Comprehensive medication guide to Sodium Phosphate, Dibasic/Sodium Phosphate, Monobasic including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$100 copay depending on insurance plan and formulary tier; many commercial plans cover OsmoPrep, though some require prior authorization. Medicare Part D coverage varies by plan.
Estimated Cash Pricing
$113–$305 retail for a 32-tablet course (OsmoPrep brand); as low as approximately $277 with a GoodRx coupon at select pharmacies. Generic versions may be available at lower prices.
Medfinder Findability Score
72/100
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Sodium phosphate, dibasic/sodium phosphate, monobasic — sold under the brand name OsmoPrep — is an FDA-approved prescription osmotic laxative used to clean the colon before a colonoscopy. It is available as oral tablets (1.5 g each), and a complete course consists of 32 tablets taken in two split doses. A separate intravenous (IV) formulation is used in hospitals to treat hypophosphatemia (low blood phosphorus) and as an additive in total parenteral nutrition (TPN).
OsmoPrep was initially FDA-approved in 2006 and is manufactured by Salix Pharmaceuticals. It became prescription-only after the FDA required a boxed warning in 2008 for acute phosphate nephropathy — a rare but serious kidney complication. Generic versions are available from manufacturers including Lupin Pharmaceuticals. OsmoPrep is not a controlled substance.
The IV form (3 mM P/mL) is a concentrated solution provided in 5 mL, 15 mL, and 50 mL single-dose vials manufactured by Hospira (Pfizer) and American Regent. It is indicated for addition to large-volume IV fluids to prevent or correct hypophosphatemia in patients with restricted oral intake.
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Oral sodium phosphate (OsmoPrep) functions as an osmotic laxative. When swallowed, the concentrated sodium phosphate tablets dissolve in the stomach and pass into the intestines. The high phosphate concentration creates an osmotic gradient that draws water from surrounding body tissues into the bowel lumen — essentially pulling fluid from the bloodstream into the intestine. This large influx of fluid triggers powerful intestinal contractions, resulting in watery diarrhea that thoroughly empties the colon.
Because OsmoPrep draws water from the body's tissues, adequate hydration is essential. Patients must drink 2 quarts (64 oz) of clear liquid during the prep to replace the fluid pulled into the colon and to help the kidneys safely process and excrete the absorbed phosphate.
The IV form works differently — it directly supplies phosphate to the bloodstream, replenishing serum phosphorus levels in patients who cannot absorb phosphorus through the gastrointestinal tract. Each mL of the IV solution provides 3 millimoles (mM) of phosphorus and 4 mEq of sodium, administered slowly after dilution in a large-volume IV fluid.
1.5 g (1.102 g monobasic + 0.398 g dibasic) — oral tablet
OsmoPrep: 32 tablets total per colonoscopy prep course (split-dose: 20 tablets evening before, 12 tablets morning of procedure)
3 mM P/mL (276 mg/mL monobasic + 142 mg/mL dibasic) — IV injection solution
Hospital use only; dilute before use; add to large-volume IV fluids; dose based on serum phosphorus level (0.25–0.5 mmol/kg IV over 4–6 hours)
Oral sodium phosphate (OsmoPrep) is not on the FDA's Drug Shortage Database as of 2026, but it can be difficult to find at many retail pharmacies. Because it's a one-time-use, prescription-only medication, most chain pharmacies don't stock it in large quantities. Small and rural pharmacies may not stock it at all. Hospital outpatient pharmacies and independent pharmacies tend to have better availability.
medfinder has a findability score of 72/100 for sodium phosphate — generally available but with inconsistent stocking at retail pharmacies. If you're having trouble locating OsmoPrep near you, medfinder calls pharmacies near you to find which ones can fill your prescription. Results are texted to you quickly.
Patients should fill their OsmoPrep prescription as soon as they receive it — ideally 5–7 days before their colonoscopy prep day — to allow time to find it at a pharmacy or arrange a special order. If OsmoPrep is unavailable, multiple effective alternatives exist including GoLYTELY, SUTAB, MoviPrep, and Suprep.
Sodium phosphate (OsmoPrep) is not a controlled substance, so any licensed prescriber with a valid DEA registration (or state prescribing authority) can write a prescription. In practice, it is most commonly ordered by providers who perform or coordinate colonoscopies. Common prescribers include:
Gastroenterologists (GI specialists — most common prescribers)
Colorectal surgeons
General surgeons
Primary care physicians (PCPs) coordinating colonoscopy referrals
Nurse practitioners (NPs) and physician assistants (PAs) in GI, surgery, or primary care practices
Hospital-based physicians (for IV formulation)
Telehealth providers can technically prescribe OsmoPrep as a non-controlled medication, but because it carries a boxed warning and requires careful patient screening for contraindications (kidney disease, age >55, certain medications), in-person evaluation or established care relationship is strongly preferred. Most OsmoPrep prescriptions are issued in connection with a scheduled colonoscopy at a GI or surgical practice.
No. Sodium phosphate, dibasic/sodium phosphate, monobasic (OsmoPrep) is NOT a controlled substance. It is not scheduled by the DEA and does not have any federal or state controlled substance restrictions. Any licensed prescriber — including physicians, nurse practitioners, physician assistants, and dentists — can write a prescription without special DEA registration.
While OsmoPrep is not controlled, it is available by prescription only because of its boxed warning for acute phosphate nephropathy. Prior to 2008, over-the-counter sodium phosphate solutions (Fleet Phospho-Soda) were available without a prescription, but the FDA mandated prescription-only status after reports of serious kidney injury. Patients cannot purchase OsmoPrep without a valid prescription.
Most side effects during OsmoPrep colonoscopy prep are expected and temporary, resolving once the prep is complete:
Diarrhea (intended and expected)
Nausea and vomiting
Abdominal cramping and bloating
Thirst and dehydration
Dizziness or lightheadedness
Anal irritation from frequent bowel movements
Acute phosphate nephropathy: Rare but potentially irreversible kidney injury — boxed warning. Signs include decreased urination, swelling, and flank pain.
Electrolyte imbalances: Hyperphosphatemia, hypocalcemia, hyponatremia — can cause seizures, cardiac arrhythmia
Cardiac arrhythmia: QT prolongation possible with severe electrolyte shifts
Severe dehydration: Rapid heart rate, fainting, inability to urinate — call doctor immediately
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GoLYTELY / NuLYTELY (polyethylene glycol)
PEG-based colonoscopy prep; gold standard; safest for patients with kidney disease or heart failure; requires drinking 4 liters of solution; generic versions available for as low as $5–$15
SUTAB (sodium sulfate tablets)
FDA-approved 2020; 24 tablets; same tablet convenience as OsmoPrep without phosphate nephropathy risk; preferred alternative when tablet format is desired
MoviPrep (PEG + ascorbate)
Lower-volume PEG prep (2L); excellent tolerability and efficacy; good alternative for patients who can't use sodium phosphate
Suprep (sodium/potassium/magnesium sulfate)
Liquid prep without phosphate nephropathy risk; low volume; widely available; good tolerability compared to GoLYTELY
MiraLAX + Gatorade (OTC combination)
OTC option under $20; not FDA-approved as colonoscopy prep but widely used in clinical practice; excellent tolerability
Clenpiq (sodium picosulfate)
Very low volume (two 160-mL bottles); palatable; avoid in severe renal impairment (eGFR <30)
Prefer Sodium Phosphate, Dibasic/Sodium Phosphate, Monobasic? We can find it.
ACE Inhibitors (lisinopril, enalapril, benazepril, etc.)
majorMajor interaction: ACE inhibitors reduce kidney perfusion and significantly increase the risk of acute phosphate nephropathy when combined with sodium phosphate. Rated AVOID / Use Alternate Drug.
ARBs (losartan, valsartan, irbesartan, olmesartan)
majorMajor interaction: ARBs impair kidney blood flow regulation similarly to ACE inhibitors, significantly increasing nephrotoxicity risk with sodium phosphate.
Diuretics (furosemide, hydrochlorothiazide, spironolactone)
majorModerate-to-major interaction: Diuretics cause volume depletion, which combined with OsmoPrep's dehydrating osmotic effects dramatically increases kidney damage risk.
NSAIDs (ibuprofen, naproxen, aspirin, celecoxib, meloxicam)
moderateModerate interaction: NSAIDs reduce renal prostaglandins needed for kidney blood flow, increasing phosphate nephropathy risk especially in dehydrated patients.
Other sodium phosphate products (Fleet Enema, phosphate solutions)
majorMajor interaction: Do not combine OsmoPrep with any other sodium phosphate-containing product — risk of severe hyperphosphatemia and kidney failure.
All oral medications (general)
moderateModerate interaction: Do not take oral medications within 1 hour before or after each OsmoPrep dose — rapid bowel transit reduces absorption of other drugs.
Erdafitinib (FGFR inhibitor)
majorMajor interaction: Avoid combination during initial dosing period (first 21 days); FGFR inhibition raises serum phosphate and can confound phosphate management.
Calcium supplements
minorMinor-to-moderate interaction: Calcium binds phosphate in the GI tract and may reduce the effectiveness of IV sodium phosphate. Hold calcium supplements on prep day.
Sodium phosphate, dibasic/sodium phosphate, monobasic (OsmoPrep) is an effective, tablet-based colonoscopy prep that many patients prefer over large-volume liquid solutions. Its FDA approval dates to 2006, and it remains a viable option for appropriate patients — specifically healthy, well-hydrated adults without kidney disease, heart failure, or significant medication interactions.
However, OsmoPrep's boxed warning for acute phosphate nephropathy means prescriber selection and patient counseling are critical. Patients with kidney disease, those over 55, or those on ACE inhibitors, ARBs, diuretics, or NSAIDs should use alternative preps like PEG-based solutions (GoLYTELY, MoviPrep) or SUTAB. The colonoscopy itself — a critical cancer screening tool — should never be delayed due to prep difficulties.
If you've been prescribed OsmoPrep and can't find it at your local pharmacy, medfinder can call pharmacies near you to locate it quickly. You provide your medication and location, and medfinder texts you results — no hold music, no runaround.
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