Lecture 4: Adrenergic Drugs Flashcards
What are two Alpha Agonist drugs? (PC) What receptors are they specific for?
phenylephrine a1 > a2
clonidine a2 > a1
What are two mixed Alpha/Beta Agonist drugs? (NE) What receptors do they like to bind to?
norephinephrine and epinephrine
NE –> a1 = a2 and B1»_space; B2
E –> a1 = a2 and B1 = B2
What are three Beta Agonist drugs? (DIA) What receptors to they utilize?
dobutamine –> B1 > B2
isoproterenol –> B1 = B2
albuterol –> B2 > B1
What indirect adrenomimetic drug inhibits the re-uptake of dopamine and norephinephrine?
cocaine
What two indirect adrenomimetic drugs are inhibitors of MAO? (SP)
selegiline and phenelzine
What three indirect adrenomimetic drugs reverse norepinephrine and dopamine mechanisms, and increase their release? (AMT)
amphetamines, methylphenidate, and tyramine (not a drug)
What drug is a releasing agent AND a direct adrenergic receptor agonist?
ephedrine
What G protein does the alpha 1 receptor type use and what are its effects?
- uses Gq
- inc. IP3 and DAG common to all
What G protein does the alpha 2 receptor type use and what are its effects?
- uses Gi
- dec. cAMP common to all
What G protein does the beta receptor type use and what are its effects?
- uses Gs
- inc. cAMP common to all
What G proteins do dopamine receptors D1 and D2 use and what are their effects?
D1 uses Gs = inc. cAMP
D2 uses Gi = dec. cAMP
What is epinephrines selectivity for receptors vs norephinephrines selectivity for receptors?
E –> a1 = a2 and B1 = B2
NE –> a1 = a2 and B1»_space; B2
What is epinephrines effect on cardiac function and what receptor does it use?
- uses B1
- inc. force of contraction, HR, and AV node conductivity
What is epinephrines effect on vascular tone and what receptors does it use?
- uses B2 and a1
- inc. systolic BP, may dec. diastolic BP and TPR, mean arterial pressure stays the same
What receptor type, when stimulated, inc. renin release?
B1 (mainly found on heart and juxtaglomerular cells)
What do D1 and D2 receptors do when activated?
D1 = dilates renal blood vessels (on SM) D2 = modulate transmitter release from nerve endings
What do B3 receptors do when activated? (2)
on bladder (relax detrusor muscle) and on fat cells (activates lipolysis)
What are epinephrines 2 effects on the respiratory system and what receptors does it bind to?
- relaxes bronchial muscles (B2)
2. dec. bronchial secretion/congestion (a1)
What are the 3 locations for B2 receptors and what are their actions? (SSL)
- Resp/uterine/vascular SM - relaxation
- Skeletal muscle - potassium uptake
- Liver - glycogenolysis and gluconeogenesis
What are the 4 locations for a1 receptors and what are their actions? (VPPH)
- most vascular SM (innervated) - contraction
- pupillary dilator muscle - contraction
- prostate - contraction
- heart - inc. force of contraction
What are the 5 locations for a2 receptors and what are their actions? (NPNVF)
- Neurons - modulate transmitter release
- Platelets - aggregation
- nerve terminals - inhibit transmitter release
- some vascular SM - contraction
- fat cells - inhibit lipolysis
What is norepinephrines effect on the heart and blood vessels?
potent cardiac stimulate (reduces HR –> baroreflex) and vasoconstrictor
- inc. peripheral vascular resistance and BP
What are the two functions of phenylephrine?
- effective mydriatic (pupil dilator) and decongestant
- causes severe vasoconstriction, BP inc., and bradycardia (baroreflex in response)
What is major function of clonidine?
- central effect on presynaptic a2 receptors in lower brainstem that helps regulate NE release
- dec. sympathetic outflow, reduce BP, cause bradycardia
- local application = vasoconstriction
What are the two functions of isoproterenol?
- inc. cardiac output (B1)
- vasodilator and bronchodilation (B2)
What are the functions of dobutamine and albuterol?
D - potent inotropic action (less prominent chronotropic effect compared to isoproterenol)
- some a1 activity (- = agonist, + = antagonist)
A - bronchodilation
What is the importance of Tyramine?
- does NOT cross BBB (hydrophilic, unlike rest of indirect drugs)
- elevates systolic blood pressure (intravenously) and is used in pressor tests to evaluate peripheral adrenergic function
What are common adverse effects of indirect acting lipophilic drugs on the central nervous system?
- insomnia, lack of appetite, anxiety, paranoia, convulsions and hemorrhagic stroke
What are two non-selective alpha receptor antagonists? (PP)
phentolamine (reversible competitive; short acting)
phenoxybenzamine
- non-competitive, irreversible; long acting
What are 3 a1 receptor selective antagonists? (PTD)
prazosin, tamsulosin, doxazosin
What are 2 mixed blocker antagonists? (LC)
Labetalol
Carvedilol
- both are B and a1 antagonists
What are 3 B1 and B2 blockers? (PNP)
propranolol, pindolol, nadolol
What are 4 B1 selective blockers? (MBAA)
metoprolol, betaxolol, acebutolol, atenolol
What indirect acting antiadrenergic drug blocks norepinephrine release and which one is an inhibitor of tyrosine hydroxlase?
- guanethidine
2. metyrosine
What suffix do all direct a1 receptor antagonists end in?
-osin
What 3 Beta blockers are full antagonists? (ANP)
atenolol, nadolol, propranolol
What 3 Beta blockers are partial agonists? (ALP) What is there an increase in with use?
acebutolol, labetalol, pindolol
- inc. in VLDL compared to HDL
What 2 Beta blockers are inverse agonists? (BM)
betaxolol, metoprolol
What two Beta Blockers are used to treat Heart Failure? (MC)
metoprolol, carvedilol
- contraindicated in acute/severe congestive heart failure
What Beta Blocker is used to treat glaucoma?
betaxolol (no local anesthetic activity)
- propranolol NOT used
What Beta Blocker is used to treat Hyperthyroidism?
propranolol
- see excessive catecholamine action on the heart
What would you switch to if a patient on beta blockers experienced either adverse cardiovascular effects or was chronically using beta blockers?
- switch to partial agonist
- see an inc. in VLDL with chronic beta blocker use
