United States Patent 5,589,180: Scope, Claims, Expiration, and Lidocaine Patch Patent Landscape

U.S. Patent No. 5,589,180 covers a topical lidocaine plaster for herpes zoster pain and post-herpetic neuralgia. Its core limitations are a physiologically acceptable adhesive, 2% to 10% lidocaine with at least part present as free-base lidocaine, propylene glycol or glycerin as a co-solvent, and a covering. The patent issued on December 31, 1996, and its ordinary U.S. patent term expired in 2015. It is no longer an enforceable barrier to generic or competing lidocaine patches.

The patent remains relevant as prior art and as a technical foundation for understanding later lidocaine patch patents, including patents associated with Lidoderm and subsequent generic products.

What does U.S. Patent 5,589,180 cover?

The patent covers a medicated plaster that delivers lidocaine through or from an adhesive matrix. The claims are directed to composition and structural features rather than to a particular manufacturing process.

Core element	Scope under the claims
Active ingredient	Lidocaine
Lidocaine concentration	2% to 10% by weight of the adhesive in claim 1
Lidocaine form	At least partly free-base lidocaine
Adhesive	Physiologically acceptable adhesive
Co-solvent	Propylene glycol, glycerin, or both
Additional solvent components	D-sorbitol and/or water under dependent claims
Covering	Polymer film, synthetic rubber, woven polyester, or non-woven polyester
Indication	Pain associated with herpes zoster or post-herpetic neuralgia
Narrow formulation	5% lidocaine with water, glycerin, sodium polyacrylate and propylene glycol
Narrow covering	Non-woven polyester
Further limitation	Sodium carboxymethylcellulose

The patent is directed to a lidocaine-containing plaster, not to all topical lidocaine products. A cream, ointment, gel, spray, injectable product, oral dosage form, or patch using an adhesive system outside the claimed compositional ranges would not fall within the literal scope of the principal claims.

What are the independent claims of U.S. Patent 5,589,180?

The patent contains two principal independent composition claims as presented in the supplied claim set.

Claim 1: Broad plaster formulation

Claim 1 requires:

A plaster composition;
For treatment of pain from herpes zoster or post-herpetic neuralgia;
A physiologically acceptable adhesive;
2% to 10% lidocaine by weight;
Lidocaine present at least partly as the free base;
Propylene glycol, glycerin, or both as a co-solvent; and
A covering.

This is the broadest claim in the supplied set. It does not require a particular polymer adhesive, a particular backing material, water, D-sorbitol, sodium polyacrylate, or sodium carboxymethylcellulose.

A competing product could avoid the literal concentration limitation by using less than 2% or more than 10% lidocaine, subject to other patent and regulatory considerations. It could also avoid the literal co-solvent limitation by omitting propylene glycol and glycerin, although formulation equivalence and other claim sets would require separate analysis.

Claim 5: Narrow 5% lidocaine embodiment

Claim 5 requires a more specific formulation:

Lidocaine at 5% by weight of the adhesive;
Water;
Glycerin;
Sodium polyacrylate;
Propylene glycol; and
A non-woven polyester covering.

This claim is materially narrower than claim 1. It is directed to a defined hydrogel or polymeric adhesive system rather than the full range of physiologically acceptable adhesives and covering materials.

Claim 6: Sodium carboxymethylcellulose version

Claim 6 adds sodium carboxymethylcellulose to the claim 5 formulation. A product would need to satisfy all limitations of claim 5 and include the additional cellulose component to fall within the literal scope of claim 6.

What patent-number and claim errors appear in the supplied text?

The supplied claim set contains apparent dependency errors:

Claim 3 states "the plaster according to claim 3," which is self-referential and technically defective.
Claim 4 also states "the plaster according to claim 3," although the intended dependency may have been claim 2 or claim 3.
Claim 5 is independent and does not depend on claim 3.
Claim 6 properly depends on claim 5.

The official issued patent controls. A claim transcription, database record, or amended version should not replace the text of the issued patent when assessing validity or infringement. The claim language supplied here is sufficient for scope analysis, but the dependency errors should be treated as drafting or transcription issues rather than as substantive expansion of claim scope.

How should the herpes-zoster limitation be interpreted?

The preamble identifies the intended therapeutic use: treatment of herpes zoster pain or post-herpetic neuralgia. The operative body of claim 1 focuses on the physical composition of the plaster.

For composition claims, an intended-use limitation may have limited effect if the claimed structure is otherwise defined by its ingredients and construction. A lidocaine plaster with the claimed formulation could potentially be structurally identical whether marketed for post-herpetic neuralgia, localized neuropathic pain, or another indication.

The indication remains commercially relevant because the patent specification and claim language connect the plaster to localized neuropathic pain. It does not, however, convert every lidocaine patch into an infringing product merely because the product can treat pain.

What formulations are protected by U.S. Patent 5,589,180?

Broad formulation category

Claim 1 potentially reaches plasters containing:

2% to 10% lidocaine;
Some lidocaine in free-base form;
A physiologically acceptable adhesive;
Propylene glycol and/or glycerin;
A covering.

The claim does not require that all lidocaine be present as free base. "At least in part as the free base" allows a formulation containing a mixture of free-base lidocaine and another lidocaine form, provided the overall claim limitations are satisfied.

Solvent-enhanced formulation

Claims 2 and 4 add D-sorbitol and/or water. These claims are narrower because they require at least one of those additional components.

Polymer adhesive formulation

Claims 5 and 6 identify sodium polyacrylate and, in claim 6, sodium carboxymethylcellulose. These limitations distinguish the narrow claims from formulations using silicone, acrylic, rubber, or other adhesive systems without the listed ingredients.

Covering materials

The covering limitation in the supplied claims includes:

Polyvinyl chloride;
Polyvinylidene chloride;
Polyethylene;
Synthetic rubber;
Woven polyester fabric; and
Non-woven polyester fabric.

The covering is an external structural component. It is not necessarily the adhesive matrix itself. A product using a different backing material could avoid a covering limitation if the relevant claim requires the listed covering as a closed Markush group.

How strong is the patent estate for U.S. Patent 5,589,180?

The current enforceability of the patent is zero because the patent term expired. Its historical claim breadth was moderate.

Factor	Assessment
Composition breadth	Moderate for 2% to 10% lidocaine plasters
Formulation specificity	Broad in claim 1; narrow in claims 5 and 6
Product-form limitation	Limited to a plaster or patch format
Active ingredient	Limited to lidocaine
Solvent dependency	Significant, because propylene glycol or glycerin is required
Covering limitation	Narrows the relevant claim scope
Current enforceability	Expired
Current commercial value	Prior-art and freedom-to-operate relevance
Biosimilar relevance	None

The patent does not claim lidocaine generally. It also does not claim every transdermal delivery system. Its strongest historical position was against lidocaine plasters using the specified concentration, free-base component, co-solvents, adhesive matrix, and backing structure.

When did U.S. Patent 5,589,180 expire?

U.S. Patent 5,589,180 issued on December 31, 1996. The patent was subject to the post-1995 term rule, under which the term generally runs for 20 years from the earliest effective U.S. nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, patent-term extension, or other statutory modifications.[1]

The patent’s ordinary term expired in 2015. No current enforceable exclusivity remains under the patent. The patent therefore cannot block a present-day abbreviated new drug application, generic launch, formulation redesign, or commercial sale on the basis of patent rights under No. 5,589,180.

What is the FDA and Orange Book status of the patent?

U.S. Patent No. 5,589,180 is not the principal Orange Book patent associated with the Lidoderm 5% lidocaine patch. Lidoderm was approved by the FDA under NDA 020612 as a prescription lidocaine patch for post-herpetic neuralgia.[2]

The commercial exclusivity history for Lidoderm involved later patents and regulatory exclusivities associated with the approved product and its formulation. The existence of a lidocaine patch approval does not establish that Patent 5,589,180 was listed in the Orange Book for that product.

Orange Book listing is product-specific. A patent must be submitted by the NDA holder and satisfy FDA listing requirements. A patent’s technical similarity to an approved product does not itself create an Orange Book listing or a Paragraph IV certification obligation.[3]

Which later patents were more important to Lidoderm generic entry?

The commercial patent dispute surrounding Lidoderm focused principally on later Endo-related patents, including U.S. Patent No. 5,827,529 and other formulation and delivery patents. Those patents were asserted against generic applicants seeking approval for 5% lidocaine patches.

U.S. Patent No. 5,827,529 was associated with the Lidoderm patent estate and covered aspects of a lidocaine patch formulation and delivery system. Litigation involving generic applicants addressed patent validity, infringement, claim construction, and the impact of abbreviated new drug application certifications.[4]

The later patents were more commercially significant than Patent 5,589,180 because they were closer in time to the marketed Lidoderm product and were relevant to FDA-listed Orange Book patent disputes.

Were there Paragraph IV challenges to lidocaine patches?

Yes. Generic applicants challenged Lidoderm-related patents through Paragraph IV certifications under the Hatch-Waxman Act. Those challenges produced patent litigation involving generic manufacturers and the branded product sponsor.

The Paragraph IV process allowed generic applicants to assert that listed patents were invalid, unenforceable, or not infringed. A Paragraph IV certification can trigger patent litigation and a statutory 30-month stay of FDA approval, subject to the timing and procedural requirements of the Hatch-Waxman framework.[5]

Patent 5,589,180 itself was not the principal modern Paragraph IV obstacle to generic lidocaine patch approval because its term had expired before the later generic competition wave.

What litigation affected the Lidoderm patent estate?

The major litigation pattern involved:

Generic applicants filing ANDAs for 5% lidocaine patches;
Paragraph IV challenges to Orange Book-listed Lidoderm patents;
Brand-side infringement suits;
District court rulings on validity and infringement;
Federal Circuit review of selected patent issues; and
Settlements or commercial arrangements affecting launch timing.

Endo Pharmaceuticals and related entities litigated against generic manufacturers over Lidoderm patents. The litigation centered on later patents rather than the expired 5,589,180 patent.[4]

A party assessing present exposure should separate three questions:

Whether Patent 5,589,180 is enforceable, which it is not;
Whether later patents remain active for a particular lidocaine patch product; and
Whether a proposed generic formulation infringes any unexpired formulation, manufacturing, or method-of-use patent.

What generic launch risks remain for lidocaine patches?

The direct risk from Patent 5,589,180 is no longer present. Current risks may arise from:

Unexpired Orange Book patents listed for a branded lidocaine patch;
Later formulation patents;
Manufacturing-process patents;
Device or backing patents;
Method-of-use patents;
Patent term adjustments or extensions;
Regulatory exclusivity;
Product-specific labeling restrictions; and
State or federal trade-secret claims involving manufacturing methods.

For a standard 5% lidocaine patch, the key technical design-around variables include adhesive chemistry, solvent selection, backing composition, release liner, drug loading, water activity, release rate, and manufacturing sequence.

A formulation that copies the exact claim 5 combination would still not infringe Patent 5,589,180 because the patent has expired. It could, however, implicate later patents if the product reproduces a protected commercial formulation or manufacturing process.

Does Patent 5,589,180 create biosimilar risk?

No. Lidocaine is a chemically synthesized small molecule. A lidocaine patch is regulated through the drug pathway, generally involving an NDA or ANDA framework, not the biologic and biosimilar pathway under the Public Health Service Act.

The relevant competitive products are generic lidocaine patches, authorized generics, branded patches, and other topical or transdermal analgesic products. Biosimilar analysis is not applicable.

How does Patent 5,589,180 compare with later lidocaine patch patents?

Issue	U.S. Patent 5,589,180	Later Lidoderm-related patents
Main focus	Basic lidocaine plaster composition	Commercial product formulation, delivery and related features
Lidocaine range	2% to 10% in claim 1	Often directed to particular patch compositions or performance characteristics
Co-solvent limitation	Propylene glycol and/or glycerin	May use different or more detailed formulation limitations
Covering	Listed polymer and polyester materials	Product-specific backing and multilayer structures may be claimed
FDA relevance	Not the main modern Orange Book barrier	More directly connected to Lidoderm regulatory disputes
Current status	Expired	Must be reviewed patent by patent
Generic risk	None from this patent	Depends on remaining patents and certifications

What is the geographic coverage of the patent estate?

U.S. Patent 5,589,180 provided rights only in the United States. Related foreign applications or counterpart patents may have existed in jurisdictions including Japan and Europe, but their scope and expiration dates were separate.

A global freedom-to-operate review must examine:

U.S. patent family members;
European Patent Office records;
Japanese patent records;
Canadian and Australian equivalents;
National-phase filings;
Continuations and divisionals; and
Local patent-term adjustments.

Expiration of the U.S. patent does not automatically establish expiration or invalidity of every foreign counterpart.

Key Takeaways

U.S. Patent 5,589,180 covers a lidocaine plaster using 2% to 10% lidocaine, at least partly as free base, with propylene glycol and/or glycerin in a physiologically acceptable adhesive.
The narrower claims cover water, D-sorbitol, sodium polyacrylate, sodium carboxymethylcellulose, and specified polyester coverings.
The supplied claim text contains apparent dependency errors in claims 3 and 4.
The patent issued on December 31, 1996, and its ordinary term expired in 2015.
It is not a current enforceable barrier to generic lidocaine patches.
Lidoderm’s principal patent disputes involved later patents, including patents associated with its commercial formulation and delivery system.
Paragraph IV risk for lidocaine patches must be assessed against currently listed and unexpired Orange Book patents, not against No. 5,589,180.
Biosimilar analysis does not apply because lidocaine is a small-molecule drug.
Current product risk is more likely to involve later formulation, manufacturing, device, or method-of-use patents.

FAQs About U.S. Patent 5,589,180

Can a generic manufacturer copy the 5% lidocaine formulation in claim 5?

Yes, as a matter of this patent, because the patent has expired. The manufacturer must still assess later patents, FDA requirements, labeling, and any applicable non-patent restrictions.

Did U.S. Patent 5,589,180 protect Lidoderm itself?

It may have described technology relevant to lidocaine plasters, but it was not the principal modern Orange Book patent barrier associated with Lidoderm generic litigation. Later patents were more commercially important.

Is the patent still listed in the FDA Orange Book?

Patent listing is product-specific, and Patent 5,589,180 is not the principal current Orange Book patent associated with Lidoderm. Its expiration independently removes any enforceable patent protection.

Does using lidocaine hydrochloride avoid the patent?

Potentially, depending on the formulation and whether any lidocaine is present as free base. The claim expressly requires lidocaine at least partly as the free base, but infringement depends on the complete formulation and the construction of the claim terms.

Can a non-woven polyester backing avoid claim 5?

No. Claim 5 expressly requires a non-woven polyester covering. Using another covering could avoid literal infringement of claim 5, but the product would still need to be evaluated against claim 1 and any later patent claims.

References

United States Patent and Trademark Office. (2024). Patent term calculator and patent term provisions. https://www.uspto.gov/patents/laws/patent-term-calculator
U.S. Food and Drug Administration. (1999). Lidoderm prescribing information, NDA 020612. https://www.accessdata.fda.gov
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book
United States Court of Appeals for the Federal Circuit. (2012). Endo Pharmaceuticals Inc. v. Actavis, Inc., and related Lidoderm patent litigation decisions. https://www.cafc.uscourts.gov
U.S. Food and Drug Administration. (2024). ANDA submissions: Paragraph IV certifications and patent-related requirements. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/abbreviated-new-drug-application-anda-forms-and-submissions||||

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	161735	⤷ Start Trial
Canada	1338779	⤷ Start Trial
Germany	69031879	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,589,180

Summary for Patent: 5,589,180