Oral sodium phosphate solution: a review of its use as a colorectal cleanser

Oral sodium phosphate solution (Fleet Phospho-soda, Casen-Fleet Fosfosoda is a low-volume, hyperosmotic agent used as part of a colorectal-cleansing preparation for surgery, x-ray or endoscopic examination. The efficacy and tolerability of oral sodium phosphate solution was generally similar to, or significantly better than, that of polyethylene glycol (PEG) or other colorectal cleansing regimens in patients preparing for colonoscopy, colorectal surgery or other colorectal-related procedures. Generally, oral sodium phosphate solution was significantly more acceptable to patients than PEG or other regimens. The use of this solution should be considered in most patients (with the exception of those with contraindications) requiring colorectal cleansing. PHARMACOLOGICAL PROPERTIES: After the first and second 45 mL dose of oral sodium phosphate solution, the mean time to onset of bowel activity was 1.7 and 0.7 hours and the mean duration of activity was 4.6 and 2.9 hours. Bowel activity ceased within 4 hours of administration of the second dose in 83% of patients. Elevations in serum phosphorus and falls in serum total and ionised calcium from baseline occurred during the 24 hours after administration of oral sodium phosphate solution in seven healthy volunteers. These changes were not associated with significant changes in clinical assessments. The decrease in serum potassium levels after administration of oral sodium phosphate solution was negatively correlated with baseline intracellular potassium levels.

Therapeutic use: A regimen that administered the first dose of sodium phosphate on the previous evening and a second dose on the morning of the procedure (10-12 hours apart) was significantly more effective than PEG-based regimens for colorectal cleansing in preparation for colonoscopy, sigmoidoscopy or colorectal surgery. A regimen that administered both doses of oral sodium phosphate on the day prior to the procedure offered no colorectal cleansing advantage over PEG-based regimens and was significantly less effective than an oral sodium phosphate solution regimen that administered one dose on the previous evening and a second dose on the morning of the procedure. Oral sodium phosphate solution was generally as effective as other colorectal cleansing solutions (including magnesium citrate-containing regimens with sodium picosulfate). The direct costs of a diagnostic colonic examination with oral sodium phosphate solution were less than those with PEG (US465 dollars vs US503 dollars per patient; 1995 values), according to data from a US study. Oral sodium phosphate solution was significantly more effective than a commercially available tablet formulation as a colorectal cleanser prior to colonoscopy (data from one study only).

Tolerability: Oral sodium phosphate solution administered as two 45 mL doses (generally 10-12 hours apart) was well tolerated in well designed trials in which adults with major comorbid conditions were excluded. Sodium phosphate-associated adverse events were mostly gastrointestinal (including abdominal pain/cramping, abdominal fullness and/or bloating, anal or perianal irritation or soreness, nausea, vomiting or hunger pains), although dizziness, weakness/fatigue, thirst, chest pain, chills, headache and sleep loss were also reported. Faecal incontinence was commonly reported in the elderly. Three doses (administered 10 minutes apart) of 15 mL of oral sodium phosphate solution, each diluted in 250 mL of clear fluid was associated with less vomiting than one 45 mL dose of the solution diluted in 250 mL of clear fluid (data from one study). In patients without major comorbid conditions, oral sodium phosphate has been associated with transient and clinically inconsequential changes in intravascular volume and electrolyte disturbances. Serious electrolyte disturbances have been associated with oral sodium phosphate administration in patients in whom sodium phosphate is contraindicated or should be use with caution (the elderly and those with bowel obstructions, small intestinal disorders, poor gut motilderly and those with bowel obstructions, small intestinal disorders, poor gut motility, renal insufficiency, cardiovascular disease or taking concomitant medication) or in patients ingesting more than the recommended dosage. Changes in the colonic mucosa have been reported in patients treated with oral sodium phosphate solution; however, the exact role of this agent in the appearance of these changes has not been fully clarified. The tolerability profile of oral sodium phosphate solution was similar to, or significantly better than, that of PEG or other colorectal cleansing regimens. Oral sodium phosphate solution was generally significantly more acceptable than PEG or other colorectal cleansing regimens. Oral sodium phosphate solution had similar tolerability, but was considered to be more acceptable than commercially available oral sodium phosphate tablets prior to colonoscopy (data from one study).