SympathoMIMETIC drugs

Question 1

Epinephrine

Answer 1

• sympathoMIMETIC
• positive inotrope
• catecholamine–endogenous substance, can also be used therapeutically!*
• activates all adrenergic receptors
• alpha-1 vasoconstriction
• Beta-1 cardiac contraction
• Beta-2 bronchodilation
• IV, IM, SQ, inhaled-depends on how urgent
• -NOT PO-systemic bioavailability=poor; topically in eye?
  1: 1000–>dilute 1:10,000
• cardiac arrest
• inotropic infusion
• anaphylaxis/anaphylactoid rxns
• vasoconstriction & local vasoconstriction (epistaxis)
• Tachyarrhythmias–ventricular ectopic beats, ventricular fibrillation, barbiturates and gas anesthetics

Question 2

Norepinephrine

Answer 2

sympathoMIMETIC drug
positive inotrope
catecholamine–endogenous substance, can also be used therapeutically!
-alpha agonist, beta-1 agonist (higher doses)
—vasoconstriction (increase bp)
—increase afterload
-not often used as exogenous drug

Question 3

Isoproterenol

Answer 3

sympathoMIMETIC drug
-positive inotrope
-Beta-1 and beta-2 agonist
-RARELY used to tx bradyarrhythmias
—-increases force of contraction (inotropic)
—-increases O2 consumption
—-decreases peripheral vascular resistance
—-bronchiolar relaxation
—-can cause tachycardia/arryhthmias
(heart pumps faster, but uses up more O2–not preferable)

• Antimuscarinics are better in short term–tachycardia may lead to myocardial hypoxia
• pacing in long term

Question 4

Dopamine

Answer 4

sympathoMIMETIC drug

• positive inotrope
• catecholamine–endogenous substance, can also be used therapeutically!*
• dose dependent response
• Low dose–>dopamine agonist
• —Activates peripheral dopamine receptors causing renal, mesenteric and coronary arteriolar vasodilation (improves perfusion)
• Med-low dose–>Beta-1 agonist
• —Pos inotrope

Med-high dose–>beta-1 agonist
—-Pos chronotrope; increase cardiac automaticity—increased HR, increased contractility

High dose–>Alpha-1 agonist/NE release
—-Vasoconstriction

• short half life
• IV infusion (necrosis if given extravascularly!)
• ->acute heart failure, shock
• Monitor ECG, ABP–>tachycardia, (supra)ventricular arrhythmias, hypo-hypertension

Question 5

Dobutamine

Answer 5

• sympathoMIMETIC drug
• positive inotrope
• Beta-1 agonist
• IV infusion
• ->pos inotropic effect
• ->mild positive chronotropic effects
• ->increase coronary, skeletal, renal and mesenteric flow
• Acute heart failure
• side effects similar to dopamine