potassium citrate
Urinary alkaliniser· Brands: Urocit-K, Cytra-K, K-Lyte, Polycitra-KPO
Mechanism of action
Potassium citrate is metabolised to bicarbonate, which raises urinary pH and increases citrate excretion. Citrate forms soluble complexes with calcium, reducing the ionised calcium available to bind with oxalate or phosphate, thus decreasing the risk of calcium stone formation. The alkalinising effect also increases the solubility of uric acid.
Pharmacokinetics
Potassium citrate is well absorbed after oral administration. It is extensively metabolised to bicarbonate, which is excreted as carbon dioxide in expired air. The citrate anion is filtered by the glomerulus and excreted in urine, where it contributes to alkalinisation. The onset of urinary alkalinisation is within hours, and the effect persists for several hours after each dose. Excretion is influenced by renal function.
Indications & dosing
Hypocitraturia and prevention of calcium oxalate kidney stones
Dose tailored to urinary citrate and pH. Usually 10-15 mEq (1080-1620 mg) three times daily. Monitor serum potassium and renal function.
- adult · PO: 1080–1620 mg TID · Dose tailored to urinary citrate and pH. Usually 10-15 mEq (1080-1620 mg) three times daily. Monitor serum potassium and renal function.
Uric acid kidney stones (prevention)
Target urine pH 6.5-7.0 to increase uric acid solubility. Avoid if urine pH >7.5 to prevent calcium phosphate stones.
- adult · PO: 1080–1620 mg TID · Target urine pH 6.5-7.0 to increase uric acid solubility. Avoid if urine pH >7.5 to prevent calcium phosphate stones.
Renal tubular acidosis (distal type 1)
Correction of acidosis and reduction of stone formation. Adjust dose based on serum bicarbonate and urinary citrate.
- adult · PO: 1080–1620 mg TID · Correction of acidosis and reduction of stone formation. Adjust dose based on serum bicarbonate and urinary citrate.
Cystinuria (adjunctive treatment)off-label
Used to alkalinize urine to increase cystine solubility. Monitor urine pH and stone recurrence. Evidence limited.
- adult · PO: 1080–1620 mg TID · Used to alkalinize urine to increase cystine solubility. Monitor urine pH and stone recurrence. Evidence limited.
Contraindications & precautions
- Hyperkalaemia · Potassium citrate can worsen hyperkalaemia, which may cause life-threatening cardiac arrhythmias.
- Severe renal impairment · Renal impairment impairs potassium excretion, leading to accumulation and risk of severe hyperkalaemia.
- Active peptic ulcer disease · Oral potassium can irritate the gastrointestinal tract and exacerbate ulceration.
- Concurrent use of potassium-sparing diuretics or other potassium supplements · Additive effect increases the risk of hyperkalaemia; avoid unless under specialist supervision.
- Monitor serum potassium and renal function regularly, especially in the elderly or those on concurrent nephrotoxic drugs.
- Use with caution in patients with cardiac disease, particularly those on digoxin, as hyperkalaemia may exacerbate arrhythmias.
- Avoid concurrent use with ACE inhibitors, angiotensin receptor blockers, or potassium-sparing diuretics unless close monitoring is in place.
- In patients with renal impairment, dose adjustment and more frequent monitoring are required.
- Do not chew potassium citrate tablets; they are designed to dissolve slowly to limit gastrointestinal irritation and proper administration is essential.
Adverse effects
- Hyperkalaemiaserious
- Nausea and vomiting
- Diarrhoea
- Abdominal pain
- Peptic ulceration or gastrointestinal bleedingserious
- Metabolic alkalosisserious
Renal & hepatic adjustment
- eGFR 0–30: Avoid in severe renal impairment (eGFR < 30 mL/min) because of the risk of hyperkalaemia. (avoid)
- eGFR 30–60: Use with caution; monitor serum potassium and renal function.
- eGFR 60+: No dose adjustment required.
Monitoring, pregnancy & toxicity
- Serum potassium · Baseline and periodically during therapy
- Renal function (serum creatinine, eGFR) · Baseline and periodically
- Urine pH · During dose titration
- Serum bicarbonate · In patients with metabolic acidosis
- Signs and symptoms of hyperkalaemia · During therapy
- Pregnancy: Potassium citrate is generally considered safe in pregnancy when used at recommended doses, but data are limited. Use only if clearly needed, particularly in the first trimester and at high doses. Consult a specialist if there is a risk of hyperkalaemia.
- Toxicity: Hyperkalaemia, which may present with muscle weakness, paraesthesia, and cardiac arrhythmias. · Stop the drug; monitor serum potassium and ECG; treat according to standard hyperkalaemia protocols (e.g., calcium gluconate, insulin with glucose, sodium bicarbonate if appropriate).
- Toxicity: Gastrointestinal upset, including nausea, vomiting, diarrhoea, and abdominal discomfort. · Reduce dose or discontinue; provide symptomatic treatment.
Clinical notes
Potassium citrate is used to prevent and treat uric acid and calcium-containing renal stones, and for renal tubular acidosis with metabolic acidosis. It is also used as a potassium supplement. Monitor serum potassium and renal function regularly; avoid in hyperkalaemia, severe renal impairment, active peptic ulcer, or uncontrolled cardiac disease. Doses are titrated to urinary pH and serum potassium. Available as tablets or oral solution; tablets should be swallowed whole with water.
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BNF; local formulary