Sodium acid Phosphate
Mechanism :
As a laxative, exerts osmotic effect in the small intestine by drawing water into the lumen of the gut; phosphorous participates in bone deposition, calcium metabolism and as a buffer in acid-base equilibrium.
Indication :
- Oral solution, rectal: Short-term treatment of constipation
- Oral tablets: Bowel cleansing prior to colonoscopy
Contraindications :
Hypersensitivity to sodium phosphate salts or any component of the formulation.
Intravenous preparation: Diseases with hyperphosphatemia, hypocalcemia, or hypernatremia.
Tablets: Acute phosphate nephropathy (biopsy proven), bowel obstruction, bowel perforation, gastric bypass or stapling surgery, toxic colitis, toxic megacolon.
Oral Solution: When used for self-medication: Dehydration, heart failure, renal impairment, electrolyte abnormalities; use for bowel cleansing, use in children <5 years.
Dosing :
Laxative:
Oral solution: (Available as 48 g Na2HPO4/18 g NaH2PO4 per 100 ml)
5-9 years: 7.5 mL as a single dose.
10-11 years: 15 mL as a single dose.
≥12 years: 15 mL as a single dose; Maximum single daily dose: 45 mL.
Rectal: (Available as 3.5 g Na2HPO4/9.5 g NaH2PO4 per 59 ml or 2.25 oz pediatric enema)
2-4 years: One-half of pediatric enema as a single dose.
5-11 years: One pediatric enema as a single dose.
≥12 years: Two pediatric enema as a single dose.
Bowel preparation for Colonoscopy:
<15 kg:
Give 22.5 ml oral solution in the afternoon and in the evening prior to colonoscopy next day.
>15 kg:
Give 45 ml oral solution in the afternoon and in the evening prior to colonoscopy next day.
Adverse Effect :
Dizziness, headache, bloating, nausea, abdominal pain, vomiting, diarrhea, mucosal bleeding, hyperphosphatemia, hypocalcemia, hypokalemia, hypernatremia.
Interaction :
Angiotensin II Receptor Blockers and ACE inhibitors: May enhance the nephrotoxic effect of Sodium Phosphates.
Antacids, Sucralfate: May decrease the absorption of Phosphate Supplements.
Calcium Salts: May decrease the absorption of Phosphate Supplements.
Diuretics: May enhance the nephrotoxic effect of Sodium Phosphates.
Iron Salts: May decrease the absorption of Phosphate Supplements.
Nonsteroidal Anti-Inflammatory Agents: Sodium Phosphates may enhance the nephrotoxic effect of Nonsteroidal Anti-Inflammatory Agents.
Tricyclic Antidepressants: May enhance the adverse/toxic effect of Sodium Phosphates.
Hepatic Dose :
No dosage adjustments are recommended.