WikiTox

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== Sodium Bicarbonate (Treatment) ======

===== - Overview =====
Sodium bicarbonate (NaHCO₃) is primarily used in toxicology to treat sodium channel blocker toxicity (e.g. TCA toxicity). 

The patient should then be [[concept_serum_alkalinization|hyperventilated]].



===== - Toxicologic Indications & Dosing =====

==== - QRS Widening Secondary to Fast Sodium Channel Blockade ====

  * Also see: Tricyclic antidepressants, bupropion, propranolol, flecainide, local anesthetic agents.
  * **Adult:**
    * 💊 **Sodium bicarbonate 1-2 mmol/kg IV** (i.e. 1-2 mL/kg of 8.4% NaHCO3), q2min.
  * **Child:**
    * 💊👶 **Sodium bicarbonate 1-2 mmol/kg IV** (i.e. 1-2 mL/kg of 8.4% NaHCO3), q2min.
  * Repeat boluses until signs of cardiotoxicity (QRS widening, wide complex dysrhythmias) improve.
  * Do not exceed serum pH 7.55, Na⁺ 155 mmol/L.


==== - Salicylate Toxicity  ====
  * Also see: Salicylate toxicity.
  * Alkalinization therapy in salicylate toxicity works by ↓ CNS redistribution of salicylates (alters drug distribution), and enhances urinary elimination (ion trapping).
  * **Adult:**
    * 💊 **Sodium bicarbonate 1-2 mmol/kg IV** (i.e. 1-2 mL/kg of 8.4% NaHCO3), as initial dose, then start infusion.
    * 💊 **Sodium bicarbonate 25 mmol/hr IV infusion**.
      * e.g. 150 mmol of Sodium bicarbonate in 850 mL 5% dextrose, at 250 mL/hr.
  * **Child:**
    * 💊👶 **Sodium bicarbonate 1-2 mmol/kg IV** (i.e. 1-2 mL/kg of 8.4% NaHCO3), as initial dose, then start infusion.
    * 💊👶 **Sodium bicarbonate 1.5-2× patient's hourly maintenance fluid requirement (weight-based) IV infusion**, then titrate to goal pH.
  * Goals:
    * Serum pH 7.5-7.55.
    * Urinary pH >7.5.
    * Urine output 2-3 mL/kg/hr.
    * Maintain normokalemia.




===== - Cautions & Contraindications =====

  * Metabolic or respiratory alkalosis - do not exceed pH 7.55.
  * Severe hypernatremia - do not exceed Na⁺ 155 mmol/L.
  * Hypokalemia.
  * Acute pulmonary edema.


===== - Special Populations =====

**Renal impairment:** Use with caution in patients with severe renal impairment due to the risk of fluid overload and hypernatremia.


===== - Adverse Effects =====
  * **Renal:** fluid overload, acute pulmonary edema.
  * **Metabolic:** metabolic alkalosis, hypernatremia, hypokalemia, hyperosmolarity.
  * **Skin:** local phlebitis, cellulitis, extravasation injury.



===== - Pharmacology =====

==== - Pharmacodynamics ====
**Mechanism of action:** Hypertonic sodium bicarbonate (e.g. 8.4%) ameliorates toxicity by multiple mechanisms, including ↑ extracellular sodium concentration, ↑ plasma bicarbonate concentration, ↑ serum pH, and ↑ urinary pH. 


==== - Pharmacokinetics ====
The pharmacokinetics of sodium bicarbonate are challenging to measure, as the bicarbonate component rapidly buffers H⁺ ions and is converted into CO₂.

**Absorption:**
  * Oral bioavailability: good oral bioavailability if ingested.

**Distribution:**
  * Vd: 0.2-0.4 L/kg.

**Metabolism:**
  * Reacts with H⁺ to form H₂O and CO₂.
  * Bicarbonate contributes to 80% of extracellular buffering capacity.

**Excretion:**
  * CO₂ is exhaled.
  * Bicarbonate and Na⁺ is excreted renally.


==== - Pharmaceutics ====
**Formulation:**  Sodium bicarbonate 8.4% vials/ampoules contain 1 mmol/mL of sodium bicarbonate solution.


===== - References =====
Useful general references:

~~REFNOTES~~