What is the antidote/reversal agent for TCA/ASA overdose with a wide QRS?

• A. Naloxone
• B. Sodium bicarbonate 50 mEq IV/IO; may repeat x1
• C. Calcium gluconate
• D. Activated charcoal

Answer: (B)

When a patient overdoses on a TCA and develops a wide QRS, the problem is blockage of the heart’s fast sodium channels, which slows conduction and can lead to serious arrhythmias. The best reversal is sodium bicarbonate given IV/IO. It helps in two ways. First, the sodium load increases extracellular sodium, which competes with the drug’s blockade of the sodium channels and improves conduction, narrowing the QRS. Second, alkaline serum (raising pH) reduces the drug’s affinity for the sodium channels and shifts the drug to a less active form, further decreasing its cardiotoxic effect. This combination not only stabilizes the conduction system but also supports blood pressure and overall rhythm stability. For this use, a common regimen is 50 mEq IV/IO, with a possible repeat dose if needed. In salicylate overdose, bicarbonate is also helpful to promote urinary excretion by alkalinizing serum and urine, but the primary reason it’s used in wide-QRS TCA overdose is to reverse sodium-channel blockade.