Potassium Content in Potassium Phosphate IV Solution
Potassium phosphate IV solution contains 4.4 mEq of potassium per milliliter. 1
Standard Formulation
The FDA-approved potassium phosphate injection contains a fixed ratio of potassium to phosphate:
- 4.4 mEq potassium per mL (equivalent to 170 mg potassium) 1
- 3 mmol phosphorus per mL (equivalent to 93 mg phosphorus) 1
This means for every 1 mL of potassium phosphate solution administered, the patient receives 4.4 mEq of potassium alongside 3 mmol of phosphate. 1
Available Vial Sizes and Total Potassium Content
The solution is available in three vial sizes with corresponding total potassium content:
- 5 mL single-dose vial: Contains 22 mEq potassium total 1
- 15 mL single-dose vial: Contains 66 mEq potassium total 1
- 50 mL pharmacy bulk package: Contains 220 mEq potassium total 1
Critical Safety Considerations
This solution must always be diluted before administration and cannot be given as a direct IV push. 1 The high potassium concentration (4.4 mEq/mL) poses significant risk of hyperkalemia and cardiac complications if administered improperly.
Practical Dosing Guideline
A commonly recommended safe infusion rate is 1 mL per hour, which delivers 4.4 mEq potassium and 3 mmol phosphate per hour—this rate is considered both safe and appropriate for most hypophosphatemic patients with normal renal function. 2
Contraindications to Potassium Administration
Do not administer potassium phosphate in patients with:
- Significant renal impairment (CrCl <20 mL/min) without careful monitoring 3
- Pre-existing hyperkalemia 4
- Hypercalcemia 4
Monitoring Requirements
When administering potassium phosphate, monitor serum potassium levels regularly, as the high potassium load can cause hyperkalemia, particularly in patients with impaired renal function or those on medications affecting potassium homeostasis. 5, 3