A child with hyperkalemia receives nebulized salbutamol. Serum potassium falls measurably within 30 minutes. What is the mechanism?
- A Beta-2 stimulation drives potassium into cells via activation of the sodium-potassium ATPase ✓
- B Salbutamol enhances renal tubular potassium secretion directly
- C Salbutamol binds potassium in the circulation and clears it renally unchanged
- D Beta-2 stimulation stabilizes myocardial membrane potential without changing potassium levels
Correct answer: A. Beta-2 stimulation drives potassium into cells via activation of the sodium-potassium ATPase
Explanation
Beta-2 adrenergic agonists increase cyclic AMP, which activates the sodium-potassium ATPase and shifts potassium from extracellular fluid into cells, lowering serum levels within 30 minutes without removing any potassium from the body. Renal excretion is not enhanced acutely, and no binding or clearance of potassium occurs, which is why salbutamol must be paired with definitive elimination measures such as calcium resonium, dialysis, or addressing the underlying cause. Membrane stabilization is the role of calcium salts, not salbutamol.
Reference: Katzung Basic and Clinical Pharmacology, 16th ed.
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