United States Patent 4,778,676: Scope, Claims, Expiration, and Cholestyramine Patent Landscape

US Patent 4,778,676 covers a chewable confectionery dosage form for cholestyramine. Its core combination is a pre-coated cholestyramine resin embedded in a gelatin and humectant confectionery matrix containing a sweetener and 1% to 30% water. The patent also covers specified coating materials, coating-to-active ratios, gums and excipients, manufacturing techniques, and methods of treating hypercholesterolemia.

The patent is expired. Its pre-1995 term ran for 17 years from issuance, subject to any applicable term adjustment or terminal disclaimer. Based on the October 18, 1988 issue date, the ordinary term ended October 18, 2005. The patent therefore does not create a current US barrier to generic cholestyramine products or new chewable cholestyramine formulations.[1]

What does US Patent 4,778,676 protect?

The patent protects a formulation and manufacturing concept intended to make cholestyramine more acceptable as an oral product. Cholestyramine is an anion-exchange resin with a strong taste and texture burden. The claimed solution uses a coating on the resin before incorporating it into a confectionery base.

The principal claim elements are:

Element	Claim requirement
Active ingredient	Cholestyramine or cholestyramine resin
Active pretreatment	Pre-coating before incorporation into the confectionery matrix
Coating materials	Lecithin, short-chain polyoxyalkylenes, low-melting glycerides, low-molecular-weight polyalkylene glycols, synthetic or natural waxes, or mixtures
Confectionery matrix	Gelatin binder, glycerin or specified glycerin ester humectant, sweetener, and 1% to 30% water
Coating amount	About 1% to 10% of the final delivery system under claim 2
Coating-to-active ratio	About 1:3 to 1:8 under claim 3
Optional materials	Nonionic hydrocolloid gums, pectin, flavors, colorants, fillers, emulsifiers and thickeners
Dosage form	Chewable confectionery delivery system
Therapeutic use	Treatment of hypercholesterolemia and related disorders
Manufacturing	Pre-coating, preparation of the confectionery matrix, admixture and shaping

Claim 1 is the primary composition claim. A product must include each material category and compositional limitation to fall within its literal scope.

How are the independent claims structured?

Claim 1: Chewable cholestyramine confectionery

Claim 1 requires two principal components:

Cholestyramine pre-coated with one or more specified materials.
A confectionery matrix containing gelatin, a qualifying humectant, a sweetener and 1% to 30% water.

The claim is narrower than a generic claim to any taste-masked cholestyramine product. It requires a confectionery dosage form and a gelatin-humectant binder system. A tablet, capsule, powder, suspension, or conventional granule would not satisfy the dosage-form limitation merely because it contains coated cholestyramine.

The coating category is broad in substance. It includes:

Lecithin.
Polyoxyalkylenes with chain lengths of about four carbons or less.
Glycerides with a melting point of 100°C or less.
Polyalkylene glycols with molecular weights of 3,700 or less.
Synthetic and natural waxes.
Mixtures of the listed materials.

The claim uses functional and approximate language, including "about" and the requirement that the coating not interfere with active release in the manufacturing claim. Those terms would require technical interpretation based on the patent specification, prosecution history and evidence concerning formulation practice.

Claim 12: Manufacturing process

Claim 12 covers a process with four stages:

Pre-coating the cholestyramine.
Forming a gelatin and humectant solution with sweetener and water.
Admixing the coated resin with the confectionery mixture.
Forming the result into shapes.

This claim is important because it focuses on manufacturing sequence rather than only the finished product. A manufacturer could avoid literal infringement if it used an uncoated resin, added the coating after the confectionery matrix was formed, or used a non-gelatin matrix, subject to any applicable doctrine-of-equivalents analysis.

Claim 15: Independent treatment method

Claim 15 covers treatment of hypercholesterolemia using a confectionery system in which the cholestyramine resin is coated with a narrower group of materials:

Lecithin.
Polyoxyalkylenes with four carbons or less.
Polyalkylene glycols with a molecular weight of 3,700 or less.
Mixtures of those materials.

Unlike claim 1, claim 15 does not expressly include glycerides or waxes in its coating group. It still requires gelatin, a qualifying humectant, a sweetener and 1% to 30% water.

Claim 16: Room-temperature coating methods

Claim 16 narrows claim 15 by requiring that the pre-coating be conducted at room temperature using one of four techniques:

Simple mixing.
Spray coating.
Spray congealing.
Fluidized-bed granulation.

The claim creates a process-specific limitation. A formulation that uses the same coating material but applies it through a different process may fall outside the literal scope of claim 16.

What do the dependent claims add?

The dependent claims define specific commercial and technical embodiments.

Claim	Added limitation
2	Coating material is about 1% to 10% of the total delivery system
3	Coating-to-active ratio is about 1:3 to 1:8
4	Coating is polyoxyethylene, polyoxypropylene, polyoxybutylene, copolymers or mixtures
5	Polyalkylene glycol is polyethylene glycol, polypropylene glycol, polybutylene glycol or mixtures
6	Binder has 0.1% to 5% gelatin and 0.1% to 25% humectant
7	Humectant is glycerine, triacetin, tributyrin or mixtures
8	Nonionic hydrocolloid gum is included
9	Gum is guar gum, locust bean gum or mixtures
10	Other excipients may include pectin, flavors, colors, fillers, emulsifiers and thickeners
13	Pre-coated cholestyramine is present in a pharmaceutically effective amount
14	Pre-coated cholestyramine is 15% to 30% of the final product

The claim set is cumulative. A dependent claim includes every limitation of the claim from which it depends. Claims 4, 5, 7 and 9 are narrower species claims that could have had greater practical value during the patent term because they identify particular coating polymers, glycols, humectants and gums.

What formulations are protected by US 4,778,676?

A formulation would have been a strong literal claim candidate if it contained all of the following:

Cholestyramine resin coated before final mixing.
Polyethylene glycol, a short-chain polyoxyalkylene, lecithin or a listed wax or glyceride.
A chewy or shaped confectionery matrix.
Gelatin at approximately 0.1% to 5%.
Glycerin, triacetin, tributyrin or a qualifying glycerin ester.
A sweetener.
Water at 1% to 30% by final weight.

The patent does not require every optional excipient. Flavor, color, pectin, gum, filler and emulsifier limitations appear only in dependent claims or as optional elements in the broader formulation disclosure.

A product would present a stronger non-infringement position if it used:

Uncoated cholestyramine.
A coating outside the listed chemical and physical categories.
A tablet or capsule rather than a confectionery system.
A binder system without gelatin.
A dry powder or suspension product.
A water level outside the claimed range.
A non-glycerin humectant outside the listed derivatives.
A manufacturing process that does not pre-coat the resin.

Because the patent has expired, these distinctions are relevant to historical infringement analysis, freedom-to-operate records, and interpretation of related patent families, but they do not currently provide an enforceable US exclusion right.

When did US Patent 4,778,676 lose exclusivity?

The patent issued on October 18, 1988.[1] For a US utility patent filed before June 8, 1995, the ordinary term was 17 years from the grant date. On that basis, the patent expired on October 18, 2005.[2]

Event	Date or status
Patent issued	October 18, 1988
Applicable term regime	17 years from grant for qualifying pre-1995 applications
Ordinary expiration	October 18, 2005
Current enforceability	Expired
Current generic blocking effect	None
Patent term extension relevance	No current extension-based exclusivity identified

The expiration analysis should distinguish patent rights from FDA exclusivity. Patent expiration does not itself determine whether an approved drug has regulatory exclusivity, but no current FDA exclusivity period can revive this expired formulation patent.

What is the Orange Book status of the patent?

US Patent 4,778,676 is not a conventional active-ingredient, formulation or method-of-use patent associated with a currently protected Orange Book-listed cholestyramine product.

The Orange Book generally lists patents submitted by an NDA holder for an approved drug product. Cholestyramine products marketed in the United States have historically been supplied primarily as oral powders for suspension, including Questran, Questran Light and generic equivalents.[3] The patent claims a chewable confectionery dosage form rather than the standard powder product.

No current Orange Book exclusivity value should be assigned to US 4,778,676. The patent's expiration also removes any present Paragraph IV litigation significance.

Are there Paragraph IV challenges to US 4,778,676?

No current Paragraph IV challenge can create a commercial event against this patent because the patent expired in 2005. A Paragraph IV certification is directed to an unexpired listed patent. An abbreviated new drug application applicant seeking approval for a powder or suspension would generally analyze the patents listed for the reference product, not rely on an expired confectionery patent as a current barrier.

Historically, a Paragraph IV challenge would have been relevant only if:

The patent had been listed for the relevant reference product.
The proposed generic used the claimed confectionery dosage form.
The patent remained unexpired at the anticipated approval or launch date.

Those conditions no longer exist for this patent.

Is there biosimilar risk for the cholestyramine patent estate?

Biosimilar risk is not applicable. Cholestyramine is a non-biologic ion-exchange resin, not a therapeutic protein or other biological product regulated through the biosimilar pathway under the Public Health Service Act.

Competitive entry occurs through generic-drug and abbreviated new drug application pathways, where applicable. The main commercial products are oral powder formulations rather than biosimilar products.[3,4]

How does this patent compare with the broader cholestyramine patent landscape?

The patent occupies a narrow formulation niche.

Product or technology	Relationship to US 4,778,676	Current risk
Generic cholestyramine powder	Usually outside the confectionery and pre-coating limitations	No risk from this expired patent
Cholestyramine oral suspension	Generally outside the claimed dosage form	No risk from this expired patent
Cholestyramine tablet	May avoid the confectionery limitation, depending on composition	No current patent risk from this patent
Chewable cholestyramine candy	Historically closest product category	Patent expired
Coated cholestyramine granules	Could overlap coating concepts but not necessarily confectionery matrix limits	No current enforceability
Taste-masked resin in food matrix	Technically related, but requires claim-by-claim analysis	No current enforceability
Bile-acid sequestrant alternatives	Different active ingredients and patent estates	Separate analysis required

The patent does not broadly control cholestyramine itself. Its commercial value depended on the combination of taste masking and confectionery delivery. It would not have blocked conventional Questran-type powders unless those products also practiced the claimed formulation features.

What manufacturing and IP barriers did the patent create?

During its enforceable term, the patent could have affected a manufacturer at three levels.

First, the coating step created a process barrier. The resin had to be treated before incorporation into the confectionery base. The patent identified several low-temperature or room-temperature coating approaches, including spray coating and fluidized-bed granulation.

Second, the confectionery matrix created a composition barrier. The combination of gelatin, humectant, sweetener and controlled water content was central to the claims. A developer seeking a chewy delivery system would have needed to manage texture, moisture migration, resin dispersion and drug release while avoiding the claimed ranges.

Third, the product had to preserve cholestyramine function. The coating was intended to improve palatability without preventing release or ion-exchange activity. This limitation could have created disputes over release testing and whether a coating materially interfered with therapeutic function.

These barriers are historical. They do not prevent current development because the patent is expired. New applications could still protect improvements involving particle engineering, taste masking, controlled release, dosage-form architecture, manufacturing parameters or combinations with other agents. Such patents would need a new inventive concept and could not restore the expired claims.

What licensing deals and litigation affect this patent?

No current licensing or settlement value should be attributed to US 4,778,676. The patent expired nearly two decades ago, and any historical license would not create present exclusivity against independent developers.

The supplied claim set does not identify a litigation history, settlement agreement or covenant not to sue. Because the patent is expired, any historical dispute would have no current ability to block generic launch or FDA approval. A commercial diligence review should treat the patent as an expired historical asset rather than a live enforcement position.

What generic launch risks exist today?

The patent creates no current US generic launch risk. A company can develop a cholestyramine chewable product without obtaining a license under US 4,778,676.

The relevant current risks are regulatory and commercial:

FDA approval requirements for the selected dosage form.
Demonstration of pharmaceutical quality and consistent cholestyramine content.
Palatability and patient acceptability.
Drug release and resin activity.
Manufacturing reproducibility.
Labeling and bioequivalence requirements applicable to the proposed product.
Competition from established powder products and branded or authorized-generic versions.

A chewable confectionery product could still encounter new patent filings by competitors covering specific excipients, particle sizes, coating processes, release profiles, flavor systems or manufacturing controls. Those later rights require a separate search and claim chart.

Key Takeaways

US Patent 4,778,676 covers a pre-coated cholestyramine resin in a gelatin-based chewable confectionery matrix.
Claim 1 is the central composition claim.
Claims 11 and 15 cover treatment methods.
Claim 12 covers the preparation sequence.
Claim 16 covers specified room-temperature coating techniques.
The patent's key technical limitations are the resin coating, gelatin-humectant binder, sweetener and 1% to 30% water.
The ordinary patent term ended October 18, 2005.
The patent has no current US exclusivity value.
It is not a current biosimilar barrier.
It does not block conventional cholestyramine powders or suspensions.
No current Paragraph IV, Orange Book or settlement risk should be assigned to this expired patent.
Current risk would come from later patents, FDA requirements and product-specific formulation or manufacturing rights.

FAQs About US Patent 4,778,676

Does US Patent 4,778,676 cover all cholestyramine products?

No. It covers a defined chewable confectionery system with pre-coated cholestyramine and a gelatin-humectant matrix. Conventional powders, suspensions, tablets and capsules are not automatically within its scope.

Can a company still obtain a license under US Patent 4,778,676?

A historical license may exist in private records, but no license is required to practice the expired US patent claims in the United States.

Does the patent cover polyethylene glycol-coated cholestyramine?

Yes, polyethylene glycol is within the claimed polyalkylene glycol category when the applicable molecular-weight and formulation limitations are satisfied. The claims also specify coating amounts and coating-to-active ratios in dependent embodiments.

Would a sugar-free cholestyramine chewable avoid the patent?

Not necessarily. The patent requires a sweetener but does not limit the sweetener to sucrose. A sugar-free formulation using an alternative sweetener could still satisfy the claim if the remaining limitations are present.

Are newer cholestyramine taste-masking patents automatically invalid because US 4,778,676 expired?

No. Expiration of this patent does not invalidate later patents. A later patent must be evaluated independently for novelty, obviousness, written description, enablement, prosecution history and remaining term.

References

United States Patent and Trademark Office. (1988). United States Patent No. 4,778,676.
United States Code, 35 U.S.C. § 154. (2024). Patent term and patent rights.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book.
U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs, cholestyramine product records.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	572036	⤷ Start Trial
Australia	6657286	⤷ Start Trial
Canada	1282700	⤷ Start Trial
China	1010549	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,778,676

Summary for Patent: 4,778,676