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What are the caveats to using sodium phosphate agents for bowel preparation?

Cleveland Clinic Journal of Medicine. 2008 March;75(3):173-176
March 1, 2008|Cleveland Clinic Journal of Medicine
Rohit Makkar, MD;Bo Shen, MD
Author and Disclosure Information

Rohit Makkar, MD
Department of General Internal Medicine, Cleveland Clinic

Bo Shen, MD
Department of Gastroenterology and Hepatology, Cleveland Clinic

Address: Bo Shen, MD, Department of Gastroenterology and Hepatology, A30, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; e-mail shenb@ccf.org

PROCEED WITH CAUTION

Certain situations such as advanced age and cardiac, renal, and hepatic dysfunction call for extreme caution in the use of NaP bowel preparation agents. Therefore, it is recommended that patients with the following conditions should avoid using NaP agents for colon preparation:

  • Hepatic or renal insufficiency (there are no data as to the degree of hepatic or renal insufficiency)
  • Congestive heart failure
  • Over age 65
  • Dehydration or hypercalcemia
  • Chronic use of drugs that affect renal perfusion, such as NSAIDs, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, or diuretics for hypertension.

Patients who take diuretics should not take them while they are using NaP for bowel preparation because of the risk of electrolyte abnormalities such as hypokalemia. In patients who have no alternative but to proceed with NaP preparation, our recommendation would be that the patient hold off taking diuretics, ACE inhibitors, and angiotensin receptor blockers while using the NaP prep. Given the importance of these medications in controlling diseases such as hypertension, the physician and the patient should jointly determine whether the benefits of using an NaP agent justify holding these drugs. We believe that patients taking these drugs should try using a PEG solution before considering NaP.

TASK FORCE GUIDELINES

Guidelines for using NaP bowel preparation agents, published by a task force of the American Society of Colon and Rectal Surgeons, the American Society for Gastrointestinal Endoscopy, and the Society of American Gastrointestinal and Endoscopic Surgeons,25 include the following caveats:

  • Aqueous and tablet NaP colonic preparations are an alternative to PEG solutions, except in pediatric populations, patients over age 65, and those with bowel obstruction or other structural intestinal disorder, gut dysmotility, renal or hepatic insufficiency, congestive heart failure, or seizure disorder.
  • Dosing should be 45 mL in divided doses, 10 to 12 hours apart, with at least one dose taken on the morning of the procedure.25
  • The significant volume contraction and resulting dehydration seen in some patients using NaP preparations may be lessened by encouraging patients to drink fluids liberally during the days leading up to their procedure, and especially during NaP bowel preparation.26
  • NaP tablets should be dosed as 32 to 40 tablets. On the evening before the procedure the patient should take 20 tablets and then 12 to 20 tablets approximately 3 to 5 hours before undergoing endoscopy. The tablets should be taken four at a time every 15 minutes with approximately 8 oz of clear liquid.25

To maximize the efficacy and safety of colonoscopy, it is paramount that the colon be adequately prepared. Agents for bowel cleansing should be inexpensive, effective, safe, palatable, and easy to take. The most commonly used regimens are based on either PEG or NaP, and each has advantages and disadvantages (Table 1). The decision whether to use PEG or NaP for bowel cleansing should be individualized and should take into consideration the pros and cons of the agents and the patient’s general health.

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