Potassium Chloride (IV)

How it works

It replaces the potassium ion, the principal intracellular cation essential for resting membrane potential, neuromuscular conduction and cardiac rhythm, correcting the consequences of potassium depletion.

Prescribing in practice

• Concentrated potassium chloride is a high-risk medicine that must always be diluted and given as a controlled-rate infusion, never as a bolus or rapid push, because inadvertent rapid administration can cause fatal cardiac arrest.
• Use ready-diluted preparations where possible and infuse faster or more concentrated solutions only with continuous cardiac monitoring, ideally via a central line for stronger concentrations.
• Caution is required in renal impairment and when co-prescribed with potassium-retaining drugs such as ACE inhibitors, ARBs and potassium-sparing diuretics, given the risk of hyperkalaemia.

Monitoring

Monitor serum potassium and renal function regularly, with ECG/cardiac monitoring during higher-rate or more concentrated infusions.

Counselling the patient

• This is a potassium replacement given slowly through a drip to correct a low blood level.
• It is always diluted and never given quickly because of the risk to the heart.
• Pain or stinging at the drip site should be reported, as the solution can irritate the vein.

Evidence & guidelines

Concentrated potassium chloride is recognised as a high-alert medicine, and UK patient-safety guidance (NPSA) mandates restricted storage and controlled dilution and infusion to prevent fatal medication errors.