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Administration of sodium phosphate products prior to colonoscopy 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 Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) be advised to adequately hydrate before, during, and after the use of Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) .

Considerable caution should be advised before Visicol® (sodium phosphate monobasic monohydrate, 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, acute bowel obstruction, bowel perforation, toxic megacolon, gastric retention, ileus, pseudo-obstruction of the bowel, severe chronic constipation, acute colitis, 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 (such as dehydration), 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 Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) with caution in patients with impaired renal function, 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 them corrected before treatment with Visicol® (sodium phosphate monobasic monohydrate, 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. Visicol® (sodium phosphate monobasic monohydrate, 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. Visicol® (sodium phosphate monobasic monohydrate, 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 3-tablet (or each 2-tablet) dose of Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) . Patients should take a total of 3.6 quarts of clear liquids with Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) . Inadequate fluid intake, as with any effective purgative, may lead to excessive fluid loss and hypovolemia. Dehydration from purgation may be exacerbated by inadequate oral fluid intake, vomiting, and/or the use of diuretics. Patients should not take additional laxatives or purgatives, particularly additional sodium phosphate-based products.

Prolongation of the QT interval has been observed in some patients who were dosed with Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) Tablets. QT prolongation with Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) Tablets has been associated with electrolyte imbalances, such as hypokalemia and hypocalcemia. Visicol® (sodium phosphate monobasic monohydrate, 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. Pre-dose and post-colonoscopy ECGs should be considered in patients with known prolonged QT. In these studies, prolongation of the QT interval was also observed in some patients treated with PEG-salt solution.

Patients with a history of swallowing difficulties or anatomic narrowing of the esophagus, such as a stricture, may have difficulty swallowing Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) Tablets. Undigested or partially digested Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) Tablets may be seen in the stool or during colonoscopy. In addition, undigested tablets from other medications may be seen in the stool or during colonoscopy.

Administration of Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) Tablets may induce colonic mucosal aphthous ulcerations, since this endoscopic finding observed with other sodium phosphate cathartic preparations. This colonoscopic finding should be considered in patients with known or suspect inflammatory bowel disease (IBD).

Because published data suggest that sodium phosphate absorption may be enhanced in patients experiencing an acute exacerbation of IBD, Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) Tablets should be used with caution in IBD patients.

Since Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) Tablets were not studied in patients who recently had cardiac surgery (including coronary artery bypass graft surgery) Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) should be used with caution in these patients.

Carcinogenesis, Mutagenesis, Impairment of Fertility

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

Pregnancy

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

Pediatric Use

Safety and efficacy of Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) Tablets have not been demonstrated in patients less than 18 years of age.

Geriatric Use

Of the 980 subjects/patients in the Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) studies, 284 (29%) subjects/patients were 65 years of age or older. Of the 548 subjects/patients who received Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) in these studies, 146 (27%) were 65 years of age or older and 42 (8%) subjects/patients were 75 years of age or older.

In two phase 3 Visicol® (sodium phosphate monobasic monohydrate, sodium phosphate dibasic anhydrous) trials (Study A and Study B), no overall differences in safety or effectiveness were observed between geriatric patients and younger patients. Greater sensitivity of some older individuals cannot be ruled out; therefore, Visicol® (sodium phosphate monobasic monohydrate, 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).

Last reviewed on RxList: 4/17/2009
This monograph has been modified to include the generic and brand name in many instances.