Which Bowel Preps Are Best for Your Patients?

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Bowel preps are no picnic. In fact, patients often consider them worse than the actual procedure. Even if virtual colonoscopy is chosen over the traditional method, a bowel prep is still required.

"What patients need is a virtual bowel prep," says Mark R. Wax, MD, vice president of medical affairs at Viatronix.1 But until that becomes an option, patients will have to undergo the conventional preparation and that requires caregivers to make informed decisions about available options.

A patient's disregard of bowel prep instructions can lead to delayed procedures or personal harm. It is crucial to find a product that is safe and easy to ingest or apply. And because colorectal cancer is the third most common cancer and the second leading cause of cancer-related death in the United States, early detection is part and parcel to reducing mortality associated with this disease. The tricky part is convincing patients that regular screening is worth the preparation and discomfort.

Enemas have been in existence almost as long as humankind. References to bowel cleansing date back to the Egyptians in 1500 B.C., and enemas were used by Babylonians, Indians, Chinese and Native Americans. Now, options for clearing out the intestines are more extensive and the choices can be confusing. Can your patients tolerate drinking a large amount of liquid more than a suppository or liquid enema? Do they need to avoid large amounts of sodium? Do they hate taking pills? Can they stick to a liquid diet for a full 24 hours before the procedure? A discerning caregiver's role includes determining which product is best for each individual.

Beutlich Pharmaceuticals

Beutlich Pharmaceuticals offers a suppository that generally stimulates a bowel movement within 30 minutes of insertion. The CEO-TWO bowel evacuant suppository is a combination of sodium bicarbonate and potassium bitartrate in a polyethylene glycol base that generates carbon dioxide. The combination of lubrication and carbon dioxide slowly distends the rectal ampulla, stimulating peristalsis.

The suppository is not associated with cramping or irritation and is easy to administer. It can be more aesthetically acceptable to patients than a liquid enema, does not interfere with normal digestion and is less expensive than liquid enemas.

Braintree Labs

Braintree Labs produces several products for bowel cleansing, including NuLytely available in cherry and orange flavors; PhosLo; GoLytely; GoLytely available in pineapple flavor; and MiraLax.

When GoLytely® products hit the market in 1984, they had few competitors. They quickly became well-known in endoscopy suites and helped create the bowel prep industry. Although GoLytely was effective, patients were complaining it was too salty. The powder is mixed with 4 liters of water and taken in one dose per day before the procedure. Researchers at Braintree decided adding flavoring could help mask the salty taste and soon the pineapple flavored product was introduced. Still, there were patients who needed something with less salt.

In their 1990 article "A Low-Sodium Solution for Gastrointestinal Lavage," John S. Fordtran, Carol A. Santa Ana and Mark B. Cleveland from the Department of Internal Medicine at Baylor University Medical Center in Dallas, Texas, discuss the differences in Braintree's formula for GoLytely and a new product with 52 percent less salt, Nulytely.®

Before 1990, bowel prep products required patients to ingest isotonic saline, but a large group of patients were unable to process the solution and could not excrete large salt and water loads. GoLytely was designed to decrease salt and water absorption. The Nulytely solution was created without sodium sulfate and included increased amounts of polyethylene glycol (PEG).

The new product was developed to be associated with negligible net absorption, secretion of water and electrolytes, and to have a lower sodium concentration to reduce the salty taste. The authors found these objectives were reached by removing the sodium sulfate and increasing the concentration of PEG within the original product to create Nulytely. The product is available in orange, lemon-lime and cherry flavors.

It is important to note that patients with gastrointestinal obstruction, gastric retention, bowel perforation, toxic colitis, toxic megacolon or ileus should not use this product.

C.B. Fleet

C.B. Fleet provides five options for bowel preparation: Fleet Phospho-soda, prep kits, enemas, oral laxatives and suppositories.

Fleet® Phospho-soda® is available in two 45-mL doses and reports better or equal cleansing vs. PEG preps and better patient tolerability due to lower volume.

Fleet's Dilution SolutionTM dosing regimen alleviates taste concerns of some patients and reduces some side effects. Instead of mixing the entire 45-mL dose into 4 ounces of clear liquid, one tablespoon (15 mL) of Phospho-soda is added to 8 ounces of clear liquid. The dose is repeated twice more in the next 20 minutes to consume the full 45 mL required for each dose.

In a clinical trial, Dilution Solution achieved its highest patient acceptance scores, and cleansing efficacy was generally rated as excellent.

Fleet Phospho-soda should not be used in patients with congenital megacolon, bowel obstructions, ascites, congestive heart failure or kidney disease.

Fleet® Prep Kit 1 is a three-step bowel cleansing regimen that includes Fleet Phospho-soda, Fleet Bisacodyl tablets and Fleet Bisacodyl suppository. It has been shown to be more effective than PEG in leaving a drier colon for a virtual colonoscopy. According to a 2001 clinical trial, if too much fluid is present in the colon, clinically important lesions can be obscured. Therefore, a dry, clean colon is preferred. The study authors concluded that, Ffor patients without heart failure or renal insufficiency, CT colonography should be performed with this Phospho-soda preparation (Fleet Prep Kit 1) to allow for optimal mucosal depiction."2

A meta-analysis comparing PEG to sodium phosphate for colonoscopy preparation found that sodium phosphate was equally effective and less costly than PEG. Although electrolyte and metabolic changes occurred more frequently in the patients using sodium phosphate, there were no related clinical side effects and adverse events were comparable in frequency between the two groups. However, the authors noted that using sodium phosphate is contraindicated in the presence of specific comorbidities (symptomatic congestive heart failure, recent myocardial infarction, ascites and renal insufficiency).3

Dr. Steven D. Wexner, chairman and residency program director of the Department of Colorectal Surgery and chief of staff at Cleveland Clinic Florida, discussed methods of optimizing the outcome of mechanical bowel preparation at the SAGES 2001 conference. He and his associates compared PEG, sulfate-free polyethylene glycol (PEG-SF) and Fleet Phospho-soda bowel prep solutions in colonoscopy patients.4

In the prospective 450-patient trial, endoscopists rated Fleet Phospho-soda superior in cleansing efficacy, while the patients rated it superior in tolerability. Ninety percent of the Fleet Phospho-soda preps were rated acceptable to the endoscopists, compared to 68 percent for PEG preps and 73 percent for PEG-SF preps. Eighty-three percent of patients using Fleet Phospho-soda said they would use it again, compared to 19 percent and 33 percent of the PEG and PEG-SF groups, respectively. According to those who preferred Fleet Phospho-soda, the prep was less trouble to drink, caused fewer chills, less abdominal fullness and bloating, and increased the ease of completing the entire prep.

E-Z-EM Inc.

E-Z-EM Inc., offers Lo-So Prep and NutraPrep. Lo-So Prep contains less than 35 mg of sodium, which makes it appropriate for patients on a sodium-restricted diet. It is low in volume -- only eight ounces of laxative must be ingested -- compared to other preps requiring consumption of several quarts of liquid. Lo-So Prep, with its citrus flavor and natural effervescence, can be dispensed from the office. Each Lo-So Prep kit contains three laxative agents: magnesium citrate effervescent granules (which yield a solution equivalent to 4.4 grams of magnesium oxide), four 5-mg Bisacodyl tablets USP, and one 10-mg Bisacodyl suppository USP.

The NutraPrep System, used in conjunction with Lo-So Prep, provides an alternative to the clear-liquid diet typically associated with bowel preparation and fulfills total nutritional requirements. The low-residue food is labeled as breakfast, lunch, dinner and snack, and is a simple program to help ensure compliance.

Inkine Pharmaceutical Company Inc.

Inkine Pharmaceutical Company Inc., produces Visicol tablets, a unique delivery system of sodium phosphate. The original dosing schedule approved for Visicol involved three tablets every 15 minutes for 20 tablets the day before and day of the procedure. Recently, however, there is speculation the prep would work just as well in a lower dosage.

The safety and efficacy of two reduced dosing regimens of Visicol were examined in a group of 98 patients scheduled for colonoscopy. Forty-nine patients were assigned to each group, but four patients who were randomized to the 32-tablet group took 20 tablets as directed the night before, and eight pills the morning of the procedure. These patients were classified in the 32-tablet group in the demographic analysis and the intention-to-treat analysis of the primary efficacy variables, but are included in the 28-tablet group in all other analyses.

Each patient underwent an evaluation of colon cleansing. Although there were no significant differences between the groups for either cleansing score distribution or the mean scores, more patients were classified in as "excellent" or "good" for overall cleansing in the 32-tablet group. No patients had inadequate overall cleansing and none were required to repeat the procedure.

For the morning dose, the duration of bowel movements was shorter with the 28-tablet group than the 32-tablet group. There was also less microcrystalline cellulose in the 28-tablet group. Although no significant difference was found between the groups in the quality of colon cleansing, there were a larger number of patients in the 32-pill group who had fewer "fair" ratings and more "good" ratings.

The reduced product intake led to a shorter duration of bowel movements, which allowed patients to take the morning dose later. Although this regimen has not been approved by the Federal Drug Administration (FDA), the authors concluded that both reduced dosages were safe and effective and that colonoscopists should recommend one of the revised dosing schedules. "Patients should experience improved convenience from the standpoint of fewer total pills, pill ingestion over a shorter interval, less fluid needed and less time to complete the bowel movements associated with the morning dose," they suggested.5

The tablets are offered with 50 percent less microcrystalline cellulose per tablet, are 18 percent smaller than the original formulation, and contain the same amount of active ingredients as before.

Despite a recent uproar over tonic-clonic seizures associated with the use of Visicol, each of the five patients with seizure had circumstances aside from the Visicol that may have contributed to seizure. The four patients discussed in a letter to the New England Journal of Medicine,6 had hyponatremia, which could be caused by sodium losses through gastrointestinal mechanisms or sweating, excessive free-water ingestion, or excessive secretion of antidiuretic hormone. Potential contributing causes include hypoparathyroidism, strenuous exercise during hot weather, administration of two 20-tablet doses of Visicol two to three hours apart, and daily use of a laxative that contained polyethylene glycol.

The fifth seizure patient, a 74-year-old female, had a history of mild hyponatremia with use of a tricyclic antidepressant. According to the FDA/Center for Drug Evaluation and Research, "it is unknown if her hyponatremia was ongoing before she started taking the sodium phosphate tablets."7

Approximately 210,000 prescriptions have been dispensed for sodium phosphate tablets since the launch in January 2001 through June 2002. The FDA backgrounder concludes that, "colonoscopy is a common procedure, and physicians should be aware of the possible risks associated with the administration of sodium phosphate-containing bowel evacuants in preparation for the procedure."

Visicol was compared to PEG in a randomized, controlled phase III trial; the study was designed to test safety, efficacy and patient acceptance of the tablet against a PEG solution in adults undergoing colonoscopy.8

Although 14 of the 859 patients did not undergo colonoscopy, safety analyses were performed for those who took the study product. In terms of colon cleansing, the difference in mean efficacy was marginally significant (p equals 0.0642) in favor of the tablets. As for patient tolerance, the complete amount of bowel prep was taken by significantly more patients in the tablet group (p greater than 0.0001). Nausea, vomiting and bloating occurred in significantly fewer patients taking the sodium phosphate pills (p equals 0.0001).

Overall, the sodium phosphate tablets produced an equivalent colon cleansing to PEG solution, were associated with fewer gastrointestinal side effects, and were better tolerated by patients. The authors proposed that an oral tablet formulation might be more acceptable to patients than drinking liquid bowel preps, and that the pill alternative might increase patient willingness to undergo colonoscopy.

Schwarz Pharma

While most colonoscopy patients understand the need to clear the bowel prior to an endoscopy procedure, many balk at ingesting large quantities of unpleasant tasting liquids. Wisconsin-based pharmaceutical firm Schwarz Pharma Inc., manufactures a PEG lavage solution in fruit flavors designed to make the bowel cleansing process more palatable. Colyte® PEG-3350 and Electrolytes for Oral Solution come in packs of citrus berry, lemon-lime, cherry, pineapple and unflavored powder.

The PEG lavage preparation is usually taken by the patient at home the night before the examination. Patients are instructed to dissolve the Colyte solution in a sufficient quantity of water to produce a full liquid volume of 4 liters. Patients are advised to ingest 8 ounces of the liquid solution every 10 minutes, drinking rapidly instead of sipping slowly. The patient should continue drinking the Colyte until the watery stool is clear and free of solid matter.

Colyte cleanses the bowel through the induction of diarrhea. The osmotic activity of Polyethylene Glycol 3350, in combination with the electrolyte concentration, results in virtually no net absorption or excretion of ions or water. Accordingly, large volumes may be administered without significant changes in fluid and electrolyte balance. Each 4-liter bottle of Colyte contains 240 g of polyethylene glycol 3350, 5.84 g of sodium chloride, 2.98 g of potassium chloride, 6.72 g of sodium bicarbonate and 22.72 g of sodium sulfate (anhydrous).

Colyte is contraindicated in patients with toxic colitis, gastrointestinal obstruction, gastric retention, bowel perforation or toxic megacolon. According to Schwarz Pharma, Colyte's flavor packs should be used with caution for individuals suffering from severe ulcerative colitis.

Adverse reactions to Colyte have included nausea, abdominal fullness and bloating in up to half of all patients ingesting the solution, with abdominal cramps, vomiting and anal irritation occurring less frequently. Isolated cases of dermatitis, rhinorrhea and urticaria resulting from allergic reactions have been reported. While the safety and efficacy of use in pediatric patients has not been established, isolated reports of serious adverse reactions in patients over the age of 60 have been noted. Such adverse events have included upper gastrointestinal bleeding from a Mallory-Weiss tear, esophageal perforation and sudden dyspnea with pulmonary edema. According to the package insert, it is not known if Colyte has the potential to affect reproductive capacity of both sexes or harm the fetus when administered to a pregnant woman. Schwarz has been marketing Colyte for bowel cleansing or barium enema X-ray examination since 1995.

The Alternatives

Generally, these mainstream methods are preferred by physicians, but there are times when preoperative mechanical bowel preparation is ineffective or impossible. Mitigating factors can include motility disorder, ob-struction, cardiac or renal failure, or poor patient compliance.

"There are alternatives to traditional preoperative bowel preparation that can minimize septic complications and the need for stoma creation, thereby reducing the multi-staged resections that are associated with prolonged disability and significant morbidity," says Dr. Eric Weiss, associate residency program director for the Department of Colorectal Surgery at Cleveland Clinic Florida.9

Options include on-table lavage, colonic stent (more fitting as a facilitator of bowel preparation than as an alternative to it) or avoidance of mechanical bowel preparation altogether. The latter opposes current professional and legal standards, but some literature suggests that preoperative bowel preparation is unnecessary.

"No data shows any clear benefit in neglecting the procedure. However, there clearly are benefits to effective bowel prep, both mechanical and antibiotic, and good alternatives when traditional bowel preparation is not feasible," Dr. Weiss concludes.

For years, healthcare providers have been asking their patients to make use of bowel preparations before undergoing a host of procedures: colonoscopy, sigmoidoscopy, even surgery unrelated to the bowel. Each of these necessitates a cleansed bowel to prevent infection if the bowel is injured and to make the intestines easier to view.

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