Which antidote is used for tricyclic antidepressant overdose?

Which antidote is used for tricyclic antidepressant overdose?

• A. Naloxone
• B. Flumazenil
• C. Atropine
• D. Sodium Bicarbonate

Answer: (D)

Blockade of cardiac fast sodium channels by tricyclic antidepressants causes dangerous QRS widening and hypotension in overdose. The antidote used to counter this effect is intravenous sodium bicarbonate. Giving bicarbonate serves two key purposes. First, it alkalinizes the blood (target around pH 7.45–7.55), which reduces the drug’s ability to bind to the sodium channels and improves conduction. Second, the extra sodium load helps overcome the channel blockade and supports healthier depolarization of cardiac tissue. This combination often narrows the QRS and stabilizes hemodynamics, addressing the core mechanism of the toxicity. Other agents listed do not reverse the sodium-channel–mediated cardiotoxicity seen with TCAs. Naloxone is for opioid overdose, flumazenil for benzodiazepines, and atropine may only offer limited symptomatic support but does not treat the underlying problem.

Blockade of cardiac fast sodium channels by tricyclic antidepressants causes dangerous QRS widening and hypotension in overdose. The antidote used to counter this effect is intravenous sodium bicarbonate.

Giving bicarbonate serves two key purposes. First, it alkalinizes the blood (target around pH 7.45–7.55), which reduces the drug’s ability to bind to the sodium channels and improves conduction. Second, the extra sodium load helps overcome the channel blockade and supports healthier depolarization of cardiac tissue. This combination often narrows the QRS and stabilizes hemodynamics, addressing the core mechanism of the toxicity.

Other agents listed do not reverse the sodium-channel–mediated cardiotoxicity seen with TCAs. Naloxone is for opioid overdose, flumazenil for benzodiazepines, and atropine may only offer limited symptomatic support but does not treat the underlying problem.