Electrolyte · Hyperkalemia treatment · Antidote
Calcium chloride
Indications
- Acute symptomatic hypocalcemia, including citrate effects in massive transfusion
- Low ionized calcium after cardiopulmonary bypass, often given to support contractility
- Hyperkalemia with ECG changes in arrest or peri-arrest (off-label)
- Calcium channel blocker or beta-blocker poisoning (off-label)
- Magnesium toxicity (off-label)
Dosing
| Where | Dose |
|---|---|
| Cardiac arrest | Calcium chloride: 1 g (10 mL of 10%) for hyperkalemia or calcium channel blocker overdose |
| Metabolic and electrolyte boluses | Calcium gluconate: 1–3 g IV over 2–5 min (stabilizes; repeat if ECG changes persist) |
| Metabolic and electrolyte boluses | Calcium chloride: 1 g via central line (three times the elemental calcium) |
| Unit conversions | Calcium (total): mg/dL ÷ 4 = mmol/L; ionized 1.1–1.3 mmol/L = 4.4–5.2 mg/dL |
| Unit conversions | Calcium gluconate 10%: 1 g = 4.65 mEq (93 mg) elemental calcium |
| Unit conversions | Calcium chloride 10%: 1 g = 13.6 mEq (272 mg) elemental calcium |
Mechanism of action
Calcium chloride is fully ionized, so ionized Ca²⁺ rises at once, and per gram it carries three times the calcium of gluconate. Ca²⁺ entering heart and vascular muscle through L-type channels triggers calcium release from the sarcoplasmic reticulum and contraction, so raising extracellular Ca²⁺ supports contractility and tone when calcium is low or the channels are blocked. Higher extracellular Ca²⁺ also raises the threshold potential, restoring conduction in hyperkalemia without lowering potassium.
Pharmacology
- Cardiovascular: raises contractility and BP when ionized calcium is low (bypass, transfusion, CCB poisoning); with normal levels any gain is small and brief
- Cardiovascular: injection faster than 1 mL/min causes hypotension, bradycardia and cardiac syncope (label)
- Neuromuscular: ends tetany and laryngospasm and antagonizes magnesium
- Metabolic: each gram adds 13.6 mEq of chloride; repeated doses cause hyperchloremic acidosis
Pharmacokinetics
| Onset | Immediate; hyperkalemic ECG changes improve within 1–3 min |
|---|---|
| Duration | 30–60 min of membrane protection; ionized calcium starts falling again within 10 min of a bolus (Martin 1990), so CCB poisoning needs repeat doses or an infusion |
| Distribution | 99% of body calcium is in bone; serum calcium is about 50% ionized, 40% albumin-bound and 8–10% complexed (label) |
| Metabolism | None; it needs no liver, and gluconate matched it in anhepatic patients (Martin 1990) |
| Elimination | Calcium by glomerular filtration with tubular reabsorption (label); chloride by the kidney |
| Equivalence | 10 mL of 10% chloride (6.8 mmol) ≈ 30 mL of 10% gluconate |
Chemistry
- Calcium chloride dihydrate (CaCl₂·2H₂O, MW 147.0), an inorganic salt that dissociates completely, so pKa, lipid solubility and stereochemistry do not apply
- 10% is 100 mg/mL: 27 mg (1.4 mEq) of elemental calcium per mL, so 1 g gives about 272 mg (13.6 mEq), three times gluconate (label)
- 2,040 mOsm/L (label), about seven times plasma; pH 5.5–7.5; no preservative; up to 1,000 mcg/L of aluminum
- Very soluble, so it does not crystallize like gluconate, but it precipitates with bicarbonate (as calcium carbonate), phosphate and ceftriaxone
Adverse effects and cautions
In the one-pagers
- Electrolyte ImbalancesHyperkalemia: stabilize, shift, remove: Stabilize (ECG changes): calcium gluconate 10% 30 mL over 10 min; in arrest or peri-arrest, calcium chloride 10% 10 mL over 5 min (same calcium). Acts in about 3 min, lasts 30–60 min; repeat if changes persist.
- Blood Products and TransfusionMassive transfusion and viscoelastic testing: The European trauma guideline (2023) targets systolic pressure 80–90 mmHg (MAP 50–60) until bleeding is controlled, or MAP 80 or more with severe TBI. It gives 3–4 g of fibrinogen (15–20 single cryo units or concentrate) when fibrinogen is 150 mg/dL or less or viscoelastic tests show a deficit, keeps platelets above 50,000 (100,000 with TBI) and ionize
- CRRT (Continuous Renal Replacement)Anticoagulation: citrate, heparin, none: Citrate is regional: infused pre-filter (the pre-blood pump line on Prismaflex) at about 3–4 mmol per liter of blood flow, it chelates ionized calcium below the 0.35 mmol/L clotting needs. Prismocitrate 18/0 (18 mmol/L) at 1,500–2,500 mL/h suits blood flows of 100–150 mL/min; 4% trisodium citrate (136 mmol/L) and ACD-A (about 113 mmol/L) need far less volum
- Pediatric Assessment and EmergenciesPALS: arrest, bradycardia, tachycardia and IO access: Calcium chloride 10%: 20 mg/kg (0.2 mL/kg): low Ca²⁺, high K⁺, CCB toxicity
- Toxidromes and AntidotesCardiotoxic drugs: Calcium channel blockers: Calcium chloride 2 g or gluconate 6 g IV: Chloride: central line preferred
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Sources
- FDA label: Calcium Chloride 10% (Hospira, 2026)
- Martin 1990 (calcium salts without a liver)
- AHA 2025 Guidelines, Part 10 (special circumstances)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.