Adrenergic Drugs Flashcards
Name the steps in the formation of norepinephrine, starting with tyrosine from the blood vessels
1) Tyrosine enters nerve and is converted to dopa by tyrosine hydroxylase
2) Dopa is converted to dopamine by dopa decarboxylase
3) Dopamine is converted to norepinephrine by dopamine beta hydroxylase and VESICLE is formed
4) norepinephrine is stored or released for use in synapse
What are β1’s actions in the heart? In the kidney?
Increases HR/contraction force, increases renin secretion
What are β2’s actions in the arterioles? In the bronchial smooth muscle? In the pregnant uterus?
dilation of blood vessels, relaxation of smooth muscle, and relaxation of uterus
What are β3’s actions in the adipose tissue?
Increases lipolysis
What are α1’s actions in the arterioles? In the veins? In the uterus? In the spleen?
Constriction for all of the above
What are α2’s actions in the presynaptic terminal? In the postsynaptic CNS terminal?
Inhibits NE release, and decreases sympathetic tone respectively
What is D1’s actions in the renal, mesenteric, and cerebral arterioles?
Dilation
How does the effect of epinephrine on blood vessels in skeletal muscle differ depending on the concentration?
Low concentration: β2 dilation
High concentration: α1 constriction
Which drug is most potent at the β1 (contraction of heart) and β2 (relaxation of bronchial smooth muscle) receptors?
A) isoproterenol
B) epinephrine
C) norepinephrine
D) dopamine
A) isoproterenol
And in case you’re wondering, the answer choices are in descending order of potency!
Which drug is most potent at the α1 (vasoconstriction) receptor?
A) isoproterenol
B) dopamine
C) norepinephrine
D) epinephrine
D) epinephrine
The answer choices are in order of increasing potencies
Which drug is most potent at the α2 receptor?
A) epinephrine
B) norepinephrine
C) clonidine
D) isoproterenol
C) clonidine
- Clon > epi > NE»_space; iso
What effect does tyramine or amphetamine have in the synapse?
Indirect adrenergic agonist, releases NE from small cytoplasmic pool (NOT from vesicles)
Something crazy is happening to your patient and they are extremely hypertensive. You realize that all of their organs are in danger. However comma you want to focus solely on getting the blood to their kidneys, brain, and abdomen. To achieve these selective effects, what receptors should you target and what drug should you use?
D1 agonist - fenoldopam
What effect does NE have on the TPR, BP, and HR?
Norepinephrine increases the TPR, which causes a subsequent increase in BP and a compensatory decrease in HR due to baroreceptors
What effects do both epinephrine and isoproterenol have on the TPR, BP, and HR? Which of the two produces more pronounced effects?
TPR is down, BP stays about the same, and HR increases. Isoproterenol produces the larger effect.
KEY POINT: Iso and epi also affect β2 receptors, so the TPR stays low and baroreceptors are not activated
What are the clinical applications of α1 agonists? What are the drugs most likely to be used for each application? There are 7… Think of all of the applications of epinephrine alone and you’ll have more than half!
1) Control hemorrhage (epi)
2) Contain local anesthetic (epi)
3) Nasal decongestant (ephedrine, phenylephrine)
4) Anaphylactic shock (epi)
5) Eye stuff - lowers intraocular pressure (epi)
6) Hypotension (dopamine)
7) Shock (norepi, iso, dopamine - maybe even α blockers are a better idea here!)
You give a patient an injection of a drug (you didn’t hear what the doctor said it was when he handed it to you) and the patient is now complaining of pain, coldness, and pale tissue at the site. You suspect local ischemia. What class of drugs did your injection most likely belong to?
α agonist
You’re on OB/GYN service and one of the patients just gave birth to a healthy baby. However comma she seems to be bleeding more than usual and it is not slowing down. What ergot alkaloid should you push to control the hemorrhage?
ergonovine (α agonist)
You’re on family med service and an older patient comes in complaining of nipple discharge; on further investigation, you discover that this is actually milk! They definitely didn’t just have a baby, so you suspect an adrenal tumor. You refer them to an oncologist, but they want the embarrassing discharge to stop today! What do you prescribe?
Bromocriptine (dopamine agonist, useful for hyperprolactinemia)
Which ergot alkaloid would you use for the prodrome of migraines, and which would you use for the prophylaxis?
Ergotamine and methysergide respectively
What is the effect of α2 receptors in the CNS?
decreases central sympathetic output, thus decreasing blood pressure
One of your patients presents with hypertension, and also admits to probably be going through withdrawal from his usual oxy and vodka regimen. What drug do you recommend to kill two birds with one stone and on which receptor does it act?
Clonidine, α2 agonist
This drug is a prodrug, is used to treat hypertension, and can cross the blood brain barrier. It is an α2 agonist.
α-methyldopa
Your patient has gone into premature labor! You hope to slow the process down… What β2 agonist should you use? What else can this drug be used for?
Terbutaline, can be used for asthma and COPD.
What drugs can be used for emergency treatment of cardiac arrest, AV block, or congestive heart failure? Which of these is only selective for β1? What is a serious side effect of these meds?
Epinephrine, isoproterenol,
dobutamine (β1)
- tachyarrhythmias
You see a child in peds clinic that moves around a lot and seems to have trouble focusing on any task at hand (ADHD), but who also randomly falls asleep during your exam (narcolepsy). What do you prescribe and what is your reasoning?
Amphetamine (or at least a version of it). His wake up! centers need a boost, and amphetamine works in the brain to increase the release of norepinehrine.
