US Patent 5,545,628: Fenofibrate Formulation Claims, Scope, Expiration, and Patent Landscape

US Patent 5,545,628 covers oral fenofibrate compositions that use polyglycolyzed glycerides to improve formulation performance, particularly in hard gelatin capsules filled with a molten fenofibrate-excipient mixture. The patent also claims manufacturing and treatment methods.

The patent issued on August 13, 1996, and its pre-URAA 17-year patent term expired on August 13, 2013, absent an unusual term adjustment or extension. The claims are therefore no longer enforceable as a patent barrier in the United States. The commercial importance of the patent is historical: it describes a formulation platform related to lipid-based and melt-filled fenofibrate products, but it does not currently block generic manufacture or sale. [1]

What does US Patent 5,545,628 protect?

The patent protects a combination of four core elements:

Fenofibrate as the active pharmaceutical ingredient.
One or more polyglycolyzed glycerides as excipients.
Formulation parameters directed to hydrophilicity, melting behavior, suspension stability, dosage strength, and capsule presentation.
Manufacturing and treatment methods using the composition.

The broadest composition claim is claim 1:

A pharmaceutical composition for treating hyperlipidemia or hypercholesterolemia comprising effective amounts of fenofibrate and an excipient containing one or more polyglycolyzed glycerides.

The claim is narrower than a general fenofibrate composition claim. It requires the presence of a polyglycolyzed glyceride. A formulation containing fenofibrate but no polyglycolyzed glyceride would not literally satisfy claim 1.

Patent identification and term

Item	Information
Patent	US 5,545,628
Subject matter	Fenofibrate pharmaceutical compositions and methods
Issue date	August 13, 1996
Principal active ingredient	Fenofibrate
Core excipient	One or more polyglycolyzed glycerides
Primary dosage form	Solid oral dosage form, particularly hard gelatin capsules
Manufacturing concept	Addition of molten fenofibrate and excipient to capsules, followed by cooling
Stated therapeutic use	Hyperlipidemia and hypercholesterolemia
U.S. term	Approximately 17 years from issue for this pre-URAA patent
Estimated expiration	August 13, 2013
Current enforcement status	Expired by ordinary statutory term

How broad is claim 1 of US 5,545,628?

Claim 1 is a composition claim with a functional therapeutic limitation. It requires:

Fenofibrate;
A polyglycolyzed glyceride excipient;
A pharmaceutical composition;
An amount effective for treating hyperlipidemia, hypercholesterolemia, or both in a mammal.

The claim does not require a specific brand, capsule size, commercial product, particle size, HLB value, stabilizer, or daily dose. Those limitations appear in dependent claims.

The use of “one or more polyglycolyzed glycerides” gives the claim flexibility across multiple excipient compositions. A formulation containing a single qualifying polyglycolyzed glyceride may satisfy the claim. A formulation containing several such excipients may also satisfy it.

The claim does not expressly require:

A hard gelatin capsule;
A molten-fill manufacturing process;
A particular fenofibrate concentration;
Non-micronized fenofibrate;
A specific HLB value;
A specific particle size;
A particular release profile.

Those limitations become relevant only under narrower dependent claims or under the separate manufacturing claims.

What do claims 2 through 9 add?

Claims 2 through 9 narrow the formulation by adding quantitative and physical limitations.

Claim	Added limitation	Scope significance
2	Fenofibrate is 5% to 95% by total weight	Covers a broad active-loading range
3	Polyglycolyzed glycerides have HLB of at least 10	Requires a relatively hydrophilic excipient system
4	HLB is 12 to 15	Narrows claim 3 to a defined hydrophilicity range
5	Polyalkylene glycols adjust HLB, melting point, or both	Covers excipient modification for formulation control
6	Suspension stabilizer is present	Adds a stabilizing component
7	Stabilizer is cellulose, povidone, poloxamer, or specified block polymer	Creates a closed or substantially defined stabilizer group
8	Fenofibrate and excipient are in unit dosage form in a hard gelatin capsule	Targets capsule products
9	Capsule contains approximately 67 to 200 mg fenofibrate	Covers common unit-dose strengths within that range

What is the significance of the HLB limitations?

The hydrophilic-lipophilic balance, or HLB, limitations are central to claims 3 and 4. Claim 3 requires an HLB value of at least 10. Claim 4 narrows that range to 12 through 15.

These limitations are potentially important in a validity or infringement analysis because the HLB value must be established for the relevant excipient or excipient blend. The analysis would depend on:

The identity of the polyglycolyzed glyceride;
The supplier’s specification;
Whether HLB is assigned to an individual excipient or calculated for a blend;
The analytical and calculation method used;
The patent’s disclosure and prosecution record.

A product may avoid claims 3 and 4 by using a qualifying polyglycolyzed glyceride with an HLB below 10. That design would not necessarily avoid claim 1, however, because claim 1 does not impose an HLB threshold.

What do claims 10 and 15 protect?

Claim 10 covers a manufacturing method for a solid oral dosage form. The process requires:

Fenofibrate and a polyglycolyzed glyceride-containing excipient;
Addition of the molten fenofibrate and excipient to hard gelatin capsules;
Cooling within the capsules.

The claim therefore focuses on a melt-fill capsule process rather than merely the final composition.

Claim 15 limits claim 10 by requiring that the fenofibrate not be co-micronized. This limitation is significant because it excludes a particular particle-engineering approach. It does not necessarily exclude all micronized fenofibrate. The literal language excludes fenofibrate that is “co-micronized,” not necessarily fenofibrate that was micronized separately or incorporated into a formulation after independent particle-size reduction.

Manufacturing elements that matter

A process would face the strongest historical claim 10 risk if it used:

Fenofibrate and the relevant excipient in molten form;
Direct filling into hard gelatin capsules;
Cooling to form the solid dosage unit inside the capsule.

A process using dry powder blending, conventional tablet compression, liquid-filled softgels, or a different capsule-filling sequence would present a different literal infringement analysis. Because the patent expired, these distinctions now matter mainly for historical freedom-to-operate reviews, technical benchmarking, and validity analysis.

What do claims 11 through 14 protect?

Claims 11 through 14 are method-of-treatment claims. They cover administration of the fenofibrate and polyglycolyzed glyceride composition to treat hyperlipidemia or hypercholesterolemia.

Claim	Limitation
11	Treating a mammal with the claimed composition
12	Human treatment with 100 to 600 mg fenofibrate per day
13	Human treatment with 100 to 300 mg fenofibrate per day
14	Oral administration

Claims 12 and 13 target clinically relevant daily dosing. Claim 13 is narrower than claim 12 because it limits the daily dose to 100 through 300 mg.

The treatment claims do not require the hard gelatin capsule limitation found in claim 8. A composition administered orally could potentially fall within claim 14 without being presented in a hard gelatin capsule, provided it satisfies the composition requirements inherited from claim 11.

When did US Patent 5,545,628 lose exclusivity?

US Patent 5,545,628 lost patent exclusivity in August 2013. The patent issued before the change to the 20-year term measured from the earliest effective nonprovisional filing date. Its ordinary term was therefore generally calculated from the issue date under the pre-URAA regime.

Event	Date
Patent issued	August 13, 1996
Ordinary 17-year term	August 13, 2013
Current status	Expired
Present generic blocking effect	None

The expiration of US 5,545,628 does not by itself determine whether a product can be marketed. A later patent, regulatory exclusivity period, labeling restriction, or separate intellectual-property right could have affected a particular fenofibrate product. Those later rights must be assessed independently.

What was the Orange Book status of the fenofibrate products?

US 5,545,628 is not the active regulatory exclusivity basis for current fenofibrate products. FDA’s Orange Book identifies patents and exclusivity associated with approved products, but an older formulation patent may not remain listed after expiration or may not have been listed against every fenofibrate product. [2]

Fenofibrate has been marketed in several dosage forms and formulations, including:

Tricor;
Antara;
Lipofen;
Fenoglide;
Generic fenofibrate tablets, capsules, and related oral products;
Fenofibric acid products such as Trilipix.

The FDA-approved products do not all use the same formulation technology. Fenofibrate products have differed in:

Particle size;
Micronization;
Bioavailability enhancement;
Capsule or tablet presentation;
Food-effect performance;
Salt or active-moiety presentation;
Immediate-release formulation design.

A product-specific Orange Book analysis must distinguish the NDA, dosage form, strength, listed patents, and expiration dates. FDA’s Drugs@FDA database and the Orange Book are the controlling sources for that regulatory review. [2, 3]

Did the patent create a Paragraph IV barrier?

US Patent 5,545,628 could historically have been relevant to an abbreviated new drug application if it had been listed against the applicable reference product and remained unexpired. A generic applicant seeking approval before patent expiration could have submitted a Paragraph IV certification alleging that the patent was invalid, unenforceable, or not infringed.

Because the patent expired in 2013:

It no longer supports a current Paragraph IV launch date;
It cannot create a present statutory stay under Hatch-Waxman;
It cannot support a current patent-infringement suit against a generic launch;
Any historic Paragraph IV dispute involving the patent is no longer a live exclusivity issue.

The presence of a Paragraph IV certification would also have depended on whether the patent was properly listed for the relevant NDA and whether the generic product was within the patent’s scope. [2, 4]

What generic entry risks exist for fenofibrate products?

The primary current risk is not US 5,545,628. Generic entry risk depends on the surviving intellectual-property and regulatory position of each individual reference product.

Generic entry risk by technology

Product or technology	Relevance of US 5,545,628	Current risk assessment
Melt-filled hard gelatin capsule using polyglycolyzed glycerides	Direct historical relevance	Patent expired; no current patent barrier from this patent
Conventional generic fenofibrate capsule	May not practice the melt-fill claims	Depends on other patents and FDA requirements
Micronized fenofibrate product	Claim 15 may have excluded co-micronized material	No current effect because patent expired
Tablet formulation	Generally outside the hard-capsule limitation of claims 8 to 10	Must be assessed against other formulation patents
Fenofibric acid product	Different active presentation	US 5,545,628 does not automatically cover it
Modified-release product	Requires separate analysis	Dependent on later release-profile or formulation patents

The commercial generic market confirms that fenofibrate has experienced substantial post-expiration competition. FDA-approved generic products have entered across multiple dosage forms and strengths. [2, 3]

Does the patent create biosimilar risk?

No. Fenofibrate is a small-molecule active pharmaceutical ingredient, not a biologic. The biosimilar pathway under section 351(k) of the Public Health Service Act does not apply.

Competitive entry occurs through the generic-drug framework, principally abbreviated new drug applications under section 505(j) of the Federal Food, Drug, and Cosmetic Act. [4]

What companies and products compete with fenofibrate?

The competitive landscape includes both generic manufacturers and branded or authorized-generic products.

Small-molecule competitors

Relevant products have included:

Tricor, historically associated with Abbott Laboratories and later AbbVie;
Antara;
Lipofen;
Fenoglide;
Generic fenofibrate products from multiple ANDA sponsors;
Trilipix, a fenofibric acid product rather than fenofibrate itself.

Competition has focused on formulation and bioavailability rather than compound exclusivity. Different products have sought to reduce the food effect, improve absorption, or permit lower-dose administration. FDA labeling remains important because bioequivalence may be product-specific. [3, 5]

Biosimilar competition

There is no biosimilar pathway for fenofibrate. No biosimilar analysis is required for the active ingredient.

What licensing or settlement issues affect US 5,545,628?

The patent record identifies the patent’s ownership and prosecution history, but the expired patent by itself does not establish a current license requirement. A license could have been relevant during the patent term if a product practiced the claimed composition or process.

A complete settlement analysis would require a verified litigation docket and the text of any confidential or public agreement. The public patent and FDA records do not establish a current settlement restriction arising from US 5,545,628. The expired status means that any surviving commercial restriction would need to arise from a separate contract, later patent, regulatory obligation, or trade-secret arrangement rather than from this patent’s enforceable claims.

How strong was the patent estate?

The patent was technically meaningful but legally narrow compared with a basic compound patent.

Strengths

Covered both composition and treatment claims;
Used broad language for one or more polyglycolyzed glycerides;
Reached formulations without requiring a particular brand or excipient;
Included a manufacturing route for melt-filled hard gelatin capsules;
Covered clinically relevant fenofibrate dose ranges;
Included HLB-based dependent claims that could map onto defined excipient systems.

Limitations

Required a polyglycolyzed glyceride;
Depended on functional treatment language in the broad composition claim;
Limited the process claims to a specific molten-fill approach;
Limited certain dependent claims to hard gelatin capsules;
Required additional proof for HLB and composition parameters;
Did not broadly cover every fenofibrate formulation;
Excluded co-micronized fenofibrate under claim 15;
Expired in 2013.

The patent therefore had its strongest historical position against lipid-based, melt-filled fenofibrate capsules using the claimed excipient system. It was materially weaker against tablets, non-lipid formulations, separate micronization strategies, different capsule technologies, and products using excipients outside the claimed class.

What manufacturing and IP barriers remain after expiration?

The patent’s manufacturing disclosure is no longer a patent barrier, but several non-patent barriers can remain:

FDA bioequivalence requirements;
Control of particle size and polymorphic form;
Dissolution and food-effect performance;
Capsule compatibility with molten excipient systems;
Stability of fenofibrate in the selected excipient matrix;
Scale-up of hot-fill operations;
Gelatin-shell deformation or brittleness;
Supplier qualification for polyglycolyzed glycerides;
Trade secrets relating to temperature, fill weight, cooling, and encapsulation conditions;
Later patents directed to specific products or formulations.

These factors can increase development cost without restoring exclusivity under US 5,545,628.

What is the revenue exposure associated with US 5,545,628?

The patent’s direct revenue exposure ended when its patent term expired. It may have supported commercial value during the period when branded fenofibrate products relied on formulation differentiation, but current sales are not protected by this expired patent.

Revenue analysis should separate:

The historical branded product revenue generated during the patent term;
Revenue from later products covered by separate patents;
Generic fenofibrate revenue after patent expiration;
Fenofibric acid revenue, which involves a different active ingredient presentation;
Revenue attributable to regulatory exclusivity rather than patent rights.

Public FDA records establish approval and product information, but they do not provide a complete product-level revenue history for every fenofibrate brand. [2, 3]

Key Takeaways

US Patent 5,545,628 covers fenofibrate compositions containing one or more polyglycolyzed glycerides.
The principal technical focus is lipid-based formulation, HLB control, suspension stability, and melt-filled hard gelatin capsules.
Claim 1 is broader than the capsule and manufacturing claims but still requires a polyglycolyzed glyceride.
Claims 10 and 15 target molten filling into hard gelatin capsules using non-co-micronized fenofibrate.
Claims 11 through 14 cover treatment of hyperlipidemia or hypercholesterolemia, including oral human dosing.
The patent issued August 13, 1996, and expired approximately August 13, 2013.
It no longer creates a U.S. patent barrier, Paragraph IV risk, or litigation basis for current generic entry.
Fenofibrate is a small molecule and has no biosimilar pathway.
Current market risk depends on later patents, FDA requirements, product-specific Orange Book listings, and manufacturing know-how.
The patent was historically strongest against melt-filled fenofibrate capsules using qualifying polyglycolyzed glycerides.

FAQs

Can a generic manufacturer use the melt-fill process disclosed in US 5,545,628?

Yes. The patent’s ordinary term expired in 2013. A generic manufacturer may use the disclosed process unless a separate unexpired patent or contractual restriction applies.

Does US 5,545,628 cover micronized fenofibrate?

Claim 15 excludes co-micronized fenofibrate from the manufacturing method of claim 10. The patent does not impose a universal prohibition on all micronized fenofibrate. The composition claims must be analyzed independently.

Does the patent cover fenofibric acid or Trilipix?

Not automatically. Fenofibric acid is a different active pharmaceutical presentation from fenofibrate. Coverage would require the product to satisfy the specific claim elements, including fenofibrate and a polyglycolyzed glyceride-containing excipient.

Are polyglycolyzed glycerides the same as all lipid excipients?

No. The claims require polyglycolyzed glycerides. A formulation using another lipid excipient does not necessarily satisfy the claims unless the excipient falls within the relevant chemical and claim construction scope.

Could US 5,545,628 support a current Hatch-Waxman lawsuit?

No. The patent expired in 2013. It cannot currently support a new patent-based Paragraph IV stay or infringement action, although it may remain relevant to historical litigation or technical prior-art analysis.

References

United States Patent and Trademark Office. (1996). US Patent No. 5,545,628: Pharmaceutical composition containing fenofibrate.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations.
U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs.
U.S. Food and Drug Administration. (2024). Abbreviated new drug application (ANDA) process.
U.S. Food and Drug Administration. (2023). Tricor (fenofibrate) prescribing information.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	4380896	⤷ Start Trial
Canada	2210985	⤷ Start Trial
Germany	69627817	⤷ Start Trial
European Patent Office	0801562	⤷ Start Trial
Spain	2200048	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,545,628

Summary for Patent: 5,545,628