US Patent 4,797,405: Pergolide Light-Stabilized Composition Claims, Expiration, and Patent Landscape

US Patent 4,797,405 protects pharmaceutical compositions and stabilization methods for pergolide, particularly pergolide mesylate formulations containing polyvinylpyrrolidone, alpha-tocopherol succinate, or propyl gallate. The strongest practical protection is concentrated in claims 3 through 5 and 8 through 10, which require pergolide mesylate and specify polyvinylpyrrolidone at 0.3% to 2.0%, or 0.5% to 1.5%, by total composition weight.

The patent issued on January 10, 1989. Because it predates the transition to the modern 20-year-from-earliest-effective-filing-date term, its ordinary US term was generally 17 years from grant, subject to any applicable adjustment, disclaimer, or regulatory extension. The patent therefore expired no later than January 10, 2006, absent an unusual term event. It does not present a current US blocking patent for pergolide products.

What does US Patent 4,797,405 protect?

The patent covers two related categories:

Pharmaceutical compositions containing pergolide or a pergolide salt and a specified light-stabilizing agent.
Methods of stabilizing such compositions against light-induced decomposition.

The claimed invention is directed to a formulation problem rather than to the discovery of pergolide itself. The patent does not broadly claim pergolide as an active pharmaceutical ingredient. It claims the combination of pergolide, a selected stabilizer, and pharmaceutically acceptable excipients, with stabilization against decomposition by light.

Core claim architecture

Claim group	Claim type	Active ingredient	Stabilizer	Additional limitation
1	Composition	Pergolide or salt	PVP, alpha-tocopherol succinate, or propyl gallate	Amount sufficient to stabilize against light decomposition
2	Composition dependent claim	Pergolide mesylate	Same as claim 1	Pergolide must be mesylate
3	Composition dependent claim	Pergolide mesylate	Polyvinylpyrrolidone	No specific concentration beyond claim 1
4	Composition dependent claim	Pergolide mesylate	Polyvinylpyrrolidone	0.3% to 2.0% by total composition weight
5	Composition dependent claim	Pergolide mesylate	Polyvinylpyrrolidone	0.5% to 1.5% by total composition weight
6	Method	Pergolide or salt	PVP, alpha-tocopherol succinate, or propyl gallate	Incorporating stabilizer into composition
7	Method dependent claim	Pergolide mesylate	Same as claim 6	Pergolide must be mesylate
8	Method dependent claim	Pergolide mesylate	Polyvinylpyrrolidone	No specific concentration beyond claim 6
9	Method dependent claim	Pergolide mesylate	Polyvinylpyrrolidone	0.3% to 2.0% by total composition weight
10	Method dependent claim	Pergolide mesylate	Polyvinylpyrrolidone	0.5% to 1.5% by total composition weight

How should the claims be construed?

The claims contain both structural and functional limitations. A potentially covered product must satisfy each required limitation.

Claim 1: broadest composition claim

Claim 1 requires:

pergolide or a salt of pergolide;
a therapeutically effective amount;
one of three specified stabilizers;
an amount of stabilizer sufficient to stabilize the composition against light decomposition; and
pharmaceutically acceptable excipients.

The stabilizer limitation is closed in substance. The claim identifies polyvinylpyrrolidone, alpha-tocopherol succinate, and propyl gallate. A formulation using a different antioxidant or polymer would not literally satisfy the listed-stabilizer limitation.

The claim does not prescribe a numerical concentration. The required amount is functional: it must be sufficient to effect stabilization against decomposition by light. That language creates a product-characterization issue. Evidence could include stability data, comparative degradation results, assay results, impurity profiles, or formulation development records.

Claim 2: pergolide mesylate limitation

Claim 2 narrows claim 1 by requiring pergolide mesylate. The salt form matters. A product containing a different pergolide salt would fall outside the literal scope of claim 2 but could remain relevant to claim 1 if the other claim elements were met.

Claims 3 through 5: commercially important PVP claims

Claim 3 requires pergolide mesylate and polyvinylpyrrolidone. It does not specify a concentration range.

Claim 4 limits the PVP content to 0.3% through 2.0% by weight of the total composition. Claim 5 narrows that range to 0.5% through 1.5%.

These narrower claims are more specific and easier to test against a finished product, manufacturing formula, or regulatory filing. They are also more vulnerable to noninfringing formulation design if a product uses a different stabilizer or PVP concentration outside the claimed ranges.

Claims 6 through 10: method claims

The method claims require incorporating the selected stabilizer into a pergolide composition. The claims are not limited to a particular manufacturing process such as wet granulation, direct compression, blending, or coating. The central method step is incorporation of the stabilizer in an amount sufficient to stabilize against light decomposition.

Claims 9 and 10 mirror the numerical PVP ranges in claims 4 and 5. A process that makes a pergolide mesylate formulation containing PVP within one of those ranges could have implicated the method claims during the patent term, even if the final dosage form differed in tablet coating, packaging, or excipient selection.

What formulations are protected by US 4,797,405?

The most clearly protected formulation profile was:

pergolide mesylate;
PVP as the stabilizer;
PVP at 0.3% to 2.0% of the total composition, or more narrowly 0.5% to 1.5%;
conventional pharmaceutical excipients; and
demonstrated or intended protection against light-induced decomposition.

The claims do not require a specific dosage strength, tablet size, release profile, coating, colorant, package, or route of administration. A conventional immediate-release tablet could fall within the claims if it satisfied the active ingredient and stabilizer limitations.

Formulation design-around pathways

During the patent term, potential design-around strategies would have included:

using alpha-tocopherol succinate or propyl gallate instead of PVP;
using a different stabilizer not named in the claims;
omitting the claimed stabilizers and relying on light-resistant packaging or an opaque coating;
using a different pergolide salt to avoid the mesylate-dependent claims;
placing PVP outside the claimed concentration ranges, subject to the broader claims;
using a formulation in which PVP was present but not shown to provide the claimed light stabilization, subject to the functional language in claim 1; or
developing a different dosage form with a formulation that did not contain one of the claimed stabilizers.

Packaging alone would not necessarily avoid claim 1 or claim 6 if the composition also contained a listed stabilizer in an amount sufficient to stabilize against light decomposition.

When did US Patent 4,797,405 lose exclusivity?

US Patent 4,797,405 issued January 10, 1989. Its ordinary patent term expired in January 2006 under the pre-1995 US patent-term regime.

Event	Date or status
Patent issued	January 10, 1989
Ordinary pre-1995 patent term	17 years from issue
Expected ordinary expiration	January 10, 2006
Current enforceability	Expired
Current product blocking effect	None based on this patent

The patent is therefore relevant to historical formulation strategy, legacy litigation analysis, and freedom-to-operate review of historical products. It is not a live US exclusivity barrier for a current generic or reformulated pergolide product.

What is the FDA and Orange Book status of pergolide?

Pergolide was marketed in the United States primarily as Permax, a pergolide mesylate product associated with Eli Lilly and Company. The FDA approved Permax for adjunctive treatment of Parkinson's disease. The product was withdrawn from the US market in 2007 after evidence linked pergolide to increased risks of cardiac valvular disease and related fibrotic disorders. The FDA requested withdrawal of pergolide products from the US market, and commercial distribution of Permax in the United States ended.

The FDA's regulatory action materially changed the commercial importance of the patent estate. By the time US Patent 4,797,405 expired, the branded product had already been withdrawn from the US market.

Orange Book implications

The patent is not a current Orange Book barrier. Any historical Orange Book listing associated with Permax or pergolide mesylate would not create an active patent or exclusivity period after expiration.

The principal regulatory points are:

pergolide is a small-molecule drug, not a biologic;
biosimilar procedures under the Biologics Price Competition and Innovation Act do not apply;
an abbreviated new drug application, rather than a biosimilar application, would be the relevant US pathway for a generic pergolide product;
an expired formulation patent cannot support a current Paragraph IV challenge; and
a new generic applicant could still face regulatory, clinical, supply, or market-access issues unrelated to patent expiration.

Which companies challenged pergolide exclusivity?

The supplied claim set does not identify a specific Paragraph IV litigation record, settlement, or license. The patent's age and expiration make current Paragraph IV activity unnecessary. Any historical challenge would have concerned a patent that expired in 2006 and a branded product later withdrawn in 2007.

No current US biosimilar challenger exists because pergolide is not a biologic. Any competitive entry would be a small-molecule generic or a new drug application for a reformulated product.

A complete litigation history should distinguish among:

patent infringement actions involving US 4,797,405;
FDA Paragraph IV notices;
product-liability litigation involving pergolide-associated cardiac risks;
regulatory withdrawal proceedings; and
commercial disputes involving Permax distribution.

Those categories have different legal issues. The FDA withdrawal was a safety and regulatory event, not a patent invalidity determination.

How strong was the patent estate for pergolide?

US 4,797,405 was a narrow formulation patent rather than a broad compound or therapeutic-use patent. Its strength depended on the presence of one of three named stabilizers and, for the narrowest claims, PVP within specified concentration ranges.

Strength assessment

Factor	Assessment
Compound coverage	None apparent from the supplied claims
Salt coverage	Broad independent claims cover pergolide salts; dependent claims focus on mesylate
Formulation coverage	Specific to three stabilizers and light stabilization
PVP coverage	Strongest in claims 3-5 and 8-10
Numerical concentration limits	0.3%-2.0% and 0.5%-1.5%
Packaging coverage	None expressly stated
Dosage-form limitation	None expressly stated
Method coverage	Incorporation of stabilizer into the composition
Current enforceability	None because the patent expired
Biosimilar relevance	None
Generic-entry relevance	Historical only

The independent claims have breadth because they cover pergolide or any pergolide salt and do not impose a dosage form or numerical stabilizer amount. Their vulnerability is that they depend on proof of light stabilization and use a limited list of stabilizers.

The dependent claims have less breadth but greater claim clarity. A tablet formula containing pergolide mesylate and PVP at 0.5% to 1.5% would have presented a direct historical infringement question.

What patent landscape surrounded pergolide?

The relevant pergolide landscape can be divided into five layers.

Compound and core pharmaceutical patents

These patents concern the chemical entity, its salts, stereochemistry, synthesis, or pharmaceutical activity. They are distinct from US 4,797,405, which does not claim the pergolide molecule itself based on the supplied claims.

Formulation and stability patents

US 4,797,405 belongs to this category. Its focus is protection against photodecomposition through selected stabilizers.

Other relevant formulation concepts would include:

moisture stabilization;
oxidation control;
tablet compression and granulation;
coating systems;
modified-release dosage forms;
packaging configurations;
impurity control; and
manufacturing processes that preserve assay and degradation limits.

Method-of-use patents

The patent claims provided do not claim treatment of Parkinson's disease, restless legs syndrome, hyperprolactinemia, or another indication. Any such rights would have to be analyzed separately.

Regulatory exclusivity

Pergolide is not protected by a current US regulatory exclusivity period. The product's market withdrawal also limits the commercial value of any historical regulatory protection.

Manufacturing and supply-chain barriers

Patent expiration does not eliminate all entry barriers. A new pergolide product would still require:

a lawful active pharmaceutical ingredient supply;
validated impurity controls;
stability data;
suitable light-protection measures;
regulatory approval or reapproval;
clinical and labeling support where required; and
a viable commercial market after the Permax withdrawal.

For this product, regulatory and market risks are more significant than the expired formulation patent.

What generic launch risks exist for pergolide products?

A generic launch based solely on patent expiration would face limited patent risk from US 4,797,405 because the patent is expired. The principal risks would arise elsewhere.

Risk category	Current significance
Expired formulation patent	Low
Active US patent blocking generic launch	Not shown by this patent
Paragraph IV exposure	None based on an expired patent
Biosimilar pathway	Not applicable
FDA safety history	High
Commercial demand	Limited and uncertain after withdrawal
API availability	Potentially material
Light-stability requirements	Technically material but not patent-blocking under this expired patent
Product-liability exposure	Material
Reintroduction strategy	May require substantial regulatory work

A product using PVP, alpha-tocopherol succinate, or propyl gallate may still be technically sensible because of pergolide's light sensitivity. The expired patent does not prevent use of those formulation approaches. It only removes the historical patent constraint.

What licensing deals and settlement agreements are publicly relevant?

The supplied patent claims do not establish a licensing agreement, royalty arrangement, or settlement. No licensing or settlement right can be inferred from the patent text alone.

Any historical commercial agreement would require separate evidence from:

assignment records;
USPTO maintenance and ownership records;
SEC filings;
litigation dockets;
FDA approval files; or
settlement documents.

Because the patent expired in 2006, any surviving license would generally be relevant only to historical accounting, chain-of-title, or dispute analysis, not to current market exclusion.

How does this patent compare with a compound patent?

Issue	US 4,797,405 formulation patent	Compound patent
Protected subject matter	Stabilized pergolide composition and method	Pergolide molecule or chemical class
Product dependence	Requires named stabilizer	May cover the active ingredient broadly
Design-around potential	Relatively high	Usually lower before expiration
Evidence required	Formulation composition and stabilization	Chemical identity
Typical commercial effect	Protects a product configuration	Can block broad generic substitution
Current status	Expired	Must be assessed separately
Regulatory relevance	Historical formulation protection	Potentially broader historical exclusivity

The patent was commercially meaningful only if the marketed or proposed pergolide product used one of the claimed stabilizer systems. It was never equivalent to a basic patent on pergolide.

Key Takeaways

US Patent 4,797,405 claims light-stabilized pergolide compositions and stabilization methods.
The listed stabilizers are polyvinylpyrrolidone, alpha-tocopherol succinate, and propyl gallate.
The narrowest and most commercially important claims require pergolide mesylate with PVP at 0.3% to 2.0%, or 0.5% to 1.5%, by total composition weight.
The patent issued January 10, 1989 and ordinarily expired January 10, 2006.
It is not a current US patent barrier to generic pergolide entry.
Pergolide is a small molecule, so biosimilar analysis does not apply.
Permax was withdrawn from the US market in 2007 after FDA safety concerns involving cardiac valvular disease.
Current commercial risk is driven more by regulatory safety, supply, liability, and market-demand issues than by this expired formulation patent.
No licensing agreement, Paragraph IV settlement, or active litigation can be established from the claim text alone.

FAQs

Does US Patent 4,797,405 cover all pergolide tablets?

No. It covers pergolide compositions containing one of the specified stabilizers in an amount sufficient to stabilize against light decomposition. A pergolide tablet using a different stabilizer or no listed stabilizer would not necessarily fall within the claims.

Does the patent cover pergolide mesylate without polyvinylpyrrolidone?

Potentially, under claims 1 and 2, if the formulation contains alpha-tocopherol succinate or propyl gallate and satisfies the light-stabilization limitation. Claims 3 through 5 require polyvinylpyrrolidone.

Is a pergolide product using PVP at 2.5% within claims 4 or 5?

No, 2.5% is outside the express 0.3% to 2.0% range in claim 4 and the 0.5% to 1.5% range in claim 5. The broader independent claims could still require separate analysis if the other elements were present, although the patent is expired.

Could opaque packaging avoid infringement of this patent?

Opaque packaging could help reduce light exposure, but it would not automatically avoid the claims if the composition also contained a listed stabilizer in a sufficient amount. The patent claims focus on the composition and stabilization method, not solely on packaging.

Can a company launch a pergolide generic based on expiration of this patent?

Patent expiration removes the barrier created by US 4,797,405. A launch would still depend on FDA regulatory requirements, product safety, API supply, stability, labeling, and commercial feasibility.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	79258	⤷ Start Trial
Australia	2408088	⤷ Start Trial
Australia	611494	⤷ Start Trial
Canada	1318253	⤷ Start Trial
Germany	3873688	⤷ Start Trial
Denmark	174831	⤷ Start Trial
Denmark	583188	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,797,405

Summary for Patent: 4,797,405