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Flashcards in Adrenergics Deck (35):
1

Epinephrine

Receptor selectivity - α1, α2, β1, β2

Cardiovascular effects
– Potent vasopressor (α1), but can dilate
some vascular beds (β2)
– Cardiostimulatory (β1)

Respiratory effects
– Bronchodilation (β2)

Metabolic effects
– Increase blood glucose and fatty acids

Absorption, fate, excretion
– Not orally effective, rapid t ½

Therapeutic uses
– Hypersensitivity reaction; anaphylaxis
– Increase duration of action of local
anesthetics
– Bradyarrhythmias
– Ophthalmic uses – mydriatic, decrease hemorrhage and conjunctival congestion

2

Epinephrine Cardiovascular effects

Cardiovascular effects
– Potent vasopressor (α1), but can dilate
some vascular beds (β2)
– Cardiostimulatory (β1)

3

Epinephrine Respiratory effects

– Bronchodilation (β2)

4

Epinephrine Metabolic effects

– Increase blood glucose and fatty acids

5

Epinephrine Absorption, fate, excretion

– Not orally effective, rapid t ½

6

Epinephrine Therapeutic uses

– Hypersensitivity reaction; anaphylaxis
– Increase duration of action of local
anesthetics
– Bradyarrhythmias
– Ophthalmic uses – mydriatic, decrease hemorrhage and conjunctival congestion

7

Norepinephrine

Receptor selectivity – α1, α2, β1

• Cardiovascular effects (α1 mainly)
– Increases PVR
– Increases mean BP
– Can cause reflex bradycardia

• Absorption, fate, excretion
– Similar to epinephrine

• Therapeutic uses
– Vasoconstrictor under certain
intensive care situations (shock,
hypotension during reduced
sympathetic tone)

8

Norepinephrine Receptor selectivity

α1, α2, β1

9

Norepinephrine Cardiovascular effects


• Cardiovascular effects (α1 mainly)
– Increases PVR
– Increases mean BP
– Can cause reflex bradycardia

10

Norepinephrine Absorption, fate, excretion

– Similar to epinephrine

11

Norepinephrine Therapeutic uses

– Vasoconstrictor under certain
intensive care situations (shock,
hypotension during reduced
sympathetic tone)

12

Dopamine

Cardiovascular actions (dose-dependent)
– Low dose (0.5-2 µg/kg/min)
• “renal dose”; dilation of renal and mesenteric arteries
– decreases peripheral vascular resistance (D1
receptor)
– Intermediate dose (2-10 µg/kg/min)
• “cardiac dose”; increases HR, contractile force,
cardiac output (D1 + β1 receptor)
– High dose (>10 µg/kg/min)
• “pressor dose”; vasoconstriction and increased
peripheral vascular resistance (D1 + β1 + α1)

13

Dopamine Absorption, fate, excretion

• Absorption, fate, excretion
– Similar to epinephrine
– Administered i.v.; dose titrated to achieve
desired effect

14

Dopmanie Therapeutic uses

Therapeutic uses
– Severe decompensated heart failure,
shock (cardiogenic, septic)

15

Non-selective β adrenergic receptor agonists

Isoproterenol
Dobutamine

16

Isoproterenol

• Receptor selectivity - β1, β2

• Cardiovascular effects
– Decrease PVR
– Increase HR, contractile force,
cardiac output
– Decrease mean blood pressure

• Respiratory effects
– Bronchodilation

• Absorption, fate, excretion
– Metabolized by COMT
– brief duration of action

• Therapeutic uses
– Emergency use to stimulate heart
rate during bradycardia or heart block

17

Isoproterenol Receptor selectivity

• Receptor selectivity - β1, β2

18

Isoproterenol Cardiovascular effects

• Cardiovascular effects
– Decrease PVR
– Increase HR, contractile force,
cardiac output
– Decrease mean blood pressure

19

Isoproterenol Respiratory effects

– Bronchodilation

20

Isoproterenol absorption, fate, excretion

• Absorption, fate, excretion
– Metabolized by COMT
– brief duration of action

21

Isoproterenol Therapeutic uses

• Therapeutic uses
– Emergency use to stimulate heart
rate during bradycardia or heart block

22

Dobutamine

• asymmetric carbon
– (-) dobutamine - α1 agonist and β agonist
– (+) dobutamine – α1 antagonist and β agonist
– Overall effect of racemic mixture functions as β1
agonist

• Cardiovascular Effects
– Increased HR, contractility, and
CO
– Minimal change in peripheral
vascular resistance & BP

• Absorption, fate, excretion
– Metabolized rapidly
– Brief duration of action

• Therapeutic Uses
– Short-term treatment of cardiac
decompensation (cardiac
surgery, CHF, infarction)
– Cardiac stress testing

23

Dobutamine (-) dobutamine

• asymmetric carbon
(-) dobutamine - α1 agonist and β agonist

24

Dobutamine (+) dobutamine

(+) dobutamine – α1 antagonist and β agonist

25

Overall what is dobutamine an agonist for

– Overall effect of racemic mixture functions as β1
agonist

26

Short-Acting β2-selective adrenergic receptor agonists

Albuterol

27

Albuterol
-Therapeutic use:
-Adverse effects:

– Acts mainly on β2 adrenergic receptors (agonist)
– Administered by inhalation or orally
– Short-acting and rapid onset

Therapeutic use:
- relief of bronchoconst. (asthma)

Adverse effects:
- tremor, anxiety, tachycardia

Other similar short-acting β2 agonists:
metaproterenol, terbutaline, levalbuterol,
pirbuterol

28

Long-Acting β2-Selective
Adrenergic Receptor Agonists

Salmeterol

29

Salmeterol

• β2 adrenergic receptor agonist (inhalation)
• Long duration of action (>12 h)
Therapeutic use:
- Chronic obstructive pulmonary disease, moderate to severe persistent
asthma
- Slow onset of action so not suitable as monotherapy for acute
bronchospasm

30

α1-selective adrenergic receptor agonists

Phenylephrine

31

Phenylephrine

– Agonist of α1 adrenergic receptors
– Increases systolic and diastolic blood pressure
– Reflex decrease in heart rate
– Decrease blood flow in most vascular beds

• Therapeutic Uses:
– Ophthalmic
• mydriatic, decrease hemorrhage & congestion
– Nasal decongestant
• oral or nasal spray
– Used with local anesthetics to increase duration of action
– Treatment of hypotension

Other similar drugs: midodrine

32

Phenylephrine therapeutic uses

• Therapeutic Uses:
– Ophthalmic
• mydriatic, decrease hemorrhage & congestion
– Nasal decongestant
• oral or nasal spray
– Used with local anesthetics to increase duration of action
– Treatment of hypotension

33

• α2-selective adrenergic receptor agonists

Clonidine
Methyldopa

34

Clonidine

• Orally active α2 adrenergic receptor
agonist that directly stimulates central α2
receptors to reduce sympathetic outflow

• Therapeutic Use:
– Anti-hypertensive agent
• Major adverse effects
– Xerostomia (dry mouth) and drowsiness occur in
~50% of patients

35

Methyldopa

and Major therapeutic use and Side effects:

• Orally active pro-drug
– Metabolized in nerve terminals to α-methyldopamine
and α-methylnorepinephrine, which are stored and
released with nerve stimulation
– Both are potent α2 receptor agonists
– Stimulate central α2 receptors to reduce sympathetic
outflow

• Major therapeutic use:
– Anti-hypertensive

• Side effects:
– Similar to clonidine