 units/minute
Clinical condition	Hypotension

The claim is therefore a combined formulation, stability, analytical, storage, and treatment claim. A product that meets only the formulation limitations but is never administered to a hypotensive human would not, by itself, practice the full method of claim 1.

How broad is claim 1 of US 9,968,649?

Claim 1 is technically detailed but commercially narrow. It requires the simultaneous presence of multiple variables that can be designed around independently.

The concentration range is broad enough to encompass common dilute vasopressin infusion presentations. The pH range is narrow. A formulation at pH 3.5 or 4.0 would fall outside the literal pH range unless a court applies an equivalent range. The acetate requirement also creates a design-around opportunity because the claim requires approximately 1 to 10 mM acetate buffer.

The claim requires dextrose, but does not specify a concentration. A formulation using saline, water for injection, or another carbohydrate without dextrose may avoid literal infringement if dextrose is not present. The use of a different buffer, such as citrate or phosphate, may also avoid literal infringement, although the doctrine of equivalents could become relevant if the substituted buffer performs substantially the same function in substantially the same way.

The impurity limitation is the most unusual element. Claim 1 requires impurities present in an amount of 0.9% to 1.7%, with the impurities having approximately 85% to 100% sequence homology to SEQ ID NO. 1. The claim does not require a single named impurity. It appears to cover a population of vasopressin-related peptide impurities falling within the stated homology and aggregate amount.

That wording creates several construction questions:

Whether the 0.9% to 1.7% range applies to all qualifying impurities collectively.
Whether every impurity in the measured population must have 85% to 100% homology.
Whether “about” expands the numerical ranges.
Whether the impurity amount is measured by the HPLC method in claim 11 or by another validated method.
Whether sequence homology applies to full-length peptides, fragments, or aligned regions.
Whether the impurity profile must be intentionally manufactured or may be inherently present.

These questions could materially affect infringement and validity analysis.

What do dependent claims 2 through 8 add?

Claims 2 through 8 define specific impurity profiles. They narrow claim 1 by requiring named sequences and concentration ranges.

Claim	Added impurity limitation
2	SEQ ID NO. 2 at 0.1% to 0.3%
3	SEQ ID NO. 3 at 0.1%
4	SEQ ID NO. 4 at 0.2% to 0.4%
5	SEQ ID NO. 7 at 0.3% to 0.6%
6	SEQ ID NO. 10 at 0.1%
7	SEQ ID NO. 2 and SEQ ID NO. 4 at their specified ranges
8	SEQ ID NO. 2, 3, 4, 7, and 10 at the specified concentrations

Claims 7 and 8 are especially important for product comparison. A generic applicant would need to determine whether its vasopressin active pharmaceutical ingredient or finished dosage form contains the specified sequences at the claimed levels.

The dependent claims may be stronger against a product using the same source material, purification process, or manufacturing controls as the reference product. They may be weaker against a product manufactured through a different synthetic, recombinant, purification, or impurity-removal process.

A key issue is whether the listed impurities are unavoidable characteristics of a particular vasopressin manufacturing process or merely optional formulation attributes. If they are process-linked and consistently present in the reference product, a generic applicant may need extensive peptide impurity characterization before finalizing its formulation.

What does claim 11 protect?

Claim 11 adds a prescribed HPLC testing protocol for determining the impurity population. The method requires:

A chromatography column containing adsorbent particles.
A first mobile phase consisting of phosphate buffer at pH 3.
A second mobile phase consisting of 50:50 acetonitrile and water.
A 55-minute run.
A flow rate of 1 mL/min for each mobile phase.
Gradient elution.
UV detection.
Identification by retention time relative to a standard.
Quantification by integration of the relevant peak.

Claim 11 is not a standalone analytical claim. It remains dependent on claim 1 and therefore retains all of claim 1’s treatment, formulation, storage, and administration requirements.

Its practical value is evidentiary. It provides a defined way to identify and quantify the peptides. It may reduce disputes over how the impurity amount is measured, but it also creates a potential noninfringement argument if an accused product is tested through a materially different validated analytical method and does not produce the claimed profile under the specified protocol.

A generic applicant should not assume that using a different HPLC column or detection method eliminates infringement. The legal question would be whether claim 11 requires strict use of the recited analytical method and whether claims 1 through 10 independently cover the same impurity profile without the claim 11 testing limitations.

What do claims 9 through 17 protect?

Claims 9 and 10 target the clinical-use setting.

Claim 9 limits the patient’s hypotension to hypotension associated with vasodilatory shock. This is commercially significant because vasopressin is used as a vasopressor in vasodilatory shock, including septic shock and post-cardiotomy vasoplegia.

Claim 10 narrows the administration rate to approximately 0.01 to 0.07 units/minute. That range is narrower than claim 1’s upper limit of 0.1 units/minute and may correspond more closely to standard clinical dosing instructions.

Claims 12 through 17 address formulation and pH:

Claim 12 adds a pH-adjusting agent.
Claims 13 and 14 separately address whether a pharmaceutically acceptable vasopressin salt is present.
Claim 15 narrows pH to 3.74 to 3.75.
Claim 16 covers approximately 1 mM acetate buffer with pH 3.7 to 3.9.
Claim 17 covers approximately 10 mM acetate buffer with pH 3.6 to 3.7.

Claims 16 and 17 divide the buffer and pH space into commercially relevant subranges. A formulation at approximately 1 mM acetate and pH 3.74 to 3.75 could potentially fall within both claims 15 and 16, provided the other limitations are met.

Claims 13 and 14 are structurally unusual because they present mutually exclusive alternatives. Claim 13 requires the salt to be present, while claim 14 requires that it not be present. Their significance will depend on how the specification defines “vasopressin,” “vasopressin salt,” and the actual chemical form in the finished product.

What formulation characteristics create the highest infringement risk?

The highest-risk product profile is a ready-to-administer intravenous vasopressin solution with the following characteristics:

Vasopressin concentration between 0.1 and 1 unit/mL.
Dextrose as a formulation component.
Approximately 1 to 10 mM acetate.
pH between 3.6 and 3.9.
Storage for at least 24 hours before administration.
Aggregate related-peptide impurities between 0.9% and 1.7%.
Identifiable SEQ ID NO. 2, 3, 4, 7, or 10 at the claimed levels.
Labeling for hypotension associated with vasodilatory shock.
Intravenous administration at 0.01 to 0.1 units/minute.

A conventional concentrated vasopressin vial that is diluted immediately before use may present a different risk profile from a premixed or pharmacy-compounded unit dosage form. The storage limitation is particularly important. If the product is not stored for at least approximately 24 hours at the claimed concentration before administration, literal infringement of claim 1 may be difficult to establish.

The storage limitation may also create proof problems. A plaintiff would need evidence concerning the product’s preparation, concentration during storage, storage duration, and administration history. A package label, hospital protocol, or standard pharmacy practice could be relevant to induced-infringement allegations, but method claims generally require proof tied to the claimed acts.

How strong is the patent estate for US 9,968,649?

The patent is strongest as a targeted product-use patent and weaker as a broad platform patent.

Strength factor	Assessment
Clinical relevance	High for vasopressin use in vasodilatory shock
Formulation specificity	High
Design-around flexibility	Moderate to high
Impurity limitations	Potentially strong if inherent and reproducible
Storage limitation	Creates both scope and proof constraints
Method-of-use coverage	Strong where labeling matches the claimed indication and dose
Manufacturing protection	Limited in the asserted claims
Biosimilar relevance	Low; vasopressin is a peptide drug rather than a conventional biologic for ordinary biosimilar analysis
Generic challenge exposure	Material if an ANDA product has matching labeling or formulation attributes

The patent does not appear, from the supplied claims, to protect the manufacturing process for producing vasopressin or the active ingredient itself. It also does not broadly claim every impurity-free vasopressin formulation. Its value depends on whether the claimed impurity pattern is a predictable consequence of the commercial product’s formulation and manufacturing process.

What Orange Book and FDA issues apply?

Vasopressin is regulated as a drug product, and an approved vasopressin injection may have patents listed in the FDA Orange Book if the listing requirements are met. The relevant FDA questions are:

Whether US 9,968,649 is listed for the applicable vasopressin reference product.
Whether the listing is for a drug substance, drug product, or method of use.
Whether the patent is identified as covering an approved method of use.
Whether the reference product’s labeling carries the claimed vasodilatory-shock indication and dosing information.
Whether the patent is still active and listed for the relevant strength and dosage form.

The patent’s method claims create an Orange Book and Paragraph IV strategy that may differ from a pure formulation patent. A generic applicant could certify that the patent is invalid, unenforceable, or will not be infringed. If the patent is listed and the reference-product sponsor files suit within the statutory period, a 30-month stay may apply under the Hatch-Waxman framework, subject to statutory exceptions and court action. (FDA, 2024; 21 U.S.C. § 355(j).)

FDA approval of a generic vasopressin product would not itself resolve infringement. Approval, labeling, formulation, and actual use are separate issues. A product may obtain approval but still face litigation based on induced infringement if its labeling encourages the claimed method.

Which companies are most likely to challenge the patent?

The principal challengers would be manufacturers developing abbreviated new drug applications for vasopressin injection. Potentially exposed companies include generic injectable manufacturers, hospital-product suppliers, and firms acquiring or licensing vasopressin ANDAs.

The most likely challenge theories are:

Anticipation by an earlier vasopressin formulation or product label.
Obviousness based on known vasopressin concentration, dextrose, acetate buffering, acidic pH, and storage practices.
Lack of enablement for the full sequence-homology and impurity ranges.
Indefiniteness of “about,” “sequence homology,” “impurities,” and the aggregate impurity amount.
Noninfringement based on different buffer, pH, concentration, impurity content, storage period, or label.
Lack of induced infringement where the generic label omits or carves out the patented use.

The impurity claims could be attacked through prior-art analytical data, batch records, pharmacopeial specifications, and earlier vasopressin stability studies. The patent holder would likely rely on product testing, comparative HPLC results, manufacturing records, and labeling language.

What Paragraph IV and generic launch scenarios exist?

Scenario	Likely consequence
No Paragraph IV challenge	Generic launch waits for patent and exclusivity barriers to expire
Paragraph IV with no timely litigation	Approval may proceed after statutory certification processing
Paragraph IV followed by litigation	Potential 30-month approval stay
Label carve-out for vasodilatory shock	May reduce induced-infringement exposure if legally effective
Reformulated product outside pH or acetate ranges	May avoid literal formulation infringement
Different impurity profile	May avoid claims 2-8, but claim 1 remains relevant
No 24-hour storage at claimed concentration	Potential defense to claim 1
Matching reference formulation and label	Highest launch risk

A successful design-around would normally target multiple limitations rather than one. Changing only the pH may not be sufficient if the doctrine of equivalents is asserted. A stronger design-around could combine a different buffer system, a different diluent, a different concentration, a different storage configuration, and a label that omits the patented method where legally permissible.

What litigation and settlement issues matter?

The supplied claim text does not establish a current infringement action, final judgment, or settlement involving US 9,968,649. Patent litigation status must be determined from PACER, district-court dockets, PTAB records, and FDA submissions. The patent number alone does not establish whether a Paragraph IV notice has been served or whether a settlement restricts generic launch.

If litigation exists, the commercially important documents are:

Paragraph IV notice letters.
Complaints and counterclaims.
Claim-construction orders.
ANDA product specifications.
Protective-order expert reports.
Settlement and license agreements.
Authorized-generic provisions.
Agreed launch dates.
Any FTC or DOJ review of settlement terms.

A settlement could permit an earlier launch without invalidating the patent. A license could also limit commercialization by dosage form, indication, customer type, or geographic market.

How does this patent compare with biosimilar and generic risks?

The principal competitive threat is generic, not biosimilar. Vasopressin is a chemically defined peptide drug and is generally addressed through the ANDA pathway rather than the abbreviated biosimilar pathway under the Public Health Service Act.

The patent risk is therefore concentrated in:

Formulation matching.
Related-peptide impurity control.
Labeling for vasodilatory shock.
Premixed or ready-to-use dosage forms.
Intravenous dosing instructions.
Storage and pharmacy preparation practices.

A competing vasopressin product with a materially different formulation may have a lower risk profile even if it uses the same active ingredient.

Key Takeaways

US 9,968,649 is a narrow method-of-use patent with extensive formulation and impurity limitations.
Claim 1 requires a hypotensive human, intravenous administration, specific vasopressin concentration, acidic pH, dextrose, acetate buffer, defined impurities, and at least 24 hours of storage.
Claims 2 through 8 create additional risk for products containing specified vasopressin-related peptide impurities.
Claim 11 defines an HPLC method but remains dependent on the full treatment method of claim 1.
Claims 9 and 10 focus on vasodilatory shock and a narrower dosing rate.
The strongest generic design-around opportunities involve buffer selection, pH, dextrose substitution, impurity removal, dosage concentration, and storage configuration.
The most important legal vulnerabilities are indefiniteness, enablement, obviousness, and proof of the storage and administration limitations.
Generic rather than biosimilar competition is the relevant commercial threat.
Orange Book listing, Paragraph IV activity, litigation, settlements, and actual expiration require confirmation from current FDA, USPTO, court, and PTAB records.

FAQs About US Patent 9,968,649

Does US 9,968,649 cover all vasopressin injections?

No. The claims require a particular formulation and administration profile, including pH, dextrose, acetate buffer, impurity content, storage, intravenous administration, and treatment of hypotension.

Can a generic use the same vasopressin active ingredient and avoid the patent?

Possibly. The active ingredient alone is not enough to practice claim 1. The generic would need to assess its formulation, impurity profile, storage conditions, labeling, and intended administration.

Does claim 11 create a separate patent on the HPLC assay?

No. Claim 11 depends on claim 1. It does not independently claim an HPLC assay divorced from the vasopressin treatment method.

Can changing acetate buffer avoid infringement?

It may avoid literal infringement of the claims requiring acetate, but the complete analysis would include the remaining limitations and any doctrine-of-equivalents argument.

Is vasopressin subject to biosimilar competition?

The principal abbreviated pathway for vasopressin competition is generally the ANDA pathway for generic drugs, not the biosimilar pathway used for biological products under the Public Health Service Act.

References

U.S. Patent No. 9,968,649. (2018). Vasopressin formulations and methods of use thereof. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.
U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. FDA.
21 U.S.C. § 355. Abbreviated applications for new drugs.
35 U.S.C. § 154. Contents and term of patent; provisional rights.
35 U.S.C. §§ 271(e)(2), 271(e)(4). Infringement and remedies relating to abbreviated new drug applications.

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	204485-005	Apr 21, 2021	AP	RX	Yes	Yes	9,968,649	⤷ 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	204485-003	Apr 15, 2020	AP	RX	Yes	Yes	9,968,649	⤷ 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	204485-006	Apr 12, 2023		DISCN	Yes	No	9,968,649	⤷ 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	204485-004	Apr 15, 2020		DISCN	Yes	No	9,968,649	⤷ 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: 9,968,649

Which drugs does patent 9,968,649 protect, and when does it expire?

Summary for Patent: 9,968,649