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Administration of sodium phosphate products prior to colonoscopy for colon cleansing has resulted in fatalities due to significant fluid shifts, severe electrolyte abnormalities, and cardiac arrhythmias. These fatalities have been observed in patients with renal insufficiency, in patients with bowel perforation, and in patients who misused or overdosed sodium phosphate products. It is recommended that patients receiving OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) be advised to adequately hydrate before, during, and after the use of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) .

Considerable caution should be advised before OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets are used in patients with the following illnesses: severe renal insufficiency (creatinine clearance less than 30 mL/minute), congestive heart failure, 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 stapling surgery, or hypomotility syndrome.

Consider performing baseline and post-colonoscopy labs (phosphate, calcium, potassium, sodium, creatinine, and BUN) in patients who may be at increased risk for serious adverse events, including those with history of renal insufficiency, history of — or at greater risk of — acute phosphate nephropathy, known or suspected electrolyte disorders, seizures, arrhythmias, cardiomyopathy, prolonged QT, recent history of a MI and those with known or suspected hyperphosphatemia, hypocalcemia, hypokalemia, and hypernatremia. Also if patients develop vomiting and/or signs of dehydration then measure post-colonoscopy labs (phosphate, calcium, potassium, sodium, creatinine, and BUN).

Renal Disease, Acute Phosphate Nephropathy, and Electrolyte Disorders

There have been rare, but serious, reports of renal failure, acute phosphate nephropathy, and nephrocalcinosis in patients who received oral sodium phosphate products (including oral sodium phosphate solutions and tablets) for colon cleansing prior to colonoscopy. These cases often resulted in permanent impairment of renal function and several patients required long-term dialysis. The time to onset is typically within days; however, in some cases, the diagnosis of these events has been delayed up to several months after the ingestion of these products. Patients at increased risk of acute phosphate nephropathy may include patients with the following: hypovolemia, baseline kidney disease, increased age, and patients using medicines that affect renal perfusion or function [such as diuretics, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers, and possibly nonsteroidal anti-inflammatory drugs (NSAIDs).

Use OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) with caution in patients with impaired renal function, patients with a history of acute phosphate nephropathy, known or suspected electrolyte disturbances (such as dehydration), or people taking concomitant medications that may affect electrolyte levels (such as diuretics). Patients with electrolyte abnormalities such as hypernatremia, hyperphosphatemia, hypokalemia, or hypocalcemia should have their electrolytes corrected before treatment with OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets.

Seizures

There have been rare reports of generalized tonic-clonic seizures and/or loss of consciousness associated with use of sodium phosphate products in patients with no prior history of seizures. The seizure cases were associated with electrolyte abnormalities (e.g., hyponatremia, hypokalemia, hypocalcemia, and hypomagnesemia) and low serum osmolality. The neurologic abnormalities resolved with correction of fluid and electrolyte abnormalities. OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) should be used with caution in patients with a history of seizures and in patients at higher risk of seizure [patients using concomitant medications that lower the seizure threshold (such as tricyclic antidepressants), patients withdrawing from alcohol or benzodiazepines, or patients with known or suspected hyponatremia].

Cardiac Arrhythmias

There have been rare, but serious, reports of arrhythmias associated with the use of sodium phosphate products. OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) should be used with caution in patients with higher risk of arrhythmias (patients with a history of cardiomyopathy, patients with prolonged QT, patients with a history of uncontrolled arrhythmias, and patients with a recent history of a myocardial infarction). Pre-dose and post-colonoscopy ECGs should be considered in patients with high risk of serious, cardiac arrhythmias.

General

Patients should be instructed to drink 8 ounces of clear liquids with each 4-tablet dose of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets. Patients should take a total of 2 quarts of clear liquids with OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) . Inadequate fluid intake, as with any effective purgative, may lead to excessive fluid loss, hypovolemia, and dehydration. Dehydration from purgation may be exacerbated by inadequate oral fluid intake, vomiting, and/or use of diuretics.

Patients should be instructed not to administer additional laxative or purgative agents, particularly additional sodium phosphate-based purgative or enema products.

Prolongation of the QT interval has been observed in some patients who were dosed with sodium phosphate colon preparations. QT prolongation with sodium phosphate tablets has been associated with electrolyte imbalances, such as hypokalemia and hypocalcemia. OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets should be used with caution in patients who are taking medications known to prolong the QT interval, since serious complications may occur. Predose and post-colonoscopy ECGs should be considered in patients with known prolonged QT.

Administration of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets may induce colonic mucosal aphthous ulcerations, since this endoscopic finding was observed with other sodium phosphate cathartic preparations. In the OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) clinical program, aphthous ulcers were observed in 3% of patients who took the 48 gram OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) dosing regimen. This colonoscopic finding should be considered in patients with known or suspected inflammatory bowel disease.

Because published data suggest that sodium phosphate absorption may be enhanced in patients experiencing an acute exacerbation of chronic inflammatory bowel disease, OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets should be used with caution in such patients.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term studies in animals have not been performed to evaluate the carcinogenic potential of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) . Studies to evaluate the effect of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) on fertility or its mutagenic potential have not been performed.

Pregnancy

Teratogenic Effects

Pregnancy Category C. Animal reproduction studies have not been conducted with OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) . It is not known whether OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) can cause fetal harm when administered to a pregnant woman, or can affect reproduction capacity. OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets should be given to a pregnant woman only if clearly needed.

Pediatric Use

The safety and efficacy of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets have not been demonstrated in patients less than 18 years of age.

Geriatric Use

In controlled colon preparation trials of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) , 228 (24%) of 931 patients were 65 years of age or older. In addition, 49 (5%) of the 931 patients were 75 years of age or older.

Of the 228 geriatric patients in the trials, 134 patients (59%) received at least 48 grams of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) . Of the 49 patients 75 years old or older in the trials, 27 (55%) patients received at least 48 grams of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) . No overall differences in safety or effectiveness were observed between geriatric patients and younger patients. However, the mean phosphate levels in geriatric patients were greater than the phosphate levels in younger patients after OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) administration. The mean colonoscopy-day phosphate levels in patients 18-64, 65-74, and ≥ 75 years old who received 48 grams of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) in the phase 3 study were 7.0, 7.3, and 8.0 mg/dL, respectively. In addition, in all three sodium phosphate treatment groups, the mean phosphate levels in patients 18-64, 65-74, and ≥ 75 years old in the phase 3 study were 7.4, 7.9, and 8.0 mg/dL, respectively, after sodium phosphate administration. Greater sensitivity of some older individuals cannot be ruled out; therefore, OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) Tablets should be used with caution in geriatric patients.

Sodium phosphate is known to be substantially excreted by the kidney, and the risk of adverse reactions with sodium phosphate may be greater in patients with impaired renal function. Since geriatric patients are more likely to have impaired renal function, consider performing baseline and post-colonoscopy labs (phosphate, calcium, potassium, sodium, creatinine, and BUN) in these patients (see WARNINGS). It is recommended that patients receiving OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) be advised to adequately hydrate before, during, and after the use of OsmoPrep (sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous) .

Last reviewed on RxList: 9/15/2009
This monograph has been modified to include the generic and brand name in many instances.