POTASSIUM PHOSPHATES IN 0.9% SODIUM CHLORIDE
Clinical safety rating: safe
No significant drug interactions Can cause hypernatremia and fluid overload.
Phosphate supplementation to correct hypophosphatemia; acts as a buffer and is essential for cellular energy metabolism (ATP), bone mineralization, and acid-base balance.
| Metabolism | Phosphate is freely filtered by the glomerulus and reabsorbed in the proximal tubule; excess is excreted renally. No significant hepatic metabolism. |
| Excretion | Renal: >90% of phosphate is reabsorbed or excreted by the kidneys; potassium is primarily excreted renally. Fecal elimination accounts for <10% of total phosphate loss. |
| Half-life | Phosphate: 3-4 hours in healthy adults; prolonged with renal impairment. Potassium: short distribution half-life (~1-1.5 hours); no true terminal half-life due to tight regulation. |
| Protein binding | Phosphate: 10-15% bound to serum proteins (albumin and immunoglobulins). Potassium: <5% protein bound. |
| Volume of Distribution | Phosphate: 0.15-0.3 L/kg (primarily extracellular fluid). Potassium: 0.5-0.7 L/kg (distributes into intracellular space). |
| Bioavailability | Intravenous: 100% bioavailability. Oral (not applicable for this formulation): 60-70% for phosphate salts; potassium salts >90%. |
| Onset of Action | Intravenous: Hypophosphatemia correction begins within minutes; potassium repletion occurs over 1-2 hours. |
| Duration of Action | Duration of electrolyte normalization: phosphate levels correct over 6-12 hours post-infusion; potassium repletion sustained for 4-6 hours. |
IV: 2.5-5 mmol phosphate/kg body weight over 24 hours; typical dose 10-30 mmol phosphate over 4-6 hours; do not exceed 60 mmol phosphate/day.
| Dosage form | SOLUTION |
| Renal impairment | GFR <30 mL/min: initiate at 50% of standard dose and titrate based on serum phosphate and potassium levels; avoid if GFR <15 mL/min unless severe hypophosphatemia. |
| Liver impairment | No specific Child-Pugh based recommendations; use with caution in severe hepatic impairment due to potential for electrolyte disturbances. |
| Pediatric use | IV: 0.5-1 mmol phosphate/kg over 12-24 hours; monitor serum phosphate and potassium closely; do not exceed 5 mmol/kg/day. |
| Geriatric use | Initiate at lower end of dosing range; monitor renal function and serum electrolytes more frequently due to age-related decline in GFR. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions Can cause hypernatremia and fluid overload.
| FDA category | Animal |
| Breastfeeding | Excretion in human milk unknown; M/P ratio not determined. Use with caution, weighing benefit against potential risk of electrolyte disturbances in the nursing infant. |
| Teratogenic Risk | FDA Pregnancy Category C. No adequate studies in pregnant women. First trimester: risk cannot be ruled out; use only if clearly needed. Second/third trimesters: may cause hypocalcemia, electrolyte imbalances in fetus; avoid prolonged use. |
■ FDA Black Box Warning
None
| Common Effects | fluid replacement |
| Serious Effects |
["Hyperphosphatemia","Hypocalcemia","Renal failure (unless on dialysis)","Patients with known hypersensitivity to any component"]
| Precautions | ["Hyperphosphatemia, especially in renal impairment","Hypocalcemia due to precipitation with calcium","Monitor serum calcium, phosphate, and renal function","Avoid extravasation (may cause tissue necrosis)","Not for IV push; give as slow infusion"] |
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| Fetal Monitoring | Monitor serum phosphate, potassium, calcium, magnesium, and renal function regularly. Monitor fetal heart rate and growth if used long-term. |
| Fertility Effects | No known adverse effects on fertility in animal studies. Human data insufficient. |