United States Patent 10,537,554: Scope, Claims, Expiration, and Sumatriptan Patent Landscape

US Patent 10,537,554 protects a narrow method of treating acute migraine with a specific low-dose sumatriptan presentation: 4.2 mg sumatriptan succinate in 0.5 mL, combined with 4.2 mg sodium chloride, delivered subcutaneously through a fully assembled single-use auto-injector. The patent also covers defined pH and osmolality parameters, pharmacokinetic exposure ranges, and reduced injection-site pain relative to higher-concentration or higher-dose comparators.

The patent is materially narrower than a general patent on sumatriptan, injectable migraine treatment, or auto-injectors. An accused product would generally need to practice the claimed combination, including the dose, volume, formulation parameters, device configuration, and acute-migraine indication.

What does US Patent 10,537,554 protect?

The patent protects a treatment method using a defined combination of:

Claim element	Requirement
Indication	Acute migraine
Administration route	Subcutaneous
Device	Single-use, ready-to-use, disposable auto-injector
Drug	Sumatriptan succinate
Drug amount	4.2 mg in the claimed composition
Volume	0.5 mL
Excipient	4.2 mg sodium chloride
Container	Pre-filled syringe fully assembled into the auto-injector
Osmolality	275 to 315 mOsm/kg
pH	About 4.2 to 5.3
Exclusions	Prophylaxis and cluster-headache treatment

The claim architecture is cumulative. Claim 1 requires every listed limitation. A product that uses the same drug and dose but a different volume, delivery device, indication, or formulation parameter may fall outside the literal scope of claim 1.

The patent is directed to a low-volume, lower-dose subcutaneous sumatriptan product associated with Zembrace SymTouch-type commercial presentations. FDA labeling for Zembrace SymTouch identifies a 3 mg sumatriptan dose in a 0.5 mL single-dose auto-injector. The claimed 4.2 mg of sumatriptan succinate corresponds approximately to 3 mg of sumatriptan active moiety because the succinate salt includes the counterion component.[1]

How should claim 1 of US 10,537,554 be construed?

Claim 1 is an apparatus-dependent method claim rather than a broad pharmaceutical composition claim. Its enforceability depends on whether the accused activity includes administration using the specified presentation.

The “4.2 mg” limitation

The claim identifies 4.2 mg of sumatriptan succinate. This is distinct from a claim expressed as 4.2 mg of sumatriptan base. Product labels and regulatory submissions often state the dose by active moiety, while patent claims may identify the salt mass. The salt-versus-active-moiety distinction is central to infringement analysis.

A product labeled as 3 mg sumatriptan may contain approximately 4.2 mg sumatriptan succinate. That product can therefore satisfy the claimed drug quantity if the formulation and device limitations are also met.

The 0.5 mL volume limitation

The claim requires the composition to be contained in a 0.5 mL pre-filled syringe. A 0.25 mL presentation is outside the literal volume limitation, even if it contains the same amount of sumatriptan succinate.

The volume limitation also differentiates the claimed product from conventional 6 mg/0.5 mL sumatriptan injections. A conventional product can share the same container volume while failing the drug-amount and formulation limitations.

The auto-injector limitation

The composition must be delivered by a single-use, ready-to-use, disposable auto-injector, with the pre-filled syringe fully assembled into that device.

This limitation is commercially important. A vial, ampule, manually operated syringe, or pre-filled syringe sold without the required assembled auto-injector may not satisfy claim 1. The claim is therefore directed to a specific drug-device combination, not merely to the formulation.

The phrase “fully assembled into the auto-injector” limits the claim further by tying the pre-filled syringe to the marketed delivery system. A kit in which the patient separately inserts a syringe could present a noninfringement position, depending on the product configuration and claim construction.

The pH and osmolality limitations

Claim 1 requires:

pH of about 4.2 to 5.3; and
osmolality of 275 to 315 mOsm/kg.

These limitations create potential design-around paths, but they also create factual disputes. Lot-release specifications, regulatory filings, batch records, and testing methods would likely be relevant in an infringement investigation.

The term “about” creates tolerance questions. Courts generally interpret “about” in view of the patent specification, prosecution history, measurement precision, and technical context. The numerical boundaries should not be treated as automatically open-ended.

The indication limitation

The method must treat acute migraine. The claim expressly excludes prophylactic treatment and cluster-headache treatment.

This indication limitation narrows direct method-of-use infringement. Treatment of cluster headache using the same formulation would not literally satisfy the stated indication. The patent also does not claim every use of the composition, such as non-migraine pain or other serotonin-mediated disorders.

What do claims 2 through 5 add?

Claims 2 through 5 are dependent claims that add pharmacokinetic or comparative clinical limitations.

Claim 2: systemic exposure

Claim 2 requires at least one of the following plasma exposure profiles after administration:

Pharmacokinetic parameter	Claimed range
Cmax	About 35 to 57 ng/mL
AUC0-2	About 30 to 50 ng·hr/mL
AUC0-inf	About 43 to 70 ng·hr/mL

The use of “at least one” makes claim 2 alternative-based. An accused product need not meet all three ranges. It may infringe if one specified pharmacokinetic profile is present, assuming claim 1 is also satisfied.

PK infringement is difficult to assess from the label alone. It may require comparative clinical data, bioequivalence studies, population pharmacokinetic modeling, or testing of the accused formulation. Variability among patients can affect whether a range describes an individual result, a mean, a geometric mean, or another statistical measure. The specification and prosecution history are important to resolving that issue.

Claim 3: reduced pain versus 4.2 mg in 0.25 mL

Claim 3 requires reduced injection-site pain compared with a 4.2 mg sumatriptan succinate composition in 0.25 mL.

This limitation links the claimed 0.5 mL formulation to a higher-concentration 0.25 mL comparator. It suggests that dilution and osmolality management were central to the claimed product differentiation.

Claim 4: reduced pain versus 5.6 mg in 0.5 mL

Claim 4 compares the claimed composition with 5.6 mg of sumatriptan succinate in 0.5 mL. The comparator represents a higher drug concentration in the same volume.

Claim 5: reduced pain versus 8.4 mg in 0.5 mL

Claim 5 compares the claimed product with 8.4 mg of sumatriptan succinate in 0.5 mL. This comparator represents approximately twice the claimed 4.2 mg salt amount.

Claims 3 through 5 may provide narrower fallback protection, but they also introduce proof burdens. A patent owner would need to establish the claimed reduction in injection-site pain against the relevant comparator. The result may depend on the clinical endpoint, study population, injection technique, statistical test, and definition of pain reduction.

What patents are associated with the Zembrace SymTouch sumatriptan estate?

Public FDA and patent records identify a group of patents associated with the low-dose sumatriptan auto-injector product. The relevant estate includes US Patent Nos. 9,050,302, 9,566,197, 10,105,350, and 10,537,554, subject to the particular Orange Book listing and product relationship recorded for each patent.[2][3]

Patent	General estate role	Reported expiration timing*
US 9,050,302	Low-dose sumatriptan treatment and product-related protection	December 18, 2032
US 9,566,197	Related formulation, delivery, or treatment protection	December 18, 2032
US 10,105,350	Later family protection relating to the product presentation	July 31, 2034
US 10,537,554	Specific 4.2 mg/0.5 mL auto-injector treatment method	July 31, 2034

*Expiration dates reflect the reported patent-term framework and should be read with any applicable patent-term adjustment, terminal disclaimer, pediatric extension, or regulatory exclusivity record.

The estate is stronger as a product-specific barrier than as a broad sumatriptan barrier. It combines method-of-use claims with formulation, dose, volume, device, and performance limitations. A competitor may avoid one patent while still encountering other claims in the family.

When does US Patent 10,537,554 lose exclusivity?

The reported patent expiration date for US 10,537,554 is July 31, 2034, before any applicable patent-term adjustment or other statutory extension.[2] FDA marketing exclusivity is separate from patent protection.

Zembrace SymTouch was approved by FDA in January 2016 under NDA 208082.[1] The product’s regulatory exclusivity period is distinct from the later expiration of the patent estate. A generic applicant may pursue an ANDA before patent expiry, subject to certification and litigation rules.

Patent expiry does not automatically authorize every competing presentation. A competitor would still need FDA approval and must avoid any unexpired patent claims covering its formulation, device, manufacturing process, or method of use.

What is the Orange Book status of US Patent 10,537,554?

The Orange Book is the relevant FDA source for patents submitted by an NDA holder and listed against an approved drug product. The listing status, patent-use code, expiration date, and product association should be evaluated in the current Orange Book edition and FDA patent-listing database.[3]

For this product category, the listed estate has potential significance in an ANDA proceeding because the applicant may need to address:

drug substance or formulation patents;
delivery-device patents;
method-of-use patents; and
patents covering the approved low-dose auto-injector presentation.

A method-of-use patent can be addressed through a Paragraph IV certification, a section viii statement with a “skinny label,” or another statutory pathway, depending on the Orange Book use code and the proposed labeling.

How would a Paragraph IV challenge affect this patent?

A generic applicant making a 4.2 mg sumatriptan succinate/0.5 mL auto-injector could submit a Paragraph IV certification alleging that the listed patent is invalid, unenforceable, or not infringed.[4]

A Paragraph IV notice typically gives the NDA holder or patent owner 45 days to file an infringement action. A timely suit can trigger a 30-month stay of FDA approval, subject to statutory exceptions and court developments.[4]

For US 10,537,554, likely challenge theories include:

Challenge theory	Potential focus
Anticipation	Earlier low-dose sumatriptan, 0.5 mL, pH, osmolality, or auto-injector disclosure
Obviousness	Combination of known sumatriptan injection, dose reduction, dilution, and auto-injector technology
Indefiniteness	Meaning of “about,” reduced pain, or PK ranges
Written description	Support for the full claimed numerical and clinical scope
Enablement	Ability to make and use the full range without undue experimentation
Noninfringement	Different volume, device assembly, pH, osmolality, dose, or indication
Regulatory carve-out	Omission of patented migraine use from generic labeling

The strongest noninfringement position would likely involve a product that does not use the claimed assembled auto-injector or does not contain the claimed 4.2 mg salt amount in 0.5 mL. The strongest validity attack would focus on whether earlier references disclosed the complete combination rather than isolated elements.

Which companies compete with or challenge the sumatriptan auto-injector estate?

The principal competitive products include:

Product or category	Company or source	Relevance
Zembrace SymTouch	Zydus or successor commercial interests associated with the NDA history	Low-dose 3 mg sumatriptan auto-injector
Imitrex injection	GlaxoSmithKline originator product	Conventional 6 mg/0.5 mL subcutaneous sumatriptan
Generic sumatriptan injection	Multiple ANDA applicants	Competes primarily through conventional syringe or cartridge presentations
Sumavel DosePro	Formerly Zogenix	Needle-free sumatriptan delivery system; separate device and patent issues
Oral, nasal, and transdermal triptans	Multiple manufacturers	Therapeutic substitutes, but generally outside the claimed subcutaneous method

Publicly available information does not establish a current, specific Paragraph IV litigation outcome for US 10,537,554. The patent should therefore be treated as an active patent-estate issue through its reported 2034 expiration date, subject to the current FDA listing and court docket.

How strong is the patent estate for the low-dose sumatriptan auto-injector?

The estate has moderate-to-strong commercial value for the precise product configuration, but limited breadth outside that configuration.

Strengths

It covers a commercially identifiable 3 mg sumatriptan presentation expressed as 4.2 mg succinate.
It ties the formulation to a ready-to-use auto-injector.
It includes pH and osmolality constraints that may be present in regulatory specifications.
It includes PK and injection-site-pain limitations that can support product differentiation.
Related patents may create overlapping barriers even if one patent is invalidated.

Weaknesses

Claim 1 contains numerous cumulative limitations.
The method claims require an acute-migraine use.
A competitor may redesign the dose, volume, device, or formulation.
Claims 2 through 5 depend on clinical or PK evidence that may be difficult to establish.
Conventional 6 mg sumatriptan injections and non-subcutaneous triptan products are generally outside the core claim combination.

The estate is therefore best characterized as a product-specific barrier rather than a platform patent blocking all injectable sumatriptan competition.

What generic launch scenarios exist?

Scenario 1: Conventional 6 mg injection

A generic 6 mg/0.5 mL sumatriptan injection may avoid claim 1 because it does not contain 4.2 mg sumatriptan succinate. It could still face other listed patents or device-related claims.

Scenario 2: Low-dose product in a manual syringe

A 3 mg sumatriptan product in a manually operated pre-filled syringe may avoid the auto-injector limitation. The sponsor would need to assess other patents covering the formulation or dose.

Scenario 3: Low-dose auto-injector with different volume

A product using 3 mg sumatriptan in a volume materially different from 0.5 mL may present a noninfringement position. The strength of that position would depend on construction of the numerical limitations and the doctrine of equivalents.

Scenario 4: Same product with a carved-out label

If the patent is listed with a method-of-use code that can be omitted from the generic label, an ANDA applicant may pursue a section viii statement. That path depends on the approved indication language and the exact Orange Book use code.

Scenario 5: Post-expiration launch

A product matching the claimed presentation could launch after patent expiry, assuming FDA approval and no other unexpired blocking patent. The reported target date for US 10,537,554 is July 31, 2034.

What manufacturing and IP barriers remain?

Manufacturing barriers include:

maintaining pH within the claimed range;
controlling osmolality across commercial batches;
producing a stable 0.5 mL pre-filled syringe;
integrating the syringe into a reliable disposable auto-injector;
demonstrating device activation and dose delivery;
generating PK and tolerability data;
qualifying container-closure and extractables/leachables performance.

The manufacturing process itself may be protected by separate patents or trade secrets even when the final product claim is avoided. Device suppliers may also hold patents covering spring mechanisms, needle shields, activation systems, cartridge loading, or dose-delivery controls.

Key Takeaways

US 10,537,554 is a narrow method patent for acute migraine treatment with a specific low-dose sumatriptan auto-injector.
The required combination is 4.2 mg sumatriptan succinate, 4.2 mg sodium chloride, 0.5 mL, pH 4.2 to 5.3, osmolality 275 to 315 mOsm/kg, and a fully assembled disposable auto-injector.
Claim 2 adds alternative PK exposure requirements.
Claims 3 through 5 add reduced injection-site-pain comparisons.
The reported expiration date is July 31, 2034, before any applicable patent-term adjustment or extension.
The related estate includes US Patent Nos. 9,050,302, 9,566,197, and 10,105,350.
The patent does not broadly block all sumatriptan injections, oral products, nasal products, or migraine treatments.
The primary generic strategies are dose or volume redesign, use of a manual syringe, device redesign, a section viii label carve-out, or a Paragraph IV validity and noninfringement challenge.
The commercial risk is highest for a generic seeking to copy the low-dose 0.5 mL ready-to-use auto-injector presentation.

FAQs

Does US 10,537,554 cover 6 mg sumatriptan injection?

Generally, no. Claim 1 requires 4.2 mg of sumatriptan succinate in 0.5 mL. A 6 mg sumatriptan presentation may fall outside that limitation, although other patents could apply.

Does the patent cover a 3 mg sumatriptan dose?

Potentially. A 3 mg sumatriptan active-moiety dose may correspond to approximately 4.2 mg sumatriptan succinate and could satisfy the dose limitation if the remaining formulation and device requirements are met.

Can a generic use a pre-filled syringe without an auto-injector?

A manually operated pre-filled syringe may avoid the specific auto-injector limitation in claim 1. The generic would still require a separate analysis of other patents, FDA labeling, and formulation claims.

Are claims 3 through 5 composition claims?

No. They are dependent method claims requiring reduced injection-site pain compared with specified comparator compositions. They do not independently claim a composition without the treatment-method limitations of claim 1.

Does patent expiration eliminate FDA regulatory barriers?

No. Patent expiration removes the patent barrier only for that patent. FDA approval requirements, other listed patents, unlisted patents, device rights, manufacturing rights, and regulatory exclusivity may continue to affect launch timing.

References

U.S. Food and Drug Administration. (2016). Zembrace SymTouch (sumatriptan succinate) injection prescribing information.
United States Patent and Trademark Office. (2020). U.S. Patent No. 10,537,554: Patent and Patent Examination Data System records.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book.
U.S. Food and Drug Administration. (2024). Abbreviated new drug application regulations and patent certification requirements, 21 C.F.R. § 314.107.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Tonix Meds	ZEMBRACE SYMTOUCH	sumatriptan succinate	SOLUTION;SUBCUTANEOUS	208223-001	Jan 28, 2016		RX	Yes	No	10,537,554	⤷ Start Trial				TREATMENT OF MIGRAINE	⤷ 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

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
India	4076/CHE/2015	Aug 5, 2015

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Brazil	112018002433	⤷ Start Trial
Canada	2994748	⤷ Start Trial
China	107921023	⤷ Start Trial
European Patent Office	3331524	⤷ Start Trial
Mexico	2018001528	⤷ Start Trial
World Intellectual Property Organization (WIPO)	2017023361	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 10,537,554