United States Patent 7,291,324: Scope, Claims, Expiration and Patent Landscape for Bisacodyl-PEG Bowel Cleansing

U.S. Patent No. 7,291,324 protects a narrow, sequential bowel-preparation method using oral bisacodyl followed by a reduced-volume polyethylene glycol electrolyte solution. The core limitation is the sequence: bisacodyl must produce a bowel movement within six hours before the patient receives approximately 50 to 400 grams of PEG in 1.5 to 2.5 liters of isotonic solution.

The patent does not broadly cover bisacodyl, PEG, isotonic bowel-preparation solutions, or colonoscopy preparation as individual products. Its commercial value lies in the claimed regimen and its potential use in labeling for combination bowel-preparation products.

The patent’s enforceability depends on its expiration date, any patent-term adjustment, terminal disclaimer, continuation rights, Orange Book listing, and the status of related patents. The claim text alone does not establish any currently enforceable patent right.

What does U.S. Patent 7,291,324 cover?

U.S. Patent 7,291,324 covers a method for cleansing the bowel and colon of a mammal through two principal administrations:

Oral administration of 5 to 40 mg of bisacodyl.
After a bowel movement occurs within six hours, oral administration of 50 to 400 grams of PEG in 1.5 to 2.5 liters of isotonic solution.

The claim requires later evacuation of the bowel and colon sufficient to permit diagnostic testing or surgery. Claim 1 also permits administration of a clear liquid after bisacodyl.

The patent is therefore a regimen patent, not a basic compound or composition patent.

Claim structure

Claim	Scope	Key limitation
1	Independent method claim	Bisacodyl first, bowel movement within six hours, then PEG in isotonic solution
2	Dependent method claim	Isotonic solution volume of about 2 liters
3	Dependent method claim	Bisacodyl dose of about 10 to 20 mg
4	Dependent method claim	Reduced preparation time and adverse symptoms

Claim 1 is the principal commercial claim. Claims 2 and 3 narrow the regimen to commercially familiar dosing parameters. Claim 4 adds a result-oriented limitation but does not specify an independent numerical threshold for reduced preparation time or adverse symptoms.

How should the “consisting essentially of” language be interpreted?

The transition “consisting essentially of” permits the claimed method to include additional steps or components that do not materially affect the basic and novel characteristics of the regimen.

The basic characteristics appear to be:

Oral bisacodyl administration.
A bowel movement within six hours.
Subsequent administration of PEG in an isotonic solution.
Final evacuation sufficient for diagnostic testing or surgery.

A method that adds ordinary clear liquids is expressly contemplated by claim 1. A method that adds another active laxative, changes the order of administration, or materially changes the cleansing mechanism could create a dispute over whether the additional step alters the claimed method’s basic characteristics.

The phrase does not mean that every additional treatment step is permitted. A materially different pharmacological or procedural intervention could fall outside the claim.

What are the key limitations of independent claim 1?

1. The treatment must be administered orally

The claim requires oral administration of bisacodyl and oral administration of PEG solution. Rectal, enteral, or other non-oral delivery would not literally satisfy the administration limitations.

2. Bisacodyl must be given before PEG

The order of administration is central. PEG cannot be administered first if the regimen is to meet the literal sequence of claim 1.

A product using simultaneous administration may face a claim-construction dispute. The stronger noninfringement position would be that simultaneous administration does not satisfy the required step of administering PEG “following the bowel movement.”

3. The bisacodyl dose is approximately 5 to 40 mg

The claim covers a broad range. Claim 3 narrows the dose to approximately 10 to 20 mg.

The term “about” creates a factual boundary issue. A dose slightly outside the numerical range may still be argued to fall within the claim depending on the specification, prosecution history, formulation precision, and technical understanding of dosing variability.

4. A bowel movement must occur within six hours

This is a major limiting condition. The claim does not merely require bisacodyl administration followed by PEG. The bisacodyl must produce a bowel movement, and the bowel movement must occur within six hours.

A patient who does not experience a bowel movement within six hours presents a potential failure of a literal claim condition. The patent holder could argue that infringement is assessed by the prescribed regimen rather than by perfect patient compliance, but that position would depend on the claim construction and facts of the case.

5. PEG must be administered after the bowel movement

The PEG administration must follow the qualifying bowel movement. This distinguishes the claimed regimen from conventional full-volume PEG-electrolyte lavage protocols administered without a stimulant-laxative priming step.

6. PEG must be administered in an isotonic solution

The claim specifies 50 to 400 grams of PEG in 1.5 to 2.5 liters of isotonic solution. The isotonicity requirement is important because PEG products vary in electrolyte composition, osmolality, and total volume.

The claim does not identify a specific PEG molecular weight, electrolyte composition, flavoring system, or branded formulation. Those features may be addressed by other composition or formulation patents.

7. The colon must be adequately cleansed

The claimed result is cleansing sufficient for diagnostic testing or surgery. “Adequately cleansed” is functional language. Its application would likely depend on clinical evidence, product labeling, colonoscopy-preparation standards, and the patent specification.

Claim 4 adds that preparation time and adverse symptoms are diminished. It does not quantify either result, which may limit its independent enforcement value.

What do dependent claims 2, 3 and 4 add?

Claim 2: approximately 2 liters

Claim 2 narrows the isotonic solution volume to approximately 2 liters. This is commercially relevant because reduced-volume PEG regimens are designed to improve patient acceptance compared with traditional 4-liter lavage systems.

A regimen using 2 liters of isotonic PEG solution could infringe both claim 1 and claim 2 if all other limitations are satisfied.

Claim 3: approximately 10 to 20 mg of bisacodyl

Claim 3 captures common bisacodyl dosing, including regimens based on one or two standard tablets depending on tablet strength. It is narrower than claim 1 and may be easier to map to approved labeling.

Claim 4: reduced preparation time and adverse symptoms

Claim 4 is directed to the asserted clinical advantages of the regimen. It does not state how much the preparation time must be reduced or which adverse symptoms must be diminished.

That lack of numerical definition may create enforcement and validity issues. The claim may still be meaningful when read with the specification, but its scope is less commercially precise than claims 2 and 3.

What formulations are protected by U.S. Patent 7,291,324?

The patent protects use of the regimen, not a particular finished formulation.

Potentially relevant PEG formulations include:

PEG 3350 with sodium chloride, sodium bicarbonate, potassium chloride, and other electrolytes.
Reduced-volume PEG-electrolyte solutions.
PEG solutions supplied as powders for reconstitution.
PEG products used with separate bisacodyl tablets.
Combination kits containing bisacodyl and PEG-electrolyte components.

The patent does not, based on the supplied claims, require:

A specific PEG molecular weight.
A specific electrolyte concentration.
A specific bisacodyl tablet formulation.
A particular flavoring system.
A fixed dosing interval other than the six-hour bowel-movement condition.
A particular diagnostic procedure.

A competitor could potentially avoid the claims by changing the treatment sequence, using a different stimulant laxative, omitting the required bisacodyl-induced bowel movement, using a non-isotonic solution, or using a materially different volume or dose. Each design-around would require analysis of literal infringement and the doctrine of equivalents.

How strong is the patent estate for the claimed bowel-preparation regimen?

The estate appears strongest against products that reproduce the full labeled sequence:

Bisacodyl is administered orally.
A bowel movement is expected within six hours.
PEG is administered afterward.
The PEG dose and volume fall within the claimed ranges.
The regimen is marketed for colon cleansing before diagnostic testing or surgery.

Its scope is weaker against products that use:

PEG alone.
Sodium picosulfate, magnesium oxide, and citric acid.
Oral sulfate solutions.
Non-PEG osmotic preparations.
Bisacodyl administered after PEG.
A high-volume PEG protocol without the bisacodyl priming step.
A regimen outside the stated dose and volume ranges.

The claims are commercially focused but technically narrow. Their strength would turn on whether the prior art disclosed the individual elements in the claimed sequence and whether the reduced-volume protocol produced an unexpected clinical result.

What prior-art issues affect validity?

The main validity risk is obviousness under 35 U.S.C. § 103.

A challenger could combine prior art involving:

Bisacodyl as a stimulant laxative.
PEG-electrolyte lavage for colon cleansing.
Use of bisacodyl before PEG to reduce required lavage volume.
Two-stage bowel-preparation regimens.
Clinical studies reporting improved tolerability or shorter preparation time.

The patent holder would likely rely on the specific timing requirement, reduced PEG volume, clinical cleansing results, and reduction in adverse symptoms to distinguish the claimed method.

Potential validity issues

Issue	Relevance
Anticipation	Requires one prior-art reference to disclose every limitation, including sequence and timing
Obviousness	Prior art may have combined bisacodyl and PEG in a predictable regimen
Indefiniteness	“About,” “adequately cleansed,” and “diminished” may invite boundary disputes
Written description	The specification must support the full ranges of doses, volumes, and timing
Enablement	The disclosure must enable the full claimed regimen across the scope of claim 1
Claim construction	“Following the bowel movement” and “consisting essentially of” are central interpretive issues

The presence of a clinical benefit does not by itself establish validity. The benefit must be tied to the claimed regimen and supported by the patent record.

When does U.S. Patent 7,291,324 lose exclusivity?

Patent expiration must be determined from the patent’s earliest effective nonprovisional priority date, adjusted for any patent-term adjustment, patent-term extension, terminal disclaimer, or applicable statutory limitation. The issue cannot be resolved from the claim text alone.

The patent was granted on November 6, 2007. Under the post-1995 patent-term system, the ordinary term is generally 20 years from the earliest effective nonprovisional filing date, not 20 years from the grant date. The relevant term calculation must be confirmed against the USPTO patent record and the patent’s continuity data. [1]

A patent’s expiration does not automatically eliminate all market barriers. Related patents may separately cover:

PEG-electrolyte compositions.
Bisacodyl formulations.
Combination kits.
Manufacturing processes.
Labeling or method-of-use claims.
Improved-volume or improved-tolerability regimens.

What is the Orange Book status of U.S. Patent 7,291,324?

The Orange Book lists patents submitted by sponsors for approved drug products. A method patent may be listed when it claims an approved method of using the drug product, subject to FDA listing rules. The patent number alone does not establish that it was listed for a particular NDA or remains listed. [2]

For a PEG-bisacodyl product, the relevant Orange Book questions are:

Whether the sponsor submitted U.S. Patent 7,291,324 to FDA.
Which NDA, if any, identified the patent.
Whether the listed use matched the approved labeling.
Whether the patent was delisted or expired.
Whether a later approved product has separate listed patents.

Orange Book relevance is product-specific. A patent can be technically relevant to a bowel-preparation regimen without creating a current Hatch-Waxman barrier for every PEG or bisacodyl product.

What Paragraph IV challenges could arise?

A generic applicant seeking approval for a PEG-bisacodyl product could file a Paragraph IV certification asserting that the patent is invalid, unenforceable, or not infringed. The most direct noninfringement theories would be:

The proposed label does not require bisacodyl before PEG.
The proposed label does not require a bowel movement within six hours.
The PEG volume falls outside 1.5 to 2.5 liters.
The PEG dose falls outside 50 to 400 grams.
The solution is not isotonic.
The product is not labeled for diagnostic testing or surgery.
The proposed product is PEG-only or uses a different active ingredient.

The strongest invalidity theory would likely be obviousness based on prior art combining a stimulant laxative with PEG lavage. A Paragraph IV analysis would require the patent’s prosecution history, approved labeling, Orange Book listing, and the proposed generic label.

What patent litigation affects this patent?

The patent record is not a litigation docket. Grant information does not establish whether a patent was asserted, challenged, settled, disclaimed, or found unenforceable.

For diligence, relevant records include:

USPTO Patent Center for prosecution and continuity.
FDA Orange Book patent and exclusivity data.
PACER for federal Hatch-Waxman litigation.
Court opinions addressing claim construction, validity, infringement, or settlement.
FDA approval packages and labeling for the relevant bowel-preparation products.

A settlement agreement could restrict an early generic launch even after a patent challenge. Conversely, patent expiration would generally remove the patent-based injunction risk, while leaving regulatory, manufacturing, trademark, and related-patent issues in place.

Which companies are likely to be relevant to the commercial patent landscape?

The relevant competitive group includes:

Sponsors of PEG-electrolyte bowel-preparation products.
Manufacturers of bisacodyl tablets and combination bowel-preparation kits.
Generic pharmaceutical companies seeking abbreviated approval.
Developers of low-volume oral sulfate and picosulfate-based preparations.
Contract manufacturers producing PEG-electrolyte powders or reconstituted solutions.

The patent is most relevant to a product marketed as a coordinated bisacodyl-plus-PEG regimen. It is less relevant to products that compete through a different active ingredient or preparation sequence.

How does this patent compare with other bowel-preparation patent categories?

Patent category	Typical protected subject matter	Relationship to U.S. 7,291,324
Regimen patents	Sequence, dose, timing, and clinical use	Directly relevant
Composition patents	PEG-electrolyte formulation and concentrations	Potentially separate barriers
Bisacodyl formulation patents	Tablet coating, release, stability, or dosage form	May overlap commercially but not necessarily in claim scope
Kit patents	Packaging and coordinated administration	Can create additional product barriers
Manufacturing patents	Mixing, granulation, filling, or stability processes	May constrain supply without covering the clinical method
Method-of-use patents	Colonoscopy, surgery, radiological testing, or preparation outcomes	May overlap or provide alternative protection

A freedom-to-operate review must evaluate all categories. U.S. Patent 7,291,324 should not be treated as the complete patent estate for any PEG-bisacodyl product.

What generic launch risks exist?

Low risk from PEG-only products

A PEG-only product would generally lack the required bisacodyl administration step. It would not ordinarily practice the full method claim.

Moderate risk from combination products

A combination product containing bisacodyl and PEG presents higher risk if its labeling reproduces the claimed sequence, dose, timing, and volume. Label language is central because method-of-use infringement may be based on induced infringement arising from the instructions for use.

Lower risk from alternative active ingredients

Products based on oral sulfate, sodium picosulfate, magnesium citrate, or other non-PEG systems would generally avoid literal infringement of the PEG limitation, although they may face separate patents.

Label carve-outs

A generic applicant may attempt to omit the patented use or sequence from its labeling. The effectiveness of a carve-out depends on the remaining label, marketing conduct, physician instructions, and whether the proposed use still encourages the patented method.

What geographic coverage does the patent provide?

U.S. Patent 7,291,324 provides rights only in the United States and its territories. It does not create protection in Canada, Europe, Japan, China, or other jurisdictions.

International protection would require corresponding national or regional patents. The commercial strategy for a global bowel-preparation product therefore requires a separate review of:

PCT filings.
European Patent Office family members.
Canadian, Japanese, Chinese, and Australian counterparts.
National expiration dates.
Local patent-term adjustments.
Supplementary protection certificates, where applicable.

A U.S. patent family member may have materially different claims or may have expired earlier through prosecution or maintenance-fee events.

What manufacturing and IP barriers remain after this patent expires?

Expiration of the regimen patent does not eliminate all barriers. A competitor may still face:

Formulation patents.
Process patents.
Trade secrets involving powder blending or stability.
Regulatory requirements for electrolyte composition and product quality.
Manufacturing scale-up constraints.
Drug-master-file controls.
Trademark and trade-dress restrictions.
Product-specific FDA exclusivity.
Supply agreements and distribution contracts.

For a PEG-electrolyte product, manufacturing quality is commercially important because electrolyte concentration, osmolality, microbial control, packaging, and reconstitution stability must meet regulatory specifications.

Revenue exposure and commercial significance

The patent’s revenue exposure depends on whether it covered a marketed product, whether that product’s label used the claimed regimen, and whether the patent remained enforceable during the product’s commercial peak.

The most exposed products would be reduced-volume bowel-preparation kits combining:

Bisacodyl in the 5 to 40 mg range.
PEG in the 50 to 400 gram range.
Approximately 1.5 to 2.5 liters of isotonic solution.
A pre-PEG bowel movement requirement.

Revenue risk from generic entry would be highest if the patent was the principal remaining listed patent and the product had no meaningful formulation or regulatory exclusivity. Revenue protection would be weaker if competitors could launch PEG-only or alternative-active-ingredient products without practicing the patented method.

Key Takeaways

U.S. Patent 7,291,324 is a narrow method patent for sequential bisacodyl and PEG bowel cleansing.
The most important limitations are oral bisacodyl, a bowel movement within six hours, and subsequent PEG in 1.5 to 2.5 liters of isotonic solution.
Claim 2 focuses on approximately 2 liters; claim 3 focuses on approximately 10 to 20 mg of bisacodyl.
The patent does not broadly cover PEG, bisacodyl, colonoscopy preparation, or PEG-electrolyte compositions.
The principal validity vulnerability is likely obviousness based on prior art combining stimulant laxatives with PEG lavage.
Orange Book significance must be assessed against a specific NDA and approved label.
Generic risk is highest for labels that reproduce the claimed sequence and dosing ranges.
Patent expiration must be confirmed from USPTO continuity, term-adjustment, and disclaimer records.
Related formulation, kit, manufacturing, and method-of-use patents may remain relevant after this patent expires.
The patent provides U.S. rights only and does not establish international protection.

Frequently Asked Questions

Can a PEG-only bowel-preparation product infringe U.S. Patent 7,291,324?

Generally, a PEG-only product would not satisfy the required bisacodyl administration limitation. Its labeling and induced-use conduct would still require separate analysis.

Does administration of bisacodyl after PEG avoid the patent?

It would provide a strong literal noninfringement position because claim 1 requires bisacodyl before PEG and requires PEG administration following the bowel movement.

Does a 4-liter PEG solution fall within the claim?

A 4-liter solution is outside the express 1.5 to 2.5 liter range of claim 1. The patent’s “about” language could create a boundary dispute, but 4 liters is materially outside the claimed volume.

Can a generic omit the patented bowel-preparation sequence from its label?

A generic may attempt a use or labeling carve-out. The legal result depends on the final label, promotional activity, physician instructions, and any remaining approved uses.

Does patent expiration permit immediate sale of a competing bowel-preparation product?

Patent expiration removes the expired patent as a patent-based exclusion right. FDA approval, manufacturing compliance, trademarks, related patents, contractual restrictions, and product-specific exclusivity may still affect launch timing.

References

United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term calculation. https://www.uspto.gov
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov
U.S. Patent No. 7,291,324. (2007). Method for cleansing the bowel. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (n.d.). Guidance for industry: Listing approved drug products in the Orange Book. https://www.fda.gov
United States Patent and Trademark Office. (n.d.). Manual of Patent Examining Procedure, §§ 2111 and 2111.03. https://www.uspto.gov/web/offices/pac/mpep/

Summary for Patent: 7,291,324