[abhinav]

why are bicarbonates given for TCA cardiac toxicities??

 

[khanar]

I think because acidosis (lots of acids in the blood in TC acids toxicity) sensitizes the myocardium to the effects of circulating epinephrine. So bicarbonate will lower this acidosis and be cardioprotective

 

[gabra]

why are bicarbonates given for TCA cardiac toxicities??

Increases protein binding
TCAs are albumin bound which is pH sensitive; minor role b/c large Vd and lipophilic thus most TCA is in tissue not serum
Alkalosis
the TCA to Elevated pH decreases the binding of the voltage gated sodium channel
Sodium loading
Na load with bicarb creates a larger gradient across the Na+ channel