Calcium Chloride and Calcium Gluconate both stabilize cardiac myocyte membranes by raising the threshold potential, which becomes unstable in the setting of hyperkalemia. Calcium Chloride has three times the elemental Calcium compared to Calcium Gluconate, thus is more potent, and works quicker. Calcium Chloride is also more caustic and can cause tissue necrosis if it extravasates, thus central line administration is preferred. Calcium Gluconate is slower acting, not as potent, and is not as caustic to the tissues, allowing safer use through a peripheral IV, which makes it more commonly used in the ER. Neither lowers the Potassium level. Both work by stabilizing and raising the firing threshold of cardiac myocytes, thus reducing arrhythmia risk and cardiac excitability.