Adrenergic receptor antagonists

Question 1

highly selective alpha-1 blocker that relaxes both arterial and venous smooth muscle

Answer 1

Prazosin

Question 2

alpha-1 blockers used to treat HTN and benign prostatic hyperplasia

Answer 2

terazosin

doxazosin

tamsulosin

Question 3

Why are alpha blockers of limited use in treating HTN?

Answer 3

When alpha-2 receptors are blocked, release of NE is not regulated and can therefore further stimulate beta receptors in the heart.

These often cause orthostatic hypotension and reflexive tachycardia

Question 4

What is epinephrine reversal?

Answer 4

occurs when a patient has received an alpha blocker.

Blood pressure reversal occurs with large dose of epinephrine -> becomes a “depressor” rather than a “pressor” because of response of beta-2 receptors.

Question 5

Why are beta-blockers useful in treatment of chronic heart failure following MI and angina?

Answer 5

1. blockade of beta-1 decreases cardiac work and oxygen demand
2. beta-blockers increase the refractory period at the AV node (see increased PR interval) ► decreases ventricular response in afib and aflutter, as well as reduces ventricular ectopic beats

Question 6

Why should you use caution in giving a beta-blocker to an insulin-dependent diabetic?

Answer 6

Glycogenolysis is partially inhibited by beta-2 blockade

Question 7

Why does a beta blocker treat HTN?

Answer 7

Activation of beta-1 receptors in the kidney causes release of renin and ultimately causes increase in bp. Blockade of renin release causes decreased bp, especially since the kidney is the major regulator of blood pressure.

Question 8

What medication should you not give a beta blocker with?

Answer 8

Verapamil

Verapamil is a calcium channel blocker and severe hypotension, bradycardia, heart failure and conduction abnormalities can result.

Question 9

How does a beta blocker affect lipid profiles?

Answer 9

Elevates VLDL

Decreases HDL

Question 10

What is the advantage of using metoprolol in patients with heart failure?

Answer 10

1. it is more beta-1 selective, so it decreases renin release
2. only beta blocker with documented improvement in outcomes

Atenolol is also more selective for beta-1 than beta-2 and is preferred for use over propanolol.

Question 11

Blocks beta-1 and beta-2 equally

not for use in asthmatics

undergoes extensive first-pass effect

can be used to treat migraine headache

Answer 11

propanolol

Question 12

Beta-blockers with some alpha-1 blockade

Causes less reflex tachycardia than other alpha-1 blockers

Useful in treating HTN with heart failure

Answer 12

labetalol

carvedilol

Note: carvedilol also decreases formation of oxygen free radicals

Question 13

non-selective beta blockers

Answer 13

nadolol

sotalol

penbutolol

Question 14

Beta-1 selective blockers

Answer 14

acebutolol

atenolol

betaxolol

bisprolol

celiprolol

esmolol

metaprolol

nebivolol

Question 15

partial beta agonists that are less likely to cause bradycardia or alter lipid profiles but do provide some measure of beta blockade

Answer 15

pindolol

acebutolol

carteolol

bopindolol

oxprenolol

celiprolol

penbutolol

Note: pindolol may be safer for use with asthma

Question 16

beta blocker useful for controlling supraventricular arrhythmias & myocardial ischemia

Answer 16

esmolol

Question 17

competitve antagonism at alpha receptors

causes reflex tachycardia due to alpha-2 blockade (NE release)

Answer 17

phentolamine

Prazosine does not cause as much reflex tachycardia as phentolamine, because it is selective for alpha-1, leaving alpha-2 receptors active.

Question 18

irreversible alpha receptor blockade (covalent binding)

useful in treating pheochromocytoma

Answer 18

phenoxybenzamine

Question 19

oral selective beta-1 blocker with additional vasodilating action

Answer 19

nebivolol

Question 20

beta blockers with vasodilation activity (dual activity)

Answer 20

labetalol (oral and IV)

carvedilol (oral and IV)

nebivolol (oral)