US Patent 5,490,987: Scope, Claim Analysis, Expiration, and Colestipol Patent Landscape

US Patent 5,490,987 protects a specific 1,000-mg colestipol hydrochloride tablet, its excipient system, coating architecture, physical-performance profile, and manufacturing process. The patent is not a composition-of-matter patent for colestipol hydrochloride. Its statutory term expired on February 13, 2013, based on the February 13, 1996 grant date. It therefore does not create a current U.S. patent barrier to generic colestipol tablets.

What does US Patent 5,490,987 protect?

The patent protects a compressed tablet containing approximately 1,000 mg of fine-milled colestipol hydrochloride combined with povidone, colloidal silicon dioxide, and magnesium stearate. The independent product claim also requires specified tablet performance:

Element	Claim 1 requirement
Active ingredient	Approximately 1,000 mg fine-milled colestipol hydrochloride
Binder	10-200 mg povidone
Glidant	1-50 mg colloidal silicon dioxide
Lubricant	1-30 mg magnesium stearate
Hardness	Greater than 40 SCUs
Friability	0-0.1% after 15 minutes

The claim is narrow because infringement requires more than the presence of colestipol hydrochloride. A potentially infringing product must satisfy the ingredient limitations and the stated physical characteristics.

The patent concerns colestipol hydrochloride tablets, including the formulation marketed historically as Colestid tablets. Colestipol hydrochloride is a nonabsorbed bile-acid sequestrant used to reduce low-density lipoprotein cholesterol. The active material is a high-molecular-weight anion-exchange resin rather than a conventional small-molecule drug substance.

How are claims 1 through 6 structured?

Claims 1 through 6 define the uncoated tablet and narrow its formulation and performance.

Claim	Scope
1	Base tablet with approximately 1,000 mg fine-milled colestipol hydrochloride, povidone, colloidal silicon dioxide, magnesium stearate, hardness above 40 SCUs, and friability of 0-0.1%
2	Claim 1 tablet with hardness of 40-75 SCUs, weight of 1,017-1,079 mg, disintegration below five minutes, and thickness of 5.08-8.64 mm
3	Claim 2 tablet with approximately 1,048 mg total weight, 40-50 SCUs hardness, and 8.13-8.64 mm thickness
4	Claim 1 tablet containing approximately 40 mg povidone
5	Claim 1 tablet containing 40-50 mg povidone, 5-10 mg colloidal silicon dioxide, and 2.5-3.5 mg magnesium stearate
6	Claim 5 formulation with approximately 40 mg povidone, 5 mg colloidal silicon dioxide, and 3 mg magnesium stearate

Claim 1 is the principal product claim. Claims 2 through 6 narrow the claim by adding tighter ranges or target quantities.

The use of “approximately” creates a fact-dependent infringement issue. It does not normally eliminate the numerical limitation. The relevant question would be whether a court interprets the accused formulation and manufacturing tolerances as falling within the claimed approximate amount. Batch records, finished-product testing, formulation specifications, and quality-control ranges would be central evidence.

What is the importance of “fine-milled” colestipol hydrochloride?

“Fine-milled” is a material limitation in claims 1, 15, and 16. The claim does not provide a particle-size value in the text supplied. The patent specification and prosecution history would therefore control how the term is construed.

A generic manufacturer using the same active ingredient quantities but a materially different particle-size distribution could argue that it does not meet this limitation. The argument would depend on:

The actual particle-size specification;
Whether milling is performed before or during granulation;
The patent specification’s examples;
The prosecution history;
Equivalence principles.

Because the patent expired, this distinction has limited current litigation value but remains relevant to historical infringement analysis and freedom-to-operate reviews.

What formulations are protected by claims 7 through 14?

Claims 7 through 14 cover coated versions of the tablet.

Seal coating

Claim 7 requires a seal coating containing cellulose acetate phthalate and triacetin. Claim 8 narrows the quantities to:

2-100 mg cellulose acetate phthalate; and
0.5-20 mg triacetin.

Claim 9 specifies approximately:

15.6 mg cellulose acetate phthalate; and
3.12 mg triacetin.

This coating is not merely an optional generic film coat under the claim structure. A tablet must contain the specified coating components to fall within claims 7 through 9.

Clear coating

Claim 10 adds a clear coating containing hydroxypropyl methylcellulose and triacetin. Claim 11 identifies two hydroxypropyl methylcellulose grades:

Hydroxypropyl methylcellulose 2910 E5 Premium USP, 5 CPS;
Hydroxypropyl methylcellulose 2910 USP, 15 CPS;
Triacetin.

Claim 12 narrows the quantities to approximately:

30 mg of the 5 CPS hydroxypropyl methylcellulose;
30 mg of the 15 CPS hydroxypropyl methylcellulose; and
12 mg triacetin.

Claims 13 and 14 add finished-tablet specifications:

Characteristic	Claim 13	Claim 14
Tablet weight	1,100-1,230 mg	Approximately 1,138 mg
Disintegration	Less than 30 minutes	Same inherited limitation
Hardness	Greater than 60 SCUs	60-80 SCUs
Thickness	5.08-10.16 mm	Approximately 9.52 mm
Friability	0-0.1% after 15 minutes	Approximately 0%

The coating claims are progressively narrower than claim 1. A product could avoid claims 7 through 14 by using a different coating system, omitting the seal coat, using a different polymer, or changing the claimed quantities. That would not necessarily avoid claim 1, which does not require a coating.

How do claims 15 through 17 protect manufacturing?

Claims 15 through 17 cover a wet-processing route for producing the tablet.

The claimed sequence is:

Add 10-200 mg povidone to a dewatered slurry of fine-milled colestipol hydrochloride;
Dry the resulting mixture;
Deaggregate the dried material;
Add colloidal silicon dioxide and magnesium stearate;
Compress the mixture into tablets.

Claim 15 is a product-by-process claim. It describes the tablet as one obtainable by the specified manufacturing sequence.

Claim 16 is the direct process claim. It requires performance of the identified steps.

Claim 17 narrows claim 16 by requiring compression using 8,000-10,000 pounds of compressional force.

The supplied text uses “providone” in claims 15 and 16. The intended excipient is almost certainly povidone, which is the term used in claims 1 and 4 through 6. The apparent spelling error would ordinarily be assessed against the patent specification, prosecution record, and correction procedures rather than treated as a separate chemical limitation.

What is the strongest infringement theory under the process claims?

Claim 16 provides the clearest process-based theory because it recites the manufacturing steps directly. Evidence would include:

Batch manufacturing records;
Granulation instructions;
Milling and deaggregation records;
Addition order for excipients;
Compression-force settings;
In-process controls;
Technical transfer documents.

Claim 17 is narrower. A manufacturer could potentially avoid it by using a compression force outside the 8,000-10,000-pound range while still facing claim 16 if the remaining steps were practiced.

Claim 15 may present more complicated issues because product-by-process claims generally focus on the claimed product and the legal effect of the process language under the applicable infringement standard. The claim should not be treated as a broad monopoly over every colestipol tablet.

When did US Patent 5,490,987 lose exclusivity?

US Patent 5,490,987 issued on February 13, 1996. For a patent subject to the pre-Uruguay Round patent term rules, the ordinary term was 17 years from issuance. On that basis, the patent expired on February 13, 2013 (U.S. Patent No. 5,490,987, 1996).

Event	Date
Patent issued	February 13, 1996
Ordinary 17-year term from grant	February 13, 2013
Current status	Expired by term

The patent was granted before the June 8, 1995 transition applicable to the modern 20-year-from-earliest-effective-filing-date regime. No current U.S. patent exclusivity should be attributed to this patent.

The patent also does not appear to represent a current patent-term-extension issue. Colestipol is a nonabsorbed resin product, and the patent’s term does not create an active regulatory or patent barrier today.

What is the Orange Book status of colestipol tablets?

The FDA Orange Book is the relevant source for approved drug products, therapeutic-equivalence evaluations, listed patents, and exclusivity. Patent 5,490,987 has no current blocking effect because it expired in 2013. Any historical Orange Book listing would not provide present-day enforceable exclusivity.

Colestipol tablets are small-molecule drug products for FDA approval purposes, even though colestipol hydrochloride is a polymeric ion-exchange resin. The relevant generic pathway is an abbreviated new drug application, or ANDA, rather than a biosimilar application under the Public Health Service Act.

The regulatory analysis is therefore:

Issue	Assessment
FDA product type	Small-molecule drug product
Likely approval pathway	ANDA
Biosimilar pathway	Not applicable
Current patent exclusivity from US 5,490,987	None
Current commercial barrier	Product development, manufacturing, supply, and approval execution
Current Paragraph IV significance	None for an expired patent

Which companies challenged the colestipol patent?

No current Paragraph IV challenge to US Patent 5,490,987 has practical significance because the patent expired more than a decade ago. A historical ANDA applicant could have addressed the patent through a Paragraph IV certification, a section viii statement, or an acknowledgment that the patent was expired, depending on the timing of the ANDA and the product’s Orange Book listing.

A Paragraph IV certification is relevant only while the listed patent remains unexpired. It is not a continuing litigation risk after expiration.

Public patent analysis should distinguish between:

Litigation involving Colestid or other colestipol products;
Litigation involving unrelated bile-acid sequestrants;
ANDA litigation against other patents;
Commercial entry after expiration without a Paragraph IV dispute.

The existence of a generic colestipol tablet does not establish that a particular company challenged this patent. Generic approval may have occurred after expiration or through a certification that did not require litigation.

How strong is the patent estate for colestipol tablets?

The estate represented by US 5,490,987 was technically focused but commercially narrow.

Strength factor	Assessment
Active-ingredient protection	None; the patent does not claim colestipol hydrochloride itself
Core formulation	Moderate historical protection because of the excipient combination and tablet-performance limits
Coating protection	Narrow, with multiple ingredient and quantity limitations
Manufacturing protection	Meaningful if the precise wet-processing sequence was used
Process workaround potential	High, through alternative granulation, excipient addition, or compression methods
Current enforceability	None after expiration
Biosimilar exposure	Not applicable
Generic substitution risk	High after patent expiration

The patent’s commercial value depended on controlling a manufacturable 1,000-mg tablet with acceptable hardness, low friability, rapid disintegration, and manageable tablet size. Colestipol’s resin properties can make direct compression and high-dose tablet production difficult. The patent addressed those manufacturing problems through fine milling, povidone incorporation, drying, deaggregation, glidant addition, lubrication, and controlled compression.

Its weakness was claim specificity. A competitor could pursue alternative excipient quantities, coating materials, tablet dimensions, granulation sequences, or compression conditions. The claims did not broadly prevent development of other colestipol dosage forms.

What generic entry risks exist for colestipol tablets?

The patent risk is now zero from US 5,490,987 itself. Generic entry and competition are instead constrained by operational and regulatory factors.

Manufacturing barriers

Colestipol hydrochloride is administered at a high mass per dose. A 1,000-mg tablet must accommodate the resin while maintaining:

Adequate mechanical strength;
Low friability;
Acceptable disintegration;
Consistent content and weight;
Patient-acceptable size;
Stable coating performance.

The patented process may have been valuable because it improved powder handling and compactability. Those technical benefits can remain relevant after expiration as know-how, even though the patent no longer prevents use of the process.

Regulatory barriers

An ANDA applicant must demonstrate pharmaceutical equivalence and bioequivalence or satisfy the applicable FDA requirements for the product. For a nonabsorbed resin, conventional systemic pharmacokinetic bioequivalence may not fully capture product performance. In vitro binding, dissolution or disintegration characteristics, clinical endpoint considerations, and FDA-specific product requirements may affect development.

The patent does not itself establish FDA approval. Patent expiration removes one legal barrier but does not eliminate formulation-development or regulatory requirements.

How does colestipol compare with competing bile-acid sequestrants?

Product	Active ingredient	Dosage-form issue	Patent position
Colestid tablets	Colestipol hydrochloride	High-dose resin tablet	US 5,490,987 expired
Colestid granules	Colestipol hydrochloride	Powder or granule administration	Separate formulation and regulatory considerations
Questran	Cholestyramine	Powder for suspension	Different active resin and formulation estate
WelChol	Colesevelam hydrochloride	High-dose tablets and suspension	Separate patents and formulation technology

Colestipol tablets compete with other bile-acid sequestrants but do not share the same active ingredient, excipient system, or patent claims. A patent clearance review must therefore be product-specific. The expiration of US 5,490,987 does not clear patents covering cholestyramine, colesevelam, combination products, or later delivery systems.

What is the geographic coverage of US Patent 5,490,987?

The patent grants rights only in the United States. Its claims do not directly establish protection in Canada, Europe, Japan, or other markets. Foreign counterparts, if any, would require separate review by country, including:

Filing and priority data;
Grant status;
Patent-term adjustments;
National-phase prosecution;
Supplementary protection certificates;
Local claim scope;
Local litigation and opposition records.

A U.S. generic launch could proceed independently of foreign patent status, subject to FDA approval and U.S. commercial requirements.

Key Takeaways

US Patent 5,490,987 covers a specific approximately 1,000-mg fine-milled colestipol hydrochloride tablet.
The main product claim requires povidone, colloidal silicon dioxide, magnesium stearate, hardness above 40 SCUs, and friability of 0-0.1%.
Dependent claims narrow the formulation through excipient quantities, coatings, tablet weight, thickness, hardness, and disintegration.
Claims 15 through 17 cover a manufacturing sequence involving povidone addition to a dewatered slurry, drying, deaggregation, excipient addition, and compression.
The patent issued February 13, 1996 and expired by ordinary 17-year term on February 13, 2013.
It is not a composition-of-matter patent for colestipol hydrochloride.
It does not create current Paragraph IV, biosimilar, or Orange Book exclusivity risk.
Historical manufacturing know-how may remain commercially useful, but the patented process is no longer exclusive.
Current competition depends on FDA approval, formulation performance, manufacturing economics, supply reliability, and market demand rather than this expired patent.

Frequently Asked Questions

Does US Patent 5,490,987 cover colestipol hydrochloride as an active ingredient?

No. It covers a tablet formulation containing approximately 1,000 mg of fine-milled colestipol hydrochloride and specified excipients and physical characteristics.

Can a generic manufacturer use the patented colestipol tablet process today?

Yes, the patent expired in 2013. The process is no longer protected by enforceable rights under this patent.

Does US Patent 5,490,987 cover colestipol powder products?

No. The asserted claims are directed to tablets and a tablet-preparation process. They do not broadly claim colestipol powder or granule products.

Is a biosimilar application required for a generic colestipol tablet?

No. Colestipol tablet approval is handled through the FDA drug-approval framework, generally involving an ANDA where applicable. It is not a biologic requiring a biosimilar application.

Could a different coating avoid the patent claims?

Historically, a different coating could avoid the coating-specific claims 7 through 14, but it would not necessarily avoid claim 1. Since the patent expired, the issue has no current U.S. infringement consequence.

References

U.S. Patent No. 5,490,987. (1996). Colestipol hydrochloride tablets. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.
U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. FDA.
U.S. Food and Drug Administration. (2024). Colestipol hydrochloride prescribing information. FDA.

PCT Information
PCT Filed	June 23, 1992	PCT Application Number:	PCT/US92/05066
PCT Publication Date:	January 21, 1993	PCT Publication Number:	WO93/00915

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	173931	⤷ Start Trial
Australia	2293392	⤷ Start Trial
Australia	669664	⤷ Start Trial
Canada	2110166	⤷ Start Trial
Czech Republic	286958	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,490,987

Summary for Patent: 5,490,987