All the following drugs are recommended for treatment of beta blocker induced excessive bradycardia and/or decrease in cardiac output, except:
Ans. is 'b' i.e. Dobutamine Effects of beta-blocker overdoseBeta-1 receptors increase the force and rate of myocardial contraction and AV node conduction velocity, therefore, blockade of beta-1 receptors lead to reduced heart rate, myocardial contractility, and blood pressure. Resulting hypotension decreases myocardial perfusion which further decreases the myocardial contractility.Beta-2 receptor blockage inhibits glycogenolysis and gluconeogenesis resulting in hypoglycemia.CNS effectsSeizures decreased the level of consciousness, even coma.Beta blockers that are lipid-soluble and have antiarrhythmic property are more lethal e.g. propranolol, sotalol, oxprenolol.Propanolol is considered most toxic.TreatmentGastric lavage, activated charcoal to remove unabsorbed drug.The goal of treatment is to restore perfusion to critical organs by increasing cardiac output - by improving myocardial contractility or increasing heart rate or both.Drugs used to treat symptomatic bradycardia and/or hypotension are :Atropine enhances sinus node atomicity by blocking effects of acetylcholine at theAV node.EpinephrineDopamine - } with both alpha and beta-selective properties, maintain the blood-pressureIsoproterenol }Glucagon - Considered DOC by many. It stimulates the production of cAMP through nonadrenergic pathways resulting in enhanced myocardial contractility, heart rate and AV conduction (Beta blockers exert their numerous metabolic and cardiovascular effect, through the decreased production of cAMP)Calcium chloride - improves nerves and muscle performance by regulating action potential thresholdMagnesium sulfate - acts as an anti-arrhythmic agentInsulin -still under investigation, but may be used if other therapies are failing.Drugs used to prevent seizuresLorazepamDiazepamPhenobarbital
Dopamine
Dobutamine
Glucagon
Calcium chloride