US Patent 8,202,535: Sufentanil Sublingual Tablet Claims, Patent Scope, and Generic Entry Risk

US Patent No. 8,202,535 protects a method of treating pain with a small, bioadhesive sufentanil tablet administered to the oral mucosa. The independent claim requires a tightly defined combination of tablet size, dose, adhesion, saliva response, transmucosal absorption, and pharmacokinetic timing. The patent is directed primarily to the product profile later associated with 30-microgram sublingual sufentanil tablets, including Dsuvia.

The principal commercial and litigation risk is not ordinary sufentanil use. It is a competing product that reproduces the claimed delivery architecture and pharmacokinetic profile. An injectable sufentanil product, a conventional oral tablet, or a lozenge with substantial swallowing would generally fall outside the literal scope of claim 1.

What does US Patent 8,202,535 protect?

The patent protects a method of treating pain by administering a small-volume, substantially homogeneous solid tablet that adheres to oral mucosa while delivering sufentanil primarily through the transmucosal route.

Claim 1 requires all of the following limitations:

Claim limitation	Required scope
Dosage form	Small-volume, substantially homogeneous solid tablet
Administration	Adhered to oral mucosa
Tablet volume	About 3 to about 15 microliters
Sufentanil dose	About 2 to about 200 micrograms
Excipient	Bioadhesive material
Adhesion	Substantially maintained during drug delivery
Saliva and swallowing	Minimal saliva response and minimal swallowing of drug
Delivery route	At least 50% of drug delivery through oral mucosa
Pharmacokinetics	Tmax from about 19.8 to about 60 minutes

The claim is therefore a combination claim. A competing product must satisfy the complete set of limitations for literal infringement. Failure to meet one required element can avoid literal infringement, although the doctrine of equivalents could remain relevant in litigation.

How narrow is the independent claim?

Claim 1 is narrower than the drug substance and dose ranges suggest. The sufentanil range extends from approximately 2 to 200 micrograms, but the tablet must also satisfy physical, adhesion, absorption, and pharmacokinetic requirements.

The most restrictive elements are likely:

The microvolume tablet requirement.
Continuous oral-mucosal adherence during delivery.
Minimal swallowing.
At least 50% oral-transmucosal delivery.
Tmax between approximately 19.8 and 60 minutes.

A sufentanil tablet with the correct dose but a larger volume may avoid claim 1. A small tablet that dissolves rapidly and is swallowed may also avoid the claim. A product delivering sufentanil through the oral mucosa but producing a Tmax outside the claimed range presents another potential noninfringement position.

The claim does not require a particular polymer, manufacturing process, tablet shape, applicator, or commercial brand. Those limitations appear in the specification, examples, dependent claims, or related patent families rather than in every asserted method claim.

What do claims 2 through 27 add?

The dependent claims create narrower positions around administration site, dosage, pharmacokinetics, use setting, and device operation.

Oral-mucosal site

Claims 2 and 3 specify:

Sublingual administration.
Buccal administration.

These claims provide separate coverage for two oral-mucosal locations. A product administered under the tongue is directly relevant to claim 2, while a product placed against the cheek is relevant to claim 3.

Tablet volume

Claim 4 narrows the tablet volume to less than 10 microliters. This limitation is commercially important because it targets highly compact tablets that can be placed under the tongue with limited saliva stimulation.

Sufentanil dose

Claim 5 lists specific doses:

5 micrograms
10 micrograms
15 micrograms
20 micrograms
40 micrograms
60 micrograms
80 micrograms
100 micrograms

Claim 23 separately covers 20 micrograms, while claim 24 covers 30 micrograms. The 30-microgram claim is particularly relevant to the FDA-approved Dsuvia strength, which contains 30 micrograms of sufentanil per sublingual tablet (FDA, 2018).

Bioavailability

Claims 6 through 8 require bioavailability greater than:

These claims are nested. A product with bioavailability above 85% would generally satisfy the lower thresholds as well, assuming the claimed testing methodology is comparable.

Tmax variability and repeat dosing

Claim 9 requires a Tmax coefficient of variation below 40%. Claim 10 requires repeated administration to produce a shorter Tmax than a single administration.

These limitations create potential infringement disputes over study design. Tmax varies with dose, patient population, sampling intervals, fasting status, administration technique, and analytical method. A patent dispute would likely focus on whether the accused product's clinical or pharmacokinetic data were generated under conditions comparable to those disclosed in the patent.

Therapeutic time ratio

Claim 11 requires a therapeutic time ratio from about 0.5 to about 2.0. This limitation is intended to capture a relationship between time to therapeutic effect and duration of effect. The meaning of the ratio depends on the specification's definition and testing protocol.

Percentage absorbed through the oral mucosa

Claim 12 lists thresholds from at least 55% through at least 99%. Claim 13 narrows the requirement to at least 60%.

These claims are technically significant because they distinguish the claimed tablet from dosage forms that depend heavily on gastrointestinal absorption after swallowing. The route-of-absorption calculation may be difficult to establish in practice and could become a central evidentiary issue in litigation.

Administration devices and self-administration

Claims 14 through 16 cover:

Administration using a device.
Self-administration.
Use of a single-dose applicator.

The single-dose applicator limitation is relevant to controlled placement of a very small tablet. It also supports operational use in emergency, military, and prehospital settings.

Pain indications and treatment settings

Claims 17 through 22 cover pain relief and specific treatment environments:

Acute pain.
Breakthrough pain.
Post-operative pain.
Treatment by a paramedic or military medic.
Field treatment.
Non-sterile conditions.

Claims 20 through 22 are narrow method-of-use claims. They are commercially relevant to battlefield, ambulance, emergency-response, and other settings where intravenous access may be difficult.

Specific Tmax and erosion timing

Claim 25 recites an average Tmax of 40.8 ± 13.2 minutes. Claim 26 requires an AUC coefficient of variation below 30% after repeated administration. Claim 27 requires visual evidence of complete tablet erosion after approximately 5, 10, or 15 minutes.

These claims convert clinical and physical-performance data into infringement limitations. They may be useful against a product that is structurally similar but attempts to distinguish itself through a different intended use or label.

When does US Patent 8,202,535 expire?

The patent is generally reported with a March 1, 2027 expiration date. The operative expiration analysis must account for patent-term adjustment, terminal disclaimers, and any applicable patent-term extension. The USPTO patent record and Orange Book listing are the controlling sources for the final enforceable term (USPTO, 2012; FDA, 2024).

Event	Date or status
Patent	US 8,202,535
Patent title	Methods and compositions for treating pain
Patent type	Utility patent
Core technology	Sufentanil oral-transmucosal solid tablet
Reported expiration	March 1, 2027
Relevant FDA product	Dsuvia, sufentanil sublingual tablet
Regulatory pathway	New drug application
Likely generic pathway	ANDA, not biosimilar application

The expiration date should not be treated as the only exclusivity date. FDA regulatory exclusivity, pediatric exclusivity, patent-term adjustment, and other listed patents can affect the earliest lawful generic launch.

What is the Orange Book status of the patent?

The FDA Orange Book identifies patents submitted by an NDA holder for an approved drug and records patent expiration dates and, where applicable, use codes. Dsuvia's Orange Book position must be reviewed together with the complete list of patents associated with the product, rather than by analyzing US 8,202,535 alone (FDA, 2024).

An Orange Book listing does not automatically establish infringement. It gives the NDA holder a basis to invoke the Hatch-Waxman patent-certification and notice procedures when an ANDA applicant challenges a listed patent.

For this patent, the relevant Orange Book questions are:

Whether US 8,202,535 remains listed for Dsuvia.
Which NDA strength and method-of-use codes are associated with the listing.
Whether the patent is listed for all approved uses or only particular uses.
Whether later-issued formulation or device patents create additional barriers.
Whether an ANDA applicant has made a Paragraph IV certification.

What Paragraph IV challenges are possible?

A generic applicant seeking approval for an equivalent sufentanil sublingual tablet could make a Paragraph IV certification asserting that the listed patent is:

Invalid.
Unenforceable.
Not infringed.

The most credible noninfringement strategies would focus on claim limitations that are difficult to establish from a product label alone:

Tablet volume outside the claimed 3-to-15 microliter range.
Lack of substantially continuous mucosal adhesion.
Greater swallowing of drug.
Less than 50% oral-transmucosal delivery.
Tmax outside the claimed interval.
Different bioavailability or absorption characteristics.
A formulation that dissolves without maintaining adhesion.

Validity challenges could target anticipation, obviousness, written description, enablement, indefiniteness, or lack of patentable distinction over known sufentanil and oral-transmucosal delivery systems. The functional terms "minimal saliva response," "minimal swallowing," "substantially throughout," and "about" could receive close scrutiny under Section 112 of the Patent Act.

A Paragraph IV filing would ordinarily trigger a 45-day period for the NDA holder to file suit. A timely suit could impose a 30-month stay on FDA approval, subject to statutory exceptions and court action under the Hatch-Waxman Act (21 U.S.C. § 355).

Which companies are challenging the patent?

The supplied claim record does not establish a named Paragraph IV challenger, ANDA filing, or active infringement case against US 8,202,535. A patent number alone cannot establish that a generic challenge exists.

Public litigation and FDA records should be examined for:

ANDA applicants for sufentanil sublingual tablets.
Abbreviated new drug application litigation involving Dsuvia.
Notices of Paragraph IV certification.
Declaratory-judgment actions.
Settlements that delay generic launch.
License or supply agreements involving the dosage form.

No biosimilar pathway applies. Sufentanil is a chemically synthesized small molecule. A competing product would generally proceed through the ANDA pathway if it qualifies as therapeutically equivalent, or through a full NDA pathway if it differs materially in formulation, dosage form, delivery system, or clinical use.

What formulations are protected by the patent?

The patent is directed to a solid, substantially homogeneous, bioadhesive tablet. It does not broadly claim every sufentanil formulation.

Potentially covered formulations include:

Sublingual sufentanil microtablets.
Buccal sufentanil microtablets.
Small tablets with bioadhesive polymers.
Tablets designed to limit saliva production and swallowing.
Tablets producing predominantly transmucosal absorption.
Tablet-and-applicator systems where the method limitations are met.

Potentially differentiated formulations include:

Intravenous sufentanil.
Intramuscular sufentanil.
Conventional oral tablets.
Sublingual films.
Buccal films.
Lozenges that dissolve in saliva and are substantially swallowed.
Nasal sufentanil products.
Transdermal products.
Larger tablets outside the claimed volume.

The analysis depends on the accused product's actual characteristics, not merely its dosage form name. A film could potentially practice a broader related patent but would not necessarily satisfy the "solid tablet" requirement of claim 1.

How strong is the patent estate for Dsuvia?

The estate's strongest protection comes from the combination of:

A proprietary sufentanil dosage form.
Microvolume tablet geometry.
Bioadhesion.
Controlled oral-transmucosal delivery.
Defined pharmacokinetics.
A single-dose administration device.
Emergency and acute-pain use cases.

The estate is more vulnerable where claims depend on broad functional or numerical limitations. Competitors may be able to design around the patent by changing tablet dimensions, excipient selection, adhesion behavior, absorption route, or release profile.

A competitor that reproduces the same 30-microgram sublingual tablet profile would face greater risk than one developing an injectable product or a non-tablet oral delivery system.

How does this patent compare with competing sufentanil and fentanyl products?

Product category	Active ingredient	Delivery route	Relationship to US 8,202,535
Dsuvia	Sufentanil	Sublingual tablet	Core commercial product profile
Injectable sufentanil	Sufentanil	Intravenous or intramuscular	Generally outside the claimed route and dosage form
Actiq	Fentanyl	Oral transmucosal lozenge	Different active ingredient and dosage form
Fentora	Fentanyl	Buccal tablet	Different active ingredient and formulation
Abstral	Fentanyl	Sublingual tablet	Different active ingredient
Nasal opioids	Various	Intranasal	Different delivery route

Fentanyl products may be commercially competitive in acute or breakthrough pain, but they do not directly anticipate infringement merely because they use oral transmucosal delivery. The active ingredient and dosage form remain important claim distinctions.

What generic launch risks exist after patent expiration?

After the reported 2027 patent expiration, generic launch risk will depend on the remaining Dsuvia patent portfolio, FDA approval requirements, manufacturing capability, and market size.

A generic entrant could pursue several strategies:

An ANDA for a 30-microgram sublingual tablet.
A different-strength product supported by a separate NDA.
A non-tablet sublingual formulation.
A buccal formulation.
A hospital-use sufentanil product with a different delivery system.
A product licensed from the incumbent or an alternate manufacturer.

Manufacturing barriers may remain significant. The product requires precise low-dose content uniformity, tablet-size control, adhesion performance, stability testing, packaging, and reliable single-dose placement. Those barriers are commercial and regulatory, even when patent protection has expired.

What is the likely revenue exposure?

US 8,202,535 is most relevant to revenue generated by a proprietary oral-transmucosal sufentanil product, not to the entire sufentanil market. Revenue exposure depends on:

Dsuvia sales by hospital and government customers.
Military and emergency-response procurement.
Hospital formulary adoption.
The extent of substitution by injectable sufentanil.
Availability of alternative fentanyl products.
Remaining patents and regulatory exclusivity.
Generic development economics.

The patent's commercial value is therefore linked to the premium associated with controlled, needle-free administration in acute-care settings. It does not create exclusivity over sufentanil as an active ingredient across all dosage forms.

Key Takeaways

US 8,202,535 is a method patent centered on a small, bioadhesive sufentanil tablet administered to oral mucosa.
Claim 1 requires all major physical, absorption, adhesion, saliva, and Tmax limitations.
The claim is most relevant to sublingual microtablets resembling the Dsuvia product profile.
Injectable sufentanil and conventional oral dosage forms generally fall outside the independent claim.
Claims 2 through 27 add sublingual and buccal use, specified doses, bioavailability thresholds, Tmax parameters, device use, and field-treatment settings.
The patent is generally reported to expire on March 1, 2027, subject to the controlling USPTO and Orange Book records.
A Paragraph IV challenge could focus on tablet size, transmucosal absorption, adhesion, pharmacokinetics, claim construction, obviousness, and enablement.
Sufentanil is a small molecule, so competing products would generally use the ANDA or NDA pathways, not the biosimilar pathway.
The commercial patent risk is concentrated in an equivalent oral-transmucosal tablet, not in the broader injectable sufentanil market.
Manufacturing precision, low-dose uniformity, applicator design, and clinical pharmacokinetic performance remain meaningful post-patent barriers.

FAQs

Does US Patent 8,202,535 cover all sublingual sufentanil products?

No. The claims require a solid tablet with specific volume, adhesion, absorption, saliva, and Tmax characteristics. A sublingual sufentanil film, lozenge, or tablet outside those parameters may not infringe.

Is a 30-microgram sufentanil tablet automatically covered?

No. Claim 24 recites a 30-microgram tablet, but the tablet must still satisfy the limitations incorporated from claim 1, including volume, bioadhesion, oral-transmucosal delivery, minimal swallowing, and Tmax.

Can a generic avoid the patent by changing the tablet excipient?

Potentially. A changed excipient may support noninfringement if it causes different adhesion, dissolution, absorption, or pharmacokinetic results. The change must be evaluated against every claim limitation and the doctrine of equivalents.

Does the patent cover a sufentanil buccal film?

Not necessarily. The independent claim specifies a solid tablet. A buccal film could fall outside the literal dosage-form limitation, although related patents or other claims could present separate risks.

Is an FDA-approved injectable sufentanil product blocked by this patent?

Generally no. The patent claims oral-mucosal administration of a small bioadhesive tablet. Injectable sufentanil products use a different dosage form and administration route.

References

AcelRx Pharmaceuticals, Inc. (2012). Methods and compositions for treating pain, U.S. Patent No. 8,202,535. United States Patent and Trademark Office.

Food and Drug Administration. (2018). Dsuvia (sufentanil) sublingual tablet prescribing information. U.S. Department of Health and Human Services.

Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.

United States Code. (2024). 21 U.S.C. § 355: New drug application approval and patent certifications.

United States Patent and Trademark Office. (2024). Patent Center and patent term information. U.S. Department of Commerce.

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	8,202,535	⤷ 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
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,202,535

Which drugs does patent 8,202,535 protect, and when does it expire?

Summary for Patent: 8,202,535