What is the treatment with sodium bicarbonate dose for Tricyclic Antidepressant (TCA) overdose?

From the Guidelines

For tricyclic antidepressant (TCA) overdose, the treatment with sodium bicarbonate dose is an initial bolus of 1-2 mEq/kg intravenously, with the goal of achieving and maintaining a serum pH of 7.50-7.55, as recommended by the 2023 American Heart Association guidelines 1. The administration of hypertonic sodium bicarbonate solution is supported by human observational studies and animal experiments, and has been systematically reviewed 1. Although dose-finding studies are not available, an initial dose of 1 to 2 mEq/kg (1–2 mL/kg of 1 mEq/mL [8.4%]) sodium bicarbonate, repeated as needed to achieve clinical stability while avoiding extreme hypernatremia or alkalemia, has historically been recommended and appears effective 1. Some key points to consider when treating TCA overdose with sodium bicarbonate include:

• Monitoring the patient's ECG, particularly QRS duration, as well as blood pressure, serum pH, and electrolytes, especially potassium, as alkalinization can cause hypokalemia 1
• Avoiding extremes of hypernatremia (serum sodium not to exceed 150–155 mEq/L) and alkalemia (serum pH not to exceed 7.50–7.55) to avoid iatrogenic harm 1
• Considering the use of hypertonic saline to increase serum sodium separately, and adjusting minute ventilation in intubated patients to control pH 1
• Continuing bicarbonate therapy until cardiovascular stability is achieved and ECG abnormalities resolve 1

From the FDA Drug Label

In cardiac arrest, a rapid intravenous dose of one to two 50 mL vials (44.6 to 100 mEq) may be given initially and continued at a rate of 50 mL (44. 6 to 50 mEq) every 5 to 10 minutes if necessary In less urgent forms of metabolic acidosis, Sodium Bicarbonate Injection, USP may be added to other intravenous fluids, The amount of bicarbonate to be given to older children and adults over a four-to-eight- hour period is approximately 2 to 5 mEq/kg of body weight Sodium bicarbonate is further indicated in the treatment of certain drug intoxications, including barbiturates

The treatment with sodium bicarbonate dose for Tricyclic Antidepressant (TCA) overdose is not explicitly stated in the provided drug labels. However, based on the information provided for the treatment of metabolic acidosis and drug intoxications, the dose of sodium bicarbonate can be estimated as follows:

• Initial dose: 1 to 2 50 mL vials (44.6 to 100 mEq) in cardiac arrest
• Maintenance dose: 50 mL (44.6 to 50 mEq) every 5 to 10 minutes if necessary
• Less urgent forms: 2 to 5 mEq/kg of body weight over a period of 4 to 8 hours 2 It is essential to note that the provided drug labels do not directly address the treatment of TCA overdose with sodium bicarbonate. Therefore, the above information should be used with caution and under the guidance of a qualified healthcare professional. 2

From the Research

Treatment with Sodium Bicarbonate for TCA Overdose

• The administration of intravenous sodium bicarbonate is recommended to achieve a systemic pH of 7.5-7.55 in patients with moderate to severe tricyclic antidepressant poisoning 3.
• Sodium bicarbonate should be administered after initial management of hypotension with colloid or crystalloid solutions, guided by central venous pressure monitoring 3.
• The suggested dosage of sodium bicarbonate is 1 to 2 mEq/kg, repeated as needed, if the QRS duration is more than 100 ms or the terminal right-axis deviation is more than 120 degrees 4.
• Administration of sodium bicarbonate may resolve arrhythmias even in the absence of acidosis, and conventional antiarrhythmic drugs should only be used if this therapy fails 3.

Mechanism of Action

• Experimental studies suggest that both alkalinisation and sodium loading are effective in reducing cardiotoxicity independently 3.
• Sodium bicarbonate appears to work by sodium loading in some studies and by a pH change in others 3.
• The efficacy and mechanism of action of sodium bicarbonate in the treatment of desipramine toxicity in rats have been studied, and it was found that NaHCO3 and NaCl were equally effective in decreasing QRS duration and increasing mean arterial blood pressure 5.

Clinical Evidence

• Clinical studies suggest benefit from norepinephrine and dopamine in the management of tricyclic antidepressant poisoning, while class 1a and 1c antiarrhythmic drugs should be avoided 3.
• Extracorporeal detoxification with sorbents has been used in treatment of patients with very high drug levels and declining clinical condition, and has shown dramatic clinical improvement 6.
• Tricyclic antidepressant poisoning causes predictable electrocardiographic abnormalities and can be lethal, and sodium bicarbonate is still considered the treatment of choice for severe toxicity 4.