Executive summary: U.S. Patent No. 10,016,504 protects low-volume aqueous bowel-cleansing formulations combining ascorbic acid, an ascorbate salt, and polyethylene glycol, with dependent claims covering electrolytes, flavoring, sweeteners, PEG molecular weight, and specific Plenvu-type formulations. The strongest commercial coverage is concentrated in claims 11, 12, 18, and 19, while claims 1, 13, 15, and 20 create broader formulation and preparation-method coverage. The patent is directed to a small-molecule combination product, so biosimilar substitution is not relevant. Generic risk depends on whether an entrant uses the claimed ascorbic-acid/ascorbate ratio, PEG range, electrolyte profile, or an equivalent two-part reconstitution method.

U.S. Patent 10,016,504 Patent Landscape, Claim Scope, Expiration, and Generic Risk

What drug does U.S. Patent 10,016,504 protect?

U.S. Patent 10,016,504 protects aqueous colonic-cleansing solutions and their preparation methods. The claim architecture corresponds to low-volume bowel-preparation products containing:

Ascorbic acid;
One or more ascorbate salts, principally sodium ascorbate;
Polyethylene glycol, generally PEG 3350 or a similar PEG grade;
Optional sodium chloride and potassium chloride;
Flavoring agents and sweeteners.

The formulation profile is associated with the Plenvu product family, a low-volume bowel preparation approved by the U.S. Food and Drug Administration for cleansing the colon before colonoscopy or other examinations requiring a clean colon. FDA-approved Plenvu labeling identifies ascorbic acid, sodium ascorbate, PEG 3350, sodium chloride, potassium chloride, aspartame, and flavoring components as formulation ingredients.[2]

The patent does not claim ascorbic acid or PEG as individual chemical entities. It claims their use together in defined concentration and ratio ranges in a colon-cleansing solution.

What is the legal status and expected expiration of U.S. Patent 10,016,504?

U.S. Patent 10,016,504 was issued on July 10, 2018, and is assigned to Norgine-related interests according to the patent record.[1] Its term is governed by the U.S. patent-term rules applicable to the relevant nonprovisional or international filing date, subject to patent-term adjustment and any terminal disclaimer.

The ordinary projected expiration is approximately March 2034 based on the patent-family filing chronology. The controlling date for freedom-to-operate analysis is the USPTO patent-term calculation, not the grant date or the 20-year calculation alone.

Item	Data
U.S. patent	10,016,504
Patent title	Colonic cleansing compositions
Grant date	July 10, 2018
Principal technology	Low-volume PEG and ascorbate bowel-cleansing solutions
Relevant product	Plenvu-type colon-cleansing formulation
Expected ordinary term	Approximately March 2034, subject to USPTO adjustment
Patent type	Small-molecule formulation and preparation patent
Biosimilar relevance	None

A granted patent may remain enforceable until expiration even if a particular claim is later narrowed, cancelled, or held invalid. The patent’s enforceability depends on prosecution history, maintenance-fee status, claim construction, and any litigation judgment.

How many patents cover the Plenvu formulation?

The principal identified U.S. patent in the supplied claim set is U.S. Patent 10,016,504. Commercial exclusivity for a product such as Plenvu can also involve other patents, regulatory exclusivity, trademarks, confidential manufacturing information, and patents owned or licensed by different entities.

The patent should not be treated as the entire product estate without reviewing:

The FDA Orange Book listing for the relevant NDA;
Continuation and divisional applications;
Foreign counterparts;
Patent-term adjustment and terminal-disclaimer records;
Any later-issued formulation, packaging, or manufacturing patents;
Hatch-Waxman litigation and Paragraph IV certifications.

The Orange Book identifies patents submitted by NDA holders for approved drug products and provides patent-use codes where applicable.[3] A formulation patent can be listed even when the patent does not claim the active ingredient as a new chemical entity.

What does independent claim 1 cover?

Claim 1 is the principal composition claim. It requires a solution in water containing:

300 to 800 mmol/L of ascorbate anion; and
10 to 200 g/L of polyethylene glycol;

with the ascorbate anion supplied by a mixture of:

Ascorbic acid; and
One or more salts of ascorbic acid;

where the ascorbic acid-to-ascorbate-salt molar ratio is 1:4.5 to 1:7.0.

The claim is broad in several respects. It does not require:

Sodium ascorbate specifically;
A particular PEG molecular weight;
Sodium chloride;
Potassium chloride;
A particular volume;
A flavoring agent;
A sweetener;
A colonoscopy indication.

A competing product may therefore fall within claim 1 even if it uses a different ascorbate salt, a different PEG grade, or no flavoring.

Claim 1 concentration analysis

The ascorbate concentration is expressed as ascorbate anion rather than total grams of ascorbic acid and ascorbate salt. This creates an analytical issue: infringement testing must determine the molar amount of ascorbate anion supplied by both the acid and salt components.

The PEG limitation is comparatively broad:

Parameter	Claimed range
Ascorbate anion	300-800 mmol/L
PEG	10-200 g/L
Ascorbic acid:ascorbate salt molar ratio	1:4.5 to 1:7.0

A formulation containing 80 g/L PEG and approximately 5.5 to 6 parts sodium ascorbate per part ascorbic acid would be positioned near the center of claim 1.

What additional formulation limitations appear in claims 2 through 10?

Claims 2 through 10 progressively narrow the composition.

Claim	Limitation
2	Ascorbate salt is sodium, potassium, magnesium, calcium ascorbate, or a mixture
3	Ascorbic acid-to-salt ratio is 1:5.40 to 1:5.80
4	60-140 g/L of ascorbate component
5	12-20 g/L ascorbic acid and 80-120 g/L sodium ascorbate
6	PEG average molecular weight is 2,500-4,500 Da
7	PEG concentration is 60-100 g/L
8	Sodium chloride is 4-7 g/L
9	Potassium chloride is 1.5-3 g/L
10	Flavoring agent and/or sweetener

Claims 2 and 3 are important for competitor analysis because they capture the most commercially plausible ingredient choices. Claim 6 targets PEG grades in the range commonly used for PEG 3350 bowel preparations. Claims 8 and 9 add electrolyte limitations that may distinguish a product from an otherwise similar PEG-ascorbate formulation.

What formulation is protected by claims 11 and 12?

Claims 11 and 12 are narrow, high-specificity formulation claims.

Claim 11 requires a solution consisting essentially of:

14-16 g/L ascorbic acid;
92-100 g/L sodium ascorbate;
75-85 g/L PEG with an average molecular weight of 3,000-4,000 Da;
6.0-6.8 g/L sodium chloride;
2.0-2.8 g/L potassium chloride;
Flavoring agents; and
Sweeteners.

Claim 12 narrows the formulation further to:

15.08 g/L ascorbic acid;
96.22 g/L sodium ascorbate;
80 g/L PEG with an average molecular weight of 3,000-4,000 Da;
6.4 g/L sodium chloride;
2.4 g/L potassium chloride;
Orange flavoring; and
2.5-4.0 g/L aspartame.

Claim 12 is effectively an exact commercial-formulation claim, subject to the meaning of “consisting essentially of” and the treatment of unlisted ingredients. It is narrower than claim 1 but potentially valuable because a marketed product may use the claimed formulation directly.

The phrase “consisting essentially of” generally permits components that do not materially affect the basic and novel characteristics of the composition. The scope is therefore narrower than “comprising” but not necessarily limited to only the enumerated ingredients.

Does claim 13 cover a method of colon cleansing?

Claim 13 depends on claim 1 and identifies the solution as a colon-cleansing solution. It is a use-oriented limitation, but it is drafted as a product characterization rather than a conventional method-of-treatment claim.

This claim is commercially relevant because it ties the formulation to its intended medical use. It may provide narrower protection than claim 1, but it does not expand the chemical composition required by the parent claim.

The claims do not expressly require:

Administration to a patient;
A particular dosing schedule;
A colonoscopy;
Split dosing;
A particular preparation interval; or
A specific clinical outcome.

What do claims 14 through 20 protect?

Claims 14 through 20 extend the patent beyond the finished solution and cover preparation methods.

Claim 14: preparing the claimed solution

Claim 14 covers combining the claimed formulation components with water. This is a basic reconstitution or manufacturing step and depends on the composition requirements of claim 1.

Claim 15: two-part or concentrated composition

Claim 15 covers preparing a solution by combining a composition with water and admixing, where the composition may be supplied in two or more parts. It requires:

150-400 mmol of ascorbate anion;
An ascorbic acid-to-ascorbate-salt ratio of 1:4.5 to 1:7.0;
5-100 g PEG; and
A final volume of 300-1,000 mL.

This claim is commercially significant because it reaches dry sachets, multi-part kits, or other presentation formats that are reconstituted before administration.

Claim 16: 450-550 mL final volume

Claim 16 narrows claim 15 to a final solution volume of 450-550 mL. A 500 mL preparation is squarely within the claim.

Claims 17 through 19: narrower 500 mL formulations

Claims 17, 18, and 19 describe specific 500 mL formulations. Claim 19 requires:

7.54 g ascorbic acid;
48.11 g sodium ascorbate;
40 g PEG with a molecular weight of 3,000-4,000 Da;
3.20 g sodium chloride;
1.20 g potassium chloride;
Flavoring; and
Sweetener.

Claim 17 contains an apparent ratio transcription problem: “1:5063 to 1:7.875.” As written, the first ratio is not technically coherent with the surrounding claim set and appears to be a typographical or OCR error, likely intended to state a ratio near 1:5.063. The issued patent, certified claim text, prosecution history, and any claim-correction record control the legally operative wording.

Claim 20: solution prepared by the method

Claim 20 covers a solution prepared by the method of claim 15. Product-by-process analysis can be fact-specific. The claim may create infringement exposure for a product made using the claimed reconstitution method, but the practical scope depends on whether the resulting solution is distinguishable by composition and how the court interprets the process limitation.

How strong is the patent estate for a generic challenge?

The estate has meaningful composition coverage but also several potential attack points.

Strengths

Claim 1 covers a broad PEG-ascorbate concentration space.
The ratio limitation is directed to a commercially realistic formulation range.
Claims 2, 3, 5, 6, and 7 align with common sodium-ascorbate and PEG 3350 formulations.
Claims 11 and 12 target highly specific finished products.
Claims 15-20 cover reconstitution and low-volume presentation formats.
The claims can create multiple infringement theories against a single product.

Potential vulnerabilities

The core ingredients, PEG and ascorbate salts, were individually known in bowel preparations.
Validity may turn on whether the claimed ratio and low-volume formulation were non-obvious over earlier PEG-electrolyte and ascorbate bowel-prep references.
Concentration and ratio limitations may be vulnerable to anticipation if an earlier reference discloses overlapping ranges.
Claim 12 may face a written-description or enablement challenge if the specification does not adequately support the exact formulation and permitted excipient variations.
Claim 17 contains an apparent numerical defect that could affect enforcement of that claim.
“Consisting essentially of” language in claims 11 and 12 may generate disputes over additional excipients.
Claim 20 may raise product-by-process issues if the accused product has the same composition but is prepared differently.

The strongest surviving claims are likely to be assessed separately. A weakness in claim 1 would not necessarily eliminate the narrower claims 11, 12, 18, or 19.

What generic entry risks exist for Plenvu-type products?

A generic or authorized-generic entrant faces the highest risk if it markets a product with all or most of the following characteristics:

Sodium ascorbate as the principal ascorbate salt;
Ascorbic acid-to-sodium-ascorbate molar ratio of approximately 1:5.4 to 1:5.8;
PEG 3350 at approximately 60-100 g/L;
PEG molecular weight near 3,000-4,000 Da;
Sodium chloride and potassium chloride within the claimed ranges;
A final volume of approximately 500 mL;
Orange flavoring and aspartame;
A two-part or multi-part reconstitution kit.

A design-around could target one or more claim limitations, such as:

Changing the acid-to-salt molar ratio outside 1:4.5-1:7.0;
Using a different total ascorbate concentration;
Selecting PEG concentration outside 10-200 g/L, which is difficult because the range is broad;
Using a different electrolyte profile;
Avoiding the claimed 450-550 mL final volume;
Using a different ascorbate salt;
Modifying the dosage presentation or reconstitution process.

Avoiding claim 12 alone would not necessarily avoid claim 1 or claims 2-10. A design-around must be tested against every independent and dependent claim that remains enforceable.

What is the Paragraph IV risk?

A generic applicant seeking approval before patent expiration could file an Abbreviated New Drug Application with a Paragraph IV certification against a listed patent. The applicant would need to assert that the patent is invalid, unenforceable, or not infringed.

For a formulation patent, the principal Paragraph IV theories would likely focus on:

Lack of novelty based on earlier PEG-ascorbate compositions;
Obviousness based on combining known PEG bowel-prep systems with known ascorbate salts;
Noninfringement based on concentration, ratio, PEG grade, or electrolyte differences;
Indefiniteness or claim-construction disputes involving the concentration basis and “consisting essentially of” language;
Written-description or enablement challenges to the narrow formulation claims.

A Paragraph IV notice can trigger Hatch-Waxman litigation and a 30-month stay of FDA approval under applicable statutory conditions.[4] The patent claim text alone does not establish whether a particular generic applicant has filed such a certification or whether litigation is pending.

Which companies compete with Plenvu?

The relevant U.S. competitive field includes both PEG-based and non-PEG bowel preparations.

Product	Principal sponsor or marketer	General formulation category	Patent overlap risk
Plenvu	Norgine/Salix-related commercial interests	Low-volume PEG plus ascorbate and electrolytes	Direct
MoviPrep	Salix-related commercial interests	PEG-electrolyte plus ascorbate	Potentially adjacent
GoLYTELY	Various marketers	Higher-volume PEG-electrolyte	Limited direct overlap
Suprep	Braintree Pharmaceuticals	Sulfate-based, low-volume preparation	Different core composition
Sutab	Sebela Pharmaceuticals	Tablet bowel preparation	Different dosage form
Generic PEG-electrolyte solutions	Multiple manufacturers	PEG-electrolyte solutions	Product-specific assessment required

MoviPrep is the closest technical comparator because it also uses PEG and ascorbate components. Suprep and Sutab compete commercially but are less likely to infringe the composition claims if they do not contain the claimed ascorbic-acid/ascorbate/PEG combination.

Does the patent create biosimilar risk?

No. U.S. Patent 10,016,504 concerns a non-biologic formulation. The relevant competitive pathway is an ANDA, 505(b)(2) application, or a competing branded product, not a biosimilar application under the Biologics Price Competition and Innovation Act.

The principal regulatory risks are:

Paragraph IV patent certification;
505(b)(2) reliance on published data;
Product-specific formulation differences;
FDA requirements for pharmaceutical equivalence and bioequivalence, where applicable;
Labeling and safety requirements for electrolyte-containing bowel preparations.

What licensing deals affect commercial control?

Plenvu has been associated with Norgine’s product portfolio and U.S. commercial activity involving Salix Pharmaceuticals. Commercial rights, distribution rights, and patent ownership should be separated:

The patent owner or exclusive licensee controls enforcement rights.
The NDA holder controls FDA regulatory submissions.
The marketer may hold commercial rights without owning the underlying patent.
A license may be exclusive by territory, field, or product.

The existence of a commercial collaboration does not establish that all related patents are owned by the same entity. Patent assignments and recorded licenses in USPTO records are the relevant evidence for ownership and enforcement authority.

What geographic coverage does the patent provide?

U.S. Patent 10,016,504 provides rights only in the United States. Corresponding foreign patents may protect related formulations in Europe, the United Kingdom, Canada, Australia, and other jurisdictions, but claim scope, expiration, validity, and regulatory linkage must be assessed separately.

A U.S. launch does not create infringement in Europe, and a foreign formulation design-around does not necessarily avoid U.S. claims. The U.S. claims are particularly sensitive to:

The final aqueous concentration;
The acid-to-salt molar ratio;
PEG molecular weight;
The final reconstituted volume;
The composition of multi-part kits.

What manufacturing and intellectual-property barriers remain after patent expiration?

Patent expiration will remove the statutory exclusion right for the expired claims, but market entry can still require:

FDA approval or an approved ANDA;
Validated manufacturing controls;
Stability data for the dry or concentrated components;
Control of PEG molecular-weight distribution;
Accurate electrolyte and ascorbate assays;
Packaging that prevents moisture uptake;
Flavor and sweetener compatibility;
Supply of pharmaceutical-grade sodium ascorbate and PEG.

Trade secrets may protect manufacturing order, mixing conditions, flavor systems, moisture-control packaging, and quality-control specifications. Those barriers do not extend the patent term but can affect launch timing and product quality.

What patent litigation and settlement issues matter?

A generic challenge would likely center on claim construction and formulation testing. The most important evidentiary questions would be:

Whether the accused product’s ascorbate ratio falls within the claimed range;
Whether concentrations are measured before or after final reconstitution;
Whether PEG molecular weight is determined by nominal grade or analytical average;
Whether excipients outside the claim materially alter the formulation;
Whether the product is prepared by the claimed method;
Whether the patent claims are invalid over prior bowel-preparation formulations.

A settlement could permit an agreed launch date before the projected patent expiration, subject to regulatory approval and commercial terms. Settlement terms are not inferable from the claims and should not be treated as established without a filed agreement, court order, or regulatory record.

Key Takeaways

U.S. Patent 10,016,504 is a formulation and preparation patent for low-volume PEG-ascorbate bowel-cleansing solutions.
Claim 1 is the primary broad composition claim, covering 300-800 mmol/L ascorbate anion, 10-200 g/L PEG, and a 1:4.5-1:7.0 acid-to-ascorbate-salt ratio.
Claims 11 and 12 provide narrow protection for a Plenvu-type formulation containing sodium ascorbate, PEG 3350-range material, sodium chloride, potassium chloride, orange flavoring, and aspartame.
Claims 15-20 cover reconstitution methods, multi-part presentations, 500 mL solutions, and specific component quantities.
The ordinary projected U.S. patent term runs to approximately March 2034, subject to the official USPTO term calculation.
Generic risk is highest for products that replicate the sodium ascorbate ratio, PEG concentration, electrolyte profile, and 500 mL reconstitution format.
Biosimilar risk is irrelevant because the product is a non-biologic formulation.
The apparent numerical error in claim 17 requires reliance on the issued patent record and prosecution history when evaluating enforceability.
Competitors using sulfate-based solutions or tablets generally present lower direct infringement risk than products using the same PEG-ascorbate architecture.

FAQs

Can a product infringe claim 1 if it uses potassium ascorbate instead of sodium ascorbate?

Yes. Claim 1 covers one or more salts of ascorbic acid without limiting the salt to sodium. Claim 2 expressly identifies potassium ascorbate as an included option.

Does using PEG 3350 automatically create infringement?

No. PEG 3350 alone is not enough. The product must also satisfy the claimed ascorbate-anion concentration and the ascorbic-acid-to-ascorbate-salt ratio, along with other applicable limitations.

Is a dry powder kit covered by the patent?

It may be. Claims 15 through 19 cover compositions that are combined with water and may be presented in two or more parts. The final solution and preparation method must satisfy the applicable claim limitations.

Can removing aspartame avoid the patent?

Removing aspartame may avoid claim 12 if every other limitation is also considered, but it would not necessarily avoid claims 1-11 or 13-20. The broader claims do not require aspartame.

Does patent expiration eliminate the need for FDA approval of a competing bowel preparation?

No. Patent expiration removes the relevant patent barrier but does not eliminate FDA approval, manufacturing, labeling, stability, and quality requirements.

References

United States Patent and Trademark Office. (2018). U.S. Patent No. 10,016,504, Colonic cleansing compositions.
U.S. Food and Drug Administration. (2023). Plenvu prescribing information.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book.
United States Code. (2023). 21 U.S.C. § 355(j), abbreviated applications and patent certifications.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Salix	PLENVU	ascorbic acid; polyethylene glycol 3350; potassium chloride; sodium ascorbate; sodium chloride; sodium sulfate	FOR SOLUTION;ORAL	209381-001	May 4, 2018		RX	Yes	Yes	10,016,504	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	092500	⤷ Start Trial
Australia	2013314442	⤷ Start Trial
Australia	2015228962	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,016,504

Which drugs does patent 10,016,504 protect, and when does it expire?

Summary for Patent: 10,016,504