adrenergic pharm Flashcards
(24 cards)
adrenergic receptors
GPCRs (like muscarinic ACh receptors)
- alpha1= vasoconstriction
- alpha2= inhibit NE release at presynaptic nerve endings and ACh release (heteroreceptor mechanism –> acts on vagal fibers in gut to decrease ACh –> gut relaxation)
- beta1= increased HR and force of contraction
- beta2= arteriole dilation in skeletal muscles and bronchodilation
- beta3= lipolyis D1= dilation of renal, mesenteric and cerebral arterioles
termination of transmitter
uptake 1: neuronal uptake - high specificity, low capacity
uptake2: non-neuronal cell - low specificity, high capacity –> metabolism via MAO and COMT mainly in liver
alpha-methyltyrosine
- neuron blocking drug
- inhibits tyrosine hydroxylase activty (rate limiting step in synthesis of NE) –> decreases noradrenergic response
- used to treat pheochromocytoma
competing alpha1/ beta2 receptors
beta2 have lower threshold –> dilation at low(physiologic) concentrations
alpha1 constriction at higher concentration (seen in shock)
norepinephrine
alpha1, beta1
used to treat hypotension
epinephrine
released by adrenals, not sympathetic nerve endings (neurohormone!)
alpha1, beta1, beta2
used for anaphylactic shock, local anesthetics, glaucoma
isoproterenol
non-selective beta1, beta2 agonist
used for bronchodilator/asthma, shock, heart block
tyramine
- indirect agent
- tyramine found in fermented foods
- causes release of NE from cytoplasm (not synaptic vesicles) — no Ca2+ necessary
- tachyphylaxis: acute tolerance when small cytoplasmic pool of NE is rapidly used up after repeated tyramine injections)
dopamine
D1, alpha1, beta1
- direct and indirect-acting
- low dose: direct action on D1 –> vasodilation of renal, mesenteric and cerebral vessels
- medium dose: some direct action on beta1 and indirect action/NE release
- high dose: direct action on alpha1 and indirect action/NE release
Fenoldopam
-Dopamine receptor agonist –> activates D1 receptors only (unlike dopamine)
- used in hypertensive emergencies and to increase renal perfusion
- short t1/2
- **fenolDOPam = DOPamine
ergot alkaloids
- alpha agonists
- vasoconstriction, uterine smooth muscle contraction, delirium and confusion
- ergonovine: oxytocic, control post-partum bleeding
- ergotamine: migraine
clonidine and alpha-methyldopa (pro-drug)
- alpha2 agonists
- central control of bp (act in brain!) –> decrease central sympathetic output
- used to treat HTN and withdrawal symptoms from opioids, alcohol
dobutamine
- beta1 selective agonist
- cardiac stimulation
- used for cardiac decompensation, shock, heart block
terbutaline and albuterol
- Beta2 selective agonists
- used to treat asthma, COPD
- side-effects= cardiac arrhythmia via reflexive response to vasodilation and lowered BP
- “bute”= asthma and B for bute and beta (as opposed to the other COPD and asthma drugs that are antimuscarinics- Ipatropium and Tiotropium)
amphetamine
- indirect-acting release of NE
- CNS stimulation
- used to treat ADHD, narcolepsy
propranolol
- non-selective beta blocker (1st generation)
- treat HTN, angina, arrhythmia
- can exacerbate asthma (via beta2 effects)
*old war horse
metropolol and atenolol
- beta1-selective blockers (2nd generation)
- treat HTN, angina, arrhythmia, CHF
- *only use 2nd or 3rd gen beta-blcoers to treat CHF!
carvedilol and labetalol
non-selective beta blockers (3rd generation A)
- also block alpha1 (prevent vasoconstriction)
- treat HTN and CHF
- “carve a lab”
- alpha antagonists have weird endings”ilol” or “alol” whereas beta antagonists end in “olol”
betaxolol
- beta1-selective blockers (3rd generation B)
- treat HTN and CHF
** only use 2nd or 3rd generation to treat CHF!
alpha blockers
- phentolamine, phenoxybenzamine, prazosin
- major application is to treat HTN, peripheral vascular disease (Raynaud’s, frostbite), pheochromocytoma (adrenal tumor), shock, BPH (reduce resistance to urine outflow)
- ** start with “p”
phentolamine and phenoxybenzamine
- non-selective alpha antagonist (alpha 1 and 2)
- phenoxy = nitrogen-must compound –> forms irreversible covalent bond with receptor)
- blockade of alpha2 receptors –> loss of feedback inhibition –> excess NE release –> tachycardia
- used to treat pheocromocytoma, raynaud’s, frostbite
- ** start with “phen”
prazosin
- alpha1 selective blocker
- less tachycardia
- used to treat primary HTN and BPH
ephedrine
- nasal decongestion
- alpha1 agonist
- vasoconstriction –> decrease swollen mucosa
phenylephrine
alpha1 agonist
nasal decongestion
