Sympathomimetics Flashcards Preview

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Flashcards in Sympathomimetics Deck (35)
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1

Epinephrine receptors activated

Potent alpha, also activated beta 1,2

2

Epinephrine clinical uses

Anaphylaxis, severe asthma, bronchospasm, CPR, hemodynamic instability, support myocardial contractility and vascular resistance, increase inotropy

3

Epinephrine cardiovascular effects

Alpha-1 = arteriolar vasoconstriction and pulmonary artery vasoconstriction, predominantly located in cutaneous, splanchnic, and renal vascular beds
Alpha-2 = vasoconstriction
Beta-1 = chronotropic, inotropic, increased cardiac output
Beta-2 = vasodilation, predominantly located in skeletal muscle

4

Alpha/Beta receptor balance and epinephrine

Alpha-1 and Beta-2 receptor balance in vasculature of an organ determines epinephrine's overall effect on blood flow to that organ

5

Overall systemic of epinephrine

Preferential distribution of cardiac output to skeletal muscle and increased systemic vascular resistance - renal blood flow substantially decreased

6

Low v High dose epinephrine

Beta-2 more sensitive at low doses, effects on alpha-1 predominate at high doses

7

Epinephrine blood pressure effect

High density of alpha receptors in venous vasculature = increased venous return, blood pressure increased by increased cardiac index and systemic vascular resistance

8

Epinephrine coronary blood flow

Increased, even at doses that do not increase SVR

9

Epinephrine airway smooth muscle

Bronchial SM relaxed, effect not observed in presence of beta-blockade

10

Epinephrine metabolic effect

Most significant effect on metabolism of all catecholamines, increases glycogenolysis, and adipose tissue lipolysis

11

Epinephrine electrolyte effects

Beta-2 stimulation activates the Na/K pump leading to movement of K into cells

12

Epinephrine coagulation effects

Accelerates coagulation by inducing platelet aggregation and increases factor 5 activity

13

Norepinephrine receptors stimulated

Beta-1 (equal to epinephrine) and Alpha-1, lacks Beta-2 agonist effects

14

Norepinephrine cardiovascular effects

Beta-1 = positive chronotrope, inotrope, and dromotrope

15

Norepinephrine SVR effects

Alpha-1 = intense arterial and venous vasoconstriction in all vascular beds besides coronary arteries

16

Epinephrine v Norepinephrine on SVR

Norepinephrine causes greater increase in SVR, DBP, MAP, SBP

17

Epinephrine v Norepinephrine on coronary circulation

Both dilate coronary arteries

18

Dopamine receptors activated

Dependent upon dose administered, however, there is a large variation in patient response to the various doses of dopamine

19

Low dose dopamine (0.5-3 mcg/kg/min)

D-1 and D-1 primarily stimulated = vasodilation, decreased arterial BP, increased renal and splanchnic vascular blood flow

20

Intermediate dose dopamine (3-10 mcg/kg/min)

Beta-1 (primarily) stimulated = positive chronotrope and inotrope effects
Alpha receptors (secondary) in vasculature, also induces Norepinephrine release from vascular sympathetic neurons

21

High dose dopamine (>10 mcg/kg/min)

Alpha-1 predominantly stimulated, acts like pure alpha agonist - reflex bradycardia may develop

22

Dopamine clinical uses

Increase cardiac output in patients with decreased contractility, low systemic blood pressure, and low urine output

23

Dopamine pulmonary effects

Increases pulmonary vascular resistance - not preferred inotrope agent in patients with pulmonary HTN or right ventricular dysfunction

24

Isoproterenol receptor activated

Beta-1 and Beta-2 MOST POTENT activator of sympathomimetics, lacks alpha stimulating effects, causes NO vasoconstriction

25

Isoproterenol cardiovascular effects

Potent chronotrope, inotrope, and dromotrope

26

Isoproterenol cardiac output effects

Increases in cardiac output may be attenuated by impaired left ventricular filling due to tachycardia, as well as decreased preload from venodilation

27

Dobutamine recetors activated

Beta-1 = potent
Beta-2 = weaker
Alpha-1 = agonist activity increases with higher doses

28

Dobutamine composition

Comprised of two stereoisomers that exert differing effects on the Alpha and Beta receptors

29

Dobutamine enantiomers

(-) enantiomer = potent alpha-1 agonist, weak beta-1 and beta-2 agonist
(+) enantiomer = competitive alpha-1 antagonist, potent beta-1 and beta-2 agonist

30

Dobutamine primary effect

Positive inotrope - increases intracellular cAMP - increased Ca release from SR - increased contractility