Autonomic pharmacology IV Flashcards
what are the three types of adrenergic agonists?
- direct acting
- mixed
- indirect acting
what are the two categories of direct acting adrenergic agonists?
- selective
2. non-selective
what are the selective direct acting adrenergic agonists?
- phenylephrine - a1
- clonidine - a2
- terbutaline - B2
- fenoldopam - D1
phenylephrine acts on what receptor?
a1
clonidine acts on what receptor?
a2
terbutaline acts on what receptor?
B2
fenoldopam acts on what receptor?
D1
what are the non-selective direct acting adrenergic agonists?
- isopreterenol
- dobutamine
- epinephrine
- norepinephrine
- dopamine
isopreterenol acts on what receptors?
B1 and B2
dobutamine acts on what receptors?
a1, B1, B2
epinephrine acts on what receptors?
a1, a2, B1, B2
NE acts on what receptors?
a1, a2, B1
dopamine acts on what receptors?
D1, D2, a1
are the effects of direct acting adrenergic agonists reduced by prior treatment with reserpine or guanethidine?
no (may be potentiated)
are the effects of mixed acting adrenergic agonists reduced by prior treatment with reserpine or guanethidine?
yes
what is the effect of phenylephrine on vascular smooth muscle? which receptor does it activate?
- increase BP, increase TPR
2. alpha adrenergic (a1)
what are the clinical indications for phenylephrine?
- hypotension, shock
- paroxysmal atrial tachycardia
- nasal decongestant
- mydriatic
what are the a2 selective adrenergic receptor agonists?
- clonidine
- a-methyldopa
- apraclonidine
- brimonidine
what is the mechanism of action for clonidine (a2 selective adrenergic receptor agonist)?
lowered BP due to decreased sympathetic outflow
what are the clinical uses for clonidine (a2 selective adrenergic receptor agonist)?
- systemic hypertension
2. glaucoma
what are the adverse effects of a2 selective adrenergic receptor agonists?
- dry mouth
- sedation
- hypotension
apraclonidine and brimonidine are used for what purposes?
decrease aqueous humor production and intraocular pressure
what are the B2 selective adrenergic receptor agonists?
- metaproterenol
- terbutaline
- albuterol
- ritodrine
which B2 selective adrenergic receptor agonists are resistant to methylation by COMT?
metaproterenol and terbutaline
what are the therapeutic uses for metaproterenol?
- long term treatment of obstructive airway diseases, asthma
- acute bronchospasm
what are the therapeutic uses for terbutaline?
- long term treatment of obstructive airway diseases, asthma
- acute bronchospasm
- emergency treatment of status asthmaticus (IV)
what are the therapeutic uses for albuterol?
- acute bronchospasm
2. delay preterm labor
what are the therapeutic uses for ritodrine?
- uterine relaxant
- arrest preterm labor
- prolong pregnancy
what are the adverse effects of excessive activation of B receptors?
- tachycardia
- increased plasma glucose
- increased plasma K+
what is the best way to avoid adverse effects of excessive activation of B receptors?
inhalation therapy
fenoldopam acts on what receptor?
D1 (some a2)
what are the effects of D1 activation by fenoldopam?
- vasodilation in (renal, mesenteric, peripheral, coronary) vascular beds:
- renal blood flow maintained and natriuresis promoted
what is the clinical use for fenoldopam?
hypertensive crisis
what is the side effect of fenoldopam?
hypotension
isopreterenol acts on which receptors?
B1 and B2
what are the cardiovascular effects of isopreterenol?
- decrease TPR
- increase HR
- increase myocardial contractility
what are the respiratory effects of isopreterenol?
bronchodilation
what are the clinical uses of isopreterenol?
- bradycardia
- AV block
- torsades de pointes
what is the reason for increase in HR following isopreterenol administration?
activation of B1 receptors
at therapeutic doses, dobutamine acts mainly on what receptor?
B1
does dobutamine affect release of NE from sympathetic nerve endings?
no
what are the cardiovascular effects of dobutamine?
- positive inotropic (more so than isopreterenol)
- positive chronotropic - SA automaticity, AV conduction
- TPR unaffected (a1 - B2 balance)
why is dobutamine considered the preferred agent for cardiac performance?
- increases contraction without increasing HR too much (no significant increase in oxygen consumption)
- a1 - B2 balancing leads to less impact on TPR
what are the adverse effects of dobutamine?
- excessive increase in BP and HR
- increased ventricular response rate in pts with atrial fibrillation
- ventricular ectopic activity
- may increase size of myocardial infarct
- tolerance
what are the therapeutic uses for dobutamine?
- short term treatment of cardiac failure
- longer term efficacy unclear
- stress test for pts with coronary artery disease