Adrenergic Antagonists

Question 1

effects of binding alpha1 receptors

Answer 1

contraction of arterial, venous and visceral smooth muscle

Question 2

effects of binding alpha2 receptors

Answer 2

suppression of sympathetic output, increased vagal tone, platelet aggregation, inhibition of the release of NE and ACh fron nerve endings, regulation of metabolic effects.

Question 3

what are the effects on alpha-AR antagonists?

Answer 3

decreased BP by relaxation of arteriolar and venous tone which decrease peripheral vascular resistance

reverses the vasopressor effects of epinephrine - epinephrine reversal

relieves urinary symptoms of BPH by blockade of alpha1 AP

Question 4

what are some reasons to use the epinephrine reversal phenomenon?

Answer 4

.

Question 5

what are the adverse effects of alpha AR antagonists?

Answer 5

orthostatic hypertension - prevention of venoconstriction

reflex tachycardia

sedation, depression, miosis, nasal stuffiness, increase GI tract motility and diarrhea, and impaired retention

Question 6

what type of drugs interact with alpha-AR antagonists?

Answer 6

peressors

phosphodiesterase-5 inhibitors: potentiates the effect causing hypotensive

alpha-adrenergic receptor antagonists - enhances hypotensive effects of other antihypertensive drugs.

combinations of antihypertensive drugs with different MOA are used to manage BP

Question 7

what are the non-selective alphaAR antagonists?

Answer 7

phenoxybenzamine

phentolamine

Question 8

phenoxybenzamine

Answer 8

irreversible alpha-adrenergic antagonist

used preoperatively for pheochromocytoma and urinary retention

Question 9

phentolamine

Answer 9

competitive nonselective alpha-adrenergic antagonist

effect - brief antagonism of circulating Epi and NE

uses:
diagnosis of pheochromocytoma
control BP in patients undergoing surgery for pheochromocytoma, reversal of the extravasation of Epi, NE, dopamine and phenylephrine, reversal of dental anesthesia (any one that has a vasoconstrictor)

Question 10

selective alpha1 R antagonists

Answer 10

Prazosin

Terazosin

Doxazosin

alfuzosin

tamsulosin

silodosin

Question 11

therapeutic uses and effects of selective alpha1 AR antagonists

Answer 11

potency is similar among alpha1 R subtypes

used for hypertension - relaxes arerial and venous smooth muscel which decreases TPR and pre/afterload

benign prostatic hyperplasia
relax smooth muscle in bladder neck and prostate improving urine flow

Question 12

adverse effects of selective alpha1 AR antagonists?

Answer 12

exhibits a first dose effect of orthostatic hypotension -> common cause of falls - palpitations, tachy, dizziness, light-headedness and syncope

intraoperative floppy iris syndrome during cataract surgery

rare - priapism

Question 13

Prazosin

Answer 13

alpha 1 receptor blocker - Quinazoline

given oral with 50-70% bioav, binds plasma proteins, hepatic metabolism, fecal excretion, 2-3 x daily dosing

Relax both arterial and venous vascular smooth muscle decreases peripheral vascular re-
sistance and venous return to the heart leading to a decreased cardiac preload and afterload

used for hypertension and BPH

orthrostatic hypotension

Question 14

tamsulosin

Answer 14

relatively selective alpha1 receptor antagonist - treatment of BPH

first dose effect occurs less commonly with this drug

can cause abnormal ejaculation

Intraoperative floppy iris
syndrome

contraindicated in pts with sulfonamide allergy due to ignorance

Question 15

Yohimbine

Answer 15

from yohimbe bark

competitive alpha2 AR antagonist

increases blood pressure and heart rate

enhances motor activity - tremors

secual stimulant, mood stimulant

Question 16

yohimbine adverse effects

Answer 16

tachycardia and hypertension

nausea, vomiting, anorexia, salivation

tremors, diaphoresis

headache, agitation, anxiety and irritability

remember alpha2 is a G-inhibitory PCR, decreasing it’s activity increases sympathetic surge.

Question 17

types of beta blockers

Answer 17

classic nonselective beta blockers

beta1 selective

nonselective beta blockers with additional actions

selective beta1 blockers with additional actions

Question 18

what are the additional actions associated with some nonselective and selective beta blockers?

Answer 18

Additional actions include α
ARs block, β oxide (NO) production, block Ca2+ entry, open K+ channels, or possess antioxidant properties; these additional properties may offer therapeutic
advantages

Question 19

how do beta blockers modulate epinephrines effects?

Answer 19

blood pressure still increases because vasoconstriction functions have not been blocked (alpha1 R effect)

HR and cardiac contractile force are not increased because the beta blocker blocked epi from binding beta R

Question 20

therapeutic uses of beta blockers

Answer 20

hypertension

ischemic heart disease

myocardial infarction

congestive heart failure

arrythmias

glaucoma

hyperthyroidism (disease causes excess beta R on heart)

Pheochromocytoma - alpha blockers needed as well

portal hypertension

migraines

situational anxiety

Question 21

adverse effects of beta blockers

Answer 21

bradycardia, insomnia, fatigue, depression, bronchospasm (COPD, asthma pts), sexual dysfunctions

crosses placenta

Question 22

what happens with abrupt discontinuation of beta blockers?

Answer 22

abrupt discontinuation of beta blockers can cause a drastic increase in BP and can cause severe angina, myocardial
infarction or ventricular
arrhythmia, and may
increase the risk of sudden
death.
-body upregs receptors during course of drug treatment

Question 23

what relationship is seen between beta blocker and diabetes mellitus patients?

Answer 23

beta blockers can hide the warning symptoms of hypoglycemia and inhibits reflex hepatic production of glucose

hypoglycemia can be very serious

Question 24

what drugs do beta blockers interact with?

Answer 24

decreases absorption of chelators

CYP inducers or inhibitors

calcium channel blockers

other antihypertensives

NSAIDS

Question 25

propranolol

Answer 25

lipophilic and enters CNS

given orally with an extensive first pass effect

affinity for beta 1 and 2 R

used for angina, MI, arrhythmias, pheochromocytoma;
thyrotoxicosis; prophylaxis of migraine; parkinsonian tremors;
prophylaxis of esophageal variceal hemorrhage; others