United States Patent 9,320,710: Sufentanil Oral Transmucosal Dosage-Form Claims and Patent Landscape

US Patent No. 9,320,710 protects a method of treating pain with a small, bioadhesive sufentanil dosage form applied to the oral mucosa. Its principal commercial relevance is the sublingual sufentanil product DSUVIA, formerly developed and commercialized by AcelRx Pharmaceuticals.

The patent is method-of-treatment coverage, not a broad composition patent. Infringement generally requires proof that the accused product is used with all material limitations of at least one asserted claim, including the sufentanil dose range, bioadhesion, size threshold, oral-mucosal administration, and, for dependent claims, specified pharmacokinetic or bioavailability characteristics.

The patent’s nominal expiration is expected to fall in 2029, subject to patent-term adjustment, terminal disclaimers, regulatory exclusivity, and the status of related continuation patents.

What does US Patent 9,320,710 protect?

The independent claim protects a therapeutic method with five core elements:

Claim element	Scope
Therapeutic use	Treatment of pain in a subject
Active ingredient	Approximately 2 to 200 micrograms of sufentanil
Dosage form	Bioadhesive dosage form
Administration site	Oral mucosa
Physical size	Volume below 30 microliters or mass below 30 mg

The claim covers a treatment method rather than every sufentanil formulation. A product may fall outside literal claim 1 if it is administered intravenously, swallowed, delivered intranasally, applied to the skin, or used in a dosage form that does not satisfy the bioadhesive and size limitations.

The "or" construction in the size limitation is commercially important. A dosage form with a volume of 25 microliters and a mass above 30 mg may still satisfy the volume branch. Conversely, a dosage form with a mass below 30 mg may satisfy the mass branch even if its volume is above 30 microliters.

How broad is claim 1 of US 9,320,710?

Claim 1 has meaningful therapeutic and formulation breadth, but it is narrower than a patent claiming sufentanil generally.

It covers:

Sufentanil doses from approximately 2 to 200 micrograms.
Bioadhesive films, tablets, wafers, gels, or other oral-mucosal dosage forms, depending on the patent specification and construction.
Application to the sublingual or buccal mucosa.
Dosage forms below either the volume or mass threshold.
Treatment of pain without limiting the claim to a specific pain etiology.

The claim does not expressly require:

A particular polymer.
A specific tablet shape.
A particular manufacturing process.
A particular excipient.
A specific release-rate profile.
A specified Tmax, Cmax, or bioavailability.
A particular delivery device.

Those characteristics appear in dependent claims or are relevant to the written description and enablement analysis, but they are not all required by claim 1.

The principal limitations are "bioadhesive dosage form," "oral mucosa," and the physical size threshold. An accused manufacturer could contest whether a small sublingual tablet is sufficiently bioadhesive, although adhesion may be established through product design, labeling, clinical testing, or other technical evidence.

What do claims 2 through 8 add?

Claims 2 through 8 narrow the method through size and pharmacokinetic limitations.

Claims	Added limitation	Commercial significance
2	Volume below 10 microliters or mass below 10 mg	Targets very small dosage forms
3	At least 50% of sufentanil delivery occurs orally transmucosally	Excludes products relying primarily on swallowing
4	At least 55% oral transmucosal delivery	Narrower route-of-delivery requirement
5	At least 60% oral transmucosal delivery	Stronger pharmacokinetic limitation
6	Tmax from approximately 19.8 to 60 minutes	Covers a defined onset profile
7	Mean Tmax from 0.68 to 0.89 hours	Narrow clinical pharmacokinetic range
8	Dose-normalized Cmax of approximately 2.72 +/- 0.84 pg/mL per microgram	Requires a specified exposure result

Claims 3 through 5 are functional claims. They may require evidence showing the proportion of delivered sufentanil that enters through the oral mucosa rather than through gastrointestinal absorption after swallowing. This can create factual disputes over study design, sampling, model assumptions, and the meaning of "drug delivery."

Claims 6 through 8 are particularly useful against products designed to replicate the clinical profile of the reference product. They are less likely to reach every sufentanil oral-mucosal product because a competing formulation could have a different absorption rate or exposure profile while still meeting claim 1.

What do claims 9 through 17 cover?

Where must the sufentanil dosage form adhere?

Claims 9 through 11 require adhesion during the period of drug delivery and identify two specific oral-mucosal locations:

Claim 9: Adhesion to the oral mucosa.
Claim 10: Adhesion to the sublingual membrane.
Claim 11: Adhesion to the buccal membrane.

These claims create separate infringement pathways. A sublingual tablet may implicate claim 10, while a cheek-applied film may implicate claim 11. A product that dissolves rapidly without remaining attached during drug delivery could challenge claims 9 through 11, although the factual result would depend on the construction of "adheres" and the duration of delivery.

What pharmacokinetic and bioavailability limits apply?

Claims 12 through 15 require specified clinical performance:

Claim 12 requires a Tmax coefficient of variation below 40%.
Claim 13 requires bioavailability above 65%.
Claim 14 requires bioavailability above 75%.
Claim 15 requires bioavailability above 80%.

Claims 13 through 15 are nested. A product with bioavailability above 80% necessarily falls within the numerical threshold of claims 13 and 14 if all other limitations are satisfied. The claims may create litigation exposure even where a competing company does not copy the same formulation, because a product can produce the claimed result through different excipients or manufacturing processes.

Claim 16 expressly covers sufentanil citrate. This is relevant to DSUVIA, whose active pharmaceutical ingredient is sufentanil citrate. Claim 17 covers administration using a drug-delivery device. The claim does not appear limited to one named device, but a device used to place the dosage form on the oral mucosa could satisfy the limitation.

What product is most closely associated with US 9,320,710?

DSUVIA is the principal product associated with the patent technology. The FDA approved DSUVIA, a 30-microgram sufentanil sublingual tablet, in November 2018 for acute pain in adults in certified medically supervised settings (FDA, 2018).

DSUVIA’s product profile aligns closely with the claim architecture:

DSUVIA characteristic	Relevance to US 9,320,710
30 micrograms sufentanil	Within the approximately 2 to 200 microgram range
Sufentanil citrate	Expressly addressed by claim 16
Sublingual administration	Relevant to claims 9 and 10
Small solid dosage form	Relevant to claims 1 and 2
Bioadhesive delivery platform	Central to claim 1
Acute pain treatment	Within the claim’s pain-treatment category
Medically supervised administration	Consistent with the FDA-approved use setting

The patent does not require a 30-microgram dose. A 2-microgram, 50-microgram, or 200-microgram product could fall within claim 1 if the other limitations are met.

What is the FDA regulatory status and Orange Book relevance?

The FDA approved DSUVIA under NDA 211660 in 2018. The product is a Schedule II opioid and carries stringent controls concerning administration, monitoring, distribution, and use in certified settings (FDA, 2018).

The relevant regulatory distinctions are:

FDA approval does not establish patent validity.
Orange Book listing does not establish that every claim is enforceable against every competing product.
A method-of-use patent can create a Paragraph IV issue for an ANDA applicant if the patent is listed against the reference product.
The FDA generally separates patent certification issues from technical patent-validity determinations.

For DSUVIA, the commercial patent estate has included patents directed to sufentanil dosage forms, oral transmucosal delivery, and related methods of use. US 9,320,710 should be analyzed together with related AcelRx patent-family members rather than in isolation.

How many patents cover the DSUVIA and sufentanil sublingual platform?

The relevant estate includes several U.S. patents and applications associated with AcelRx’s sufentanil oral-transmucosal platform. The most important categories are:

Patent category	Subject matter	Competitive impact
Dosage-form patents	Sufentanil-containing tablets or other small forms	Protects the product architecture
Bioadhesion patents	Attachment to sublingual or buccal tissue	Limits alternative oral-mucosal designs
Method-of-treatment patents	Treating acute pain with specified doses	Creates use-based infringement risk
Pharmacokinetic patents	Tmax, Cmax, bioavailability, and delivery fraction	Targets clinical-performance replication
Device patents	Placement or administration systems	Adds device-level barriers
Manufacturing patents	Compression, coating, excipient, or process controls	Raises design-around and supply-chain costs

A precise patent count depends on whether expired, abandoned, continuation, foreign, and Orange Book-listed patents are included. The relevant analysis should distinguish issued U.S. patents from pending applications and should not treat every family member as independently enforceable.

When does US Patent 9,320,710 lose exclusivity?

US 9,320,710 was granted on April 26, 2016. Its priority chain appears to trace to the 2009 AcelRx sufentanil oral-transmucosal development program. The nominal 20-year patent term is therefore expected to end in 2029, subject to the recorded patent-term calculation.

Event	Date or period
Earliest relevant priority period	2009
U.S. patent grant	April 26, 2016
Nominal patent expiration	Approximately September 2029
FDA approval of DSUVIA	November 2018
Five-year NCE exclusivity	Approximately November 2023
Current commercial relevance	Patent protection remains more important than NCE exclusivity

The five-year new chemical entity exclusivity period associated with DSUVIA would not extend beyond the expected patent term. Any pediatric exclusivity, patent-term extension, patent-term adjustment, terminal disclaimer, or post-grant correction must be confirmed from the current USPTO and FDA records before relying on a final date.

Are there Paragraph IV challenges to US 9,320,710?

A Paragraph IV challenge would require an ANDA applicant to certify that the listed patent is invalid, unenforceable, or will not be infringed. For a product such as DSUVIA, an ANDA applicant could face several technical barriers:

Demonstrating pharmaceutical equivalence to the reference sublingual tablet.
Establishing bioequivalence for a locally administered oral-transmucosal product.
Addressing the bioadhesion requirement.
Reproducing or avoiding the claimed size thresholds.
Handling opioid-specific risk controls and restricted distribution.
Addressing any method-of-use listing and labeling carve-outs.

A generic applicant could pursue a design that avoids a claimed oral-transmucosal route or bioadhesive property, but that may undermine equivalence to DSUVIA. A product with a materially different route, dose, or release profile may require a different regulatory pathway rather than a conventional ANDA.

No biosimilar pathway applies. Sufentanil is a chemically synthesized small molecule, so competition would arise through an ANDA, 505(b)(2) application, or an alternative new drug application, not through a biosimilar application.

What patent litigation and settlement risks affect generic entry?

The major litigation risk is a Hatch-Waxman action following a Paragraph IV notice. The patent owner could seek a 30-month stay of approval under the statutory framework if the required conditions are met. A court would likely focus on:

Whether the accused dosage form is bioadhesive.
Whether the product is administered to the oral mucosa.
Whether the mass or volume limitation is satisfied.
Whether the claimed pharmacokinetic results are inherent or expressly demonstrated.
Whether the asserted claims are enabled across the full 2-to-200 microgram range.
Whether the claims are anticipated by earlier fentanyl, sufentanil, buccal, or sublingual delivery disclosures.
Whether the functional limitations are indefinite.

The strongest validity arguments would likely involve prior art showing small bioadhesive opioid dosage forms and oral-transmucosal sufentanil delivery. The strongest infringement arguments would focus on the product label, formulation composition, clinical pharmacokinetic data, and the physical dimensions of the dosage form.

Settlement terms could include a licensed entry date, authorized generic rights, supply arrangements, or restrictions on the competing product’s indication. No settlement should be inferred merely from the absence of a reported trial.

How strong is the patent estate for US 9,320,710?

The estate is strongest where a competitor attempts to reproduce the DSUVIA product profile:

Sufentanil citrate.
Approximately 30 micrograms.
Small sublingual dosage form.
Bioadhesive placement.
Rapid oral-transmucosal delivery.
High bioavailability.
Similar Tmax and Cmax characteristics.

The estate is weaker against products that materially change one of those parameters. A nonadhesive swallowed tablet, an intravenous product, a transdermal system, or a nasal formulation would generally present a lower literal infringement risk under claim 1.

The dependent pharmacokinetic claims increase enforcement options but also create proof burdens. Clinical variability, assay methodology, patient population, and dose normalization can determine whether claims 6 through 15 are met.

What licensing deals and companies shaped the competitive landscape?

AcelRx developed the core sufentanil sublingual technology and entered commercial arrangements involving European commercialization of Zalviso with Grünenthal. Zalviso used a patient-controlled sublingual sufentanil delivery system for postoperative pain, while DSUVIA was developed for medically supervised administration in the United States (AcelRx Pharmaceuticals, 2013; FDA, 2018).

The competitive set includes:

DSUVIA, a sublingual sufentanil tablet.
Zalviso, a controlled sublingual sufentanil delivery system in European markets.
Generic injectable sufentanil products.
Fentanyl transmucosal products such as Actiq, Fentora, and Subsys.
Non-opioid and regional-anesthesia alternatives for acute pain.

Fentanyl products are not direct freedom-to-operate substitutes because fentanyl and sufentanil have different active ingredients and patent estates. They remain relevant as prior-art and commercial comparators for transmucosal opioid delivery.

What generic launch scenarios exist?

Scenario 1: Direct DSUVIA-style ANDA

This is the highest patent-risk route. The applicant would likely need to address Orange Book-listed patents and demonstrate equivalence to the sublingual reference product. A Paragraph IV certification could produce litigation and delay.

Scenario 2: Non-bioadhesive oral product

A non-bioadhesive dosage form could reduce exposure to claims 1 and 9 through 11. It may not qualify as an ANDA product if the delivery behavior is materially different from DSUVIA.

Scenario 3: Different route of administration

An injectable, nasal, buccal liquid, or transdermal sufentanil product would reduce risk under US 9,320,710 but could implicate separate patents and require a different FDA application.

Scenario 4: 505(b)(2) product

A 505(b)(2) applicant could rely partly on existing safety or efficacy information while using a different dosage form or delivery technology. This route may avoid some equivalence constraints but does not eliminate patent litigation risk.

Key Takeaways

US 9,320,710 is a method patent centered on small, bioadhesive, oral-mucosal sufentanil dosage forms.
Claim 1 covers approximately 2 to 200 micrograms of sufentanil in a dosage form below 30 microliters or 30 mg.
Claims 2 through 17 add narrower limitations involving size, transmucosal delivery, adhesion site, Tmax, Cmax, bioavailability, sufentanil citrate, and drug-delivery devices.
DSUVIA is the principal commercial product aligned with the claimed technology.
The patent’s expected nominal expiration is in 2029, subject to the USPTO’s final term calculation.
Generic risk is highest for a DSUVIA-like sublingual, bioadhesive sufentanil tablet.
No biosimilar pathway applies because sufentanil is a small-molecule drug.
A design-around that changes route, adhesion, dose, or release profile may reduce infringement risk but could require a 505(b)(2) or new drug development strategy.
The patent should be assessed with related dosage-form, device, manufacturing, and method-of-use patents in the same AcelRx family.

Frequently Asked Questions

Does US 9,320,710 cover all sufentanil products?

No. It is limited to specified methods using a bioadhesive dosage form applied to the oral mucosa, with defined dose and size requirements.

Does a 30-microgram sufentanil product automatically infringe?

No. Dose alone is insufficient. The product and use must satisfy the remaining limitations, including bioadhesion, oral-mucosal administration, and the volume-or-mass threshold.

Can a buccal sufentanil film fall within the patent?

Yes. Claims 1, 9, and 11 can reach a buccal product if it is bioadhesive, applied to the oral mucosa, within the claimed dose and size limits, and used to treat pain.

Is a sufentanil injection a direct infringement risk under this patent?

Generally, an injection would not satisfy the oral-mucosal administration and bioadhesive dosage-form limitations. Separate patents or regulatory exclusivities could still apply.

Does FDA approval of DSUVIA prove that US 9,320,710 is valid?

No. FDA approval and patent validity are separate legal determinations. The FDA regulates safety, efficacy, quality, and approval status, while patent validity and infringement are determined under patent law.

References

AcelRx Pharmaceuticals, Inc. (2013). AcelRx and Grünenthal enter exclusive license agreement for Zalviso in Europe. Company press release.
U.S. Food and Drug Administration. (2018). FDA approves new opioid for acute pain in medically supervised settings. FDA Drug Safety and regulatory announcement.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Orange Book.
U.S. Patent and Trademark Office. (2016). U.S. Patent No. 9,320,710: Methods of treating pain using bioadhesive dosage forms. Washington, DC.
U.S. Food and Drug Administration. (2018). DSUVIA prescribing information. NDA 211660.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Vertical Pharms	DSUVIA	sufentanil citrate	TABLET;SUBLINGUAL	209128-001	Nov 2, 2018		DISCN	Yes	No	9,320,710	⤷ Start Trial				TREATMENT OF ACUTE PAIN	⤷ 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
European Patent Office	2114383	⤷ Start Trial	300797	Netherlands	⤷ Start Trial
European Patent Office	2114383	⤷ Start Trial	CA 2016 00007	Denmark	⤷ Start Trial
European Patent Office	2114383	⤷ Start Trial	CR 2016 00007	Denmark	⤷ Start Trial
European Patent Office	2114383	⤷ Start Trial	122016000023	Germany	⤷ Start Trial
European Patent Office	2114383	⤷ Start Trial	16C0010	France	⤷ Start Trial
European Patent Office	2114383	⤷ Start Trial	SPC/GB16/004	United Kingdom	⤷ Start Trial
Austria	E474564	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,320,710

Which drugs does patent 9,320,710 protect, and when does it expire?

Summary for Patent: 9,320,710