Sympatholytics Flashcards
Propranolol (Inderal)
MOA
&
Receptor
Competitive antagonists to β adrenergic receptors - GCPRs
Non-selective β1 & β2
Propranolol (Inderal)
Dosing
IV: 1-10 mg
Q5 min
Propranolol (Inderal)
Onset
1/2 Time
Onset
≤ 5 min
1/2 Time
2-3 hrs
Propranolol (Inderal)
Metabolism
&
Elimination
Metabolism
Hepatic
**Active metbolite: **
4-OH propranolol
Elimination
Renal
Propranolol (Inderal)
Side Effects
&
Considerations
↓ 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
Metoprolol (Lopressor)
MOA
&
Receptor
Competitive antagonists to β1 adrenergic receptors - GCPR
Cardio-selective β1
Metoprolol (Lopressor)
Dosing
IV: 1-15 mg
Typical: 1 mg
Q5 min
Metoprolol (Lopressor)
Onset
Duration
1/2 Time
Onset
IV: 5 min
Duration
1-4 hrs
1/2 Time
IV: 3-4 hrs
Metoprolol (Lopressor)
Metabolism
&
Elimination
Metabolism
Hepatic
Inactive metabolite:
α-hydroxymetoprolol &
O-demethylmetoprolol by CYP2D6
Elimination
Renal - only 5% unchanged in urine
Metoprolol (Lopressor)
Side Effects
&
Considerations
↓ 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
Atenolol (Tenormin)
MOA
&
Receptor
Competitive antagonists to
β1 adrenergic receptors - GCPR
**MOST Cardio-selective β1 **
Atenolol (Tenormin)
Dosing
IV: 5-10 mg
Q10 min
Atenolol (Tenormin)
Onset
1/2 Time
Onset
IV: 5 min**
1/2 Time**
6-7 hrs
Atenolol (Tenormin)
Metabolism
&
Elimination
Metabolism
Hepatic 5 %
Elimination
Renal 95%
Atenolol (Tenormin)
Side Effects
&
Considerations
↓ 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
Esmolol (Blevibloc)
MOA
&
Receptor
Competitive antagonists to β1 adrenergic receptors - GCPR
Cardio-selective β1
Esmolol (Blevibloc)
Dosing
IV: 10-80 mg
**Common: **20-30 mg
Esmolol (Blevibloc)
Onset
Duration
1/2 Time
Onset
Rapid; Peak: 5 min
Duration
10-30 min
1/2 Time
0.15 hrs (<9 min)
Esmolol (Blevibloc)
Metabolism
&
Elimination
Metabolism
Plasma hydrolysis by plasmaesterases; NOT plasma cholinesterases
Elimination
Plasma hydrolysis;
Renal: low %
Esmolol (Blevibloc)
Side Effects
&
Considerations
↓ 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
Labetalol (Trandate)
MOA
&
Receptors
MIXED:
Selective α1
Non-selective β1 & β2 adrenergic receptors - GCPRs
7:1 β:α ratio
Labetalol (Trandate)
Dosing
IV: 2.5-5 mg
Q5-10 min
May ↑ to 10 mg
Labetalol (Trandate)
Onset
Duration
1/2 Time
Onset
Peak: 5-10 min
Duration
1-4 hrs
1/2 Time
6 hrs
Labetalol (Trandate)
Metabolism
&
Elimination
Metabolism
Hepatic
Elimination
Renal
Labetalol (Trandate)
Side Effects
&
Considerations
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
