Sodium Phosphate, Bowel Evacuant

Pronunciation: SOE-dee-um FOS-fate
Class: Bowel evacuant

Trade Names

OsmoPrep
- Tablets 1.5 g

Visicol
- Tablets 1.5 g

Pharmacology

Induces diarrhea through the osmotic effect of sodium, which causes large amounts of water to be drawn into the colon, promoting evacuation.

Pharmacokinetics

Duration

1 to 3 h.

Special Populations

Elimination of the large phosphate load may be impaired. Use with caution.

Pharmacokinetics have not been studied.

Plasma half-life is 2-fold higher in subjects older than 70 yr of age.

No difference in AUC has been observed between healthy men and women.

Indications and Usage

Cleansing of the colon for colonoscopy.

Contraindications

Biopsy-proven acute phosphate nephropathy; known allergy to sodium phosphate salts or any component of the product.

Dosage and Administration

PO 48 g (32 tablets) of sodium phosphate with a total of 2 quarts of clear liquids taken as follows: On the evening prior to the colonoscopy procedure take 6 g (4 tablets) with 240 mL (8 oz) of clear liquid every 15 min for a total of 30 g (20 tablets). On the day of the colonoscopy procedure, starting 3 to 5 hours before the procedure, take 6 g (4 tablets) with 240 mL (8 oz) of clear liquid every 15 min for a total of 18 g (12 tablets).

PO 60 g (40 tablets) of sodium phosphate with a total of 3.6 quarts of clear liquids as follows: On the evening prior to the colonoscopy procedure take 4.5 g (3 tablets; the last dose will be 3 g [2 tablets]) with 240 mL (8 oz) of clear liquid every 15 min for a total of 30 g (20 tablets). On the day of the colonoscopy procedure, starting 3 to 5 hours before the procedure, take 4.5 g (3 tablets; the last dose will be 3 g [2 tablets]) with 240 mL (8 oz) of clear liquid every 15 min for a total of 30 g (20 tablets).

General Advice

• Patients should be adequately hydrated before, during, and after the use of sodium phosphate.
• Patients should not use OsmoPrep or Visicol for colon cleansing within 7 days of previous administration.
• Patients should not take additional agents (eg, enemas, laxatives), particularly those containing sodium phosphate.

Storage/Stability

Store at 59° to 86°F. Discard any unused portion.

Drug Interactions

Medications administered in close proximity may not be absorbed from the GI tract because of rapid intestinal peristalsis. Use with caution in patients taking medications known to prolong the QT interval.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Arrhythmias (postmarketing).

CNS

Dizziness, headache, seizures (postmarketing).

GI

Bloating (47%); nausea (37%); abdominal pain (30%); vomiting (10%); aphthous ulcers (3%).

Genitourinary

Acute phosphate nephropathy, acute renal failure, nephrocalcinosis, renal impairment, renal tubular necrosis (postmarketing).

Hypersensitivity

Hypersensitivity reactions including anaphylaxis, bronchospasm, dysphagia, dyspnea, paresthesia, pharyngeal edema, pruritus, rash, throat tightness, urticaria, and swelling of the face, lips, and tongue (postmarketing).

Lab Tests

Hyperphosphatemia (96%); hypocalcemia (47%); hypokalemia (28%); increased BUN, increased creatinine (postmarketing).

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Elderly

Use with caution.

Special Risk Patients

Use with caution in patients with severe renal insufficiency (CrCl less than 30 mL/min), CHF, ascites, unstable angina, gastric retention, ileus, acute bowel obstruction, pseudo-obstruction of the bowel, severe chronic constipation, bowel perforation, acute colitis, toxic megacolon, gastric bypass or stabling surgery, hypermotility syndrome, or recent cardiac surgery.

Cardiac arrhythmias

May occur.

Electrolyte disorder

May occur.

Hydration

Adequate hydration before, during, and after use is important. Fatalities due to fluid shifts, severe electrolyte abnormalities, and cardiac arrhythmias have occurred. These fatalities occurred in patients with renal insufficiency or bowel perforation, and in patients who misused or overdosed with sodium phosphate.

Inflammatory bowel disease

Use with caution; sodium phosphate absorption may be enhanced.

Renal disease

Renal failure and acute phosphate nephropathy may occur.

Seizures

Generalized tonic-clonic seizures and/or loss of consciousness have been reported.

Overdosage

Symptoms

Severe electrolyte disturbances, including cardiac arrhythmias, death, dehydration, hypernatremia, hyperphosphatemia, hypocalcemia, hypokalemia, hypovolemia, renal failure, seizures.

Patient Information

• Instruct patients to take product exactly as prescribed.
• Inform patients that it is important to take the recommended fluid regimen to assist in adequate hydration.
• Instruct patients not to use OsmoPrep or Visicol for colon cleansing within 7 days of previous administration.
• Instruct patients not take additional laxative or purgative agents, particularly those containing sodium phosphate.
• Instruct patients to drink 240 mL (8 oz) of clear liquid with each dose of the sodium phosphate product.
• Instruct patients to tell health care provider if they have any of the following symptoms while taking the sodium phosphate product: bloating, dizziness, headache, less than normal urination, nausea, severe stomach cramping, trouble drinking clear fluids, or vomiting.
• Instruct patients to immediately contact their health care provider if they take too much sodium phosphate product.
• Inform patient that undigested or partially digested tablets may be seen in the stool.

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