Adrenergic Receptors 2 Flashcards
What are the general local risks with alpha-agonists?
localized ischemia, extravasation, weaning down the dose is required
What are ergot alkyloids?
Lycergic acid compounds from a rye grass fungus that affect a variety of neural systems (LSD comes from here!)
What family contains ergonovine and ergotamine? Where is their action?
Ergots; alpha agonists
What is the indication for ergonovine?
Post partum bleeding
What is the indication for ergotamine?
acute migraine treatment
What are the general side effects of alpha agonists?
hypertension or headache, local ishemia, withdrawal symptoms including dramatic BP drop, nervousness, anxiety, and insomnia
What is the mechanism of action of a2 agonists such as clonidine?
post-synaptic a2 receptors in the solitary tract of the midbrain are activated, decreasing CNS sympathetic outflow and tone
What is the major difference between a-methyl dopa and clonidine?
a-methyl dopa is a prodrug while clonidine is innately active
What is the major indication of B1 agonists?
cardiac stimulation (according to Dr. Brown this is of limited effect due to pre-existing unfixable heart damage)
What is the major indication of B2 agonists?
Smooth muscle relaxation including in asthma and uterine relaxation (i.e. to halt premature labor)
Which beta adrenergic receptors are found in the heart?
B1, B2, and very low levels of B3
What are the side effects of beta agonists?
cardiac arrhythmia (B1 activation) and vasodilation (B2-selective) leading to tachcardia
What are the 3 classes of adrenergic blockers?
alpha, beta, and nerve-ending blockers
Name the two first generation beta blockers. What is their selectivity?
Propranolol (most important) and Timolol; B1 and B2 non-selective
Why are B1 blockers more desirable than B2 blockers?
B1 blockers have heart-specific effects, but a B2 blocker can induce an asthma-like attack
What are the two second generation beta blockers? What is their selectivity?
Atenolol and Metoprolol; B1 selective
What is the meaning of ‘third’ generation beta blockers?
additional actions are seen beyond beta blocking (B1/B2 or B1 only)
List additional properties of third generation beta blockers.
NO production, B2 agonism, a1 antagonism, Ca entry blockers, K channel openers, antioxidants
What are the two major 3a generation beta blockers? What is the major additional action?
Labetalol and Carvedelol; B1/B2 non-selective with a1 antagonism
Why do beta blockers help hypertension?
Who knows? Possible actions on renin (antagonist), norepinephrine control, NO production, a1 blocking, Ca entry blocking, K channel opening (Note that the JGA produces renin and beta blockers always work in patients with high renin levels)
What is the effect of activation of pre-synaptic beta receptors?
Increase in norepinephrine release (a beta blocker would inhibit this effect)
What major disease etiologies are treated with beta blockers?
hypertension, arrhythmia, angina, glaucoma, migraine, stage fright, congestive heart failure
Are beta blockers contraindicated or first line therapy for heart failure patients?
Both. By weaning in a beta blocker, you can slow down the hypersympathetic tone and reduce stress on the heart. The dose must be titrated, but if done properly it is highly effective.
Which beta blockers should be used in heart failure patients?
second and third generation only to limit general beta blocking effects
