Rx: Beta-Blockers

Question 1

Major clinical CV indications for Beta-Blockers?

*General- all not created best for every indication

Answer 1

1. HTN (often used w/ either a diuretic or vasodilator)
2. Ischemic Heart Disease
   - reduce angina freq, and improve exercise tolerance
   - Decrease cardiac work, reduce 02 demand, slow + regularize HR
   (Timolol, Propanolol, or metoprolol)
3. Supraventricular (above AV node) and Ventricular Arrhythmias
   - beta blockers increase AV nodal refractory period => slow ventricular response rates in atrial flutter and fibrillation
4. CHF (Metoprolol ER, bisoprolol, carvedilol)

Question 2

Off-target CNS effects of Beta-Blockers

Answer 2

1. mental disorders
2. Fatigue
3. vivid dreams

*lipophilic agents (less common w/ hydrophilic beta-blockers)

Question 3

Non-selective beta-Blockers

Answer 3

Nadolol
Pindolol
Propanolol
Timolol

“OLOLs” (N –>T) *except Nebivolol

Question 4

Class II antiarrhythmic compounds

Answer 4

“2-PAC”
Propanolol
Acebutolol
Carvedilol

MOA: Bind and block fast Na+ channels responsible for rapid depolarization of fast-response cardiac action potentials (=> decrease in amplitude of action potentials)

Question 5

Off-target “glucose” effects

Answer 5

*Lipophillic agents

1. Hypoglycemia
   - beta-2 receptors stim hepatic glycogen breakdown and pangreatic glucagon release
2. Diabetics
   - beta-1 blockers mask the tachycardia that serves as a warning sign for insulin-induced hypoglycemia
   * Beta-blockers need to be used cautiously in diabetics

Question 6

Non-CV uses of Beta-blockers

Answer 6

1. essential tremor
2. Thyrotoxicosis
3. Anxiety
4. Prophylactic for Migraines
5. Glaucoma (topical)
6. Secondary prophylactic of bleeding for esophageal varicies

Question 7

Adverse effects of Sotalol (antiarrhythmic agent) overdose?

Answer 7

Prolongs QT interval and may cause Torsade de poimtes (specific arrhythmia) and Ventricular Fibrilation

Question 8

Beta-Blockers w/ extended actions

Answer 8

Carvedilol
Nebivolol
Labetalol
Betaxolol

Question 9

Extended Actions of Nebivolol? (2)

Answer 9

1. Nitric Oxide (NO) production

2. Antioxidant activity

Question 10

Extended action of Bextaxolol?

Answer 10

Ca2+ entry blocker

Question 11

Location and effect of Beta-2 stimulation?

Answer 11

Beta-2 = Lungs

Vasodilation
bronchodilation

Question 12

Extended actions of Carvedilol? (3)

Answer 12

1. Ca2+ entry blocker
2. Alpha-1 antagonist
3. Antioxidant activity

Question 13

Drugs w/ Intrinsic Sympathomemetic activity

Answer 13

1. Acebutulol
2. Pindolol
   (partial agonists)

Given when PT can’t handle bradycardia or diminished inotropy

**Disadventageous in context of secondary prevention of MI

Question 14

Extended action of Labetalol ?

Answer 14

Alpha-1 antagonist

Question 15

Adverse effects of ISA drug overdose?

Answer 15

Tachycardia and Hypertension

Question 16

Location and effect of stimulation of Beta-1 receptors?

Answer 16

Beta-1 = Heart

Increases: C.O. and BP

1. Accelerated heart rate
2. increase contractile force
3. Increase speed of contraction
4. increase conduction speed
5. Renin release
6. lipolysis

Question 17

Adverse effects of beta-blockers with extended actions overdose?

Answer 17

Hypotension (via direct vasodilation)

Question 18

Beta-1 selective drugs

Answer 18

Acebutolol
Atenolol
Betaxolol
Esmolol
Metroprolol

“OLOLs” (A –> M)

Question 19

Off-target lipid profile effects of beta-blockers?

Answer 19

*varies by individual agent
1. increase TGs, and decrease plasma HDLs
(ISA drugs and those w/ cardio-selectivity have less effect)

Question 20

General Adverse effects of Beta-blocker overdose?

Answer 20

General: Bradycardia and Bradyarrhythmia

*underlying CV or pulmonary disease places patient at increased risk of lethal outcome

Question 21

Off-target Pulmonary effects of Beta-blockers?

Answer 21

Beta-2 receptors have important role in tx of bronchospasm of asthma and COPD

• NON-SPECIFIC Beta-Blockers CONTRAINDICATED in asthmatics and caution in COPD patients
• *Selective Beta-Blockers should also be cautioned in the PTs due to dose-related cross-over to beta-2 receptors

Question 22

T or F: Beta-blockers tx can be stopped abruptly

Answer 22

False

Abrupt discontinuation of beta-blocker tx is ill advised. Doses should be tapered over time

*Upregulation in beta-receptor expression can lead to rebound and life-threatening cardiotoxic effects

Question 23

Adverse effects of propranolol overdose?

Answer 23

Seizures and coma

Question 24

What is Intrinsic sympathomimetic activity

Answer 24

Partial agonists - provide some cardio stim but prevent excess

i.e. beta blockers that can show both agonism and antagonism