Adrenergic Drugs 2 & 3 Flashcards
direct-acting drugs
act on adrenergic receptors
indirect-acting drugs
increase the availability of NE or Epi to stimulate adrenergic receptors (do not act on receptors themselves)
indirect-acting drugs increase availability of NE or Epi by _
releasing NE from nerve terminal, blocking reuptake of NE back into neuron, and inhibiting metabolic degradation
mixed-acting drugs
indirectly release NE and act on receptors
alpha-1 receptor agonists
increase peripheral vascular resistance, maintaining or increasing BP
alpha-1 receptor agonists treatment
hypotension
example of alpha-1 receptor agonist
phenylephrine (direct-acting)
phenylephrine
increases BP, nasal decongestant, mydriasis
alpha-2 receptor agonists
BP is reduced by activation of alpha-2 receptors in cardio-vasculature control centers of the CNS, suppressing sympathetic outflow
alpha-2 receptor agonist treatment
hypertension
example of alpha-2 receptor agonist
clonidine
clonidine
central sympathetic outflow is decreased and parasympathetic is increased; reduces blood pressure
beta-receptor agonist
primarily for treatment of bronchoconstriction in asthma or COPD; isoproterenol or epinephrine
epinephrine
can bind alpha and beta receptors so not used as much as a beta-receptor agonist
isoproterenol
contains a methyl group that makes it selective for only beta receptors; not selective for beta-1 or beta-2
isoproterenol therapeutic uses
relaxes most smooth muscle when tone is high; prevents and relieves bronchoconstriction
side effects of isoproterenol
will cause cardiac side effects because it can bind beta-1 receptors as well as beta-2
dobutamine
selective beta-1 agonist; increase cardiac output and stroke volume
beta-2 receptor agonists
best option for treating bronchoconstriction
albuterol
administered via inhalation, targeting only beta-2 receptors in the lungs
beta-3 receptor agonist
mirabegron
mirabegron
induces detrusor muscle relaxation for treating overactive bladder
indirect-acting sympathomimetics
amphetamine and methylphenidate
amphetamine
induces IC catecholamine release, inhibits reuptake, inhibits MAO
methylphenidate (Ritalin)
inhibits transport of dopamine and NE out of synapse
mixed-acting sympathomimetics
ephedrine
ephedrine
binds both alpha and beta receptors
mixed-acting agonists response can be reduced by _
treatment with reserpine or guanethidine
indirect-acting agonists response can be abolished by _
treatment with reserpine or guanethidine
epinephrine therapeutic use
acute asthma, anaphylactic shock, increase duration of action of local anasthetics
epinephrine can bind _
alpha-1, alpha-2, beta-1, or beta-2
norepinephrine can bind _
alpha-1, alpha-2, beta-1
non-selective alpha antagonists
phentolamine and phenoxybenzamine
phentolamine
prevents NE from binding receptors and inducing hypertension
phentolamine use
treats hypertensive episodes caused by clonidine withdrawal
phenoxybenzamine
induces decrease in peripheral resistance and increases cardiac output
phenoxybenzamine use
short-term control of hypertension associated with adrenal gland tumor (pheochromocytoma)
alpha-1 antagonists
inhibit vasoconstriction induced by endogenous catecholamines; decrease blood pressure
alpha-1 antagonist example
prazosin
prazosin use
used to decrease peripheral resistance in hypertensive episodes
yohimbine
selective alpha-2 antagonist
yohimbine action
receptors can not sense how much NE in synaptic cleft so continuously secreting
yohimbine causes _
increased HR and BP (dangerous level)
beta-antagonists (beta-blockers)
useful for treatment of hypertension, ischemic heart attack, congestive heart failure, arrhythmias
1st generation beta-antagonists
propranolol; non-selective
propranolol
non-selective with equal affinity for beta-1 and beta-2
propranolol effects
when active sympathetic response, can increase cardiac output and peripheral resistance
beta-1 antagonists (2nd generation)
metaprolol
non-selective beta-antagonists should not be used in patients with _
asthma (bronchospastic disease) or type 1 diabetes
metaprolol
treatment of hypertension
3rd generation beta-antagonist
labetalol
labetalol
competitive antagonist for beta-1, beta-2, and alpha-1; useful for hypertension
alpha blockers
reduce peripheral resistance –> relax blood vessels
beta blockers
reduce cardiac output
