Beta Blockers

Question 1

Beta Adrenergic Receptor Antagonists

Answer 1

Disallow sympathomimetics from provoking a beta response on the heart, airway, blood vessels, JG cells, and pancreas

Question 2

BB on the Heart

Answer 2

bradycardia, decreased contractility, conduction velocity, improve O2 supply and demand balance

Question 3

BB on the Airway

Answer 3

bronchoconstriction and can provoke bronchospasm in patients with asthma or COPD

Question 4

BB on the Blood Vessels

Answer 4

Vasoconstriction in skeletal muscles; PVD symptoms (increase)

Question 5

BB on the JG cells

Answer 5

Decreased renin release (indirect way of decreasing BP)

Question 6

BB on the Pancreas

Answer 6

Decreased stimulation of insulin release by epi/NE at B2 and masks s/s of hypoglycemia beta 1

Question 7

Beta Blockers MOA

Answer 7

selective binding to beta receptors: influence on inotropy and chronotropy
competitive and reversible inhibition: large doses of agonist (epi & glucagon) can overcome block
chronic use, upregulation of receptor (dont abruptly stop, can lead to increased HR and BP)

Question 8

Nonselective BB

Answer 8

beta 1 & 2

propranolol, nadalol, timolol, pindolol

Question 9

Cardioselective BB

Answer 9

beta 1 only
metoprolol, atenolol, acebutolol, betaxolol, esmolol
large doses or repeated doses can lose selectivity

Question 10

Clinical Use of BB

Answer 10

HTN, angina, tachyarrythmias, block excessive SNS activity, pts at risk for MI, decreases mortality in tx of post MI patients

Question 11

Relative Contraindications

Answer 11

Pre-existing AV heart block or cardiac failure
Reactive airway disease
DM (without BS monitoring)
Hypovolemia

Question 12

Side Effects of BB

Answer 12

see other cards for specific systems

1. reduction in IOP d/t decreased aqueous humor production
2. N/V/D
3. fatigue, lethargy
4. inhibition of potassium uptake into skeletal muscles
5. alter carb & fat metabolism, mask hypoglycemia increased in HR

Question 13

Propranolol (prototype)

Answer 13

non-selective beta blocker (longer acting)
ADMIN WITH A GOAL OF 55-60 BPM
limited use in current anesthesia practice
concerns with chronic use: decreased clearance of amide L.A. & pulmonary clearance of fentanyl (both drugs are lipophilic amines)

Question 14

Propranolol CV effects

Answer 14

decreased HR, contractility, and CO (b1)
O2 demand lowered
increased PVR, coronary vascular resistance (b2)
reduced renin release (b1)

Question 15

Propranolol PK

Answer 15

undergoes 1st pass effect liver (90-95%)
PO dose larger than IV
PPB: 90-95%
liver metabolism: E1/2 T 2-3 hours
DECREASES CLEARANCE OF AMIDE LAs D/T DECREASE IN HEPATIC BLOOD FLOW INHIBITING LIVER METABOLISM (RISK OF SYSTEMIC TOXICITY OF AMIDE LAs)

Question 16

Metoprolol

Answer 16

B1 selective (inotropic & chronotropic) 
60% 1st pass effect 
liver metabolism, E1/2T 3-4 hours

Question 17

Atenolol

Answer 17

MOST selective B1 blocker with LEAST CNS effects
E1/2T: 6-7 hrs
no liver metabolism, excreted renally (e1/2t increased in renal disease)
advantageous to those who need beta 2 receptor activity
PO drug for HTN
long lasting

Question 18

Esmolol (breviblock)

Answer 18

RAPID ONSET AND SHORT DOA
Beta 1 Selective Blocker (used to treat HTN and tachycardia with DL)
IV only
onset: 60 seconds, DOA: 10-30 min
metabolism: plasma esterases
does not cross BBB or placenta (poor lipid solubility)

Question 19

Timolol (at home med pt may come in on)

Answer 19

nonselective BB
Use: glaucoma (decreases IOP via reduction of AH production)
eye drop admin can cause decreased HR, BP & increased airway resistance

Question 20

Nadolol (at home med pt may come in on)

Answer 20

nonselective BB (used to tx esophageal varices)
no significant metabolism (renal/biliary elim)
E1/2T: 20-40hrs take 1x daily

Question 21

Betaxolol (at home med pt may come in on)

Answer 21

Cardioselective B1 Blocker
E 1/2 T: 11-22 hrs
single dose daily for HTN
topical admin for patients with glaucoma and asthma (less bronchospasm risk

Question 22

Labetalol

Answer 22

combined alpha 1 and beta 1 & 2 blocker (slow HR and vasodilate)
IV beta to alpha block 7:1
PO beta to alpha block 3:1
metabolism: conjugation to glucuronic acid
E1/2T: 5-8 hrs (prolonged in liver disease)

Question 23

Periop use of BB

Answer 23

CV surgery: reduced risk of SVT an ventricular arrhythmias after surgery
Non CV surgery: increase in all-cause mortality and stroke with the use of BB’s

Question 24

Centrally Acting Agents MOA

Answer 24

reduce SNS outflow from VMC in brain stem.
CNS non-adrenergic binding sites and alpha 2 receptor agonism
Uses: HTN, induce sedation, decrease anesthetic requirements, improve periop hemodynamics and analgesia

Question 25

Centrally Acting Agents Side Effects & PK

Answer 25

bradycardia, sedation, dry mouth, impaired concentration, nightmares, depression, vertigo, EPS, lactation in men
PK: PO or transdermal patch, 50/50 hepatic and renal excretion

Question 26

Clonidine

Answer 26

BP reduction from decreased CO d/t decreased HR and peripheral resistance
rebound HTN with quick d/c

Question 27

Withdrawal syndrome

Answer 27

occurs with doses of >1.2 mg/day
happens 18 hours after ACUTE d/c of drug
Duration: 24-72 hours
Tx: rectal or transdermal clonidine

Question 28

Treatment of Hypotension (sympathomimetics)

Answer 28

ephedrine 
phenylephrine 
vasopressin 
epinephrine 
norepinephrine 
dopamine 
dobutamine