Mechanism of Action of Calcium Gluconate
Calcium gluconate works by dissociating into ionized calcium and gluconate in plasma, directly increasing serum ionized calcium levels without requiring hepatic metabolism. 1, 2
Primary Mechanism
- Intravenous administration of calcium gluconate increases serum ionized calcium concentration through direct dissociation in plasma. 1, 2
- The release of ionized calcium from calcium gluconate is immediate and does not require first-pass hepatic metabolism, making it equally effective as calcium chloride even in the complete absence of liver function. 3
- Both ionized calcium and gluconate are normal physiologic constituents of body fluids. 1, 2
Pharmacologic Properties
- Calcium gluconate is 100% bioavailable following intravenous injection. 1, 2
- Each mL of 10% calcium gluconate solution contains 9.3 mg (0.465 mEq) of elemental calcium. 1, 2
- The calcium itself does not undergo direct metabolism; it functions immediately upon dissociation. 1, 2
Distribution and Physiologic Role
- Once released, ionized calcium represents the biologically active form, comprising approximately 50% of total serum calcium. 1, 2
- Calcium distributes primarily to the skeleton (99% of total body calcium), with only 1% distributed within extracellular fluids and soft tissues. 1, 2
- The remaining serum calcium is either protein-bound (primarily to albumin, ~40%) or bound to organic and inorganic acids (8-10%). 1, 2
Functional Effects
- Ionized calcium is essential for multiple critical physiologic processes including nerve conduction, muscle contraction, blood coagulation, and skeletal mineralization. 4
- Calcium plays a vital role in signal transduction pathways throughout the body. 4
Elimination
- Urinary calcium excretion increases significantly following intravenous calcium gluconate administration, representing the primary elimination pathway. 1, 2
Clinical Advantage Over Calcium Chloride
- While calcium chloride provides more rapid increases in ionized calcium during cardiac arrest situations, calcium gluconate demonstrates equally rapid and effective increases in ionized calcium in other clinical scenarios, including complete absence of hepatic function. 3
- This makes calcium gluconate a reliable option across diverse clinical conditions without concern for hepatic metabolism requirements. 3