Generic Name

Potassium chloride

Mechanism

• Direct cation replacement: Increases extracellular plasma K⁺ concentration, thereby restoring the normal electrochemical gradient necessary for:
• Cardiac muscle depolarization (phase 4 of the cardiac action potential).
• Neuromuscular transmission at the neuromuscular junction.
• Modulation of potassium channels: Elevated extracellular K⁺ decreases the resting membrane potential, leading to a reduction in excitability of cardiac and skeletal myocytes.

Pharmacokinetics

• Absorption: Oral tablets dissolve rapidly; peak plasma levels achieved within 1–2 h.
• Distribution: Widely distributed in extracellular fluid; limited binding to plasma proteins.
• Metabolism: Not metabolized; eliminated unchanged.
• Elimination: Renal excretion; half‑life ≈ 15–20 h, highly dependent on glomerular filtration rate (GFR).
• Special considerations:
• In patients with renal impairment, *hypo‑uricemic* alternatives may be preferable; dose adjustments are required.

Indications

• Acute or chronic hypokalemia (e.g., due to diuretics, diarrhoea, renal losses).
• Prevention of potassium depletion in ICU sedation protocols.
• Post‑operative prophylaxis for atrial fibrillation and arrhythmias.
• Treatment of neuromuscular disorders associated with potassium deficiency.

Contraindications

• Hyperkalemia or serum K⁺ > 5.5 mmol/L – risk of life‑threatening arrhythmias.
• Severe renal dysfunction (eGFR < 30 mL/min/1.73 m²) – accumulation risk.
• Advanced heart block, sick sinus syndrome – contraindicated IV administration.
• Use with caution in:
• Hypo‑acidic urine (alkalosis)
• Pregnancy (category C)
• Premixed with solutions containing glucose or glycerol – avoid osmotic incompatibilities.

Dosing

Oral Tablets

Oral Solution
• 20 mEq in 250 mL water, taken 4–6 × daily.

Intravenous Infusion
• Maximum rate: 10–20 mEq per hour.
• Initial bolus: 10–20 mEq in 250 mL 5% dextrose, over 30 min, in patients with acute hypokalemia.
• Rate adjustment: Modulate according to serum K↓↑ and ECG changes.

Intramuscular – rarely used due to local irritation.

Adverse Effects

• Common:
• Irritation of GI mucosa (nausea, vomiting).
• Crystalluria (if IV overdosed).
• Serious:
• Hyperkalemia: muscle weakness, arrhythmias, pseudo‑electrocardiographic changes.
• Exogenous arrythmias: ventricular tachycardia/fibrillation.
• Renal tubular acidosis (in rare IV infusions).

Monitoring

• Serum potassium (every 4 h initially, then daily).
• Serum creatinine & eGFR (baseline; repeat at 48 h if renal function impaired).
• ECG (QT, PR intervals; monitor for arrhythmias).
• Urine output (monitor for oliguria).
• Fluid status (avoid volume overload).

Clinical Pearls

• IV Potassium Chloride should never be administered as a bolus in patients with pre‑existing cardiac conduction defects; a slow infusion is mandatory to prevent sudden arrhythmias.
• Use the “10/20 rule”: 10 mEq/hour is the safety ceiling; 20 mEq/hour only in emergent post‑operative hypokalemia and with continuous ECG monitoring.
• The oral tablet dose of 40 mEq/day is equivalent to 10 mEq/h IV infusion for long‑term maintenance; adjust for renal impairment by 50% if eGFR < 30 mL/min.
• Potassium chloride is often confused with potassium citrate – the former has greater solubility in water and is the standard for IV usage; the latter is preferred for oral long‑term therapy due to better tolerability.
• Always add a small amount of oral acidifying agent (e.g., HCl) to the oral solution when patients have alkaline urine to avoid crystalluria.

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• *For further reading, consult the latest guidelines from the American Heart Association and the U.S. FDA labeling for Potassium Chloride.*