Sympatholytics

Question 1

Propranolol (Inderal)
MOA
&
Receptor

Answer 1

Competitive antagonists to β adrenergic receptors - GCPRs

Non-selective β1 & β2

Question 2

Propranolol (Inderal)
Dosing

Answer 2

IV: 1-10 mg
Q5 min

Question 3

Propranolol (Inderal)
Onset
1/2 Time

Answer 3

Onset
≤ 5 min

1/2 Time
2-3 hrs

Question 4

Propranolol (Inderal)
Metabolism
&
Elimination

Answer 4

Metabolism
Hepatic

**Active metbolite: **
4-OH propranolol

Elimination
Renal

Question 5

Propranolol (Inderal)
Side Effects
&
Considerations

Answer 5

↓ CO by ↓ HR

↓ HR effects synergistic w/ concurrent CCB; bronchiole smooth muscle constriction

Hypoglycemia d/t insulin potentiation
& prevents glycogenolysis

Cardioprotective from peri-op ischemia & infarction

Question 6

Metoprolol (Lopressor)
MOA
&
Receptor

Answer 6

Competitive antagonists to β1 adrenergic receptors - GCPR

Cardio-selective β1

Question 7

Metoprolol (Lopressor)
Dosing

Answer 7

IV: 1-15 mg
Typical: 1 mg
Q5 min

Question 8

Metoprolol (Lopressor)
Onset
Duration
1/2 Time

Answer 8

Onset
IV: 5 min
Duration
1-4 hrs
1/2 Time
IV: 3-4 hrs

Question 9

Metoprolol (Lopressor)
Metabolism
&
Elimination

Answer 9

Metabolism
Hepatic

Inactive metabolite:
α-hydroxymetoprolol &
O-demethylmetoprolol by CYP2D6
Elimination
Renal - only 5% unchanged in urine

Question 10

Metoprolol (Lopressor)
Side Effects
&
Considerations

Answer 10

↓ CO by ↓ HR

↓ HR effects synergistic w/ concurrent CCB; bronchiole smooth muscle constriction

Cardioselective β1 blockers have little to no effect on pts w/ COPD or asthma
Okay to use β2 agonists

Question 11

Atenolol (Tenormin)
MOA
&
Receptor

Answer 11

Competitive antagonists to
β1 adrenergic receptors - GCPR

**MOST Cardio-selective β1 **

Question 12

Atenolol (Tenormin)
Dosing

Answer 12

IV: 5-10 mg
Q10 min

Question 13

Atenolol (Tenormin)
Onset
1/2 Time

Answer 13

Onset
IV: 5 min**
1/2 Time**
6-7 hrs

Question 14

Atenolol (Tenormin)
Metabolism
&
Elimination

Answer 14

Metabolism
Hepatic 5 %
Elimination
Renal 95%

Question 15

Atenolol (Tenormin)
Side Effects
&
Considerations

Answer 15

↓ CO by ↓ HR

↓ HR effects synergistic w/ concurrent CCB; bronchiole smooth muscle constriction

CNS effects: less fatigue; does NOT cross BBB

Cardioselective β1 blockers have little to no effect on pts w/ COPD or asthma
Okay to use β2 agonists

Question 16

Esmolol (Blevibloc)
MOA
&
Receptor

Answer 16

Competitive antagonists to β1 adrenergic receptors - GCPR

Cardio-selective β1

Question 17

Esmolol (Blevibloc)
Dosing

Answer 17

IV: 10-80 mg
**Common: **20-30 mg

Question 18

Esmolol (Blevibloc)
Onset
Duration
1/2 Time

Answer 18

Onset
Rapid; Peak: 5 min
Duration
10-30 min
1/2 Time
0.15 hrs (<9 min)

Question 19

Esmolol (Blevibloc)
Metabolism
&
Elimination

Answer 19

Metabolism
Plasma hydrolysis by plasmaesterases; NOT plasma cholinesterases
Elimination
Plasma hydrolysis;
Renal: low %

Question 20

Esmolol (Blevibloc)
Side Effects
&
Considerations

Answer 20

↓ CO by ↓ HR

↓ HR effects synergistic w/ concurrent CCB;
bronchiole smooth muscle constriction

Cardioselective β1 blockers have little to no effect on pts w/ COPD or asthma
Okay to use β2 agonists

Drug of choice for CEA

Question 21

Labetalol (Trandate)
MOA
&
Receptors

Answer 21

MIXED:
Selective α1
Non-selective β1 & β2 adrenergic receptors - GCPRs

7:1 β:α ratio

Question 22

Labetalol (Trandate)
Dosing

Answer 22

IV: 2.5-5 mg
Q5-10 min
May ↑ to 10 mg

Question 23

Labetalol (Trandate)
Onset
Duration
1/2 Time

Answer 23

Onset
Peak: 5-10 min
Duration
1-4 hrs
1/2 Time
6 hrs

Question 24

Labetalol (Trandate)
Metabolism
&
Elimination

Answer 24

Metabolism
Hepatic
Elimination
Renal

Question 25

Labetalol (Trandate)
Side Effects
&
Considerations

Answer 25

α1 Antagonism
↓ BP by ↓ SVR & ↑ inotropy

β1 & β2 Antagonism
Blunts SNS response of potential ↑ HR d/t ↓ BP

Preferred for PIH

β blockers appear to reduce lung function in both healthy & obstructive diseased pts d/t poorly selective for cardiac β1 adrenoceptors over respiratory β2 adrenoceptors

Higher β agonist doses may be required to overcome the β-blockade

↓ HR effects synergistic w/ concurrent CCB;
bronchiole smooth muscle constriction