United States Patent 10,398,686: Claim Scope, Exclusivity, and Bupivacaine Patent Landscape

U.S. Patent No. 10,398,686 protects a specific injectable bupivacaine delivery system based on a polyorthoester polymer and dimethyl sulfoxide (DMSO). Independent claim 1 requires all three core elements: a qualifying Formula III polyorthoester, DMSO that is miscible with the polymer to form a single phase, and bupivacaine dispersed or solubilized in that phase. Claims 2-10 narrow the system by specifying physical state, viscosity, molecular weight, drug loading, DMSO concentration, and polymer concentration.

The patent is composition-focused. It does not broadly cover every long-acting bupivacaine formulation, every polyorthoester, or every injectable depot. A competing product can avoid literal infringement by omitting DMSO, using a non-qualifying polymer, forming multiple phases, or using a different anesthetic. The principal commercial relevance is the relationship between this claim set and extended-release bupivacaine products, including Heron Therapeutics' Zynrelef and other depot formulations.

What does U.S. Patent 10,398,686 protect?

The patent protects a single-phase delivery composition with the following mandatory architecture:

Required element	Claim requirement	Scope implication
Polymer	Polyorthoester of Formula III	Generic polyorthoesters outside Formula III are not captured by claim 1
Solvent	DMSO	Other solvents alone do not satisfy the claim
Physical relationship	Polymer is miscible in DMSO and forms a single phase	A suspension, emulsion, or intentionally separated phase may fall outside the claim
Active ingredient	Bupivacaine dispersed or solubilized in the single phase	Bupivacaine must be part of the claimed polymer-DMSO phase
Polymer structure	A, R*, n, R1, R3, R5, R6, p, q, x and mole-fraction limitations	Structural compliance must be established analytically
Optional narrowing features	Viscosity, molecular weight, drug loading, DMSO loading and polymer loading	Claims 4-10 create narrower but potentially more commercially targeted positions

Claim 1 is an open-ended "comprising" claim. Additional excipients, stabilizers, preservatives, or other formulation ingredients generally do not avoid infringement if the accused composition still contains every claimed element.

The central limitation is not simply the presence of a polyorthoester and bupivacaine. The polymer must be miscible with DMSO and create a single phase containing bupivacaine. This gives the claim a narrower technical boundary than a broad claim to a bupivacaine-containing biodegradable polymer.

How should claim 1 be construed?

Formula III polyorthoester limitation

The structural limitation is the principal gatekeeper. Claim 1 requires a polyorthoester of Formula III in which:

A is R1 or R3;
R* is C1-C4 alkyl;
n is 5-1000;
p and q range from approximately 1-20;
the average p, or average sum of p and q, is between 1 and 7;
R3 and R6 have the specified independently variable structures;
x is 0-10;
R5 is hydrogen or methyl; and
the fraction of A units having the R1 structure is 0-25 mole percent.

These limitations create a chemically defined genus rather than a single polymer species. The use of average values means that the polymer is likely characterized as a distribution of chain lengths and repeat-unit structures, rather than as a single uniform molecular entity.

A patent dispute would likely focus on:

Whether the accused polymer satisfies the Formula III structure.
Whether the required substitution fraction is within the 0-25 mole-percent range.
How average p and q are measured.
Whether the polymer's molecular weight distribution falls within any asserted dependent claim.
Whether DMSO and the polymer form one thermodynamically stable phase under the relevant conditions.

Single-phase requirement

The phrase "dimethyl sulfoxide in which the polyorthoester is miscible to form a single phase" is commercially important. It excludes formulations in which:

DMSO is present only as a separate liquid phase;
the polymer is suspended rather than dissolved;
the formulation is an emulsion;
the polymer precipitates after mixing; or
bupivacaine is present in a separate crystalline or particulate phase outside the polymer-DMSO phase.

The specification and prosecution history would control whether "single phase" is assessed immediately after manufacture, during storage, at administration, or at body temperature. Claim 4's viscosity limitation expressly references 37°C, but claim 1 does not. A formulation that is single-phase at room temperature but phase-separates at 37°C could present a construction and infringement issue.

Dispersed versus solubilized bupivacaine

Claims 2 and 3 separately recite bupivacaine dispersed or solubilized in the single phase. Claim 1 already includes both alternatives. Claims 2 and 3 therefore appear to clarify the two physical states rather than materially expand claim 1.

The distinction matters analytically:

"Solubilized" ordinarily indicates molecular or substantially molecular incorporation into the phase.
"Dispersed" ordinarily indicates distributed drug particles or domains within the phase.

A generic or follow-on developer may attempt to create a formulation in which bupivacaine is chemically complexed, encapsulated, precipitated in situ, or held in a separate particulate depot. The infringement result would depend on whether that state still qualifies as dispersed or solubilized in the claimed single phase.

What do claims 4-10 add?

The dependent claims target formulation attributes that are relevant to injection, handling, and drug loading.

Claim	Limitation	Commercial significance
4	Viscosity below about 10,000 cP at 37°C	Limits the claim to a formulation with an administrable rheology
5	Polyorthoester molecular weight of about 1,000-10,000 daltons	Targets relatively low-molecular-weight injectable polymers
6	Bupivacaine at about 1-20 wt%	Covers a broad active loading range
7	Bupivacaine at about 2-5 wt%	Narrower range likely aligned with a commercial formulation
8	DMSO at about 10-60 wt%	Covers a broad solvent range
9	DMSO at about 10-20 wt%	Narrower range likely directed to a practical formulation
10	Polyorthoester at about 50-80 wt%	Covers a polymer-rich depot composition

The ranges use "about," which introduces ordinary claim-construction flexibility. Courts generally assess the intrinsic record, technical meaning, prosecution amendments, and whether the accused value is materially outside the claimed range. A formulation at 5.1% bupivacaine or 20.1% DMSO cannot be assessed solely by arithmetic. The specification's examples and prosecution history would be material.

Claims 7, 9, and 10 are likely the most commercially relevant dependent claims because they define a concentrated polymer depot with moderate DMSO and bupivacaine levels. Claims 4 and 5 can also be important if a competitor's formulation uses similar injection properties and molecular weight.

When does U.S. Patent 10,398,686 expire?

U.S. Patent 10,398,686 issued on August 27, 2019. The enforceable term is generally 20 years from the earliest effective nonprovisional U.S. filing date, subject to patent-term adjustment, terminal disclaimers, and any applicable patent-term extension under 35 U.S.C. §§ 154 and 156.[1]

The patent's practical exclusivity date must be determined from the official USPTO patent record and the FDA Orange Book listing, if the patent is listed against an approved drug product. The issue date alone does not establish the expiration date. Any Orange Book patent term extension or pediatric exclusivity would affect the regulatory exclusivity analysis but would not necessarily change the underlying patent term in the same way.

Patent expiration should be separated from FDA exclusivity:

Patent protection depends on the enforceable patent term.
New-drug exclusivity depends on the NDA approval and statutory exclusivity period.
Orange Book listing affects notice and Paragraph IV litigation procedures.
A patent may remain enforceable after FDA exclusivity ends.
FDA exclusivity may expire before all listed patents expire.

What is the Orange Book status of U.S. Patent 10,398,686?

The patent's Orange Book relevance depends on whether it is listed for a particular approved bupivacaine product and whether the listing identifies a drug substance, drug product, or method-of-use claim. The supplied claims are formulation claims, not method-of-use claims. If listed, the patent would ordinarily be treated as a drug-product patent.

For an ANDA applicant, the key certification would usually be:

Paragraph I, if no relevant patent is listed;
Paragraph II, if the listed patent has expired;
Paragraph III, if the applicant will wait until expiration; or
Paragraph IV, if the applicant asserts that the patent is invalid, unenforceable, or not infringed.[2]

A Paragraph IV notice against a listed formulation patent can trigger a 30-month stay of FDA approval if the NDA holder or patent owner files suit within the statutory period.[2] The stay does not automatically prevent commercial activity in every circumstance, and it does not establish patent validity.

Which products compete with the claimed delivery system?

Zynrelef

Zynrelef is an extended-release solution containing bupivacaine and meloxicam. It uses Heron Therapeutics' Biochronomer drug-delivery technology and is approved for postsurgical analgesia.[3] The product is the clearest commercial context for analyzing polyorthoester-based bupivacaine patent claims.

The supplied claims recite bupivacaine but do not require meloxicam. A product containing both bupivacaine and meloxicam can still infringe a "comprising" claim if it satisfies the polymer, DMSO, single-phase, and structural limitations. The presence of meloxicam would not, by itself, create a non-infringing design-around.

Exparel

Exparel is a liposome injection containing bupivacaine and is associated with Pacira Pharmaceuticals.[4] Its liposomal delivery architecture is materially different from the claimed polyorthoester-DMSO system. Exparel is therefore a useful example of a competing bupivacaine delivery technology that would not ordinarily satisfy claim 1 because it does not use the claimed polymer-DMSO single phase.

Xaracoll and other local bupivacaine products

Xaracoll is a bupivacaine implant based on a collagen matrix. It differs from the claimed injectable polyorthoester solution. Conventional bupivacaine hydrochloride injections, liposomal products, collagen implants, microspheres, nanoparticles, and lipid depots may also avoid literal infringement if they lack the required Formula III polymer or DMSO single phase.

How strong is the patent estate?

The strength of Patent 10,398,686 is concentrated rather than broad.

Strengths

It covers a complete formulation architecture rather than an isolated excipient.
The claim uses "comprising," allowing additional ingredients.
The polymer structural definition may capture a substantial family of related polyorthoesters.
The DMSO single-phase limitation can map directly onto a proprietary formulation platform.
Dependent claims cover practical commercial parameters, including drug loading, viscosity, and polymer concentration.
A competitor using the same Biochronomer-type platform may face literal infringement risk even if it changes the active-drug combination.

Weaknesses

The claim does not cover all bupivacaine depots.
The Formula III limitations create opportunities for chemical design-around.
The single-phase requirement may create factual disputes over formulation state and test conditions.
The claims do not expressly require a particular duration of analgesia, release profile, indication, or administration site.
A competitor can move to liposomal, collagen, lipid, microsphere, hydrogel, or alternative polymer systems.
Prior art directed to polyorthoesters, DMSO-based injectable depots, and bupivacaine delivery could support anticipation or obviousness challenges.

The most significant validity risks would likely arise from combining references that disclose biodegradable polyorthoesters, DMSO as a solvent or delivery vehicle, and local anesthetics. The patentee's strongest response would be evidence that the claimed combination produces a technically distinct single-phase injectable system with acceptable viscosity, stability, drug loading, and release behavior.

What generic entry risks exist?

A conventional bupivacaine generic is not automatically blocked by this patent. An ANDA applicant would face materially different risk depending on its product architecture.

Follow-on design	Likely risk under Patent 10,398,686
Conventional bupivacaine injection	Low, absent the claimed polymer-DMSO system
Liposomal bupivacaine	Low under literal claim scope
Collagen implant	Low
Polyorthoester depot without DMSO	Potentially avoidable
DMSO formulation with a different polymer	Potentially avoidable
Formula III polyorthoester with DMSO but separate drug phase	Fact-dependent
Same polymer-DMSO platform with altered drug concentration	High if claim 1 is met; dependent-claim exposure may vary
Same platform with bupivacaine and another analgesic	High because claim 1 is open-ended
Polymer outside the specified mole-fraction range	Potentially avoidable, subject to equivalents analysis

The doctrine of equivalents could limit the value of a design-around that makes only an insubstantial change to the claimed polymer structure or phase behavior. Prosecution-history estoppel may restrict that argument if the patentee narrowed the claims to obtain allowance.

Are there Paragraph IV challenges or patent litigation?

A complete litigation assessment requires the current USPTO, PACER, FDA Orange Book and FDA Paragraph IV records. Patent litigation risk should be evaluated separately from the text of the claims. The claim set alone does not establish whether:

a Paragraph IV certification has been filed;
the NDA holder has sued;
a 30-month stay has been triggered;
a settlement agreement exists;
a license has been granted; or
the patent has been challenged through inter partes review.

For business planning, the decisive records are the patent's current USPTO status, Orange Book listing, approved NDA patent information, ANDA litigation docket, and any terminal disclaimer or patent-term adjustment entry.[1,2]

What manufacturing and IP barriers does the patent create?

The patent can create barriers beyond the written claim language. A follow-on developer may need to reproduce or independently develop:

the Formula III polymer;
the required polymer molecular-weight distribution;
DMSO-polymer miscibility;
a stable single phase;
injectable viscosity at 37°C;
bupivacaine loading within the target range;
sterility and storage stability;
controlled in situ depot formation; and
manufacturing controls for polymer substitution and degradation.

Trade secrets may protect polymer synthesis, monomer purity, reaction conditions, molecular-weight control, formulation mixing, sterilization, and release testing even when patent claims are avoided. These manufacturing barriers can increase development time and create supply-chain dependence on specialized polymer production.

How does this patent compare with competing bupivacaine patents?

Technology	Delivery architecture	Relationship to Patent 10,398,686
Patent 10,398,686	Formula III polyorthoester, DMSO, bupivacaine single phase	Directly targeted claim set
Zynrelef	Extended-release bupivacaine/meloxicam platform	Potentially within the same formulation technology space
Exparel	Liposomal bupivacaine	Different delivery architecture
Xaracoll	Collagen bupivacaine implant	Different matrix and dosage form
Standard bupivacaine HCl	Immediate-release aqueous injection	Outside the claimed polymer-DMSO architecture

The patent is strongest against products that copy the delivery platform. It is less relevant to products that compete through a different depot mechanism or conventional immediate-release injection.

Key Takeaways

Claim 1 requires a Formula III polyorthoester, DMSO, a single phase, and bupivacaine.
The patent does not broadly cover all extended-release bupivacaine products.
Claims 4-10 narrow the scope through viscosity, molecular weight, drug loading, DMSO loading, and polymer concentration.
Zynrelef is the principal commercial product relevant to the claimed technology space.
Exparel and collagen-based products use materially different delivery systems.
A follow-on product using the same polyorthoester-DMSO platform faces the highest infringement risk.
Patent term must be calculated from the earliest effective nonprovisional filing date, with USPTO term adjustments and Orange Book data controlling the practical expiry analysis.
Generic bupivacaine products using liposomes, collagen, alternative polymers, or conventional aqueous injection may avoid literal infringement.
Formula III structure, single-phase behavior, and prosecution history are likely to determine litigation outcomes.

FAQs

Does adding meloxicam avoid infringement of Patent 10,398,686?

No. Claim 1 is a "comprising" claim. Adding meloxicam or another analgesic does not avoid infringement if the formulation still contains the claimed polyorthoester, DMSO single phase, and bupivacaine.

Could a liposomal bupivacaine product infringe this patent?

Ordinarily, a liposomal product would not satisfy the polyorthoester-DMSO single-phase limitation. The specific formulation and any equivalents argument would still require technical analysis.

Does claim 1 require the formulation to be injectable?

Claim 1 recites a "delivery system" and does not expressly state an injection step. The specification, prosecution history, and technical context may affect construction, but the claim's express limitations focus on composition and phase behavior.

Can a competitor avoid the patent by using a different solvent instead of DMSO?

A formulation that omits DMSO would not literally satisfy claim 1. The risk would then depend on whether another claim covers the alternative solvent or whether the patentee asserts the doctrine of equivalents.

Is bupivacaine concentration of 1-20% required for every infringing product?

No. The 1-20% range is in dependent claim 6. A product outside that range could still infringe claim 1 if it satisfies the broader composition and structural limitations.

References

United States Patent and Trademark Office. (2019). U.S. Patent No. 10,398,686, Bupivacaine delivery system.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2021). Zynrelef prescribing information. Heron Therapeutics, Inc.
U.S. Food and Drug Administration. (2015). Exparel prescribing information. Pacira Pharmaceuticals, Inc.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Heron Theraps Inc	ZYNRELEF KIT	bupivacaine; meloxicam	SOLUTION, EXTENDED RELEASE;PERIARTICULAR	211988-001	May 12, 2021		DISCN	Yes	No	10,398,686	⤷ Start Trial	Y				⤷ Start Trial
Heron Theraps Inc	ZYNRELEF KIT	bupivacaine; meloxicam	SOLUTION, EXTENDED RELEASE;PERIARTICULAR	211988-002	May 12, 2021		RX	Yes	Yes	10,398,686	⤷ Start Trial	Y				⤷ Start Trial
Heron Theraps Inc	ZYNRELEF KIT	bupivacaine; meloxicam	SOLUTION, EXTENDED RELEASE;PERIARTICULAR	211988-003	May 12, 2021		DISCN	Yes	No	10,398,686	⤷ 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
Australia	2014228313	⤷ Start Trial
Australia	2019202415	⤷ Start Trial
Australia	2020250230	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,398,686

Which drugs does patent 10,398,686 protect, and when does it expire?

Summary for Patent: 10,398,686