Potassium Phosphate
Potassium phosphate is a phosphate-replacement preparation that also supplies potassium. Its principal veterinary role is correction of clinically important hypophosphatemia, including deficits arising during diabetic ketoacidosis treatment or nutritional rehabilitation. Mono- and dibasic salt proportions and product concentration determine the phosphate and potassium content of a preparation.
Group
Phosphate supplement
Mechanism of Action
Potassium phosphate dissociates to replenish inorganic phosphate needed for ATP production, phosphorylation reactions, red-cell metabolism and cellular membrane function. Correcting a deficit supports energy-dependent cellular processes and can reverse phosphate-depletion-associated dysfunction. The accompanying potassium also enters body potassium pools. Effects on acid–base balance depend partly on the mono- and dibasic phosphate composition.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Acute hypophosphatemia | 0.03–0.12 mmol/kg/hour | IV | Continuous | Amount is phosphate, not potassium or total salt. |
| Daily phosphate supplementation | Reference only | IV | 0.1 mmol phosphate/kg/day IV is reported; administer as controlled supplementation rather than an unspecified bolus. | |
| Oral phosphate supplementation | 4 mg/kg | PO | Every 6 h | Amount expressed as elemental phosphorus; reported says up to four times daily. |
| Oral phosphate supplementation | 0.1 mmol/kg | PO | Every 6 h | Approximate molar alternative to 4 mg/kg elemental phosphorus; up to four times daily. |
| Hypophosphatemia | 0.01–0.06 mmol/kg/hour | IV | Continuous | Dilute in saline or dextrose; monitor phosphate every 4-8 hours, calcium and potassium. Amount is phosphate/elemental phosphorus equivalent. |
| Hypophosphatemia | 0.01–0.03 mmol/kg/hour | IV | Continuous | Dilute in saline or dextrose; monitor phosphate every 4-8 hours, calcium and potassium. Amount is phosphate/elemental phosphorus equivalent. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Acute hypophosphatemia | 0.03–0.12 mmol/kg/hour | IV | Continuous | Amount is phosphate, not potassium or total salt. |
| Daily phosphate supplementation | Reference only | IV | 0.1 mmol phosphate/kg/day IV is reported; administer as controlled supplementation rather than an unspecified bolus. | |
| Oral phosphate supplementation | 4 mg/kg | PO | Every 6 h | Amount expressed as elemental phosphorus; reported says up to four times daily. |
| Oral phosphate supplementation | 0.1 mmol/kg | PO | Every 6 h | Approximate molar alternative to 4 mg/kg elemental phosphorus; up to four times daily. |
| Hypophosphatemia | 0.01–0.06 mmol/kg/hour | IV | Continuous | Dilute in saline or dextrose; monitor phosphate every 4-8 hours, calcium and potassium. Amount is phosphate/elemental phosphorus equivalent. |
| Hypophosphatemia | 0.01–0.03 mmol/kg/hour | IV | Continuous | Dilute in saline or dextrose; monitor phosphate every 4-8 hours, calcium and potassium. Amount is phosphate/elemental phosphorus equivalent. |
| Diabetic ketoacidosis-associated hypophosphatemia | 0.03–0.06 mmol/kg/hour | IV | Continuous | Reported for phosphate below 2 mg/dL; reassess after 6-12 hours. |
| Severe hypophosphatemia | 0.12–0.2 mmol/kg/hour | IV | Continuous | Separate severe-rescue range for phosphate below 1 mg/dL; intensive serial electrolyte monitoring required. |
Indications
- Treatment of clinically significant hypophosphatemia in veterinary patients.
- Phosphate replacement during diabetic ketoacidosis treatment when hypophosphatemia develops or worsens.
- Treatment of selected refeeding-associated or other depletion-related hypophosphatemia when a potassium-containing phosphate source is appropriate.
Contraindications
- Renal disease requires caution.
Adverse effects
- IV supplementation may cause hypocalcemia.
Toxicity
Excess phosphate can cause hypocalcemia, hyperphosphatemia and soft-tissue mineralization; potassium load can also cause hyperkalemia. Stop infusion and correct measured abnormalities while avoiding calcium-phosphate precipitation.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Potassium phosphate injection (3 mmol phosphate/mL) Label-equivalent basis: 3 mmol phosphate (3 mmol phosphorus) and 4.4 mEq potassium per mL. Original chemical composition: monobasic potassium phosphate 224 mg plus dibasic potassium phosphate 236 mg/mL. Dilute before IV infusion; monitor both electrolytes. | Injection | phosphorus 3 mmol / mL + potassium 4.4 mEq / mL | IV |
Monitoring and Administration
Monitor phosphate, calcium and potassium; control infusion rate and consider the concurrent potassium load.
Avoid phosphate infusion with hyperphosphatemia, hypocalcemia, oliguric renal failure or tissue necrosis; potassium phosphate is unsuitable with hyperkalemia. Dilute before use and avoid calcium precipitation. Parenteral potassium phosphate provides 3 mmol phosphate and 4.4 mEq potassium/mL. Sodium-phosphate ruminant regimens are different preparations and are not converted to this medicine.