NATIONAL
CALIFORNIA
VENTURA
mechanism
  • Selective inhibitor of Beta-1 receptors - competitively blocks Beta-1, with little or no effect on Beta-2 receptors
indications
  • Atrial fibrillation or atrial flutter for acute ventricular rate control
contraindications
  • Sick sinus syndrome (except in patients with a functioning artificial pacemaker)
  • Second- or third-degree AV block (except in patients with a functioning artificial pacemaker)
  • Administration with, or within a few hours of the administration of IV calcium channel blockers
dosing

IV: 2.5 to 5 mg over 2 minutes; repeat dose every 5 minutes as needed; maximum total dose: 15 mg

administration
IV: May administer undiluted IV push over 1 minute for acute treatment
onset

IV: ~20 minutes

duration

4-6 hours

notes
  • Hypoglycemia: Beta-blockers may worsen, prolong, or cause hypoglycemia. Additionally, beta-blockers may mask symptoms of hypoglycemia (tremor, irritability, palpitations), making diaphoresis the only symptom unaffected by beta-blockers
  • Withdrawal: Beta-blocker therapy should be gradually tapered to avoid acute tachycardia, hypertension, and/or ischemia
dosage form
Solution, Intravenous: 5 mg/5 mL (5 mL)
brand name
Lopressor
adverse reactions
  • Bradyarrhythmias
    • May cause bradycardia, sinus pause, first-degree atrioventricular (AV) block, second-degree atrioventricular block, or complete heart block
  • Bronchospasm
    • May cause bronchospasm but selective beta-blockers (ie Beta-1 specific) like metoprolol have a lower risk of bronchospasm
  • CNS effects
    • May cause fatigue, sleep disturbance, insomnia
structure
metoprolol.svg molecular structure