Rx: Beta-Blockers Flashcards
Major clinical CV indications for Beta-Blockers?
*General- all not created best for every indication
- HTN (often used w/ either a diuretic or vasodilator)
- Ischemic Heart Disease
- reduce angina freq, and improve exercise tolerance
- Decrease cardiac work, reduce 02 demand, slow + regularize HR
(Timolol, Propanolol, or metoprolol) - Supraventricular (above AV node) and Ventricular Arrhythmias
- beta blockers increase AV nodal refractory period => slow ventricular response rates in atrial flutter and fibrillation - CHF (Metoprolol ER, bisoprolol, carvedilol)
Off-target CNS effects of Beta-Blockers
- mental disorders
- Fatigue
- vivid dreams
*lipophilic agents (less common w/ hydrophilic beta-blockers)
Non-selective beta-Blockers
Nadolol
Pindolol
Propanolol
Timolol
“OLOLs” (N –>T) *except Nebivolol
Class II antiarrhythmic compounds
“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)
Off-target “glucose” effects
*Lipophillic agents
- Hypoglycemia
- beta-2 receptors stim hepatic glycogen breakdown and pangreatic glucagon release - 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
Non-CV uses of Beta-blockers
- essential tremor
- Thyrotoxicosis
- Anxiety
- Prophylactic for Migraines
- Glaucoma (topical)
- Secondary prophylactic of bleeding for esophageal varicies
Adverse effects of Sotalol (antiarrhythmic agent) overdose?
Prolongs QT interval and may cause Torsade de poimtes (specific arrhythmia) and Ventricular Fibrilation
Beta-Blockers w/ extended actions
Carvedilol
Nebivolol
Labetalol
Betaxolol
Extended Actions of Nebivolol? (2)
- Nitric Oxide (NO) production
2. Antioxidant activity
Extended action of Bextaxolol?
Ca2+ entry blocker
Location and effect of Beta-2 stimulation?
Beta-2 = Lungs
Vasodilation
bronchodilation
Extended actions of Carvedilol? (3)
- Ca2+ entry blocker
- Alpha-1 antagonist
- Antioxidant activity
Drugs w/ Intrinsic Sympathomemetic activity
- Acebutulol
- Pindolol
(partial agonists)
Given when PT can’t handle bradycardia or diminished inotropy
**Disadventageous in context of secondary prevention of MI
Extended action of Labetalol ?
Alpha-1 antagonist
Adverse effects of ISA drug overdose?
Tachycardia and Hypertension
Location and effect of stimulation of Beta-1 receptors?
Beta-1 = Heart
Increases: C.O. and BP
- Accelerated heart rate
- increase contractile force
- Increase speed of contraction
- increase conduction speed
- Renin release
- lipolysis
Adverse effects of beta-blockers with extended actions overdose?
Hypotension (via direct vasodilation)
Beta-1 selective drugs
Acebutolol Atenolol Betaxolol Esmolol Metroprolol
“OLOLs” (A –> M)
Off-target lipid profile effects of beta-blockers?
*varies by individual agent
1. increase TGs, and decrease plasma HDLs
(ISA drugs and those w/ cardio-selectivity have less effect)
General Adverse effects of Beta-blocker overdose?
General: Bradycardia and Bradyarrhythmia
*underlying CV or pulmonary disease places patient at increased risk of lethal outcome
Off-target Pulmonary effects of Beta-blockers?
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
T or F: Beta-blockers tx can be stopped abruptly
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
Adverse effects of propranolol overdose?
Seizures and coma
What is Intrinsic sympathomimetic activity
Partial agonists - provide some cardio stim but prevent excess
i.e. beta blockers that can show both agonism and antagonism
