Indications
Sodium Dihydrogen Phosphate Dihydrate (monobasic sodium phosphate) is one of the two sodium phosphate salts in oral bowel-cleansing solutions. It is combined with Disodium Hydrogen Phosphate Dodecahydrate in the same solution. These solutions are used to empty and clean the bowel before colonoscopy, X-ray of the bowel or bowel surgery. Similar products are sometimes used for short-term relief of constipation.
How It Works
Sodium phosphate is an osmotic laxative. It is poorly absorbed, so it stays in the bowel and draws a large amount of water into it. This softens and increases the bowel contents and causes frequent watery stools, usually within 30 minutes to 6 hours, which clears the bowel.
Dosage and Administration
Use only as prescribed by your doctor for the bowel preparation, following the timing given by the hospital or clinic exactly. The dose is usually split, with part taken the evening before and part on the morning of the procedure. Each dose must be diluted in water as the instructions say, and followed by plenty of clear fluids (water, clear soup, oral rehydration solution) to prevent dehydration. Do not take an extra dose and do not use it with other laxatives unless told to.
Interactions
- Diuretics (such as Furosemide or Hydrochlorothiazide), ACE inhibitors (such as Enalapril), angiotensin receptor blockers (such as Losartan) and NSAIDs (such as Ibuprofen) increase the risk of kidney damage and salt imbalance.
- Medicines that affect heart rhythm, such as Amiodarone, and Lithium need extra care.
- Other medicines taken by mouth around the same time may not be absorbed properly; ask your doctor about timing.
Contraindications
- Kidney disease or reduced kidney function.
- Heart failure, bowel blockage or perforation, toxic megacolon, severe ulcerative colitis.
- Dehydration, high phosphate, low calcium or other salt imbalances.
- Children, unless specifically prescribed by a specialist.
Side Effects
Common effects are bloating, stomach cramps, nausea, vomiting, feeling cold and dizziness. Loss of fluid can lead to thirst, weakness and imbalance of sodium, potassium, calcium and phosphate. Rarely it can cause serious kidney injury (acute phosphate nephropathy), especially in older people and those on blood pressure medicines.
Get urgent medical help if you have fainting, very little urine, severe vomiting so you cannot keep fluids down, muscle cramps or twitching, numbness around the mouth, irregular heartbeat, fits, or severe stomach pain.
Pregnancy and Lactation
Use in pregnancy only if your doctor decides it is needed. It is not expected to harm a breastfed baby when used once for bowel preparation, but follow your doctorx27s advice.
Precautions and Warnings
- Drink all the clear fluids advised; dehydration increases the risk of kidney damage.
- Older people and those with heart, kidney or liver disease may need blood tests before and after.
- Do not use it more than once within the time your doctor sets.
- Stay near a toilet after each dose.
Overdose
Too much can cause severe dehydration, high phosphate, low calcium, muscle spasms, heart rhythm problems and kidney failure. Seek emergency medical help.
Therapeutic Class
Osmotic laxative, bowel-cleansing preparation (sodium phosphate salt).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.