Adrenergic Antagonists, Drug Experiments B&B

Question 1

Phenoxybenzamine versus phentolamine

Answer 1

both are nonselective alpha blockers (alpha1/2)

Phenoxybenzamine = irreversible, used in pheochromocytoma

Phentolamine = reversible

Both can cause hypotension, and subsequent reflex tachycardia

Question 2

what side effect should you be wary of with alpha blockers such as phenoxybenzamine and phentolamine?

Answer 2

can cause hypotension and subsequent reflex tachycardia

Phenoxybenzamine = irreversible, used in pheochromocytoma
Phentolamine = reversible

Question 3

nonselective alpha blocker used to treat pheochromocytoma

Answer 3

Phenoxybenzamine - binds irreversibly, which is helpful in the use of pheochromocytoma in which there are very high catecholamines (thus high HTN)

Question 4

What is the effect of phentolamine?

Answer 4

nonselective alpha blocker (alpha1/2)

Historically used to reverse “cheese effect” - when MAOi drugs were used to treat depression, they would block NT breakdown, as well as breakdown of tyramine (found in cheese)

tyramine has similar structure to dopamine, and in high quantities can cause dangerously high HTN

Question 5

what kind of drugs are prazosin, terazosin, doxazosin, and tamsulosin? What are they used to treat (2)?

Answer 5

selective alpha1 blockers used in HTN and urinary retention in BPH

Question 6

Name 4 selective alpha1 blockers used to treat hypertension and urinary retention in BPH

Answer 6

1. prazosin
2. terazosin
3. doxazosin
4. tamsulosin

Question 7

What kind of drug is mirtazapine and what is it used to treat?

Answer 7

selective alpha-2 blocker used to treat depression - affects serotonin and NE levels in CNS

Question 8

selective alpha-2 blocker used to treat depression

Answer 8

Mirtazapine

Question 9

what type of beta blockers are esmolol, atenolol, and metoprolol?

Answer 9

selective beta1 blockers

MET with ESsential ATtention
(focusing SELECTIVELY on beta1)

Question 10

what type of beta blockers are propranolol, timolol, and nadolol?

Answer 10

nonselective (beta1/2) blockers

NADa (“not”) PROPer nor TIMid
(will take anything and not afraid to speak out - will block beta 1 or 2)

Question 11

what type of beta blockers are carvedilol and labetalol?

Answer 11

beta1 + beta2 + alpha1 blockers

CARVEing out time for OTHERS (alpha1) and not LABEling (beta1 or beta 2 - doesn’t matter!)

Question 12

what kind of beta blockers are pindolol and acebutolol?

Answer 12

partial beta agonists

Partial (Pindolol) Agonists (Acebutolol)

Question 13

what are the heart rate effects of activating the following receptor types?
a. beta1
b. beta2
c. alpha1
d. alpha2

Answer 13

a. beta1 —> tachycardia
b. beta2 —> vasodilation —> reflex tachycardia
c. alpha1 —> vasoconstriction —> reflex bradycardia
d. alpha2 —> decrease NE —> bradycardia

Question 14

what is the primary determinant of systolic vs diastolic BP?

Answer 14

systolic BP - cardiac output

diastolic BP - peripheral resistance

Question 15

a drug is given which causes HR, MAP, and SBP to increase - which adrenergic receptor was activated?

Answer 15

beta1: increases HR, contractility, and CO —> main effect is to raise systolic BP

Question 16

a drug is given which increases HR but decreases MAP and DBP - which adrenergic receptor was activated?

Answer 16

beta2: vasodilator, causing diastolic BP to fall —> overall result is fall in mean blood pressure and reflex tachycardia

Question 17

a drug is given which decreases HR but increases MAP and DBP - what type of adrenergic receptor was activated?

Answer 17

alpha1: vasoconstrictor, main effect is to increase diastolic BP —> overall, rise in mean blood pressure and reflex bradycardia

Question 18

a drug is given which decreases HR and MAP - which adrenergic receptor was activated?

Answer 18

alpha2: blunts sympathetic activity, causing HR and MAP to fall

Question 19

what is the mechanism of clonidine and methyldopa used to treat hypertension?

Answer 19

alpha2 agonists: blunts sympathetic activity, causing HR and MAP to fall

Question 20

describe the effects of dobutamine on heart function (CO, HR, MAP)

Answer 20

mostly beta1 agonist —> raise CO and HR

some beta2 AND alpha1 action —> lower MAP, but only slightly

affects myocytes (inotropy) > SA node (chronotropy)

Question 21

describe the effects of dopamine and epinephrine on heart function (CO, HR, MAP)

Answer 21

beta1,beta2,alpha1 agonists

increase CO (—> increase SBP), HR, and MAP

can also increase DBP (via alpha1) but dose dependent

Question 22

describe the effects of norepinephrine on heart function (CO, HR, MAP)

Answer 22

alpha1&raquo_space;> beta1 agonist
—> major effect is increased TPR (increased DBP + increased MAP)

some increase in HR via beta1 + some decrease in HR via reflex bradycardia = no change in HR

CO usually increases via beta1 (rise in SBP)

Question 23

describe the effects of isoproterenol on heart function (CO, HR, MAP)

Answer 23

beta1 and beta2 agonist

—> increase HR, CO, and SBP via beta1
—> decrease MAP via beta2 (lower DBP + reflex tachycardia)

lower DBP + higher SBP = increase in pulse pressure (difference between)

Question 24

describe the effects of phenylephrine on heart function (CO, HR, MAP)

Answer 24

alpha1 and alpha2 agonist

vasoconstriction via alpha1 —> increased TPR (increased DBP + MAP)
—> reflex bradycardia

more afterload —> decrease CO

so overall: lower CO, lower HR, INCREASE MAP

Question 25

Drug A = increase HR + increase MAP

Drug A + Drug B = increase HR + decrease MAP

what are drug A and B?

Answer 25

Drug A = epinephrine - agonist of beta1, beta2, alpha1

Drug B = phenoxybenzamine - blocks alpha1

therefore, beta2 effects dominate, lowering BP

this is called “epinephrine reversal”

Question 26

Drug A = decrease HR + increase MAP

Drug A + B = no change (neutral) HR and MAP

what are drug A and B?

Answer 26

Drug A = phenylephrine - alpha1 agonist causes increase in MAP and reflex bradycardia

Drug B = phenoxybenzamine - alpha1 blocker, reverses the effects of phenylephrine