Bupropion associated cardiac toxicity widens the QRS complex by inhibiting the cardiac gap junction, not cardiac Na channel blockade. NaHCO3 is often administered when EKG changes are noted. But the effectiveness of NaHCO3 in bupropion toxicity is not well established.
A retrospective study between 2010-2020 showed, that administration of NaHCO3 only decreased QRS duration by 2 msec (median). The median NaHCO3 administered was 100 mEq. Although this study was limited by the fact that it only had a small sample size of 13, NaHCO3 administration may provide limited clinical benefit in patients with QRS widening from bupropion overdose.
References
Simpson M et al. Sodium bicarbonate treatment for QRS widening in bupropion overdoses
