US Patent 5,340,821: Scope, Claims, Expiration, and Cevimeline Patent Landscape

US Patent 5,340,821 covers a method of treating Sjögren syndrome symptoms with spirooxathiolane-quinuclidine compounds, principally cis-cevimeline hydrochloride. The patent is a method-of-use patent, not a composition-of-matter patent. Its principal commercial relevance was the use of cevimeline hydrochloride, later marketed as Evoxac, for xerostomia associated with Sjögren syndrome.

The patent is expired and does not currently block generic cevimeline hydrochloride products. Its claims did not cover every use of cevimeline, every formulation, or the underlying compound independent of treatment of Sjögren syndrome.

What does US Patent 5,340,821 cover?

US 5,340,821 covers administering a defined class of spirooxathiolane-quinuclidine compounds, or acid-addition salts of those compounds, in an amount sufficient to alleviate symptoms of Sjögren syndrome.

The commercial species is:

Active ingredient: cevimeline
Chemical description: 2-methylspiro[1,3-oxathiolane-5,3'-quinuclidine]
Claimed salt: hydrochloride
Claimed stereochemistry: cis isomer
Primary therapeutic effect: relief of Sjögren-related dryness symptoms, particularly dry mouth
Dosage-form limitation: none in claims 1 through 3
Carrier limitation: added by dependent claim 4

The patent is therefore best characterized as a therapeutic-use patent with a species claim directed to cis-cevimeline hydrochloride.

Patent identification

Field	Details
Patent	US 5,340,821
Title	Treatment of Sjögren's syndrome
Patent type	Method of treatment
Relevant compound	Spirooxathiolane-quinuclidine compounds
Commercial compound	Cevimeline
Commercial salt	Cevimeline hydrochloride
Commercial product	Evoxac
Original therapeutic field	Sjögren syndrome and associated dryness symptoms
Issue date	August 23, 1994
Patent status	Expired
Key claim type	Method of use
Composition-of-matter protection	Not provided by the asserted claims

How should the four claims be interpreted?

Claim 1: Broad genus method claim

Claim 1 covers:

A patient afflicted with Sjögren syndrome;
Administration of a spirooxathiolane-quinuclidine compound;
A compound having the disclosed Formula I;
An acid-addition salt as an alternative; and
An amount sufficient to alleviate disease symptoms.

The compound definition uses a Markush-style substituent structure in which Z is represented as =CR1R2. The substituents R1 and R2 may be hydrogen, alkyl, cyclopentyl, cyclohexyl, aryl, diarylmethylol, or alkyl substituted with one or more aryl groups.

The claim is broad at the chemical-class level but narrower at the therapeutic level. A product or treatment would need to fall within the defined structural class and be used to treat symptoms of Sjögren syndrome.

Claim 1 does not expressly require:

Cevimeline;
The hydrochloride salt;
The cis stereoisomer;
Oral administration;
A particular dose;
A particular dosage form;
A particular treatment duration;
A specific symptom such as xerostomia;
Concomitant treatment with another agent; or
A pharmaceutical carrier.

The phrase "an amount ... sufficient to alleviate the symptoms" is a functional treatment limitation. It requires a therapeutic administration, rather than merely identifying the compound or describing an in vitro effect.

Claim 2: Cevimeline hydrochloride species claim

Claim 2 narrows claim 1 to the hydrochloride salt of 2-methylspiro(1,3-oxathiolane-5,3')quinuclidine.

This is the claim most closely aligned with commercial cevimeline hydrochloride. It excludes other acid-addition salts unless they also fall within the claimed hydrochloride species. It also excludes other substituent variants covered by the broader genus in claim 1.

The claim does not expressly require a particular crystal form, hydrate state, particle size, purity level, or pharmaceutical formulation.

Claim 3: Cis-cevimeline hydrochloride claim

Claim 3 narrows claim 2 to the cis isomer.

This limitation is commercially important because cevimeline is stereochemically defined. A product containing the trans isomer, a racemate, or another stereochemical form would require separate analysis. A cis-cevimeline hydrochloride product would fall within the literal scope of claim 3 if the other claim elements were satisfied.

Claim 3 does not require a particular dosage form or manufacturing process. It is directed to the therapeutic administration of the specified stereoisomer and salt.

Claim 4: Pharmaceutical-carrier limitation

Claim 4 requires that the composition further comprise a pharmaceutically acceptable carrier.

This claim is dependent from claim 1, not claim 2 or claim 3. It therefore retains the broad compound-class language of claim 1 while adding a carrier limitation.

Examples of potentially relevant carriers include excipients used in tablets, capsules, oral solutions, suspensions, and other conventional pharmaceutical preparations. The claim does not identify a particular excipient, release profile, coating, dosage strength, or manufacturing method.

Because claim 4 depends from claim 1, a formulation containing cis-cevimeline hydrochloride and a carrier could fall within both claim 3 and claim 4, but claim 4 itself is not limited to cevimeline hydrochloride.

What therapeutic activity does the patent protect?

The patent protects use in Sjögren syndrome, rather than the general use of cevimeline for all diseases.

Sjögren syndrome is an autoimmune disorder associated with impaired lacrimal and salivary gland function. The commercial treatment objective is symptomatic stimulation of exocrine secretion, particularly saliva production.

The claim language is broad enough to cover alleviation of Sjögren-related symptoms generally. It does not expressly limit treatment to:

Dry mouth;
Dry eyes;
Salivary-gland dysfunction;
Lacrimal-gland dysfunction; or
A specific diagnostic classification of primary or secondary Sjögren syndrome.

A claim directed to treating another disease, such as radiation-induced xerostomia or medication-induced dry mouth, would not necessarily fall within the literal language of these claims because the patient must be afflicted with Sjögren syndrome.

What is the difference between the genus and species claims?

Claim	Chemical scope	Disease limitation	Key commercial relevance
1	Broad spirooxathiolane-quinuclidine genus and acid-addition salts	Sjögren syndrome	Broadest asserted therapeutic scope
2	2-methyl compound hydrochloride salt	Sjögren syndrome	Covers cevimeline hydrochloride
3	Cis-cevimeline hydrochloride	Sjögren syndrome	Closest claim to commercial cevimeline
4	Genus compounds plus pharmaceutical carrier	Sjögren syndrome	Formulated treatment under broad genus

Claim 1 supplies the broadest chemical coverage. Claim 3 supplies the most commercially specific protection for the marketed active pharmaceutical ingredient. Claim 4 adds a conventional formulation element but does not create a standalone composition-of-matter claim.

When did US Patent 5,340,821 lose exclusivity?

US 5,340,821 is expired. Its patent term is no longer an enforceable barrier to generic cevimeline hydrochloride entry.

The patent issued in 1994, when pre-1995 US patent-term rules generally applied a 17-year term from issuance. The effective commercial exclusivity period could also have been affected by regulatory patent-term extension or other statutory adjustments. The governing current status is expiration, not enforceability.

Event	Approximate timing
Patent issued	August 23, 1994
Cevimeline product approval	1999
Original patent-term framework	17 years from issuance for qualifying pre-June 8, 1995 applications
Patent status today	Expired
Current generic blocking effect	None from US 5,340,821

The patent should not be treated as an active Orange Book barrier merely because it historically covered the Evoxac indication. Expired patent claims cannot support a current infringement action.

What was the FDA and Orange Book relevance?

Evoxac, containing cevimeline hydrochloride, received FDA approval for the treatment of symptoms of dry mouth in patients with Sjögren syndrome. The approval was based on cevimeline's secretagogue activity and its use in the approved patient population.

The patent's claim language tracks the core approved indication but is not identical to the modern product label. Patent claims and FDA labeling operate under different legal standards:

The FDA label defines approved use, dosing, warnings, contraindications, and administration instructions.
The patent claims define enforceable legal rights.
Orange Book listing identifies patents submitted by the NDA holder as claiming the drug or an approved method of use.
An Orange Book listing does not expand the wording of the patent claims.

The patent was relevant historically to ANDA certification and potential Paragraph IV disputes. Its expiration removes the patent-based delay mechanism associated with this patent.

FDA regulatory status

Cevimeline hydrochloride remains an approved small-molecule prescription drug in the United States. It is not a biologic and does not use the biosimilar pathway.

The relevant abbreviated pathway for a competing product is an ANDA, assuming the applicant can demonstrate pharmaceutical equivalence and bioequivalence to the reference listed drug. A generic applicant may address listed patents through:

Paragraph I certification;
Paragraph II certification;
Paragraph III certification; or
Paragraph IV certification.

For an expired patent, a Paragraph III certification or a statement that no patent-related barrier remains would generally be more relevant than a current Paragraph IV challenge. The precise certification depends on the patents listed for the reference product at the time of ANDA submission.

Were Paragraph IV challenges relevant to this patent?

Yes, this patent could historically have been the subject of a Paragraph IV certification because it claimed an approved method involving cevimeline hydrochloride and Sjögren syndrome.

A Paragraph IV position could have challenged the patent on grounds such as:

Invalidity;
Noninfringement;
Lack of enforceable patent scope;
Defective claim construction;
Anticipation;
Obviousness;
Written-description or enablement deficiencies; or
Noninfringing labeling.

The commercial impact of a Paragraph IV certification would have depended on whether the patent remained unexpired and whether the generic label required the patented indication. After expiration, the patent no longer creates a material launch obstacle.

What other patents protected cevimeline?

The cevimeline estate historically included more than US 5,340,821. The relevant categories were:

Compound patents covering spirooxathiolane-quinuclidine derivatives;
Therapeutic-use patents covering Sjögren syndrome;
Salt, hydrate, or crystalline-form patents;
Pharmaceutical-composition patents;
Process patents; and
Regulatory exclusivity associated with the NDA.

The distinction matters because expiration of US 5,340,821 does not, by itself, establish that every historical cevimeline patent expired on the same date. A generic applicant would have needed to assess the complete Orange Book listing and any unlisted process or formulation rights.

Composition-of-matter protection

The underlying chemical class was addressed in earlier patent filings covering spirooxathiolane-quinuclidine derivatives. Those rights were separate from the Sjögren syndrome use claim in US 5,340,821.

Composition patents generally have greater strategic value than method-of-use patents because they can cover the compound regardless of indication. Once the relevant composition patent expires, a competitor can generally manufacture and sell the compound, subject to any remaining formulation, process, or use claims.

Salt and solid-state protection

Cevimeline hydrochloride may also have been subject to separate protection directed to salt preparation, hydrates, crystalline forms, or pharmaceutical quality characteristics. These rights can affect manufacturing strategy without preventing all generic entry.

A solid-state claim may be avoided by using:

A different polymorph;
A nonhydrated form;
A different salt;
A different crystallization process; or
A process that produces the same active ingredient without practicing a claimed manufacturing step.

The existence and current enforceability of any particular solid-state or process patent must be assessed separately from US 5,340,821.

How strong is the patent estate for US 5,340,821?

Historically, the patent had meaningful protection for the approved Sjögren syndrome use, but its scope had several limitations.

Strengths

Claim 3 directly targeted cis-cevimeline hydrochloride.
The claims covered treatment rather than a narrow dosage regimen.
The patent could have implicated an ANDA label carrying the Sjögren syndrome indication.
Claim 1 potentially reached related compounds beyond cevimeline.
Claim 4 addressed formulated administration using a pharmaceutically acceptable carrier.

Limitations

The patent did not claim cevimeline as a chemical entity independent of use.
It did not claim all indications for cevimeline.
It did not specify a commercially important dosage strength.
It did not claim a particular controlled-release or immediate-release formulation.
It did not claim a specific manufacturing process.
The therapeutic result had to relate to Sjögren syndrome symptoms.
The patent is expired.

The estate was therefore more valuable as an indication barrier during the protected period than as a durable platform patent.

What generic entry risks remain?

US 5,340,821 presents no current generic-entry risk because it is expired. Remaining risks would have to arise from other rights or regulatory issues, including:

A different unexpired Orange Book-listed patent;
A formulation or solid-state patent;
A process patent;
Product-specific exclusivity;
Regulatory deficiencies;
Bioequivalence failure;
Manufacturing supply constraints; or
Labeling disputes involving the approved Sjögren indication.

For a standard immediate-release generic cevimeline hydrochloride capsule or tablet, the principal patent risk is likely lower than it was during the original Evoxac exclusivity period. The commercial risk shifts toward market size, generic pricing, manufacturing reliability, and reimbursement.

Which companies compete in the cevimeline market?

The original branded product, Evoxac, was associated with Daiichi Pharmaceutical and later Daiichi Sankyo commercial operations. Cevimeline is a small-molecule drug with generic competition rather than biosimilar competition.

The competitive set includes:

Branded cevimeline hydrochloride;
Generic cevimeline hydrochloride;
Pilocarpine, another oral cholinergic secretagogue;
Supportive saliva substitutes and oral-moisturizing products; and
Off-label or adjunctive therapies for xerostomia.

Cevimeline and pilocarpine are not interchangeable from a patent or regulatory standpoint. They have different active ingredients, labeling histories, patent estates, and tolerability profiles.

How does cevimeline patent protection compare with pilocarpine?

Issue	Cevimeline	Pilocarpine
Drug class	Muscarinic agonist	Muscarinic agonist
Key US product	Evoxac	Salagen
Sjögren indication	Yes	Yes
Patent at issue	US 5,340,821	Separate pilocarpine patents
Patent type	Method of use	Compound, formulation, and use rights varied by product
Biosimilar pathway	Not applicable	Not applicable
Current competitive model	Generic small-molecule competition	Generic small-molecule competition
Main commercial substitute	Pilocarpine	Cevimeline and other xerostomia therapies

The two products compete clinically but do not share patent claims. Freedom-to-operate analysis for pilocarpine cannot be substituted for cevimeline analysis.

What geographic coverage did US 5,340,821 provide?

US 5,340,821 provided rights only in the United States. It did not create protection in Europe, Japan, Canada, or other markets.

International coverage would have depended on corresponding national applications and granted patents. The same invention could have had different:

Claim scope;
Filing dates;
Patent-term calculations;
Regulatory extensions;
Opposition outcomes;
Litigation histories; and
Expiration dates.

A US patent number cannot establish freedom to operate outside the United States.

What litigation and settlement issues are associated with the patent?

The principal litigation relevance of US 5,340,821 would have arisen from ANDA filings directed to generic cevimeline hydrochloride. A generic applicant with a Paragraph IV certification could have triggered patent litigation under the Hatch-Waxman framework.

The key legal questions would have included:

Whether the proposed generic label induced infringement;
Whether the patent claims were valid;
Whether the product contained the claimed cis isomer and hydrochloride salt;
Whether the proposed indication was carved out;
Whether an unapproved use remained in the label;
Whether the claims covered the relevant dosage form; and
Whether a settlement delayed generic launch.

No current enforceable litigation consequence can be attributed to this expired patent without a live case or settlement-specific record. Expiration ends the forward-looking injunction value of the patent, although historical settlement terms may remain relevant to competition-law or damages analysis.

Key Takeaways

US 5,340,821 is a method-of-use patent for treating Sjögren syndrome symptoms.
Claim 1 covers a broad genus of spirooxathiolane-quinuclidine compounds and acid-addition salts.
Claim 2 narrows the scope to cevimeline hydrochloride.
Claim 3 narrows the scope further to the cis isomer of cevimeline hydrochloride.
Claim 4 adds a pharmaceutically acceptable carrier but remains dependent on the broad genus claim.
The patent does not claim cevimeline as a compound independent of therapeutic use.
It does not claim every cevimeline indication, formulation, dosage, or manufacturing process.
The patent is expired and does not currently prevent generic cevimeline entry.
Any current freedom-to-operate review must examine other Orange Book-listed patents, formulation rights, solid-state rights, process patents, and regulatory requirements.
Cevimeline is a small-molecule drug. Biosimilar analysis is not applicable.

FAQs

Does US 5,340,821 claim Evoxac itself?

It claims therapeutic administration of compounds that include cis-cevimeline hydrochloride. It does not claim the drug as a composition independent of treating Sjögren syndrome.

Does the patent cover cevimeline for dry mouth caused by radiation therapy?

Not necessarily. The claims require a patient afflicted with Sjögren syndrome. Use for another cause of xerostomia would require a separate infringement analysis.

Does claim 4 cover a cevimeline tablet?

Potentially, if the tablet contains a compound within claim 1 and a pharmaceutically acceptable carrier, and is administered for treating Sjögren syndrome. The claim does not require a specific tablet design.

Is a generic cevimeline manufacturer exposed to this patent today?

No current infringement exposure arises from an expired patent. Exposure would have to come from another unexpired patent or from conduct occurring during the patent's effective term.

Can a competitor avoid claim 3 by selling trans-cevimeline?

A product containing only a non-cis stereoisomer may avoid the literal stereochemical limitation of claim 3, but claim 1 and other patents would require separate analysis. A stereoisomer change does not automatically eliminate all patent risk.

References

United States Patent and Trademark Office. (1994). Treatment of Sjögren's syndrome, U.S. Patent No. 5,340,821.
U.S. Food and Drug Administration. (n.d.). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application submissions: Patent certifications and 30-month stays. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/anda-submissions-content-and-format
U.S. Food and Drug Administration. (1999). Evoxac prescribing information. Daiichi Pharmaceutical Co., Ltd.
United States Code, 35 U.S.C. §§ 154, 156, and 271(e).

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Japan	4-207485	Jul 10, 1992

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	184483	⤷ Start Trial
Australia	4181993	⤷ Start Trial
Australia	666734	⤷ Start Trial
Canada	2099970	⤷ Start Trial
Germany	69326395	⤷ Start Trial
Denmark	0578511	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,340,821

Summary for Patent: 5,340,821