Bowel Preparations: A Review for Community Pharmacists

Diana Chang, PharmD; Kevin Van, PharmD; Janette D. Lie, PharmD, BCACP; Jason P. Smith, PharmD; Kristie N. Tu, PharmD, BCPS, CGP


US Pharmacist. 2013;38(12):30-34. 

In This Article

Education and Counseling

Patient education regarding preparation, administration, and AE management reduces the rates of missed polyps (up to 48%), procedure complications, and repeat colonoscopies.[10,32,33] Community pharmacists can play a key role in ensuring that patients are prepared for colonoscopy. Information on topics such as timing, concomitant medications, diet, improving tolerability, and hydration is helpful for successful bowel preparation.

For optimal colonic cleansing, at least a portion of the bowel preparation must be ingested within 6 to 8 hours of the procedure. To ensure optimal visualization of the colon, patients must precisely follow the instructions provided by their healthcare professional (HCP) or the manufacturer.[34]

Patients should review their current medication list with their HCP. For patients taking antithrombotic agents, the risks and benefits of interrupting therapy should be weighed. OTC medications with bleeding risk (e.g., aspirin, other nonsteroidal anti-inflammatory drugs) are generally safe to continue, but should be reviewed with the HCP. Patients taking diabetic medications, particularly insulin, may need to adjust the dose when completing a bowel-preparation regimen. All other prescription medications generally can be continued, unless otherwise advised. Patients taking diuretics, ACE inhibitors, or angiotensin receptor blockers should use NaP-containing regimens with caution. OTC bulk-forming laxatives (e.g., Metamucil, Citrucel), as well as iron and iron-containing products (e.g., multivitamins), should be avoided 5 days before the procedure.[26]

In general, for 2 to 3 days prior to a colonoscopy (range 1–5 days, depending upon HCP instructions), patients are advised to adhere to a low-residue diet, limiting intake of fiber and other indigestible foods. Patients should also maintain a clear liquid diet starting 24 hours before the procedure. Red or purple liquids, alcohol, and milk or milk-based fluids should be avoided. In general, nothing should be ingested 2 hours prior to the procedure.[26,34,35]

Suggestions addressing taste and volume have been developed to improve the tolerability of bowel preparations. Pharmacists can work with HCPs to suggest split-dose regimens, lower-volume preparations, and the use of adjunctive agents to address concerns regarding fluid volume. To improve taste, patients can chill the solutions, use a straw to bypass the taste buds, or add flavor (e.g., the included flavor packets, clear sugar-free powder mixes, or lemon juice). Sucking on fresh lemon or lime slices or rubbing them on the tongue may also improve palatability, as citrus appears to best mask the saltiness of the preparations.[35]

Because of the significant fluid and electrolyte imbalance that can result from bowel-cleansing regimens, adequate hydration throughout the preparation period is essential. Patients should be advised to consume at least 64 oz (approximately 2 L) of clear liquid on the day before the colonoscopy. Clear fluids may be consumed for up to 2 hours prior to the procedure. A minimum of 32 oz of fluid should be consumed within 8 hours after the colonoscopy to prevent any complications.[25]

Patients also should be counseled about common AEs (e.g., diarrhea, nausea, bloating) and the need to stay at home or near a restroom because of the frequent bowel movements triggered by the preparation. After ingestion, the expected onset of action is approximately 1 hour for PEG-based bowel preparations and 3 to 6 hours for NaP preparations.[8] Patients may experience anal irritation, which can be alleviated by using wet wipes or petrolatum.[26]