Autonomic Drugs - Adrenergics (Krasowski) Flashcards
adrenergic receptors found in blood vessels that increase IP3, DAG, and Ca++ leading to smooth muscle contraction
α1 receptors
adrenergic receptors that are pre-synaptic, found in the brain, and when activated inhibit adenylyl cyclase and NE release
α2 receptors
what pathway do the β adrenergic receptors participate in, and what effects do they each mediate?
they all inhibit adenylyl cyclase, like the α2 receptors;
β1: increase heart rate and conduction velocity
β2: smooth muscle/bronchiole relaxation
β3: lypolysis in adipose tissue and bladder relaxation
Activation of α1 adrenergic receptors causes all of the following responses except which?
A. Mydriasis B. Vasoconstriction C. Relaxation of the bladder trigone D. Contraction of smooth muscle E. Contraction of the urinary sphincter
C. Activation of these receptors causes contraction of the bladder trigone as well as the urinary sphincter.
specific agonist of the α1 receptor that is used to treat nasal congestion, and when injected intravenously, to raise blood pressure
phenylephrine
specific agonist of the α2 receptor that is used to treat hypertension (though prone to cause rebounding) and reduces central NE release
clonidine
_____ is a specific α1 anatagonist used to treat hypertension; _____ is a specific α1 anatagonist used to treat benign prostatic hypertrophy, by relaxing the prostatic capsular smooth muscle
prazosin;
terazosin
these two nonspecific α1 anatagonists are used in the treatment of pheochromocytoma, a tumor that oversecretes catecholamines
phenoxybenzamine and phentolamine
β1 receptor agonist used in the acute setting to treat carodiogenic shock and heart failure
dobutamine
class of drugs used in the treatment of angina, hypertension and arrhythmias
β blockers (β receptor antagonists)
Activation of β2 adrenergic receptors causes all of the following responses except which?
A. Increased preload B. Muscle tremor C. Bronchodilation D. Glycogenolysis E. Vasodilation
A. These receptors when activated cause decreased preload. Remember that preload = end diastolic volume and reflects the pressure that must be overcome un the ventricle for the aortic valve to open. Vasodilation of the vessels lowers the mean arterial pressure and the amount of pressure in the ventricle needed to pump blood into the general circulation (ie, decreased preload).
short-acting β2 agonist used to treat asthma, though it nonselectively stimulates β1 receptors as well, causing cardiac symptoms
albuterol
long-acting β2 agonists, often marketed in an inhaler together with corticosteroid for chronic asthma therapy (though they carry an increased risk of asthma death)
salmeterol, formoterol, and bambuterol
fast-acting β2 bronchodilater that was taken off the market for treatment of premature labor, as it was shown to be unsafe for this use
terbutaline
nonselective β agonist which lowers peripheral vascular resistance while increasing heart rate, used primarily in the treatment of bradycardia
isoproterenol
the only clinically useful β3 adrenergic agonist, used in the treatment of overactive bladder
mirabegron
agonist of both α and β adrenergic receptors that causes a strong pressor effect followed by compensatory vagal action, and is used to raise blood pressure in an acute clinical setting
norepinephrine
agonist of both α and β adrenergic receptors that has particularly prominent effects on the heart and vascular smooth muscle, and is used to treat anaphylaxis
epinephrine. also used to treat severe asthma and cardiac arrest.
agonist of both α and β adrenergic receptors that causes a modest rise in MAP with an increase in both pulse rate and systolic pressure but a decrease in diastolic pressure
epinephrine
in addition to their uses in hypertension, angina, and heart failure, β blockers such as _____ are also indicated in the treatment of glaucoma, as they decrease aqueous humor secretion
timolol
prototype β blocker that is nonselective (blocks β1/2), whose adverse effects include problems associated with blocking the β2/3 receptors (e.g., aggravation of asthma and inhibition of glycogenolysis)
propranolol
why are selective β blockers a better choice for asthmatic and diabetic patients?
because nonselective β blockers inhibit the functions of of both the β2 receptor (blockage leads to bronchoconstriction) as well as the β3 receptor (blockage interferes with lipolysis)
Which of these drugs would NOT be safe for use in patients with diabetes?
A. Acebutolol
B. Atenolol
C. Propranolol
D. Esmolol
C. This is because propranolol is a nonselective beta blocker while the others are cardioselective β1 blockers. Nadolol would also not be a good choice (is nonselective and has long half life, ~24 hours).
2 drugs that are partial agonists of the β receptors, have ‘intrinsic sympathiomimetic activity’, and act as antagonists only if there is high adrenergic activity
Acebutolol and pindolol (not widely used)
β blockers with both α and β antagonist effects: _____ is used for managing certain forms of heart failure and ____ used for hypertension in pregnancy.
carvedilol; labetalol
Which of these drugs is NOT a selective agonist of adrenergic receptors?
A. Dobutamine B. Clonidine C. Mirabegron D. Phenylephrine E. Isoproteronol
E.
Dobutamine = β1 agonist Clonidine = α2 agonist Mirabegron = β3 agonist Phenylephrine = α1 agonist
Other nonselective agonists include the β2 agonists used in long-acting inhalers: bambuterol, formoterol, and salmeterol
