This week, I am joined by Leon Gussow, MD of the excellent blog: The Poison Review (TPR). TPR is my source for new toxicology articles; I highly recommend it as an incredible read. I got to meet Leon for a few beers a month ago; he is a great guy.
My Canadian pal, Ram, suggested calcium channel blocker OD as a podcast episode. Ram, here you go.
Calcium Channel Blocker OD
Nifedipine and other dihydropyridines (amlodipine, felodipine, isradipine, nicardipine, nimodipine, nisoldipine) will cause profound hypotension without bradycardia, due to poor affinity for myocardial calcium channels. This selectivity is not lost in overdose. They may actually present with reflex tachycardia
How to tell CCB OD from B-Blocker
CCBs do not cause AMS
CCBs block receptor in B-Islet cells, preventing insulin release, so can see hyperglycemia as opposed to the normal-low sugar in B-Blockers
Weak/Dizzy, mild confusion, bradycardia progressing to severe hypotension and shock
Selectivity is lost in overdose (except dihydropyridines)
· Activated Charcoal x 1
· Whole bowel-Irrigation is not recommended by Leon’s group
· Frequent glucose and k checks
· Atropine (can try it once, but it will limit gastric motility and probably won’t work)
· Calcium, 1 g of CaCl or 3 g of CaGluc. Give slowly over 3 minutes for CaCl and 10 min for CaGluc.
· Glucagon 5 mg bolus, probably won’t do much, unlike in beta blocker OD
· High Dose Insulin. Start with 1 unit/kg push followed by 0.5-1 unit/kg/hr. Fingersticks q30 minutes and adequate glucose replacement if needed. Check potassium; supplement if < 2.5. (Crit Care 2006;10:212) You can see our protocol on High-Dose Insulin Euglycemic Therapy (for informational purposes only, don’t use clinically until approved by your P&T committee).
· May need to use norepinephrine or dopamine (alternatively Epi). May need much higher doses of epi or norepi. Dopamine must be stopped at 20 mcg/kg/min, which is kind of a joke in this OD. Switch to one of the others if you get this high.
· Levosimendan may have a role, but not available in the US.
· IABP, CP Bypass