Sympathetic antagonists Flashcards
1
Q
Phenoxybenzamine
A
- MOA
- irreversibly blocks α1 and α2
- indirect baroreflex activation
- Effects
- lowers BP
- HR rises due to baroreflex activation
- Clinical
- pheochromocytoma/high catecholamine states
- Kinetics, tox, int.
- irreversible blocker, duration>1 day
- tox: orthostatic hypotension, tachycardia, myocardial ischemia
2
Q
Phentolamine
A
- MOA
- reversibly blocks α1 and α2
- Effects
- blocks α-mediated vasoconstriction, lowers BP, increases HR (baroreflex)
- Clinical
- pheochromocytoma
- Kinetics, tox, int.
- t1/2 approx 45min after IV injection
3
Q
Prazosin, doxazosin, terazosin
A
- MOA
- block α1 but not α2
- Effects
- lower BP
- Clinical
- hypertension
- benign prostatic hyperplasia
- Kinetics, tox, int.
- larger depressor effect with first dose may cause orthostatic hypotension
4
Q
Tamsulosin
A
- MOA
- slightly selective for α1A
- Effects
- may relax prostatic smooth muscle more than vascular smooth muscle
- Clinical
- benign prostatic hyperplasia
- Kinetics, tox, int.
- orthostatic hypotension less common with this subtype
5
Q
Yohimbine
A
- MOA
- blocks α2
- elicits increased central sympathetic activity
- increased norepinephrine release
- Effects
- raises BP and HR
- Clinical
- male erectal dysfunction
- hypotension
- Kinetics, tox, int.
- may cause anxiety
- excess pressor effect if norepinephrine transporter is blocked
6
Q
Labetalol
A
- MOA
- β>α1 block
- Effects
- lowers BP with limited HR increase
- Clinical
- hypertension
- Kinetics, tox, int.
- oral, parenteral
- tox: less tachycardia than other α1 agents
7
Q
Propranolol, nadolol, timolol
A
- MOA
- block β1 and β2
- Effects
- lower HR and BP
- reduce renin
- Clinical
- hypertension, angina, arrythmias, migraine, hyperthyroidism, glaucoma
- Kinetics, tox, int.
- oral, parenteral
- tox: bradycardia, worsened asthma, fatigue, vivid dreams, cold hands
8
Q
Metoprolol, atenolol, betaxolol, nebivolol
A
- MOA
- block β1>β2
- Effects
- lower HR and BP
- reduce renin
- may be safer in asthma
- Clinical
- angina, hypertension, arrythmias, glaucoma
- Kinetics, tox, int.
- tox: bradycardia, fatigue, vivid dreams, cold hands
9
Q
Butoxamine
A
- MOA
- blocks β2>β1
- Effects
- increases peripheral resistance
- Clinical
- no clinical indication
- Kinetics, tox, int.
- tox: asthma provocation
10
Q
Pindolol, acebutolol, carteolol, bopindolol, oxprenolol, celiprolol, penbutolol
A
- MOA
- β1, β2, with intrinsic sympathomimetic (partial agonist) effect
- Effects
- lower BP
- modestly lower HR
- Clinical
- hypertension, arrythmias, migraine, may avoid worsening of bradycardia
- Kinetics, tox, int.
- oral
- tox: fatigue, vivid dreams, cold hands
11
Q
Carvedilol, medroxalol, bucindolol
A
- MOA
- β>α1 block
- Effects
- same as labetalol?
- Clinical
- heart failure
- Kinetics, tox, int.
- oral, long t1/2
- tox: fatigue
12
Q
Esmolol
A
- MOA
- β1>β2
- Effects
- very brief cardiac β blockade
- Clinical
- rapid control of BP and arrythmias
- thyrotoxicosis
- myocardial ischemia intraoperatively
- Kinetics, tox, int.
- parenteral only, t1/2 approx 10 min
- tox: bradycardia, hypotension
13
Q
Metyrosine
A
- MOA
- blocks tyrosine hydroxylase
- reduces synthesis of dopamine, norepinephrine, and epinephrine
- Effects
- lowers BP
- may elicit extrapyramidal effects (due to low dopamine in CNS)
- Clinical
- pheochromocytoma
- Kinetics, tox, int.
- tox: extrapyramidal symptoms, orthostatic hypotension, crystalluria