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Potassium Phosphate and Sodium Phosphate

Pronunciation

(poe TASS ee um FOS fate & SOW dee um FOS fate)

Index Terms

  • Neutra-Phos
  • Sodium Phosphate and Potassium Phosphate

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Powder for solution, oral:

Phos-NaK: Dibasic potassium phosphate, monobasic potassium phosphate, dibasic sodium phosphate, and monobasic sodium phosphate per packet (100s) [sugar free; equivalent to elemental phosphorus 250 mg (8 mmol), sodium 160 mg (6.9 mEq), and potassium 280 mg (7.1 mEq) per packet; fruit flavor]

Tablet, oral:

Av-Phos 250 Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]

K-Phos Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]

K-Phos No. 2: Potassium acid phosphate 305 mg and sodium acid phosphate 700 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 134 mg (5.8 mEq), and potassium 88 mg (2.3 mEq)]

Phospha 250 Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]

Virt-Phos 250 Neutral: Monobasic potassium phosphate 155 mg, dibasic sodium phosphate 852 mg, and monobasic sodium phosphate 130 mg [equivalent to elemental phosphorus 250 mg (8 mmol), sodium 298 mg (13 mEq), and potassium 45 mg (1.1 mEq)]

Brand Names: U.S.

  • Av-Phos 250 Neutral
  • K-Phos Neutral
  • K-Phos No. 2
  • Phos-NaK
  • Phospha 250 Neutral
  • Virt-Phos 250 Neutral

Pharmacologic Category

  • Electrolyte Supplement, Oral

Pharmacology

See individual agents.

Absorption

1% to 20%

Excretion

Oral forms excreted in feces

Onset of Action

Catharsis: Oral: 3 to 6 hours

Use: Labeled Indications

Phosphate supplement: As a phosphorus supplement

Urinary acidification: To increase urinary phosphate and pyrophosphate

K-Phos No. 2: Urinary acidifier for patients with elevated urinary pH to help keep calcium soluble and reduce odor and rash caused by ammoniacal urine; increases the antibacterial activity of methenamine.

Contraindications

Hyperphosphatemia; infected urinary phosphate stones; severe renal impairment (<30% of normal)

Dosing: Adult

Note: Dosage expressed in terms of elemental phosphorus.

Phosphate supplement: Oral: 250 to 500 mg 4 times daily

Urinary acidification (K-Phos No. 2): Oral: 250 mg 4 times daily; may be increased to 250 mg every 2 hours when the urine is difficult to acidify (maximum: 2,000 mg/day)

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Phosphate supplement: Note: Dosage expressed in terms of elemental phosphorus: Children ≥4 years and Adolescents: Oral: 250 mg 4 times daily

Dosing: Renal Impairment

There are no dosage adjustment provided in the manufacturer’s labeling. Use with caution. Contraindicated in patients with severe impairment (<30% of normal function).

Dosing: Hepatic Impairment

There are no dosage adjustments provided in the manufacturer’s labeling. Use with caution.

Reconstitution

Oral powder: Mix 1 packet in 75 mL water or juice; stir well and administer promptly. Proper dilution may help prevent GI injury associated with concentrated oral potassium preparations.

Administration

Administer with a full glass of water at mealtime and at bedtime.

Oral powder: Must be diluted in water or juice prior to administration.

Dietary Considerations

Take with meals. In addition to phosphate, products contain potassium and sodium.

Storage

Oral powder: Store at room temperature; protect from moisture.

Tablets: Store at 20°C to 25°C (68°F to 77°F). Protect from light and moisture. Contact of Virt-Phos with moisture may produce surface discoloration or erosion.

Drug Interactions

ACE Inhibitors: Potassium Salts may enhance the hyperkalemic effect of ACE Inhibitors. Monitor therapy

Aliskiren: Potassium Salts may enhance the hyperkalemic effect of Aliskiren. Monitor therapy

Angiotensin II Receptor Blockers: Potassium Salts may enhance the hyperkalemic effect of Angiotensin II Receptor Blockers. Monitor therapy

Antacids: May decrease the absorption of Phosphate Supplements. Management: This applies only to oral phosphate administration. Separating administer of oral phosphate supplements from antacid administration by as long as possible may minimize the interaction. Consider therapy modification

Calcium Salts: May decrease the absorption of Phosphate Supplements. Management: This applies only to oral phosphate and calcium administration. Administering oral phosphate supplements as far apart from the administration of an oral calcium salt as possible may be able to minimize the significance of the interaction. Consider therapy modification

Eplerenone: May enhance the hyperkalemic effect of Potassium Salts. Management: This combination is contraindicated in patients receiving eplerenone for treatment of hypertension. Consider therapy modification

Heparin: May enhance the hyperkalemic effect of Potassium Salts. Monitor therapy

Heparin (Low Molecular Weight): May enhance the hyperkalemic effect of Potassium Salts. Monitor therapy

Iron Salts: May decrease the absorption of Phosphate Supplements. Management: This applies only to oral phosphate and iron administration. Administer oral phosphate supplements at least 1 hour before, or 2 hours after, oral iron salt administration. Exceptions: Ferric Carboxymaltose; Ferric Gluconate; Ferric Hydroxide Polymaltose Complex; Ferric Pyrophosphate Citrate; Ferumoxytol; Iron Dextran Complex; Iron Sucrose. Consider therapy modification

Magnesium Salts: May decrease the serum concentration of Phosphate Supplements. Management: This applies only to oral phosphate and magnesium administration. Administer oral phosphate supplements at least 1 hour before, or 2 hours after, oral magnesium salt administration. Consider therapy modification

Multivitamins/Minerals (with ADEK, Folate, Iron): May decrease the serum concentration of Phosphate Supplements. Management: This applies only to oral phosphate and multivitamin administration. Administer oral phosphate supplements at least 1 hour before, or 2 hours after, administration of an iron-containing multivitamin. Consider therapy modification

Nicorandil: May enhance the hyperkalemic effect of Potassium Salts. Monitor therapy

Potassium-Sparing Diuretics: Potassium Salts may enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Consider therapy modification

Sucralfate: May decrease the absorption of Phosphate Supplements. Management: This applies only to oral phosphate administration. Administering oral phosphate supplements at least 1 hour before or 2 hours after administration of sucralfate may reduce the significance of the interaction. Consider therapy modification

Adverse Reactions

Frequency not defined.

Cardiovascular: Bradycardia, cardiac arrhythmia, chest pain, edema, lower extremity edema, tachycardia

Central nervous system: Confusion, dizziness, fatigue, headache, paresthesia, seizure, tetany (with large doses of phosphate)

Endocrine & metabolic: Alkalosis, hyperkalemia, weight gain

Gastrointestinal: Diarrhea, flatulence, nausea, sore throat, stomach pain, vomiting

Genitourinary: Decreased urine output

Neuromuscular & skeletal: Arthralgia, limb pain, muscle cramps, ostealgia, paralysis, weakness

Renal: Acute renal failure

Respiratory: Dyspnea

Miscellaneous: Increased thirst

Warnings/Precautions

Concerns related to adverse effects:

• Laxative effect: A mild laxative effect may occur within the first few days of therapy; if the laxative effect persists, reduce the dose or discontinue use until diarrhea improves.

Disease-related concerns:

• Adrenal insufficiency: Use with caution in patients with severe adrenal insufficiency (eg, Addison disease)

• Cardiac disease: Use with caution in patients with cardiac disease, including heart failure (especially patients receiving digoxin) and hypertension.

• Dehydration: Use with caution in patients with acute dehydration.

• Edema: Use with caution in patients with peripheral or pulmonary edema.

• Hepatic impairment: Use with caution in patients with cirrhosis or severe hepatic impairment.

• Hypernatremia: Use with caution in patients with hypernatremia.

• Myotonia congenita: Use with caution in patients with myotonia congenita.

• Pancreatitis: Use with caution in patients with acute pancreatitis.

• Parathyroid disease: Use with caution in patients with hypoparathyroidism.

• Preeclampsia: Use with caution in pregnant patients with preeclampsia of pregnancy.

• Renal calculi: Patients with renal calculi may pass preformed stones when phosphate therapy is initiated.

• Renal impairment: Use with caution in patients with renal impairment or chronic renal disease; use is contraindicated in patient with severe renal impairment (<30% of normal).

• Rickets: Use with caution in patients with rickets; may increase the risk of extraskeletal calcification.

• Tissue breakdown: Use with caution in patients with extensive tissue breakdown (eg, severe burns).

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Monitoring Parameters

Serum potassium, sodium, calcium, phosphorus, magnesium (to facilitate potassium repletion), and renal function at periodic intervals

Pregnancy Risk Factor

C

Pregnancy Considerations

Animal reproduction studies have not been conducted with this combination. See individual agents.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience diarrhea, abdominal pain, vomiting, or nausea. Have patient report immediately to prescriber signs of high potassium (abnormal heartbeat, confusion, dizziness, passing out, weakness, shortness of breath, numbness or tingling feeling), tachycardia, weakness, severe diarrhea, severe headache, muscle cramps, seizures, shortness of breath, excessive weight gain, swelling of arms or legs, severe loss of strength and energy, bone pain, joint pain, urinary retention, or increased thirst (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

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