May 25, 2017
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(sodium phosphate monobasic monohydrate, USP and sodium phosphate dibasic anhydrous, USP)


There have been rare, but serious reports of acute phosphate nephropathy in patients who received oral sodium phosphate products for colon cleansing prior to colonoscopy. Some cases have resulted in permanent impairment of renal function and some patients required long-term dialysis. While some cases have occurred in patients without identifiable risk factors, patients at increased risk of acute phosphate nephropathy may include those with increased age, hypovolemia, increased bowel transit time (such as bowel obstruction), active colitis, or baseline kidney disease, and those using medicines that affect renal perfusion or function (such as diuretics, angiotensin converting enzyme [ACE] inhibitors, angiotensin receptor blockers [ARBs], and possibly nonsteroidal anti-inflammatory drugs [NSAIDs]). [See WARNINGS AND PRECAUTIONS]

It is important to use the dose and dosing regimen as recommended (pm/am split dose). [see DOSAGE AND ADMINISTRATION]


OsmoPrep (sodium phosphate monobasic monohydrate, USP, and sodium phosphate dibasic anhydrous, USP) is an osmotic laxative used to clean the colon prior to colonoscopy. OsmoPrep is manufactured with a highly soluble tablet binder and does not contain microcrystalline cellulose (MCC). OsmoPrep Tablets are oval, white to off-white compressed tablets, debossed with “SLX” on one side of the bisect and “102” on the other side of the bisect. Each OsmoPrep tablet contains 1.102 grams of sodium phosphate monobasic monohydrate, USP and 0.398 grams of sodium phosphate dibasic anhydrous, USP for a total of 1.5 grams of sodium phosphate per tablet. Inert ingredients include polyethylene glycol 8000, NF; and magnesium stearate, NF. OsmoPrep is gluten-free.

The structural and molecular formulae and molecular weights of the active ingredients are shown below:

  • Sodium phosphate monobasic monohydrate, USP

Sodium phosphate monobasic monohydrate Structural Formula Illustration

Molecular Formula: NaH2PO4• H2O
Molecular Weight: 137.99

  • Sodium phosphate dibasic anhydrous, USP

Sodium phosphate dibasic anhydrous Structural Formula Illustration

Molecular Formula: Na2HPO4
Molecular Weight: 141.96

OsmoPrep Tablets are for oral administration only.

What are the possible side effects of sodium biphosphate and sodium phosphate (Fleet Enema, Fleet Enema for Children, OsmoPrep, Visicol)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using sodium biphosphate and sodium phosphate and call your doctor at once if you have a serious side effect such as:

  • rectal bleeding;
  • no bowel movement after use;
  • sores or ulcers around your rectum;
  • seizure (black-out or convulsions);
  • fast, slow, or uneven heart rate;
  • urinating less than...

Read All Potential Side Effects and See Pictures of OsmoPrep »

What are the precautions when taking sodium phosphate monobasic monohydrate and sodium phosphate dibasic anhydrous (OsmoPrep)?

See also How to Use section.

Before taking sodium phosphate, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart problems (such as heart failure, irregular heartbeat, QT prolongation in the EKG, chest pain, heart attack or heart surgery within the last 3 months), stomach/bowel problems (such as blockage, irritable bowel disease, ulcerative colitis, severe constipation), gastric bypass/stapling, low blood minerals, severe loss of body water (dehydration), kidney problems, liver problems...

Read All Potential Precautions of OsmoPrep »

Last reviewed on RxList: 12/8/2016
This monograph has been modified to include the generic and brand name in many instances.

OsmoPrep - User Reviews

OsmoPrep User Reviews

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