Core pharmacology

Class Group

Electrolytes and Buffers

Legacy Cicm Level

Level 1

Indications Uses

1. for the correction of profound metabolic acidosis, especially that complicating cardiac arrest
2. for the alkalinization of urine and
3. as an antacid

Chemical Pharmaceutics

inorganic salt

Presentation

300mg tablets.
Clear, colourless sterile solution: 1.26/4.2/9.4% w/v NaHCO3 in aqueous solution
8.4% solution contains 1mmol/ml of sodium and bicarbonate ions, osmolarity of 2000mOsm/L

Mechanism of action

Freely dissociates to HCO3- ions (main extracellular buffer)
1gm NaHCO3 will neutralize 12mEq of H+ ions

Physiological effects

CVS: Overcorrection → Metabolic Alkalosis → Myocardial dysfunction and hypoxia due to left shift of O2 dissociation curve
RS: Alkalosis reduces pulmonary ventilation
CNS: excitability →nervousness, convulsions, muscle weakness, tetany
AS: Oral – release of CO2 → belching
Metabolic: ↑Na, ↑K, ↓Ca

Adverse Effects Toxicity

Hypernatremia, Hyperosmolar syndromes
Irritant to tissues when extravasated → skin necrosis and sloughing

Absorption

Data incomplete

Metabolism

React with H+ to yield CO2 and water

Excretion

Renal excretion of bicarbonate and exhalation of CO2

Route And Dose

Antacid: 600-1800mg as required
Alkalinization: 3g PO Q2hrly till urine pH 7
IV:
Dose (mmol) = [base deficit (mEg/l) x body weight (kg)] / 3
Half dose administered and reassess acid-base status