Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 38-24: Beta-Adrenergic Blockers Poisoning + Key Features Download Section PDF Listen +++ ++ The most toxic beta-blocker is propranolol It competitively blocks beta-1- and beta-2-adrenoceptors Has direct membrane-depressant and CNS effects + Clinical Findings Download Section PDF Listen +++ ++ Hypotension and bradycardia are common with mild or moderate intoxication Cardiac depression from more severe poisoning is often unresponsive to conventional β-adrenergic stimulants such as dopamine and norepinephrine With propranolol and other lipid-soluble drugs, seizures and coma may occur Propranolol, oxprenolol, acebutolol, and alprenolol Have membrane-depressant effects Can cause conduction disturbance (wide QRS interval) similar to tricyclic antidepressant overdose + Diagnosis Download Section PDF Listen +++ ++ Diagnosis is clinical Routine toxicology screening does not usually include β-blockers + Treatment Download Section PDF Listen +++ ++ Activated charcoal Administer 60–100 g orally or via gastric tube, mixed in aqueous slurry Repeated doses may be given Attempts to treat bradycardia or heart block with atropine (0.5–2 mg intravenously), isoproterenol (2–20 mcg/min by intravenous infusion, titrated to the desired heart rate), or an external transcutaneous cardiac pacemaker are often ineffective, and specific antidotal treatment may be necessary For persistent bradycardia and hypotension, give glucagon, 5–10 mg intravenously, followed by infusion of 1–5 mg/h High-dose insulin (0.5–1 unit/kg/h intravenously) along with glucose supplementation has also been used to reverse severe cardiotoxicity Membrane-depressant effects (wide QRS interval) may respond to boluses of sodium bicarbonate (50–100 mEq intravenously) as for tricyclic antidepressant poisoning Intravenous lipid emulsion (Intralipid 20%, 1.5 mL/kg) has been used successfully in severe propranolol overdose