Calcium repletion / membrane stabilization

Restores ionized calcium; raises the cardiac threshold against hyperkalemia

Ca²⁺ re-steepens the myocyte depolarization threshold hyperkalemia has flattened — works in minutes, moves no potassium
Also the antidote scaffold for CCB overdose and hypocalcemic tetany
➔ calcium gluconate — peripheral-line safe; 3 g ≈ 1 g CaCl₂ elemental
➔ calcium chloride — 3× the elemental calcium; central line (extravasation necrosis)
⚠ Digoxin toxicity caution ("stone heart") is traditional teaching, weakly evidenced

Drugs with this mechanism (2)

Calcium chloride — Concentrated IV calcium for severe hypocalcemia, hyperkalemia, and calcium-channel blocker toxicity.
Calcium gluconate — Calcium replacement and cardiac membrane stabilizer; safer peripherally than calcium chloride.

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