United States Drug Patent 5,248,505: Claim Scope, Expiration, and Patent Landscape

U.S. Patent No. 5,248,505 covers methods of treating diarrhea accompanied by flatulence or gas with a combined composition containing simethicone and one of four antidiarrheal agents: loperamide, bismuth subsalicylate, diphenoxylate, or polycarbophil. The patent issued on September 28, 1993, and its 17-year pre-Uruguay Round patent term expired on September 28, 2010. Its claims no longer create an enforceable U.S. exclusionary right.

The commercial combination most closely aligned with the claims is loperamide hydrochloride plus simethicone, including products marketed in the United States as Imodium Multi-Symptom Relief. The patent protected both the therapeutic combination and narrower dosage-form configurations, including enteric-coated loperamide in a layered solid dosage form.

What does U.S. Patent 5,248,505 cover?

The patent covers a method of administering a combined pharmaceutical composition to a human with an intestinal disorder characterized by both diarrhea and flatulence or gas.

The principal claim elements are:

Claim element	Scope
Patient	Human
Disease condition	Intestinal disorder characterized by diarrhea and flatulence or gas
Antidiarrheal component	Loperamide, bismuth subsalicylate, diphenoxylate, polycarbophil, acceptable salts, or mixtures
Antiflatulent component	Simethicone
Administration	Combined pharmaceutical composition
Dosage limitations	Added in dependent claims
Dosage-form limitations	Enteric coating, solid dosage form, and separate layers
Treatment sequence	Initial 4 mg loperamide dose followed by 2 mg doses until diarrhea is controlled

The claims are method-of-treatment claims rather than composition claims. That distinction matters. The patent does not broadly claim every tablet, capsule, or suspension containing loperamide and simethicone as a composition of matter. It claims administering the combination to a human with the specified symptoms.

How broad is claim 1 of Patent 5,248,505?

Claim 1 is the broadest independent claim. It requires:

A human patient;
An intestinal disorder;
Diarrhea and flatulence or gas as characteristic symptoms;
A combined pharmaceutical composition;
An effective amount of one listed antidiarrheal agent; and
An antiflatulent effective amount of simethicone.

The antidiarrheal limitation is structured as a Markush group. A product or treatment using one of the four named active ingredients can fall within the claim if the remaining limitations are satisfied.

Antidiarrheal alternatives in claim 1

The claim covers:

Loperamide;
Bismuth subsalicylate;
Diphenoxylate;
Polycarbophil;
Pharmaceutically acceptable salts of the listed compounds; and
Mixtures of those agents.

Claim 1 does not require a particular dose, dosage form, release profile, tablet architecture, brand, manufacturer, or treatment duration. Those limitations appear in later claims.

The claim does require simethicone. A diarrhea product containing only loperamide, only bismuth subsalicylate, or only diphenoxylate would not satisfy the combination limitation.

Which patent claims cover loperamide and simethicone?

Claims 3, 4, and 10 through 14 focus on loperamide-based combinations.

Claims	Limitation
3	Loperamide from about 0.5 mg to about 8.0 mg
4	Loperamide hydrochloride
10	Enterically coated loperamide
11	Loperamide and simethicone in a solid dosage form
12	At least first and second layers, with enterically coated loperamide in one layer and simethicone in another
13	2 mg loperamide and 80 mg simethicone per dosage unit
14	2 mg loperamide and 125 mg simethicone per dosage unit

Claim 14 is commercially significant because the 2 mg loperamide/125 mg simethicone combination corresponds closely to U.S. loperamide-simethicone antidiarrheal products.

Claim 12 is materially narrower than claim 1. It requires a solid dosage form with at least two layers and allocation of the active ingredients between layers. A liquid suspension or a homogeneous single-layer tablet would not meet that claim's express structural limitations.

What dosage ranges are protected by Patent 5,248,505?

The patent contains several dosage-specific claims.

Active ingredient	Claimed amount
Simethicone	About 20 mg to about 125 mg per dosage unit
Loperamide	About 0.5 mg to about 8.0 mg
Bismuth subsalicylate	About 120 mg to about 1,200 mg
Diphenoxylate	About 0.7 mg to about 10 mg
Polycarbophil	About 150 mg to about 2,000 mg

Claim 15 covers 300 mg bismuth subsalicylate with 80 mg simethicone per dosage unit. Claim 16 covers a loading and maintenance regimen:

Initially, 4 mg loperamide with simethicone; and
Subsequently, 2 mg loperamide with simethicone until diarrhea is controlled.

The dose limitations are cumulative. For example, claim 14 requires the claim 2 simethicone range, the loperamide limitation from claim 3, and the exact 2 mg/125 mg combination.

What formulations are protected by Patent 5,248,505?

The most technically specific formulation claims are claims 10 through 12.

Enteric coating

Claim 10 requires loperamide in an enterically coated form. An enteric coating generally delays release in the stomach and permits release at a higher intestinal pH. The claim does not, on its face, require a specific enteric polymer, coating thickness, dissolution profile, or manufacturing process.

Layered solid dosage form

Claim 12 requires:

A solid dosage form;
At least a first layer and a second layer;
Enterically coated loperamide in the first layer; and
Simethicone in the second layer.

This claim targets product architecture rather than only ingredient identity. A product could avoid claim 12 if it used a non-layered structure, did not enterically coat the loperamide, or placed both ingredients in a different configuration. That design-around analysis would not necessarily avoid the broader method claims if the product still met their other limitations.

When did U.S. Patent 5,248,505 lose exclusivity?

U.S. Patent 5,248,505 expired on September 28, 2010.

Event	Date
Patent issued	September 28, 1993
Applicable base term	17 years from issue
Base expiration	September 28, 2010
Current status	Expired

The patent issued before the change to the modern 20-year term measured from the earliest effective nonprovisional filing date. The pre-1995 patent-term rule therefore governs. No active patent term extension or regulatory exclusivity appears to preserve an enforceable right under this patent.

The expired status eliminates current infringement risk based solely on Patent 5,248,505. It does not eliminate the possibility that a later patent could cover a particular formulation, coating process, manufacturing method, label, or use.

What is the Orange Book status of Patent 5,248,505?

Patent 5,248,505 should not be treated as a current Orange Book barrier to loperamide-simethicone products.

The relevant products are generally sold under the FDA over-the-counter framework rather than as prescription products dependent on an active, product-specific Orange Book patent listing. The FDA Orange Book primarily records patents and exclusivity associated with approved drug products and their abbreviated new drug application pathways. OTC monograph products are not ordinarily blocked by an expired patent of this type.

The FDA OTC monographs separately address antidiarrheal and antiflatulent ingredients. Loperamide is regulated under the OTC antidiarrheal framework, while simethicone is regulated under the OTC antiflatulent framework. The presence of both ingredients in a product does not revive the expired patent or create new patent exclusivity under the OTC monograph system. (FDA, 2024a; FDA, 2024b; 21 C.F.R. pts. 331, 335.)

Are there Paragraph IV challenges to Patent 5,248,505?

No current Paragraph IV challenge can create a new dispute over Patent 5,248,505 because the patent expired in 2010.

A Paragraph IV certification is relevant when a generic applicant challenges a listed patent associated with an approved reference product. After expiration, an applicant does not need to invalidate the patent or wait for its expiration. Any historical Paragraph IV certification involving this patent would now be legally moot as a barrier to launch.

The commercial relevance of the patent during its term would have depended on whether the relevant product was tied to an approved application with a listed patent and whether an ANDA applicant pursued the relevant regulatory pathway. Because the leading loperamide-simethicone products are OTC products, their market-entry analysis was not identical to a conventional prescription-drug ANDA challenge.

Which companies have commercial exposure to the patent?

The patent was directed at a product category associated with McNeil Consumer Products and the Imodium brand. The closest product-level match is a loperamide hydrochloride and simethicone product using the 2 mg/125 mg dosage combination.

Company or product category	Relationship to Patent 5,248,505
McNeil Consumer Products / Imodium	Historical branded-product relevance
Generic OTC manufacturers	Potential historical design-around or licensing exposure
Store-brand loperamide-simethicone products	Current competition, with no exposure to the expired patent as an enforceable right
Bismuth-simethicone combinations	Potential claim overlap only if all method and dosage limitations are met
Diphenoxylate-simethicone products	Potential historical claim overlap, but limited current commercial significance
Polycarbophil-simethicone products	Covered by the claim language if the treatment and dosage limitations are satisfied

No biosimilar issue exists. Loperamide, simethicone, bismuth subsalicylate, diphenoxylate, and polycarbophil are small-molecule or nonbiologic active ingredients. The relevant competition is generic and private-label OTC competition, not biosimilar substitution.

How strong was the patent estate?

The patent had moderate breadth during its enforceable term but limited depth.

Strengths

Claim 1 covered four antidiarrheal categories.
The claim required only the combination of an antidiarrheal and simethicone, without a narrow formulation architecture.
Claims 13 and 14 aligned with commercially practical loperamide-simethicone doses.
Claim 16 covered a clinically recognizable loading-dose regimen.
The claims addressed both symptom treatment and formulation structure.

Limitations

The patent was limited to treatment of humans with diarrhea plus flatulence or gas.
It did not claim loperamide or simethicone individually.
It did not broadly claim every composition containing the two ingredients.
The enteric and layered-form claims were narrower and easier to design around.
The patent expired in 2010.
A product using only one symptom indication, or using a different active ingredient, might fall outside particular claims depending on labeling and actual use.

The patent's strongest commercial claims were likely claims 1, 2, 3, 13, and 14. Its strongest formulation-specific claim was claim 12, but that claim required a detailed dosage-form configuration.

What patent litigation and licensing issues affect the product category?

Patent 5,248,505 presents no current litigation risk because it is expired. A review of the patent record and public regulatory framework does not establish a current enforceable dispute involving this patent.

The principal historical commercial issue would have been whether competing loperamide-simethicone products used:

The 2 mg/80 mg or 2 mg/125 mg combinations;
An enteric-coated loperamide component;
A layered tablet;
A label directing treatment of both diarrhea and gas; or
The 4 mg loading dose followed by 2 mg maintenance dosing.

No public license is necessary to practice the expired patent. Historical licensing arrangements, if any, would be private commercial matters and would not extend the patent's term.

What generic launch risks exist today?

The expired patent creates no present-day launch block. A generic or private-label manufacturer can market a loperamide-simethicone product without obtaining a license under Patent 5,248,505, subject to FDA requirements, labeling rules, manufacturing controls, trademark restrictions, and any later unexpired patent.

Current launch risks are more likely to arise from:

FDA monograph compliance;
Product labeling and dosage instructions;
Trademark or trade-dress claims involving Imodium;
Manufacturing and stability requirements;
New formulation patents;
Patent claims directed to coatings, excipients, release profiles, or manufacturing processes; and
State and federal requirements applicable to OTC products.

The expired patent does not prevent a manufacturer from using the 2 mg/125 mg combination or other claimed dosage combinations.

How does Patent 5,248,505 compare with current competitive protection?

Protection type	Status or relevance
U.S. Patent 5,248,505	Expired September 28, 2010
Loperamide active ingredient	Long off-patent
Simethicone active ingredient	Long off-patent OTC ingredient
Loperamide-simethicone combination	Available for generic and private-label competition
OTC monograph pathway	Primary regulatory framework
Biosimilar pathway	Not relevant
Brand trademark protection	Potentially remains relevant
New formulation patents	Must be assessed separately
Manufacturing patents	Must be assessed separately

Key Takeaways

U.S. Patent 5,248,505 covers methods of treating diarrhea and flatulence or gas with simethicone plus loperamide, bismuth subsalicylate, diphenoxylate, or polycarbophil.
The broadest claim is claim 1, which requires a human treatment method and a combined pharmaceutical composition.
Claims 13 and 14 specifically cover 2 mg loperamide with 80 mg or 125 mg simethicone.
Claim 12 covers a layered solid dosage form containing enterically coated loperamide and simethicone in separate layers.
The patent expired on September 28, 2010.
It presents no current Paragraph IV, Orange Book, licensing, or infringement barrier.
Current competition is primarily among branded, generic, and private-label OTC loperamide-simethicone products.
New patents covering formulations, coatings, manufacturing methods, or labeling would require a separate freedom-to-operate review.

FAQs About U.S. Patent 5,248,505

Does Patent 5,248,505 cover Imodium Multi-Symptom Relief?

Its claims closely correspond to loperamide-simethicone products, particularly the 2 mg loperamide/125 mg simethicone combination. The patent expired in 2010, so it no longer blocks that product category.

Can a generic manufacturer use 2 mg loperamide and 125 mg simethicone?

Yes. Patent 5,248,505 does not currently prevent use of that dosage combination because the patent has expired.

Does the patent cover simethicone by itself?

No. The claims require simethicone together with a specified antidiarrheal treatment.

Is claim 12 limited to tablets?

Claim 12 requires a solid dosage form with at least two layers. It is most naturally applied to layered tablets or similar solid products, but claim interpretation would depend on the product structure and applicable claim-construction principles.

Are loperamide-simethicone products subject to biosimilar competition?

No. These products contain nonbiologic active ingredients and compete through generic or OTC pathways rather than the biosimilar framework.

References

Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services. https://www.accessdata.fda.gov/scripts/cder/ob/
Food and Drug Administration. (2024b). Over-the-counter monograph M007: Antidiarrheal drug products for over-the-counter human use. U.S. Department of Health and Human Services.
Google Patents. (n.d.). US5248505A: Antidiarrheal-antiflatulent compositions and methods of use. https://patents.google.com/patent/US5248505A/en
U.S. Patent and Trademark Office. (1993). U.S. Patent No. 5,248,505: Antidiarrheal-antiflatulent compositions and methods of use. U.S. Department of Commerce.
Electronic Code of Federal Regulations. (2024). 21 C.F.R. Part 331: Antiflatulent drug products for over-the-counter human use; 21 C.F.R. Part 335: Antidiarrheal drug products for over-the-counter human use. https://www.ecfr.gov/

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0428296	⤷ Start Trial	SPC/GB98/013	United Kingdom	⤷ Start Trial
European Patent Office	0428296	⤷ Start Trial	99C0029	Belgium	⤷ Start Trial
Austria	106737	⤷ Start Trial
Australia	634833	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,248,505

Summary for Patent: 5,248,505