FPGEE for National Association of Boards of Pharmacy (NABP) Practice Exam

Which treatment is used for TCA toxicity?

1. Activated charcoal

2. Flumazenil

3. Sodium bicarbonate

4. Calcium gluconate

The correct answer is: Sodium bicarbonate

In the management of tricyclic antidepressant (TCA) toxicity, sodium bicarbonate is recognized as a key treatment option. TCAs can cause significant myocardial depression and cardiotoxicity, often leading to arrhythmias, especially in overdose scenarios. Sodium bicarbonate serves multiple roles in this context. First, it helps to correct metabolic acidosis that may occur due to the accumulation of toxic metabolites. More importantly, it can also help to stabilize the cardiac membrane and diminish the effects of sodium channel blockade commonly seen with TCA overdose. The alkalinization of plasma through sodium bicarbonate can counteract the hyperactive state of the heart muscle, potentially preventing life-threatening arrhythmias. While activated charcoal is useful for gastrointestinal decontamination if administered shortly after ingestion, it does not directly address the cardiac and central nervous system effects of TCA toxicity. Flumazenil is a benzodiazepine antagonist but can precipitate seizures in a setting where TCA is involved, as it does not have an antidotal effect on TCAs. Calcium gluconate is typically used for the treatment of calcium channel blocker or magnesium toxicity rather than TCA overdose. Therefore, sodium bicarbonate is specifically indicated due to its effectiveness in mitigating the cardiovascular complications