Antiadrenergics

Question 1

What is phentolamine?

Which receptors it selective for?

What is its effect on the receptor?

Answer 1

Non-selective, competitive α antagonist

• short acting
• does not covalently bind

Question 2

What are the expected effects of phentolamine?

Answer 2

Vasculature:

• vasodilation (-α₁) -> desceased BP -> reflex tachycardia
• orthostatic hypotension

Nerves/Heart:

-decreased modulation of NE release (-α₂) -> NE stimulation of β₁ -> tachycardia

Question 3

What is phenoxybenzamine?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 3

Non-competitive α antagonist

• long acting
• covalently binds receptor

Question 4

What are the expected effects of phenoxybenzamine?

Answer 4

Vasculature:

• vasodilation (-α1) -> desceased BP -> reflex tachycardia
• orthostatic hypotension

Nerves/Heart:

-decreased modulation of NE release (-α2) -> NE stimulation of β1 -> tachycardia

Question 5

What is a common suffix for alpha-1 blockers?

Answer 5

“-osin”

Question 6

What is prazosin?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 6

Selective α₁ antagonist

Question 7

What are the expected effects of prazosin?

Answer 7

Vasculature:

• vasodilation (-α₁) -> decreased BP
• less risk for tachycardia due to α₁ selectivity

GU:

-relaxation of prostate smooth muscle (-α₁) -> decreased urethral resistance -> increased urine flow

Question 8

What is tamsulosin?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 8

Selective α₁ antagonist

(specifically a subtype predominatley found in the prostate)

*trade name is flomax

*BPH

*kidney stones

Question 9

What are the expected effects of tamsulosin?

Answer 9

GU:

-relaxation of prostate smooth muscle (-α₁) -> decreased urethral resistance -> increased urine flow

Vasculature:

-less low BP effect due to specificity for subtype of α₁ found in prostate

Question 10

What is doxazosin?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 10

Selective α₁ antagonist

Question 11

What are the expected effects of doxazosin?

Answer 11

Vasculature:

• vasodilation (-α₁) -> decreased BP
• less risk for tachycardia due to α₁ selectivity

GU:

-relaxation of prostate smooth muscle (-α₁) -> decreased urethral resistance -> increased urine flow

Question 12

What is a common suffix for beta-blockers?

Answer 12

“-olol”

Question 13

What is labetalol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 13

Non-selective, partial β agonist/selective α₁ antagonist

Question 14

What is carvediolol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 14

Competitive, non-selective β/selective α1 antagonist

Question 15

What is propanolol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 15

Non-selective β antagonist (beta-blocker)

Question 16

What is pindolol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 16

Non-selective β partial agonist (beta-blocker)

Question 17

What is nadolol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 17

Non-selective β antagonist (beta-blocker)

Question 18

What is metoprolol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 18

Selective β1 inverse agonist (beta-blocker)

Question 19

What is betaxolol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 19

Selective β1 inverse agonist (beta-blocker)

Question 20

What is acebutolol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 20

Selective β₁ partial agonist (beta-blocker)

Question 21

What is atenolol?

Which receptors is it selective for?

What is its effect on the receptor?

Answer 21

Selective β1 antagonist (beta-blocker)

Question 22

Which beta-blockers are non-selective?

Answer 22

• propanolol
• pindolol
• nadolol

Question 23

Which beta-blockers are β₁ selective?

Answer 23

• metoprolol
• betaxolol
• acebutolol
• atenolol

Question 24

What are the expected effects of non-specific beta-blockers?

Answer 24

Cardiovascular:

• decreased force and rate of contraction (decreased cardiac work and oxygen demand, -β₁)
• decreased AV conduction velocity (decreased arrhythmia risk, -β₁)
• initial elevation of BP (vasoconstriction, -β₂), eventual decreased BP (decreased renin, -β₁)

Lungs:

-increased airway resistance (-β₂​)

Metabolic:

• inhibit lipolysis (-β₂)
• inhibit gluconeogenesis/glycogenolysis (-β₂​) -> hypoglycemia

Eyes:

-decreased aqueous humor production (-β₂​)

Question 25

What are the expected effects of selective β₁ beta-blockers?

Answer 25

_Cardiovascular:_ - decreased force and rate of contraction (**decreased cardiac work and oxygen demand,** -β₁) - decreased AV conduction velocity (**decreased arrhythmia risk,** -β₁) - **eventual decreased BP** (decreased renin, -β₁)

Question 26

Which beta-blockers are antagonists?

Answer 26

PAN - propranolol (β non-selective) - atenolol (β₁ selective) - nadolol (β non-selective)

Question 27

Which beta-blockers are partial agonists?

Answer 27

PAL - pindolol (β non-selective) - acebutolol (β₁ selective) - labetolol (β non-selective/α₁ selective)

Question 28

Which beta-blockers are inverse agonists?

Answer 28

- metroprolol (β1 selective) - betaxolol (β1 selective)

Question 29

What is the signicifant difference between antagonisitic, partially agonistic, and inversely agonistic beta-blockers?

Answer 29

In order, partial agonists, antagonists, and inverse agonists have: - **increased risk for bradycardia** - increased VLDL/HDL ratio

Question 30

What is the risk of abrupt discontiunation of beta-blockers?

Answer 30

Long-term beta-blocker use upregulates β receptor expression. When beta-blocker use is discontinued, endogenous agonists have increased receptors available leading to exagerated response resulting in **tachycardia and possible arrhythmia**.

Question 31

What advantages do selective β₁ blockers have over non-selective beta-blockers?

Answer 31

Loss of the potentially harmful effects from blockade of the β₂ receptor such as: - risk of **bronchospasm**/asthma exacerbation due from bronchoconstriction - risk of **hypoglycemia** from inhibition of gluconeogenesis and glycogenolysis

Question 32

What does quanethidine do?

Answer 32

NE release inhibitor -\> indirect antiadrenergic

Question 33

What does metyrosine do?

Answer 33

inhibits **tyrosine hydroxylase**, preventing dopamine synthesis -\> antiadrenergic effect

Question 34

What **antiadrenergics** would be most effective in treating **pheochromocytoma**?

Answer 34

Pheochromocytoma - adrenal tumor producing large amounts of catecholamines - **phentolamine** (non-specific α antagonist) - **phenoxybenzamine** (non-specific α antagonist) - **metyrosine** (indirect antiadrenergic)

Question 35

What **antiadrenergics** would be most effective in treating **chronic hypertension**?

Answer 35

**selective α₁ antagonists** - **prazosin** - **doxazosin**

Question 36

What **antiadrenergics** would be most effective in treating **PBH**?

Answer 36

-**tamsulosin** (increased specificity for smooth muscle of prostate)

Question 37

What **antiadrenergics** would be most effective in treating **heart failure**?

Answer 37

- metoprolol - carvedilol

Question 38

What **antiadrenergics** would be most effective in treating **glaucoma**?

Answer 38

-betaxolol

Question 39

What **antiadrenergics** would be most effective in treating side effects of **hyperthyroidism**?

Answer 39

-propanolol