A Pilot Study of Commercially Available Bowel Preparation Regimens Packaged and Ingested Via Vegan Capsules

This is a prospective, single-site, open-label, sequential, non-randomized pilot feasibility study of capsule-based bowel preparation before colonoscopy.

The study will evaluate whether approved commercially available bowel preparation powders can be administered in vegan hydroxypropyl methylcellulose capsules instead of being mixed into a liquid solution before ingestion. The approved products used in this study are Pico-Salax and Bi-PegLyte. The active products, total approved dose, oral route, required clear-fluid intake, and split-dose timing will be preserved. The investigational aspect is the capsule-based method of administration.

The rationale for the study is that many people find liquid bowel preparation difficult to complete because of taste, texture, nausea, and the amount of liquid required. Capsule-based administration may reduce exposure to unpleasant taste and mouthfeel while maintaining the intended bowel cleansing effect, provided participants drink the required clear fluids.

The study will enroll adults aged 18 to 75 years who are scheduled for elective outpatient colonoscopy for screening, surveillance, or diagnostic indications and who have previously completed a conventional bowel preparation. Participants must be able to swallow solids, liquids, and pills without difficulty.

The study will proceed in three sequential parts:

In Part I, approximately 40 participants will receive Pico-Salax powder packaged in HPMC capsules prepared by a partner pharmacy. Twenty participants will receive size "000" capsules and 20 participants will receive size "00" capsules. This part will assess capsule ingestion completion, clear-fluid completion, swallowing acceptability, tolerability, safety, and bowel cleansing quality for the two capsule sizes.

After Part I, the study team will review tolerability, swallowing difficulty, capsule and fluid completion, safety findings, and bowel cleansing results. One capsule size will be selected for use in the later parts of the study.

In Part II, approximately 20 participants will receive Bi-PegLyte powder packaged in HPMC capsules prepared by the partner pharmacy using the capsule size selected after Part I. This part will assess whether a higher capsule-burden preparation is feasible and tolerated.

In Part III, approximately 20 participants will prepare the capsules themselves at home using study-supplied materials and written instructions. Ten participants will prepare Pico-Salax capsules and 10 participants will prepare Bi-PegLyte capsules. This part will assess whether participant-led home capsule preparation is practical, acceptable, and safe.

Across all parts, participants will take the capsule-based bowel preparation using a split-dose schedule before colonoscopy. Participants will drink the required clear fluids according to the study instructions. Participants assigned to Bi-PegLyte will take the bisacodyl tablets separately according to the usual regimen.

The primary outcomes are tolerability and feasibility. These include the proportion of participants who can ingest at least 80% of the prescribed capsules within the study dosing window, the proportion who complete the required clear-fluid intake, and the proportion who complete bowel preparation without stopping early because of capsule burden or swallowing difficulty. In the home-preparation part, feasibility will also include the proportion of participants who prepare at least 80% of the required capsules, preparation time, capsule count reconciliation, and participant-reported difficulty and confidence.

Secondary outcomes include participant-reported symptoms, adverse events, serious adverse events, clinically significant changes in electrolytes or creatinine, dehydration, emergency department presentation or hospitalization, and bowel cleansing quality at colonoscopy. Bowel cleansing will be assessed using the Boston Bowel Preparation Scale. Adequate bowel preparation is defined as a total score of at least 6 with no segment score below 2.

This pilot study is descriptive and is not designed for formal hypothesis testing. The results will help determine whether capsule-based bowel preparation is feasible, acceptable, and safe enough to support a future randomized controlled trial comparing capsule-based bowel preparation with standard liquid bowel preparation.

Inclusion criteria

• Age 18 to 75 years.
• Scheduled for elective outpatient colonoscopy for a screening, surveillance, or diagnostic indication.
• Has previously undergone colonoscopy using a conventional bowel preparation solution, without requiring repeat colonoscopy because of poor bowel preparation.
• Able to provide informed consent.
• Willing and able to comply with study procedures, including timed dosing, required clear-fluid intake, and capsule preparation procedures for participants enrolled in Part III.
• Able to swallow solids, liquids, and pills without difficulty.

Exclusion criteria

• Higher risk for clinically significant fluid or electrolyte shifts, including chronic renal impairment, severely reduced renal function, congestive cardiac failure, unstable cardiovascular disease, or any other condition in which large-volume fluid intake or rapid catharsis may be unsafe.
• Baseline clinically significant electrolyte abnormalities.
• Diabetes mellitus, gastroparesis, gastric retention, intestinal dysmotility, or any other condition that may impair gastric emptying, gastrointestinal transit, mixing, dissolution, or passage of the bowel preparation.
• Current use of medications that may impair gastrointestinal motility or safe bowel preparation completion, including opioid medications, anticholinergic medications, or glucagon-like peptide-1 receptor agonists.
• Known or suspected gastrointestinal obstruction, bowel obstruction, ileus, bowel perforation, gastrointestinal perforation, or any condition associated with increased risk of obstruction or perforation.
• Acute abdominal or gastrointestinal condition in which bowel preparation may be unsafe, including acute surgical abdomen, acute appendicitis, gastroenteritis, diverticulitis, toxic colitis, toxic megacolon, severe colitis requiring urgent care, or another acute inflammatory, infectious, or structural gastrointestinal condition judged by the investigator to make participation unsafe.
• Known gastrointestinal ulceration or clinically significant active gastrointestinal bleeding, including unexplained rectal bleeding.
• Active nausea or vomiting at screening or before bowel preparation administration that, in the opinion of the investigator, would interfere with safe ingestion of the assigned capsule-based bowel preparation regimen.
• Emergency colonoscopy, including colonoscopy for lower gastrointestinal bleeding or any clinical condition requiring urgent endoscopic evaluation that would not allow adherence to the study bowel preparation protocol.
• Known hypersensitivity, allergy, or intolerance to Bi-PegLyte, Pico-Salax, bisacodyl, polyethylene glycol, sodium picosulfate, magnesium oxide, citric acid, electrolytes contained in the formulations, HPMC/hypromellose capsules, or any ingredient in the formulation or product container.
• Pregnancy or known or suspected pregnancy at screening or before bowel preparation administration.
• Capsule-specific feasibility or safety concern, including dysphagia, esophageal dysmotility, achalasia, esophageal stricture, high risk of aspiration, anatomical abnormality affecting swallowing, or any condition in which swallowing a large number of capsules is considered unsafe.
• Practical or adherence-related concern, including inability to follow timed dosing instructions, inability to comply with the required clear-fluid intake, lack of reliable contact, or anticipated nonadherence to study procedures.
• For Part III only: inability or unwillingness to self-prepare capsules using study-provided materials and instructions; inadequate manual dexterity or vision to prepare capsules safely and accurately; inability to complete the teach-back procedure, if required; or unwillingness to follow the standardized home preparation workflow, including use only of study-supplied materials, preparation within the defined time window, and storage as instructed.
• Any contraindication listed in the product monograph for Bi-PegLyte or Pico-Salax.