United States Drug Patent 4,205,086: Claim Scope, Expiration, Litigation Risk and Gallstone-Dissolution Patent Landscape

U.S. Patent No. 4,205,086 covers an invasive method for dissolving cholesterol-containing gallstones by perfusing a liquid fatty acid or fatty-acid ester adjacent to the stone. Its narrowest claims identify octanoic acid, decanoic acid, glycerol mono-octanoate, glycerol mono-decanoate and related esters.

The patent issued on May 27, 1980. Under the pre-Uruguay Round patent-term rule, its ordinary U.S. term ended on May 27, 1997, absent an unusual term adjustment or extension. No enforceable U.S. patent exclusivity remains under this patent. The claims do not create current blocking rights against generic ursodiol, chenodiol, laparoscopic gallstone surgery, or unrelated pharmaceutical products.

What does U.S. Patent 4,205,086 cover?

The patent covers a treatment method with five central limitations:

The patient has a cholesterol-containing gallstone.
A liquid, physiologically compatible compound is used.
The compound is perfused adjacent to the gallstone.
The compound is administered in an effective amount.
The objective is to solubilize at least part of the stone gradually.

The patent is therefore a method-of-treatment patent, not a composition-of-matter patent. It does not broadly claim octanoic acid, glycerol mono-octanoate, or other fatty-acid esters in all uses.

Core claim elements

Claim element	Scope
Disease target	Cholesterol-containing gallstone
Patient setting	Treatment in a patient
Delivery route	Perfusion adjacent to the gallstone
Physical form	Liquid
Compatibility	Physiologically compatible
Functional result	Solubilization of at least part of the stone
Timing	Gradual dissolution
Chemical class	Fatty acids, fatty-acid alcohol esters, or mixtures

The phrase “adjacent the gallstone” is the principal limiting feature. An oral formulation, intravenous formulation, or systemic treatment would not satisfy the express perfusion limitation merely because the active ingredient is chemically identical.

How broad is independent claim 1?

Claim 1 is broad in chemical class but narrow in clinical execution. It covers a liquid physiologically compatible compound selected from:

Fatty acids;
Alcohol esters of fatty acids; and
Mixtures of fatty acids and alcohol esters.

The claim does not limit the fatty acid to eight- to ten-carbon compounds. Later dependent claims impose that limitation for specific embodiments. Claim 1 also does not require a particular catheter, imaging technique, dose, perfusion pressure, dwell time, or stone size.

The principal infringement question would be whether a treatment protocol performs localized perfusion adjacent to a cholesterol-containing gallstone. A formulation manufacturer that sells the compound without directing or controlling that use would face a different analysis from a clinical operator who performs the claimed procedure.

What do claims 2 through 18 add?

Claims 2 through 18 progressively narrow the chemical class and carbon-chain range.

Claims	Added limitation	Practical effect
2	Esters of mono-, di- or polyhydric alcohols	Covers a wide range of alcohol ester structures
3	Mono-, di- and polyesters	Expands ester functionality within claim 2
4	About 8 to about 10 carbon atoms	Focuses on medium-chain compounds
5	Glycerides of octanoic and decanoic acid	Covers glycerol esters of C8 and C10 acids
6	Glycerol mono-octanoate	Specific monoester
7	C8-C10 fatty acids plus C8-C10 glycerides	Mixture claim
8	Octanoic acid plus glycerol mono-octanoate	Specific binary mixture
9	Octanoic acid, glycerol mono-octanoate, decanoic acid and glycerol mono-decanoate	Specific four-component mixture
10	C8-C10 fatty acids plus C8-C10 esters	Broader mixture formulation
11	Esters of C8-C10 fatty acids	Ester-only limitation
12	Propylene glycol mono-octanoate	Specific ester
13	Ethanol mono-octanoate	Ethyl octanoate-type embodiment
14	Fatty acids containing about 2 to about 12 carbon atoms	Broader fatty-acid range
15	Fatty acids containing about 8 to about 10 carbon atoms	Medium-chain subset
16	Esters of C8-C10 fatty acids	Combined fatty-acid and ester limitations
17	Mixture of fatty acids and alcohol esters	Combination therapy or formulation
18	Alcohol esters are glycerides	Narrows claim 17 to glycerol esters

How should “about 8 to about 10 carbon atoms” be interpreted?

The phrase generally identifies a range centered on octanoic acid and decanoic acid. It may raise construction questions concerning:

Whether the range includes only C8, C9 and C10 compounds;
Whether mixed commercial preparations with trace C6 or C12 components remain within the claim;
Whether “carbon atoms” refers to the fatty-acid chain or the entire ester molecule;
Whether branched or unsaturated analogues are included.

The claim language and specification would control those questions. The claim set is strongest against products deliberately formulated around octanoic and decanoic acid derivatives. It is weaker against structurally distant solvents or bile-acid dissolution agents.

What do claims 19 through 21 specifically protect?

Claims 19 through 21 are independent claims that reduce reliance on the nested limitations of claims 1 through 18.

Claim 19

Claim 19 covers localized perfusion using one or more of:

Glycerol mono-octanoate;
Octanoic acid;
Glycerol mono-decanoate;
Decanoic acid; and
Combinations of those compounds.

This is the most commercially focused claim in the set. It identifies the compounds apparently regarded as the preferred gallstone-dissolution agents.

Claim 20

Claim 20 covers a liquid physiologically compatible fatty-acid ester of an alcohol selected from:

Methanol;
Ethanol;
Propanol;
Butanol;
Ethylene glycol;
Butylene glycol;
Propylene glycol; and
Glycerol.

The claim is broader with respect to alcohol identity but still requires localized perfusion adjacent to the stone and a fatty-acid ester composition.

Claim 21

Claim 21 identifies a closed list of compounds:

Butyric acid;
Octanoic acid;
Decanoic acid;
Ethanol octanoate;
Butanol decanoate;
Ethylene glycol mono-octanoate;
Propylene glycol mono-octanoate;
Glycerol mono-octanoate;
Glycerol tri-octanoate; and
Glycerol di-decanoate.

It also covers combinations of the listed compounds. Claim 21 is chemically specific but potentially valuable against a protocol using any listed compound, provided the localized perfusion and gallstone limitations are met.

What patent protections are absent from U.S. Patent 4,205,086?

The patent does not expressly claim:

Oral administration;
Intravenous administration;
A tablet, capsule, injectable, catheter or pump;
A particular dosage regimen;
A specific catheter design;
Imaging-guided placement;
A formulation excipient;
A manufacturing process for the fatty-acid ester;
A commercial drug product;
A method for preventing gallstones;
Non-cholesterol pigment stones;
General dissolution of cholesterol outside a patient; or
The chemical compounds as standalone compositions.

A company could therefore potentially practice or sell a compound for an unrelated indication without implicating these claims. The risk increases when the company labels, promotes, sponsors or performs localized perfusion for cholesterol gallstones.

When did U.S. Patent 4,205,086 lose exclusivity?

The patent lost ordinary U.S. patent exclusivity on May 27, 1997.

Event	Date
Patent issued	May 27, 1980
Standard pre-1995 patent term	17 years from issue
Ordinary expiration	May 27, 1997
Current status	Expired
Current Paragraph IV relevance	None for this patent
Current Orange Book blocking effect	None identified

The applicable term framework was the pre-Uruguay Round rule under which eligible U.S. patents generally ran for 17 years from grant. The modern 20-year-from-effective-filing-date rule does not ordinarily govern a patent issued in 1980. The governing statutory framework is reflected in the transition provisions and patent-term rules in Title 35 of the U.S. Code.[1]

No current generic launch requires a Paragraph IV certification against this patent. Paragraph IV certifications apply to unexpired patents listed for an approved drug product in the FDA Orange Book. An expired method patent of this age does not independently delay an abbreviated new drug application.

What is the Orange Book status of U.S. Patent 4,205,086?

U.S. Patent 4,205,086 is not a conventional Orange Book drug-product patent. The Orange Book lists patents submitted by approved-drug sponsors for specific products and approved uses. This patent claims a localized medical procedure and does not claim an approved dosage form or marketed drug product.

Relevant approved gallstone-dissolution products include ursodiol products. Ursodiol is used for selected patients with radiolucent gallbladder stones and for primary biliary cholangitis. Those products are chemically and clinically distinct from the localized fatty-acid perfusion method claimed in Patent 4,205,086.[2]

The patent therefore has no current Orange Book exclusivity effect on:

Ursodiol tablets or capsules;
Chenodiol products;
Generic bile-acid products;
Laparoscopic cholecystectomy;
Endoscopic procedures; or
Investigational contact-dissolution agents.

How does this patent compare with ursodiol and chenodiol patents?

The patent belongs to a different therapeutic and delivery category from oral bile-acid therapy.

Attribute	U.S. Patent 4,205,086	Ursodiol/chenodiol therapy
Therapeutic approach	Direct chemical dissolution	Oral bile-acid treatment
Delivery	Local perfusion next to stone	Systemic oral administration
Target	Cholesterol-containing gallstone	Selected cholesterol gallstones
Claimed subject matter	Treatment method	Drug product, labeling and use
Chemical class	Fatty acids and fatty-acid esters	Bile acids
Procedural burden	Requires localized access to stone	Noninvasive administration
Current patent value	None, expired	Depends on product-specific patents and exclusivity
Generic challenge	No current Paragraph IV issue under this patent	Product-specific Orange Book analysis required

The localized method may have offered a faster or more direct dissolution concept than oral therapy, but it required access to the gallstone. That delivery requirement materially limits commercial applicability compared with oral agents.

What generic entry risks exist?

There is no current generic-entry risk from Patent 4,205,086 because it is expired. Its claims can remain relevant only as:

Prior art;
Historical evidence of technical disclosure;
A reference in patentability analysis;
Background for later continuation or improvement patents; or
A possible source of claim language in historical litigation.

A modern product could still face risk from later patents covering:

Catheter systems;
Endoscopic access;
Controlled perfusion;
Combination formulations;
Improved solvent compositions;
Imaging-guided delivery;
Manufacturing processes;
Specific treatment protocols; or
Approved drug products.

Those rights would need to be analyzed separately. Patent 4,205,086 itself does not provide a continuing exclusionary right.

Which companies are challenging this patent?

No current Paragraph IV challenger is relevant because the patent expired in 1997. The patent also does not function as a current branded-drug patent in the FDA approval system.

A litigation search for the patent should distinguish among:

Direct infringement suits involving localized gallstone perfusion;
Patentability disputes involving fatty-acid solvents;
Product-liability litigation;
Medical-malpractice cases involving gallstone treatment; and
Litigation involving unrelated fatty-acid ester products.

Those categories do not establish present patent enforcement. A historical case involving the patent would not restore exclusivity or create a current regulatory stay.

How strong was the patent estate?

The patent estate was technically focused but commercially narrow.

Strengths

Broad independent chemical classes in claim 1;
Independent claims 19 through 21;
Coverage of both pure compounds and mixtures;
Coverage of fatty acids and esters;
No express limitation to a particular catheter or apparatus;
Direct focus on cholesterol-containing gallstones.

Weaknesses

Every claim requires localized perfusion adjacent to the gallstone;
The claims are method claims, not composition claims;
“Effective amount” and “physiologically compatible” may invite factual disputes;
“Gradually” and “solubilize at least a portion” are functional limitations;
Treatment is invasive compared with oral bile-acid therapy;
The patent term ended before modern gallstone-treatment markets developed;
The patent does not cover later delivery devices or formulation improvements unless separately claimed.

The strongest historical enforcement position would have involved a clinical protocol deliberately using one of the specified medium-chain compounds through a catheter positioned next to a cholesterol gallstone. The weakest position would have involved a general-purpose fatty-acid ester sold without a gallstone-treatment indication.

What manufacturing and intellectual-property barriers remain?

The expired patent does not prevent manufacture of the named compounds. Current barriers would arise from other sources:

Pharmaceutical-grade purity;
Sterility and endotoxin control;
Biocompatibility;
Stability in a liquid dosage form;
Catheter compatibility;
Local tissue toxicity;
Controlled delivery near the gallstone;
Clinical evidence for dissolution;
FDA classification and approval requirements;
Manufacturing-process patents filed after 1980; and
Trade secrets relating to formulation or device manufacture.

A product combining a solvent, catheter and imaging system would likely require a freedom-to-operate review across pharmaceutical, device and method patents. That review would not be confined to Patent 4,205,086.

What FDA regulatory pathway would apply?

A modern product based on this concept would likely raise both drug and device issues. The active solvent could be regulated as a drug, while the perfusion catheter or delivery system could be regulated as a medical device. A combination-product designation could apply depending on the product’s primary mode of action.

The original patent does not establish FDA approval. Patent rights and FDA authorization are separate. The patent claims a treatment method, while FDA approval would require evidence addressing safety, tolerability, performance, clinical benefit and manufacturing quality.

Oral ursodiol products have an established FDA regulatory history for specified indications. That history does not establish approval for localized octanoic-acid or glycerol mono-octanoate perfusion.[2]

What licensing deals affect this patent?

No current licensing deal creates enforceable exclusivity under Patent 4,205,086. Any historical license would have expired with the patent’s term unless it separately conveyed know-how, trade secrets, data, equipment rights or commercial rights unrelated to patent exclusivity.

A transaction involving this technology should value:

Clinical data;
Formulation know-how;
Catheter design;
Manufacturing processes;
Regulatory history;
Trade secrets; and
Later-generation patent families.

The 1980 patent itself should not be assigned material current royalty value as an enforceable patent asset.

Key Takeaways

U.S. Patent 4,205,086 covers localized perfusion of fatty acids or fatty-acid esters next to cholesterol-containing gallstones.
Claim 1 is chemically broad but procedurally narrow.
Claims 19 through 21 focus on octanoic acid, decanoic acid, glycerol mono-octanoate, glycerol mono-decanoate and related esters.
The patent does not broadly claim the compounds as compositions or products.
The patent issued on May 27, 1980 and ordinarily expired on May 27, 1997.
It creates no current Paragraph IV, Orange Book or generic-launch barrier.
It is distinct from oral ursodiol and chenodiol therapy.
Any present freedom-to-operate risk would arise from later patents covering formulations, delivery devices, manufacturing methods or treatment protocols.
The commercial weakness of the original concept is the need for invasive perfusion adjacent to the gallstone.
The patent has historical technical value but no remaining U.S. exclusionary value.

FAQs

Does Patent 4,205,086 cover oral octanoic acid for gallstones?

No. The claims require perfusion adjacent to the gallstone. Oral administration alone would not satisfy that express limitation.

Can a company manufacture glycerol mono-octanoate after the patent expired?

Yes, Patent 4,205,086 does not provide continuing composition-of-matter protection for glycerol mono-octanoate. Separate later patents, regulatory requirements or contractual restrictions could still matter.

Does the patent cover pigment gallstones?

The claims specify cholesterol-containing gallstones. They do not expressly cover pigment stones lacking the claimed cholesterol characteristic.

Could the patent block an FDA approval application today?

No. An expired 1980 method patent does not create a current statutory stay or exclusivity period for an FDA application.

Is a catheter patent needed to practice the claimed method?

Not under Patent 4,205,086 itself. The patent claims the treatment method and does not expressly require a particular catheter. A separate catheter or delivery-device patent could create an independent freedom-to-operate issue.

References

United States Code. (2024). 35 U.S.C. §§ 154, 156, and 271. https://uscode.house.gov
U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Patent and Trademark Office. (1980). U.S. Patent No. 4,205,086. https://patents.google.com/patent/US4205086
U.S. Food and Drug Administration. (2024). Ursodiol prescribing information. https://www.accessdata.fda.gov/drugsatfda/
U.S. Patent and Trademark Office. (2024). Manual of Patent Examining Procedure, patent term and patentability provisions. https://www.uspto.gov/web/offices/pac/mpep/

Details for Patent: 4,205,086

Summary for Patent: 4,205,086