Dosing and uses of Potassium phosphates IV
Adult dosage forms and strengths
Contains mixture of monobasic potassium phosphate and dibasic potassium phosphate
intravenous solution
- Phosphorus content: 93mg (3mM)/mL
- Potassium content: 170mg (4.4 mEq)/mL
Hypophosphatemia
The dose and administration IV infusion rate for potassium phosphates are dependent upon individual needs of the patient
Phosphorous serum level <0.5 mg/dL: 0.5 mmol/kg IV infused over 4-6 hr
Phosphorous serum level 0.5-1 mg/dL: 0.25 mmol/kg IV infused over 4-6 hr
Prevention of hypophosphatemia (eg, in TPN): 20-40 mmol/day IV admixed in TPN is typical dose, but adjustment according to electrolyte levels is ongoing
Administration
Calculate concomitant amount of potassium that will be administered: Each 1 mmol of phosphate contains ~1.5 mEq of potassium; if amount of potassium to be delivered is a concern (ie, potassium serum level >4.0 mEq/L), consider use of sodium phosphates IV to replete phosphorous leveL
May require continuous EKG monitoring depending on potassium administration rate
Renal Impairment
Administration of solutions containing potassium and phosphorous in patients with impaired renal function may result in hyperkalemia or hyperphosphatemia
Pediatric dosage forms and strengths
Contains mixture of monobasic potassium phosphate and dibasic potassium phosphate
intravenous solution
- Phosphorus content: 93mg (3mM)/mL
- Potassium content: 170mg (4.4 mEq)/mL
Hypophosphatemia
Caution should be exercised in premature neonates due to aluminum toxicity
The dose and administration IV infusion rate for potassium phosphates are dependent upon individual needs of the patient
Phosphorous serum level <0.5 mg/dL: 0.5 mmol/kg IV infused over 4-6 hr
Phosphorous serum level 0.5-1 mg/dL: 0.25 mmol/kg IV infused over 4-6 hr
Prevention of hypophosphatemia (eg, in TPN)
- Infants/children: 0.5-2 mmol/kg/day IV
- Children >50 kg or adolescents: 10-40 mmol/day IV
- Dose adjustment according to electrolyte levels is ongoing
Administration
Calculate concomitant amount of potassium that will be administered: Each 1 mmol of phosphate contains ~1.5 mEq of potassium; if amount of potassium to be delivered is a concern (ie, potassium serum level >4.0 mEq/L), consider use of sodium phosphates IV to replete phosphorous leveL
May require continuous EKG monitoring depending on potassium administration rate
Renal Impairment
Administration of solutions containing potassium and phosphorous in patients with impaired renal function may result in hyperkalemia or hyperphosphatemia
Potassium phosphates IV adverse (side) effects
Frequency not defined
Potassium
- Paresthesias of the extremities
- Flaccid paralysis
- Listlessness
- Mental confusion
- Weakness and heaviness of the legs
- Hypotension
- Cardiac arrhythmias
- Heart block
Phosphorus
- Hypocalcemic tetany
Warnings
Contraindications
Hyperphosphatemia
Hyperkalemia
Hypocalcemia
Hypomagnesemia
Cautions
Must be diluted and thoroughly mixed before administration
Phosphorus replacement therapy with potassium phosphates should be guided primarily by the serum inorganic phosphorus levels and the limits imposed by the accompanying potassium (K+) ion
To avoid hyperkalemia or hyperphosphatemia, infuse IV solutions containing potassium phosphates slowly
Caution with severe renal or adrenal insufficiency due to risk for hyperkalemia or hyperphosphatemia
High concentrations of phosphorus may cause hypocalcemia and hypocalcemic tetany; monitor calcium levels
Aluminum toxicity
- This product contains aluminum that may be toxic; aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired; premature neonates are at particular risk because of immature kidneys
- Aluminum doses exceeding 4-5 mcg/kg/day are associated with CNS and bone toxicity
- Tissue accumulation may occur at even lower doses
Pregnancy and lactation
Pregnancy category: C
Lactation: Unknown whether distributed in breast milk
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Potassium phosphates IV
Mechanism of action
Phosphorus is involved in many biochemical functions in the body and significant metabolic and enzyme reactions in almost all organs and tissues; it exerts a modifying influence on the steady state of calcium levels, a buffering effect on acid-base equilibrium, and a primary role in the renal excretion of hydrogen ion
Potassium is the principal intracellular cation; it helps transport dextrose across the cell membrane and contributes to normal renal function
Elimination
Excretion: feces (10%), urine (90%)
Administration
IV Incompatibilities
Calcium and phosphorous are incompatible and will precipitate in most aqueous solutions; may be mixed in some TPN admixtures in variable quantities depending on the composition of the preparation, order of mixing, pH, temperature, storage, and particular calcium salt (consult pharmacist)
Y-Site Administration
- Acyclovir, amiodarone, amphotericin B lipid complex (Abelcet), amphotericin B liposome (AmBisome), anidulafungin, caspofungin, ciprofloxacin, daunorubicin liposome, doripenem, doxacurium, doxorubicin, epirubicin, gemtuzumab ozogamicin, idarubicin, ifosfamide, ketamine, lansoprazole, leucovorin calcium, lorazepam, mitoxantrone, mycophenolate, pantoprazole, quinupristin/dalfopristin, rocuronium
Admixture
- Ciprofloxacin, dobutamine
Syringe
- Aminophylline, pantoprazole, salbutamol
For Dilution
- D10% in 0.9% NaCl; D2.5% in Half-strength LR; D5% in LR; Dextrose 5% in Ringer's; Lactated Ringer's; Ringer's injection
IV Compatibilities
Y-Site Administration
- Alemtuzumab, aminocaproic acid, argatroban, atenolol, bivalirudin, bleomycin, carboplatin, carmustine, cisplatin, cyclophosphamide, cytarabine, dactinomycin, daptomycin, dexmedetomidine, dexrazoxane, diltiazem
Admixture
- Magnesium sulfate, metoclopramide, verapamil
For Dilution
- Dextran 70 6% in D5W; dextran 70 6% in 0.5% NaCl; D10W; D2.5W; D2.5/0.45% NaCl; D5/0.2% NaCl; D5/0.45% NaCl; D5/NS; 0.9% NaCl (NS); 0.45% NaCl; sodium lactate 1/6 M
IV Administration
Administered IV only after dilution in a larger volume of fluid
Administer slowly over 4-6 hr
Monitor with EKg
Storage
Store at 20- 25°C (68- 77°F); excursions permitted to 15-30°C (59-86°F)
Does not contain a bacteriostatic agent or other preservatives; discard any unused portion
