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Urinary Alkaliniser Pregnancy: UK SPC §4.6 verbatim, in full: 'There is no, or inadequate epidemiological evidence of safety of the ingredients of Cystopurin sachets in human pregnancy but they have been in wide use for many years without apparent ill consequence. If drug therapy is needed in pregnancy, this drug can be used if there is no safer alternative. However, pregnant women should be advised to seek medical advice on the treatment of cystitis rather than using OTC medicines.' No breast-feeding or fertility statement was present in the fetched §4.6 text.

Potassium Citrate

Brand names: Cymex, Potassium Citrate Mixture BPC

Potassium citrate is an oral urinary alkalinising agent used to relieve the discomfort of mild urinary tract infections and, in some settings, to reduce the risk of recurrent uric acid and certain calcium stone formation.

Adult dose

Dose: One 3 g sachet, dissolved in 200 mL of cold water. §4.2 verbatim: 'Adults: One 3g sachet, dissolved in 200mls of cold water, three times daily for two days. All six sachets must be taken to complete the treatment.' Elderly — §4.2 verbatim: 'Elderly As adults.' The 3 g strength is pinned by the product name and by §4.2 itself.
Route: Oral, dissolved in water. §4.2 verbatim: 'Orally: Dissolved in water.'
Frequency: Three times daily for two days — a six-sachet course. §4.2: 'three times daily for two days. All six sachets must be taken to complete the treatment.' §4.4: 'Intended for short term treatment.'
INDICATION: urinary alkalinisation for the symptomatic relief of cystitis — this page's primary indication (category 'Urinary Alkaliniser'). The SPC confirms the indication indirectly at §4.4 ('Patients should seek doctor's advice if symptoms persist after 48 hours treatment') and at §4.6 ('pregnant women should be advised to seek medical advice on the treatment of cystitis rather than using OTC medicines'). || maxDose is left blank deliberately: the SPC states no ceiling. 'All six sachets must be taken to complete the treatment' is a course TOTAL framed as a minimum requirement, not a maximum, so it is not reproduced as a cap. The only ceiling-like figure in the bundle — the US label's 'Doses of potassium citrate extended-release tablets greater than 100 mEq/day have not been studied and should be avoided' — belongs to a different product AND a different indication and must not be used as this dose's cap. || ⚠️ FORMULATION SCOPE: the fetched UK SPC covers the 3 g GRANULE SACHET only. The page's other listed brand, 'Cymex', is also unsourced here. || EXCIPIENT WARNINGS (§4.4 verbatim): 'This product also contains aspartame, a source of phenylalanine. This may be harmful to people with phenylketonuria. This medicine contains less than 1mmol sodium (23 mg) per sachet, that is to say essentially 'sodium-free'.' || ADMINISTRATION TIP (§4.8 verbatim): 'Potassium salts may give rise to gastric irritation, the effects of which may be minimised by diluting sachet contents well with water. Doses may also be given with or after meals.' || US CROSS-CHECK ONLY, NOT THIS PAGE'S DOSE (openFDA §2.2, potassium citrate EXTENDED-RELEASE TABLETS for severe hypocitraturia — a stone-prevention indication this page does not cover): 'In patients with severe hypocitraturia (urinary citrate 150 mg/day) therapy should be initiated at 30 mEq/day (15 mEq two times/day or 10 mEq three times/day with meals or within 30 minutes after meals or bedtime snack).' US strengths: 'Tablets: 5 mEq, 10 mEq and 15 mEq'.

Paediatric dose

Route: Oral, dissolved in water — as for adults.
Frequency: As for adults in children over six years of age: three times daily for two days.
dosePerKg is null because the SPC gives NO weight-based paediatric dose — it gives an age rule only. §4.2 verbatim, in full: 'Children Not recommended for children under six years of age. For children over six years of age use adult dosage.' So a child over six takes the adult regimen: one 3 g sachet in 200 mL of cold water, three times daily for two days (six sachets in total). concentration is null because the product is a granule sachet, not a liquid — the bundle states no mg/mL, and the 3 g-in-200 mL reconstitution is a dilution instruction, not a labelled concentration; deriving one would be an unsourced calculation. || Verify all under-18 dosing against a children's formulary.

Dose adjustments

Renal

No numeric dose adjustment is given. UK SPC §4.3 verbatim: 'There are no specific contraindications but use with caution in patients with impaired renal function or cardiac disease.' ⚠️ The US label for potassium citrate extended-release tablets is considerably more restrictive and is recorded here as a labelled cross-check: §5.1 verbatim: 'In patients with impaired mechanisms for excreting potassium, potassium citrate administration can produce hyperkalemia and cardiac arrest. Potentially fatal hyperkalemia can develop rapidly and be asymptomatic. The use of potassium citrate in patients with chronic renal failure, or any other condition which impairs potassium excretion such as severe myocardial damage or heart failure, should be avoided. Closely monitor for signs of hyperkalemia with periodic blood tests and ECGs.' The US §4 contraindication for renal insufficiency is cut off mid-sentence at the source-fetch limit ('In patients with renal insufficiency (glomerular filtration rate of less …'), so its GFR threshold was NOT retrieved — take it from the full label.

Hepatic

Not stated. Neither the UK SPC sections nor the US label sections in this bundle contains a hepatic impairment statement or a hepatic dose adjustment.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • UK SPC §4.3 verbatim, in full: 'There are no specific contraindications but use with caution in patients with impaired renal function or cardiac disease.'
  • UK SPC §4.4 verbatim: 'This product also contains aspartame, a source of phenylalanine. This may be harmful to people with phenylketonuria.'
  • US LABEL CROSS-CHECK ONLY (potassium citrate EXTENDED-RELEASE TABLETS — a different product and indication from the UK sachet dosed above), §4 verbatim: contraindicated 'In patients with hyperkalemia (or who have conditions predisposing them to hyperkalemia), as a further rise in serum potassium concentration may produce cardiac arrest. Such conditions include: chronic renal failure, uncontrolled diabetes mellitus, acute dehydration, strenuous physical exercise in unconditioned individuals, adrenal insufficiency, extensive tissue breakdown or the administration of a potassium-sparing agent (such as triamterene, spironolactone or amiloride).'
  • US LABEL CROSS-CHECK ONLY, §4 verbatim: contraindicated 'In patients in whom there is cause for arrest or delay in tablet passage through the gastrointestinal tract, such as those suffering from delayed gastric emptying, esophageal compression, intestinal obstruction or stricture, or those taking anticholinergic medication.'
  • US LABEL CROSS-CHECK ONLY, §4 verbatim: contraindicated 'In patients with peptic ulcer disease because of its ulcerogenic potential.'
  • US LABEL CROSS-CHECK ONLY, §4 verbatim: contraindicated 'In patients with active urinary tract infection (with either urea-splitting or other organisms, in association with either calcium or struvite stones). The ability of potassium citrate extended-release tablets to increase urinary citrate may be attenuated by bacterial enzymatic degradation of citrate. Moreover, the rise in urinary pH resulting from potassium citrate therapy might promote further bacterial growth.'
  • ⚠️ The US §4 list is TRUNCATED at the source-fetch limit part-way through the renal-insufficiency entry — further contraindications beyond that point were NOT retrieved.

Side effects

  • UK SPC §4.8 verbatim: 'Some patients may experience mild diuresis.'
  • UK SPC §4.8 verbatim: 'Potassium salts may give rise to gastric irritation, the effects of which may be minimised by diluting sachet contents well with water. Doses may also be given with or after meals.'
  • US label cross-check, §6.1 verbatim: 'Some patients may develop minor gastrointestinal complaints during potassium citrate therapy, such as abdominal discomfort, vomiting, diarrhea, loose bowel movements or nausea. These symptoms are due to the irritation of the gastrointestinal tract, and may be alleviated by taking the dose with meals or snacks, or by reducing the dosage.'
  • US label cross-check (extended-release tablet only), §6.1 verbatim: 'Patients may find intact matrices in their feces.'
  • US label cross-check, §5.1 verbatim: potassium citrate 'can produce hyperkalemia and cardiac arrest. Potentially fatal hyperkalemia can develop rapidly and be asymptomatic' in patients with impaired potassium excretion.
  • US label cross-check, §5.2 (Gastrointestinal Lesions) verbatim: 'if there is severe vomiting, abdominal pain or gastrointestinal bleeding, potassium citrate should be discontinued immediately and the possibility of bowel perforation or obstruction investigated'.
  • This side-effect list may be incomplete — check the full SPC.

Monitoring

  • Reassess if symptoms do not settle — UK SPC §4.4 verbatim: 'Intended for short term treatment. Patients should seek doctor's advice if symptoms persist after 48 hours treatment.'
  • Serum potassium where hyperkalaemia is a risk — UK SPC §4.5 verbatim: 'Concurrent administration of the following drugs may lead to hyperkalaemia: potassium sparing diuretics, ACE inhibitors, aliskiren, angiotensin-II receptor antagonists, ciclosporin and tacrolimus.'
  • Serum potassium where a cardiac glycoside is co-prescribed — UK SPC §4.5 verbatim: 'The activity of cardiac glycosides is to some extent dependent upon serum potassium levels. Therefore, there is a possible interaction and caution is advised.'
  • US label cross-check (long-term extended-release tablet therapy for hypocitraturia, NOT the short OTC course dosed above), §2.1 verbatim: 'Monitor serum electrolytes (sodium, potassium, chloride and carbon dioxide), serum creatinine and complete blood counts every four months and more frequently in patients with cardiac disease, renal disease or acidosis. Perform electrocardiograms periodically. Treatment should be discontinued if there is hyperkalemia, a significant rise in serum creatinine or a significant fall in blood hematocrit or hemoglobin.'
  • US label cross-check (stone-prevention indication only), §2.2 verbatim: 'Twenty-four hour urinary citrate and/or urinary pH measurements should be used to determine the adequacy of the initial dosage and to evaluate the effectiveness of any dosage change.'

Clinical monograph

How it works

It is metabolised to bicarbonate, which raises urinary pH, increasing the solubility of uric acid and cystine and reducing the tendency to crystallise; it also provides a potassium load.

Prescribing in practice

  • It is hazardous in renal impairment and in patients taking other agents that raise serum potassium, as it can precipitate dangerous hyperkalaemia.
  • Avoid concurrent use with potassium-sparing diuretics, ACE inhibitors or angiotensin receptor blockers without close electrolyte monitoring.
  • It should be well diluted in water before administration to reduce gastrointestinal irritation.

Monitoring

Monitor serum potassium and renal function, particularly in those with impaired renal function or on interacting medicines.

Counselling the patient

  • Always dilute the medicine well in water before drinking it.
  • Report muscle weakness, palpitations or tingling, which may indicate a high potassium level.

Evidence & guidelines

Urinary alkalinisation is an established adjunct in selected stone disease; see the SPC and current prescribing references for indications and monitoring.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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