United States Patent 6,946,149: Scope, Claims, Expiration, and SUPREP Patent Landscape

U.S. Patent No. 6,946,149 covers low-volume, phosphate-free bowel-cleansing compositions based on sodium sulfate, magnesium sulfate, potassium sulfate, and, in several claims, polyethylene glycol (PEG). Its most commercially important embodiment is approximately 20 g sodium sulfate, 20 g magnesium sulfate, 3 g potassium sulfate, and 34 g PEG in about 330 mL of water, corresponding to the formulation marketed as SUPREP Bowel Prep Kit. The patent issued on September 20, 2005, and its enforceable term ended in 2022 under the ordinary 20-year patent-term framework, subject to the precise term calculation and any applicable adjustments recorded by the USPTO.[1,2]

The patent remains important as a formulation and historical Orange Book asset, but it does not provide an active barrier to generic entry after expiration. The claims do not cover every bowel-preparation product, every sulfate solution, or every PEG-containing purgative.

What does U.S. Patent 6,946,149 cover?

The patent covers three related categories:

Low-volume aqueous hypertonic compositions for inducing colonic purgation.
Compositions containing one or more sulfate salts, with or without PEG.
Oral methods of administering those compositions to produce colonic purgation.

The independent claims impose several cumulative limitations:

Limitation	Claims in which it appears
Colonic-purgation purpose	1, 6, 10, 15, 18, 19, 20
Aqueous hypertonic solution	1, 6, 15, 18
Sodium sulfate, magnesium sulfate, or potassium sulfate	1, 6, 9, 14-18, 20-23
PEG	1-14
No phosphate	1, 6, 15, 18
No clinically significant electrolyte shifts	1, 6, 15, 18
Small-volume administration	1, 6, 8, 15, 17, 18, 21
Oral administration method	10-14, 19-23
Two or more treatment doses	12, 23

The central inventive concept is a concentrated sulfate-based bowel-preparation solution intended to achieve effective purgation with a substantially lower liquid volume than conventional large-volume PEG-electrolyte lavage solutions.

Which claims are independent in Patent 6,946,149?

Claims 1, 6, 10, 15, 18, and 20 are the principal independent claims.

Composition claims with PEG

Claims 1 and 6 cover compositions containing:

An aqueous hypertonic solution;
One or more salts selected from sodium sulfate, magnesium sulfate, and potassium sulfate;
An effective amount of PEG;
No phosphate; and
No clinically significant electrolyte shifts.

Claim 1 uses the transitional term "comprising," which generally permits additional ingredients unless another limitation excludes them. Claim 6 uses "consisting essentially of," which narrows the permitted additional ingredients to those that do not materially affect the claimed characteristics of the composition.

Sulfate-only composition claims

Claims 15 and 18 cover a sulfate combination without requiring PEG. They require effective amounts of sodium sulfate, magnesium sulfate, and potassium sulfate, together with the same no-phosphate and electrolyte-shift limitations.

Claim 15 uses "comprising." Claim 18 uses "consisting essentially of." That distinction creates different infringement exposure for products containing additional active or inactive components.

Method claims

Claims 10, 19, and 20 require:

Oral administration of the claimed composition; and
Allowing the composition to induce colonic purgation.

The method claims do not cover manufacture, packaging, labeling alone, or non-oral administration. They are directed to treatment use.

What formulation does Patent 6,946,149 most specifically protect?

The narrowest and commercially most recognizable formulation is recited in claims 4, 7, 11, and 22.

Ingredient or characteristic	Claimed amount
Sodium sulfate	About 20 g
Magnesium sulfate	About 20 g
Potassium sulfate	About 3 g
PEG	About 34 g in claims 4, 7, and 11
Water	About 330 mL in claim 7
Total solution volume	Less than 500 mL in claim 5; 100-500 mL in claim 8

Claim 7 is the most formulation-specific PEG claim. It requires approximately 20 g of sodium sulfate, 20 g of magnesium sulfate, 3 g of potassium sulfate, and 34 g of PEG in approximately 330 mL of water.

Claim 22 covers the corresponding sulfate-only method without PEG. Claims 4 and 5 cover the PEG formulation and add the less-than-500-mL volume limitation.

The use of "about" creates a range of ordinary engineering and formulation tolerance rather than an unlimited departure from the stated values. A court would likely assess the numerical limitations in view of the specification, prosecution history, pharmaceutical equivalence, and ordinary formulation practice.

How broad are the salt limitations?

The patent does not require all three salts in every claim.

Claim 1 covers one or more salts selected from:

Na2SO4;
MgSO4; and
K2SO4.

Claim 9 narrows the PEG formulation to two or more of those salts. Claims 2 and 3 require all three salts and provide concentration ranges.

The principal ranges in claim 3 are:

Component	Claimed range
Na2SO4	About 2-40 g
MgSO4	About 2-20 g
K2SO4	About 1-10 g
PEG	About 0.1-50 g

Claims 15-18 are narrower because they require all three sulfate salts. A product containing sodium sulfate and PEG but no magnesium sulfate or potassium sulfate may fall within claim 1 if the other limitations are met, but it would not fall within claims requiring two or three specified salts.

What does "does not produce clinically significant electrolyte shifts" mean?

This is a functional limitation that is central to the patent's distinction from some earlier osmotic cathartics, particularly phosphate-based preparations.

The phrase does not establish a fixed numerical threshold in the claims. Its construction would likely depend on:

The clinical population;
Baseline electrolyte values;
Dose and dosing schedule;
Measured serum sodium, potassium, magnesium, chloride, bicarbonate, calcium, and phosphate;
Clinical consequences of any change; and
The evidence and definitions in the patent specification and prosecution record.

The limitation creates both claim scope and litigation risk. A generic or competing formulation might match the ingredient profile but contest whether the product satisfies the no-clinically-significant-shift requirement. Conversely, clinical study data showing material electrolyte abnormalities could undermine literal infringement of this limitation, although the result would depend on the product, dose, patient population, and claim construction.

What is the difference between "comprising" and "consisting essentially of"?

The distinction is commercially significant.

"Comprising" is an open-ended transition. A composition meeting the listed ingredients and functional limitations may still contain additional excipients, flavorants, sweeteners, colorants, preservatives, or other components.

"Consisting essentially of" is partially closed. Additional ingredients may be present only if they do not materially alter the basic and novel characteristics identified by the claim. For this patent, those characteristics include low-volume hypertonic sulfate purgation without phosphate and without clinically significant electrolyte shifts.

A product could therefore avoid a "consisting essentially of" claim by using an additional ingredient that materially changes the claimed composition, but that same product could remain exposed to a broader "comprising" claim.

How does Patent 6,946,149 compare with conventional PEG bowel-preparation products?

Product category	Typical liquid-volume concept	Primary osmotic approach	Relevance to Patent 6,946,149
Conventional PEG-electrolyte lavage	Several liters	Iso-osmotic PEG-electrolyte lavage	Generally outside the low-volume limitation
Sulfate-based low-volume solution	Approximately 100-500 mL of concentrate, followed by required additional liquids	Hypertonic sulfate salts, often with PEG	Most directly aligned
Sodium-phosphate preparations	Low volume	Phosphate osmotic load	Expressly excluded by the no-phosphate limitations
Magnesium- or sulfate-only products	Product-specific	Osmotic salt purgation	May implicate claims 15-18 or related claims depending on all limitations
Solid or tablet bowel preparations	Product-specific	Solid-dose osmotic or stimulant system	Usually outside the aqueous-solution limitations

The patent's competitive position came from combining a low-volume delivery format with sulfate salts and a safety profile designed to avoid clinically significant electrolyte shifts. It did not eliminate the need for patients to consume additional clear liquids under the FDA-approved labeling.

What was the FDA and Orange Book status?

SUPREP Bowel Prep Kit was approved by the FDA under NDA 022372 on November 15, 2010, for cleansing of the colon before colonoscopy in adults.[3] The product contains sodium sulfate, potassium sulfate, and magnesium sulfate and is supplied as a concentrate diluted before administration.

The Orange Book historically identified U.S. Patent No. 6,946,149 in connection with the product. The relevant patent term expired in 2022 under the ordinary patent-term framework. FDA approval and Orange Book listing do not extend an expired patent. FDA regulatory exclusivity, if applicable, is separate from patent protection and is governed by the NDA approval and exclusivity provisions of the Federal Food, Drug, and Cosmetic Act.[2,4]

Was Patent 6,946,149 an NCE patent?

The active ingredients in SUPREP are sulfate salts with established pharmaceutical and medical uses. The patent is principally a formulation and method-of-use patent, not a classic new chemical entity patent. Any regulatory exclusivity associated with the product therefore had to be analyzed separately from the patent term.

Does the patent have current Orange Book blocking power?

No active blocking effect remains from an expired patent. An expired patent may remain relevant to historical ANDA certifications, litigation history, damages analysis, and freedom-to-operate records, but it cannot support an injunction against post-expiration commercial manufacture or sale.

Were there Paragraph IV challenges to SUPREP?

Generic applicants seeking approval before patent expiration could file Paragraph IV certifications against the listed patent under the Hatch-Waxman Act. A Paragraph IV certification asserts that the patent is invalid, unenforceable, or not infringed.[5]

The critical commercial date was the patent's expiration in 2022. Before that date, a Paragraph IV challenger faced potential litigation under 35 U.S.C. § 271(e)(2), a 30-month FDA approval stay if litigation was timely filed, and possible settlement restrictions. After expiration, the patent could no longer create a continuing patent-based approval barrier.

The supplied claims alone do not establish the identity of every ANDA applicant, the dates of individual Paragraph IV notices, litigation outcomes, or settlement terms. Those matters must be taken from the FDA ANDA record, PACER, district court dockets, and Orange Book history rather than inferred from the patent claims.

Which companies challenged the SUPREP patent?

The commercial landscape included the NDA holder and generic applicants seeking approval for sodium sulfate, potassium sulfate, and magnesium sulfate oral solutions. Generic competition was expected to focus on:

The exact sulfate ratios;
Presence or absence of PEG;
Concentrate volume;
Dilution instructions;
Clinical electrolyte data;
Product labeling;
Pharmaceutical equivalence; and
The legal status of U.S. Patent 6,946,149.

The patent number alone does not establish a complete list of challengers or the outcome of every Paragraph IV dispute. Current challenger and litigation information is a docket-level issue, not a claim-scope issue.

What patent litigation affected Patent 6,946,149?

The patent could support litigation against an ANDA applicant if the proposed product was alleged to practice one or more composition or method claims before expiration. The strongest infringement theories would have focused on:

A low-volume aqueous hypertonic solution;
The three-sulfate combination;
PEG in the claimed amount;
A phosphate-free formulation;
The approximate 330-mL presentation; and
Labeling that directed oral administration for colonic purgation.

The strongest invalidity theories would likely have addressed:

Anticipation by earlier bowel-preparation formulations;
Obviousness based on PEG-electrolyte and sulfate cathartic references;
Written-description support for broad "one or more salts" and dosage ranges;
Enablement of the full claimed ranges;
Definiteness of "effective amount" and "clinically significant electrolyte shifts"; and
Patent-term or prosecution-history issues.

The patent's expiration makes current merits litigation commercially immaterial except for damages, historical launch timing, settlement interpretation, or ownership disputes.

How strong was the patent estate?

Claim-strength assessment

Issue	Assessment
Core formulation	Stronger for the specific three-sulfate plus PEG formulation
Broad salt selection	Vulnerable to prior-art and obviousness arguments
330-mL formulation	Commercially specific and easier to identify, but narrower
No-phosphate limitation	Clear commercial distinction, but potentially limiting
Electrolyte-shift limitation	Important but fact-intensive
Method claims	Dependent on product labeling and actual administration
Expiration position	No current exclusionary value after 2022
Biosimilar relevance	None; this is a small-molecule drug product

The strongest historical protection was concentrated around the commercial formulation and its low-volume, sulfate-based use. The broadest claims were also the most exposed to prior-art, written-description, enablement, and claim-construction challenges.

What manufacturing and IP barriers remain after patent expiration?

Patent expiration removes the primary composition and method barrier, but commercial entry still requires:

FDA approval through an ANDA or other applicable pathway;
Demonstration of pharmaceutical equivalence;
Appropriate active-ingredient strength and dosage form;
Manufacturing controls for sulfate salts and PEG;
Stability and container-closure data;
Labeling that satisfies bowel-preparation warnings;
Controls for electrolyte-related safety risks;
Compliance with current good manufacturing practice requirements; and
Reliable supply of pharmaceutical-grade sulfate salts.

These are regulatory and operational barriers rather than continuing exclusivity under Patent 6,946,149. A separate patent could still affect a particular device, container, flavor system, manufacturing process, or formulation, but such protection must be evaluated independently.

Does biosimilar risk apply to SUPREP?

No. SUPREP contains chemically defined small-molecule salts and PEG. It is not a biologic subject to the biosimilar pathway under the Public Health Service Act. Competitive entry occurs through generic-drug pathways, principally an ANDA supported by pharmaceutical-equivalence and bioequivalence requirements appropriate to the product.[5]

What generic launch scenarios existed?

Before patent expiration

A generic applicant could:

File a Paragraph IV certification;
Trigger patent litigation;
Seek a 180-day exclusivity period if eligible as a first Paragraph IV filer;
Launch at risk after a court decision or settlement; or
Delay launch until patent expiration.

After patent expiration

The principal patent-specific restriction disappeared. Market entry then depended on FDA approval, manufacturing readiness, commercial contracting, and the number of approved generic suppliers.

The most likely competitive products were sulfate oral solutions using the same or similar active ingredients but potentially differing in PEG content, excipient composition, flavoring, package configuration, or administration instructions.

What is the geographic coverage of Patent 6,946,149?

The patent provides protection only in the United States. Equivalent protection would require separate patents in other jurisdictions. The scope of foreign rights would depend on the international application, national-phase filings, prosecution outcomes, claim amendments, and local patent-term rules.

A U.S. patent does not block manufacture, use, or sale outside the United States, although U.S. importation and U.S.-directed commercial activity can create domestic infringement issues.

Key Takeaways

U.S. Patent 6,946,149 covers low-volume, phosphate-free, hypertonic sulfate bowel-preparation compositions and oral purgation methods.
The most important embodiment is approximately 20 g sodium sulfate, 20 g magnesium sulfate, 3 g potassium sulfate, and 34 g PEG in about 330 mL of water.
Claims 1 and 6 are broader PEG composition claims; claims 15 and 18 cover sulfate combinations without requiring PEG.
Claims using "comprising" are broader than claims using "consisting essentially of."
"Clinically significant electrolyte shifts" is a material, fact-intensive functional limitation.
SUPREP was approved under NDA 022372 in 2010 and historically associated with Patent 6,946,149 in the Orange Book.
The patent expired in 2022 under the ordinary patent-term framework.
No biosimilar pathway applies. Competition proceeds through generic-drug pathways.
Current generic entry is not blocked by this expired patent, although FDA approval, manufacturing, labeling, and any separate unexpired IP remain relevant.
The patent's strongest historical position was the specific commercial sulfate-plus-PEG, low-volume formulation rather than every sulfate-based bowel preparation.

FAQs

What drug is associated with U.S. Patent 6,946,149?

The patent is associated with the low-volume sulfate bowel-preparation formulation marketed as SUPREP Bowel Prep Kit, containing sodium sulfate, potassium sulfate, and magnesium sulfate, with PEG in the principal patented embodiment.

Does Patent 6,946,149 cover sodium phosphate bowel preparations?

No. The claims expressly require that the composition not include phosphate. A sodium-phosphate product would not meet that express limitation.

Can a product containing only sodium sulfate infringe Patent 6,946,149?

Potentially under a broad claim only if it also satisfies the remaining limitations, including PEG where required, low-volume aqueous hypertonicity, colonic-purgation purpose, no phosphate, and the electrolyte-shift limitation. It would not satisfy claims requiring all three sulfate salts.

Is claim 7 limited to exactly 330 mL?

No. Claim 7 uses "about 330 ml," which generally allows a technically meaningful range around 330 mL. The permissible range would depend on claim construction and the patent record.

Is Patent 6,946,149 relevant to a tablet bowel-preparation product?

Usually not. The claims require an aqueous solution, and the principal claims are directed to liquid compositions or oral administration of those solutions. A tablet product would require a separate analysis of its composition, reconstituted form, labeling, and any applicable doctrine-of-equivalents theory.

References

United States Patent No. 6,946,149, "Osmotic bowel cleansing composition" (U.S. Patent and Trademark Office, issued Sept. 20, 2005).
U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term calculation resources. https://www.uspto.gov
U.S. Food and Drug Administration. (2010). SUPREP Bowel Prep Kit, NDA 022372: Approval letter and prescribing information. https://www.accessdata.fda.gov
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.fda.gov
Food and Drug Administration. (2024). Abbreviated new drug application process and patent certifications. https://www.fda.gov

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1499331	⤷ Start Trial	C300615	Netherlands	⤷ Start Trial
European Patent Office	1499331	⤷ Start Trial	C20130010 00080	Estonia	⤷ Start Trial
European Patent Office	1499331	⤷ Start Trial	13C0055	France	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,946,149

Summary for Patent: 6,946,149