US Patent 11,135,215: Buprenorphine Pre-Filled Syringe Claims, Scope and Patent Landscape

US Patent 11,135,215 claims a pre-filled syringe containing a narrowly defined buprenorphine lipid formulation. The core composition contains approximately 5% buprenorphine, 10% ethanol, 42% phosphatidylcholine and 42% glycerol dioleate. The dependent claims add low fill volume, viscosity, needle-gauge, stability, delivery-device, pharmacokinetic and liquid-crystal limitations.

The patent is materially narrower than a general patent on injectable buprenorphine or long-acting buprenorphine. A competing product would need to avoid at least one required element of the applicable independent claim, or establish that the claim is invalid or unenforceable.

What does US Patent 11,135,215 claim?

Claims 1 and 25 are the two independent claims. Both require a pre-filled syringe and a buprenorphine composition with specified excipients.

Claim element	Claim 1	Claim 25
Dosage form	Pre-filled syringe	Pre-filled syringe
Buprenorphine	About 5 wt%	About 5.29 wt%
Ethanol	About 10 wt%	About 10 wt%
Phosphatidylcholine	About 42 wt%	About 42.36 wt%
Glycerol dioleate	About 42 wt%	About 42.36 wt%
Explicit sub-milliliter limitation	No	No
Dependent claim narrowing	Claims 2-24	Claims 26-30

The claim set is directed to a product combination rather than merely to the chemical composition. The accused product must contain the claimed formulation in a pre-filled syringe. A bulk vial, cartridge or non-filled syringe may fall outside the literal wording of the independent claims even if it contains a chemically similar formulation.

The patent claims a formulation in which the phosphatidylcholine and glycerol dioleate together account for approximately 84% by weight. Ethanol is approximately 10% by weight, leaving approximately 5% to 5.29% for buprenorphine and measurement variation.

How broad is the core formulation claim?

Claim 1 is compositionally narrow but uses the modifier “about.” That term generally permits some variation around the stated percentages, but its scope depends on the specification, examples, analytical methods and prosecution history. The claim does not identify:

A particular phosphatidylcholine molecular species;
A particular phosphatidylcholine purity;
A particular glycerol dioleate isomer or commercial grade;
A specific buprenorphine salt or free-base form;
A defined ethanol-water ratio;
A particular syringe manufacturer;
A specific route of administration.

The absence of those limitations gives the claim potential breadth within the specified percentage profile. The claim does not, however, cover every lipid-based buprenorphine formulation.

A formulation containing a substantially different lipid ratio, a different lipid excipient, no ethanol, or a materially different buprenorphine concentration may avoid literal infringement of claim 1. The doctrine of equivalents could still be relevant, but it would be constrained by the prosecution history and by the numerical limitations.

What formulations are protected by US 11,135,215?

The patent protects several formulation characteristics through dependent claims.

Concentration and fill volume

Claims 2-6 and 26-28 narrow the syringe to the following ranges:

Limitation	Claimed range
Syringe fill volume	Less than 5 mL
Further narrowed volume	Less than 2 mL
Further narrowed volume	Less than 1 mL
Buprenorphine amount	About 3 mg to about 40 mg
Narrower amount	About 5 mg to about 30 mg
Specific syringe capacity	About 1 mL

These claims are important for products designed for subcutaneous or other depot administration in a compact, ready-to-use presentation. A product with a larger container could still infringe claim 1 or claim 25 if it contains the claimed composition. The volume limitations apply only to the relevant dependent claims.

Viscosity

Claims 7-8 and 29 require viscosity measured at 20°C using a CarriMed CSL 100 rheometer with automatic gap setting.

Claim	Viscosity
Claims 7 and 29	About 1-1,000 mPa·s
Claim 8	About 100-500 mPa·s

The measurement instrument and temperature are express claim limitations. An infringement analysis should examine the testing protocol, spindle or geometry, shear conditions, sample preparation and the meaning of the reported viscosity value. Testing the same composition under different rheological conditions may produce materially different results.

Delivery-device limitations

Claims 9-17 and 30 cover implementation in a delivery device:

Needle-stick prevention safety device;
Auto-injector;
Disposable syringe;
Needle gauge greater than 18 G;
Needle gauge greater than 20 G;
Needle gauge greater than 22 G;
Needle gauge higher than 23 G;
Needle gauge higher than 25 G;
Approximately 1 mL syringe capacity.

The needle-gauge sequence is unusual. In standard needle nomenclature, a higher gauge number generally means a smaller outside diameter. The phrase “higher than 25 G” should be assessed against the patent specification and prosecution record. It may reflect intended gauge terminology, but the wording could create claim-construction and indefiniteness issues depending on the relevant intrinsic evidence.

Does the patent cover long-acting buprenorphine injection?

It can cover certain long-acting buprenorphine products if they use the claimed formulation and are supplied in the claimed pre-filled syringe presentation.

The patent does not, by its text alone, cover every extended-release buprenorphine product. A product using a different depot technology may avoid the formulation limitations. The principal commercial comparison is between lipid-based liquid-crystalline systems and polymeric depot systems.

Product	Sponsor or manufacturer	Depot technology	Relevance to US 11,135,215
Brixadi	Braeburn Pharmaceuticals; Camurus technology platform	FluidCrystal lipid-based depot	Potentially relevant
Buvidal	Camurus	FluidCrystal lipid-based depot	Potentially relevant, but not a US FDA product as of the cited FDA materials
Sublocade	Indivior	ATRIGEL polymeric depot	Formulation differs materially
Subutex/Suboxone	Various	Sublingual or buccal dosage forms	Not the claimed syringe product

Brixadi is an FDA-approved extended-release buprenorphine injection supplied in prefilled syringes. Its FDA labeling describes weekly and monthly subcutaneous administration and identifies the product as an extended-release formulation.[2] The technology relationship between the product and the claimed lipid formulation is commercially important, but product-specific infringement and Orange Book conclusions require comparison of the approved formulation, syringe presentation and listed patent data.

Sublocade uses a different depot system. Its label describes buprenorphine extended-release injection and the ATRIGEL delivery system, which is based on a biodegradable polymer formulation rather than the phosphatidylcholine-glycerol dioleate composition recited in claims 1 and 25.[3]

What pharmacokinetic limitations are protected?

Claims 20-22 add pharmacokinetic limitations:

A steady-state Cmin-to-Cmax variation between 0.4 and 10 ng/mL;
A narrower variation between 0.5 and 8 ng/mL;
A single-administration Cmax of no more than 0.3 ng/mL per milligram of administered buprenorphine.

These claims attempt to protect the clinical performance of the formulation, not merely its ingredients. They raise several enforcement questions:

Whether the pharmacokinetic result is an inherent property of every product meeting the formulation limitations;
Whether the result must be demonstrated in a particular patient population;
Whether the claim requires a defined dosing interval and steady-state regimen;
Whether the Cmax measurement must use a specified assay;
Whether a product can infringe without the sponsor having measured the claimed parameter.

An accused formulation that satisfies claims 1 or 25 may not necessarily satisfy the pharmacokinetic limitations. Conversely, failure to meet a pharmacokinetic dependent claim does not avoid infringement of the independent claim.

What liquid-crystal structures are protected?

Claims 23 and 24 cover a composition that forms a liquid crystalline phase after contact with an aqueous fluid. Claim 24 narrows the structure to a non-lamellar crystalline phase.

This limitation is consistent with a lipid-based depot that changes phase after exposure to tissue fluid. The claim potentially reaches formulations that are administered as a low-volume liquid but form an ordered depot in vivo.

The technical questions likely to control scope include:

What aqueous fluid is used for testing;
Whether the phase must form immediately or over a defined period;
Whether “liquid crystalline phase structure” includes multiple mesophases;
What analytical method establishes a non-lamellar phase;
Whether the phase must persist for a clinically relevant period.

These claims may be more difficult to practice and enforce than the composition claims because they require structural characterization after contact with aqueous fluid. They may also provide a stronger distinction over non-lipid polymeric depots.

When does US Patent 11,135,215 lose exclusivity?

The patent issued on October 5, 2021. The nominal expiration date is determined by the earliest effective nonprovisional priority date, not by the issue date. Any terminal disclaimer, patent-term adjustment or patent-term extension can alter the operative expiration date.[1]

Event	Date or rule
Patent issuance	October 5, 2021
Standard patent term	Generally 20 years from the earliest effective nonprovisional filing date
Potential adjustments	PTA, terminal disclaimer, applicable continuation relationship
Regulatory exclusivity	Separate from patent term
Generic entry date	Depends on validity, infringement, settlement and FDA approval

The claims supplied do not establish the priority chain or the patent-term-adjustment certificate. The issue date alone is insufficient to state a reliable expiration date. For commercial planning, the relevant date is the expiration shown in the USPTO continuity and patent-term records, together with any Orange Book listing or litigation settlement.

What is the Orange Book status of US 11,135,215?

A patent number is not automatically an Orange Book-listed patent. Listing depends on the approved NDA holder, the drug product, the patent’s relationship to the approved formulation or method of use, and FDA submission requirements.[4]

For a drug such as Brixadi, the relevant analysis is:

Orange Book question	Business significance
Is US 11,135,215 listed against the NDA?	Determines whether an ANDA applicant receives a statutory patent certification obligation
Is it listed for the drug substance, formulation or method of use?	Determines the scope of a Paragraph IV challenge
Is it listed for all strengths and presentations?	Determines the product coverage of an ANDA certification
Is the patent delisted or removed?	Can change the timing and litigation consequences
Is the listed claim a method-of-use claim?	May permit a section viii carve-out rather than a Paragraph IV certification

The supplied claim set is principally a formulation and device claim set, not a conventional method-of-treatment claim. If listed against an NDA, an ANDA applicant would generally need to address the listed claims through the applicable patent certification process. A Paragraph IV notice could trigger Hatch-Waxman litigation and a statutory 30-month stay, subject to the statutory exceptions and litigation outcome.[5]

Which companies face the greatest patent risk?

Braeburn and Camurus

A lipid-based extended-release buprenorphine product supplied in a pre-filled syringe presents the highest technical overlap. Brixadi is the clearest commercial product requiring review because its product presentation and depot technology are aligned with several claim themes, including low-volume injection and liquid-crystal depot formation.[2]

The commercial risk depends on whether the approved product’s exact composition falls within the “about” ranges, whether the syringe is pre-filled as claimed, and whether the relevant patent is listed or otherwise enforceable against the product.

Indivior

Sublocade presents a different formulation architecture. Its polymeric ATRIGEL system does not appear, from the FDA labeling description, to match the claimed phosphatidylcholine and glycerol dioleate composition.[3] The principal patent risk for Sublocade would therefore arise from other patents, not from a direct formulation match to claims 1 and 25.

Generic applicants

A generic or follow-on applicant targeting a lipid-based injectable would face several design-around choices:

Change the phosphatidylcholine-to-glycerol dioleate ratio;
Replace glycerol dioleate with another lipid;
Alter the ethanol concentration;
Use a vial, cartridge or non-prefilled presentation;
Change the buprenorphine concentration;
Use a formulation that does not form the claimed non-lamellar phase;
Develop a polymeric or alternative depot system.

Each route creates separate regulatory, manufacturing and clinical-development burdens.

How strong is the patent estate?

US 11,135,215 has meaningful commercial value because it combines formulation, presentation and performance limitations. Its strongest practical features are the pre-filled syringe requirement, the specific lipid composition and the low-volume delivery configuration.

Its vulnerabilities are equally clear:

The numerical percentages may create claim-construction disputes over “about.”
The claim requires a particular product presentation, which may not cover bulk formulation or alternative containers.
The pharmacokinetic claims require reproducible clinical or analytical proof.
The liquid-crystal claims require a defensible structural test.
The gauge language may create ambiguity.
Prior-art analysis may identify earlier lipid-based buprenorphine formulations or pre-filled syringe disclosures.

The patent is stronger against a close-copy product than against an independently engineered depot platform. A competitor using the same lipid system and similar syringe presentation would face greater risk than a competitor using a polymeric depot or different lipid composition.

What generic launch scenarios exist?

Scenario 1: Same formulation and same pre-filled syringe

This is the highest-risk pathway. A Paragraph IV challenge would likely focus on anticipation, obviousness, written description, enablement, indefiniteness and noninfringement of the “about” ranges.

Scenario 2: Same composition in a vial

This may avoid the literal pre-filled-syringe limitation, but commercial substitution would depend on FDA requirements, device compatibility, administration instructions and any separate patents covering the composition or method of use.

Scenario 3: Modified lipid ratio

This is a conventional design-around strategy. It must account for the doctrine of equivalents and any related patent family claims that use broader composition language.

Scenario 4: Polymer-based depot

A polymeric formulation is less likely to satisfy the claimed excipient limitations, but it requires a separate development program and may encounter the patent estate for the incumbent polymeric product.

Scenario 5: Alternative presentation or injector

An auto-injector or safety syringe may still fall within claims 1 or 25 because those claims do not require a particular device accessory. The device-dependent claims add protection but do not define the full independent-claim scope.

Key Takeaways

US 11,135,215 is directed to a pre-filled syringe containing a specific lipid-based buprenorphine formulation.
The key composition is approximately 5% buprenorphine, 10% ethanol, 42% phosphatidylcholine and 42% glycerol dioleate.
Claims 2-19 protect low fill volumes, dose ranges, viscosity, storage stability and syringe-device characteristics.
Claims 20-22 protect pharmacokinetic performance.
Claims 23-24 protect formation of liquid-crystalline, including non-lamellar, structures after aqueous contact.
The patent is potentially relevant to lipid-based products such as Brixadi, but the approved product composition and Orange Book listing must be matched against the claims.
Sublocade uses a materially different polymeric depot platform and presents lower direct formulation overlap.
The patent’s commercial strength is highest against a close-copy pre-filled syringe product.
The exact expiration date cannot be derived from the issue date or claims alone; continuity, PTA and terminal-disclaimer records control.
A generic launch would most likely require a Paragraph IV strategy, a formulation design-around, a different presentation, or an alternative depot technology.

Frequently Asked Questions

Does US 11,135,215 cover buprenorphine tablets?

No. The independent claims require a pre-filled syringe containing the specified composition.

Does the patent cover every phosphatidylcholine buprenorphine injection?

No. The claims require the approximate phosphatidylcholine, glycerol dioleate, ethanol and buprenorphine composition stated in claims 1 or 25.

Can a vial avoid US 11,135,215?

Potentially, because the independent claims require a pre-filled syringe. A vial could still implicate other patents or the doctrine of equivalents.

Is Brixadi automatically infringing?

No. Infringement requires comparison of the marketed product’s formulation, container, concentration, presentation and relevant claim limitations.

Are the claims eligible for a Paragraph IV challenge?

Yes, if the patent is listed in the Orange Book for the relevant NDA and an ANDA applicant seeks approval for a product covered by the listed claims. The applicant would need to select the applicable certification and defend any resulting litigation.

References

United States Patent and Trademark Office. (2021). U.S. Patent No. 11,135,215, pre-filled syringe containing a pharmaceutical composition.
U.S. Food and Drug Administration. (2024). Brixadi (buprenorphine) extended-release injection: Prescribing information.
U.S. Food and Drug Administration. (2024). Sublocade (buprenorphine extended-release) injection: Prescribing information.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book.
Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Braeburn	BRIXADI	buprenorphine	SOLUTION, EXTENDED RELEASE;SUBCUTANEOUS	210136-001	May 23, 2023		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
Braeburn	BRIXADI	buprenorphine	SOLUTION, EXTENDED RELEASE;SUBCUTANEOUS	210136-002	May 23, 2023		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
Braeburn	BRIXADI	buprenorphine	SOLUTION, EXTENDED RELEASE;SUBCUTANEOUS	210136-003	May 23, 2023		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
Braeburn	BRIXADI	buprenorphine	SOLUTION, EXTENDED RELEASE;SUBCUTANEOUS	210136-004	May 23, 2023		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ 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

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	E401054	⤷ Start Trial
Austria	E462409	⤷ Start Trial
Austria	E501710	⤷ Start Trial
Australia	2005249274	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 11,135,215

Which drugs does patent 11,135,215 protect, and when does it expire?

Summary for Patent: 11,135,215