Sodium Acid Phosphate

Sodium acid phosphate is used as bowel preparation for colonoscopy and as a laxative.

Sodium acid phosphate is available under the following different brand names: OsmoPrep, Phospho Soda, sodium biphosphate, sodium phosphate, and Visicol.

Dosage Forms and Strengths

Na2HPO4/NaH2PO4

Aqueous Solution

• (48g/18g)/100mL

Tablet

• 0.398 g/1.102 g

Enema

• (7 g/19 g)/118mL

Pediatric Enema

• (3.5 g/9.5 g)/59mL

Dosage Considerations – Should be Given as Follows:

Bowel Preparation for Colonoscopy

• OsmoPrep: 4 tablets with 8 oz of water orally every 15 minutes (total 20 tablets) evening before procedure, and repeat regimen (12 tablets) next day 3-5 hours before procedure
• Visicol: 3 tablets with 8 oz of water orally every 15 minutes (last dose 2 tablets, total 20 tablets) evening before procedure, and repeat same regimen next day 3-5 hours before procedure
• Aqueous: 30-45 mL (of 48 g Na2HPO4-18 g NaH2PO4/100 mL) orally twice 10-12 hours apart; each dose with at least 8 oz liquid; each dose followed by additional minimum 16 oz liquid; 2nd dose at least 3 hours before procedure
• Children under 15 kg: 22.5 mL aqueous orally afternoon and evening before colonoscopy
• Children 15 kg and greater: 45 mL aqueous orally afternoon and evening before colonoscopy

Laxative (Rectal)

• Adults and children 12 years and older: Administer contents of 4.5 oz enema rectally as single dose
• Children 4-12 years: Administer contents of 2.25 oz pediatric enema as single dose
• Children 2-4 years: Administer one half content of 2.25 oz pediatric enema as single dose
• Children under 2 years: Safety and efficacy not established

Laxative (Oral)

• Adults and children 12 years and older: Administer 15 mL as single dose once daily; not to exceed 45 mL/day
• Children 10-12 years: 15 mL as single dose; not to exceed 15 mL/day
• Children 5-10 years: 7.5 mL as single dose; not to exceed 7.5 mL/day
• Children under 5 years: Safety and efficacy not established

Side effects of Sodium Acid Phosphate may include:

• Flushing
• Low blood pressure (hypotension)
• Dizziness
• Dizziness on standing
• Fast heart rate
• Headache
• Hypersensitivity
• Rash
• Nausea

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

• Severe interactions of sodium acid phosphate include:
  • sodium phosphate rectal
• Serious interactions of sodium acid phosphate include:
  • baloxavir marboxil
  • potassium phosphates, IV
• Moderate interactions of sodium acid phosphate include:
  • deflazacort
  • dextroamphetamine
  • lisdexamfetamine
  • methamphetamine
  • methylenedioxymethamphetamine
  • omadacycline
  • sarecycline
• Sodium acid phosphate has no listed mild interactions with other drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

Warnings

This medication contains sodium acid phosphate. Do not take OsmoPrep, Phospho Soda, sodium biphosphate, sodium phosphate, or Visicol if you are allergic to sodium acid phosphate or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.

Black Box Warning

• Rare reports of acute phosphate nephropathy with oral sodium phosphate products used for colon cleansing before colonoscopy
• Some cases have resulted in permanent renal function impairment requiring long-term hemodialysis
• Risk factors for acute phosphate nephropathy include age over 55 years, low blood volume (hypovolemia), baseline kidney disease, bowel obstruction, active colitis, and those using medicines that affect renal perfusion or function [e.g., diuretics, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), nonsteroidal anti-inflammatory drugs (NSAIDs)]
• Carefully follow dosing regimen as recommended (p.m./a.m. split dose) with adequate hydratio

Contraindications

• Enema: Renal failure, congestive heart failure, ascites, obstruction, megacolon, perforated bowel, ulcerative colitis, fecal impaction
• Intravenous (IV): Hyperphosphatemia, hypocalcemia, hypernatremia
• Oral: Bowel obstruction, bowel perforation, gastric bypass, toxic colitis, toxic megacolon, acute phosphate nephropathy

Effects of Drug Abuse

• No information available.

Short-Term Effects

• See "What Are Side Effects Associated with Using Sodium Acid Phosphate?"

Long-Term Effects

• See "What Are Side Effects Associated with Using Sodium Acid Phosphate?"

Cautions

• Should not be re-administered for at least 7 days
• Risk of acute phosphate nephropathy
• Osmotic laxative products may produce colonic mucosal ulcerations, and there have been reports of more serious cases of ischemic colitis requiring hospitalization
• QT interval prolongation reported
• Use caution in heart failure, unstable angina, cardiomyopathy, patients at risk for arrhythmias, patients with pre-existing electrolyte disturbances, gastric retention or hypomotility, severe chronic constipation, colitis, or ileus, chronic inflammatory bowel disease, or history of seizures
• Severe dehydration and electrolyte abnormalities associated with serious complications (e.g., acute kidney injury, arrhythmias, and death) have occurred in adults and children who overdosed using oral or rectal over-the-counter (OTC) sodium phosphate solutions to treat constipation

Pregnancy and Lactation

Use sodium acid phosphate with caution during pregnancy if benefits outweigh risks. Animal studies show risk and human studies are not available or neither animal nor human studies were done.

Use sodium acid phosphate caution while breastfeeding. Consult your doctor.