Calcium Channel Blocker Poisoning

Description

• 3 classes of calcium channel blockers (CCBs):
  • Phenylalkylamines (verapamil):
    • Vasodilation resulting in a decrease in BP
    • Negative chronotropic and inotropic effects: Reflex tachycardia not seen with a drop in BP
  • Dihydropyridine (nifedipine):
    • Decreased vascular resistance resulting in a drop in BP
    • Little negative inotropic effect: Reflex tachycardia occurs
  • Benzothiazepine (diltiazem):
    • Decreased peripheral vascular resistance leading to a decrease in BP
    • Heart rate (HR) and cardiac output initially increased
    • Direct negative chronotropic effect, which leads to a fall in HR
• Effects of calcium channel blockade
  • Calcium plays key role in cardiac and smooth muscle contractility
  • CCBs prevent:
    • The entry of calcium, resulting in a lack of muscle contraction
    • The normal release of insulin from pancreatic islet cells, resulting in hyperglycemia