pharm: adrenergic receptors Flashcards
what are some examples of adrenergic direct acting agonists? give 2 overarching types
- Catecholamines
- Non-catecholamines
what are examples of catecholamines that are direct acting adrenergic agonists?
epinephrine
norepinephrine
isoproterenol
dopamine
dobutamine
why do catecholamines need to be given parenterally (taken by a route other than through the mouth ie. IM or IV)?
what affects a catecholamines efficiency?
catecholamines are rapidly metabolized in the gut, liver, and other tissues by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT)
Catecholamines effects depend on affinity and specificity for type of Adrenergic receptor
Epinephrine (direct adrenergic agonist)
- effects on body (in various receptors)
- when is it used?
can bind to ALL the adrenergic receptors
vasoconstriction & increase BP (ALPHA 1)
cardiac stimulation (BETA 1)
bronchodilation & skeletal muscle vasodilation (BETA 2)
used in anaphylactic shock and cardiac arrest
Norepinephrine (direct adrenergic agonist)
- effect on body (various receptors)?
- when is it used?
vasoconstriction & increase BP (A1)
cardiac stimulation (B1)
used in hypotension and shock
Isoproterenol (direct adrenergic agonist)
- effect on body?
- when is it used?
cardiac stimulation (B1)
bronchodilation (B2)
used to tx. asthma, AV block, and bradycardia
Dopamine (direct adrenergic agonist)
*what is it a precursor to?
- effect on body?
- what is it used for?
*precursor to epi, NE
- renal vasodilation (D1)
- cardiac stimulation (B1)
- increase BP (A1)
- used to tx. cardiogenic shock, septic shock, heart failure, and adjunct to fluid administration in hypovolemic shock
Dobutamine (direct adrenergic agonist)
- affinity for what receptor?
- what is it used for?
- highest affinity for B1 receptor
- less activity at A1 receptor
- used to tx. cardiogenic shock, cardiac arrest, and heart failure
what are examples of non-catecholamines that are direct acting adrenergic agonists?
phenylephrine
albuterol
clonidine
terbutaline
Phenylephrine (direct adrenergic agonist)
- effect on body?
- what is it used for?
(A1) effects:
- vasoconstriction
- increase BP
- mydriasis
- used as nasal decongestant, ocular decongestant, and maintenance of BP during surgery
Albuterol (direct adrenergic agonist)
- effect on body?
- what is it used for?
Bronchodilation (B2)
used in asthma
Clonidine (direct adrenergic agonist)
- effect on body?
- what is it used for?
- inhibits NE release from nerve terminal of postganglionic neuron (feedback inhibition - A2)
- can have effects in CNS (sedation)
- used to treat chronic hypertension
Terbutaline (direct adrenergic agonist)
- effect on body?
- what is it used for?
- Bronchodilation and uterine relaxation (B2)
- used to tx. asthma and premature labor (tocolytic)
SIDE NOTE – tocolytic = anti-contraction med used to prevent premature labor
what are some examples of adrenergic indirect acting agonists? (3)
amphetamine
cocaine
tyramine
Amphetamine (indirect adrenergic agonist)
(THINK ADDERALL)
- increase release of NE & DA from sympathetic NS neurons
- vasoconstriction
- cardiac stimulation
- increase BP
- penetrates CNS – CNS stimulation (increases mood and alertness, but decreases appetite)
Cocaine (indirect adrenergic agonist)
- local anesthetic
- stimulates sympathetic NS by blocking reuptake of NE & DA in the parasymp & symp NS –> similar effects as ampetamine
Tyramine (indirect adrenergic agonist)
- normal by-product of tyrosine metabolism in body
- found in high conc. in fermented foods (cheese, beer, red wine, cured meats - salami & pepperoni)
- indirect sympathomimetric b/c it causes the release of stored catecholamines
- (SIDE NOTE: SYMPATHOMIMETRIC means: mimic the effects of transmitter substances of the sympathetic nervous system such as catecholamines)*
- normally metabolized by MAO –> so if taking MAO inhibitor must avoid tyramine-containing food
what is a mixed acting adrenergic agonist?
give an example of one
- works both directly and indirectly
- causes vasoconstriction by binding to A1
- increases release of NE from sympathetic neurons
- EX: pseudoephrine – nasal decongestant
what are the types of adrenergic antagonists?
alpha adrenergic receptor antagonists (a-blockers)
beta adrenergic receptor antagonists (b-blockers)
-can be nonselective and selective
what are nonselective a-blockers?
block both a1 and a2 receptors (hence nonselective)
what are 2 examples of non-selective alpha-blockers?
phenoxybenzamine
phentolamine
Phenoxybenzamine (non-selective a-blocker)
- noncompetitive, irreversible
- tx: hypertensive episodes associated w/ pheochromocytoma
(tumor in adrenal gland that secretes catecholamines)
Phentolamine (non-selective a-blocker)
- competitive, reversible
- Dx and tx hypertensive episodes from pheochromocytoma
- tx. necrosis and ischemia from extravasations (leakage) of epinephrine
what are selective a1-blockers?
how do they work/ what are they used for?
“azosin”
- relax vascular smooth muscle and smooth muscle in bladder and prostate
- produce vasodilation and decrease BP
- used to tx hypertension and urinary retention due to benign prostatic hyperplasia (BPH)
examples of selective-A1 blockers?
doxazoin
prazosin
terazosin
tamsulosin, alfuzosin – only for BPH not for hypertension
what are non-selective b- blockers?
- what they do?
- what are they used for?
- “olol”
- block b1 receptors in heart and b2 in smooth muscle, liver, and other tissues
- B1 blockade: decreases BP, CO, renin release, and aqueous humor selection
-B2 blockade: bronchoconstriction, decreases glycogenolysis, mask signs of hypoglycemia
tx: hypertension, angina, arrythmias, MI, migraine, glaucoma
examples of non-selective b-blockers?
“olol”
propanolol
nadolol
timolol
what are selective B1 blockers?
- selective for B1 receptors (primarily in cardiac tissue)
- AKA - “cardioselective B-blockers”
- produce less bronchoconstriction and other B2 receptor mediated effects
Tx: hypertension, angina, MI
examples of selective B1 blockers?
Atenolol
Metaprolol (Lopressor)
what are mixed alpha and beta adrenergic receptor antagonists?
block both a- and b- receptors
examples of mixed alpha and beta receptor agonists?
Carvedilol – tx: hypertension and CHF
Labetalol – tx: hypertension
