Sympatholitics

Question 1

Side effects of alpha blockade?

Answer 1

Orthostatic hypotension, reflex tachycardia, and impotence

Question 2

Absence of beta blockade with alpha blockade causes what?

Answer 2

Norepi release (tachycardia)

Question 3

What 3 drugs are reversible sympatholytics?

Answer 3

Phentolamine, yohimibine, and prazosin

Question 4

What sympatholytic is non-reversible?

Answer 4

Phenoxybenzamine

Question 5

Phenoxybenzamine and phentolamine work on what receptors?

Answer 5

alpha 1 receptors (post-synaptic) and alpha 2 receptors (pre-synaptic)

Question 6

What can phenoxybenzamine treat?

Answer 6

high BP and sweating from pheochromocytoma and essential HTN

Question 7

Typical dose of phentolamine?

Answer 7

30-70 mcg/kg IV - doesn’t last but about 10-15 minutes and creates transient BP drops.

Question 8

Does phentolamine cause para or sympathetic stimulation?

Answer 8

Parasympathetic - Increased peristalsis, abdominal pain, and diarrhea

Question 9

Continuous infusion dose of phentolamine is what?

Answer 9

0.1 - 2 mg/min - will decrease bp during intra op

Question 10

What receptor is phenoxybenzamine more potent at?

Answer 10

Alpha 1

Question 11

Onset of phenoxybenzamine?

Answer 11

60 minutes - becomes pharmacologically active one metabolized - 24 hour elimination half life

Question 12

What causes orthostatic hypotension with phenoxybenzamine?

Answer 12

Pre-existing hypertension or hypovolemia - adequate volume may not drop BP that good

Question 13

What patients cannot receive phenoxybenzamine?

Answer 13

Pregnant women - can cause hypotension and respiratory distress in baby

Question 14

Typical pre-op dose of phenoxybenzamine in patients with pheochromocytoma?

Answer 14

0.5 - 1 mg/kg PO

Question 15

What needs to take place before phenoxybenzamine can work?

Answer 15

Adequate volume

Question 16

Alpha adrenergic blockade is most beneficial in what patient population?

Answer 16

diseases with largely cutaneous vasoconstriction (raynauds) where smaller arteries that supply blood to skin are narrowed

Question 17

Where are most alpha 2 receptors found?

Answer 17

brainstem - locus ceruleus

Question 18

Pharmacological effects of alpha 2 agonists?

Answer 18

sedation, hypotension, bradycardia

Question 19

Why does alpha 2 agonists need titration?

Answer 19

Dramatic outflow of sympathetic outflow of norepi - rebound hypertension and tachycardia

Question 20

What is clonidine and how it it metabolized?

Answer 20

alpha 2 agonist; metabolized by liver but excreted in bile/feces - it is dose dependent for HR and BP control

Question 21

Typical dose of dexmedetomidine?

Answer 21

0.1 - 1.5 mcg/kg/min - half life 2 hours (most often used in ICU as sedative)

Question 22

Big risk with precedex?

Answer 22

withdrawal symptoms - wean off to prevent tachycardia, hypertension, anxiety, etc.

Question 23

What do large doses of precedex do

(0.25 - 1 mcg/kg over 3-5 minutes)?

Answer 23

vasoconstriction and bradycardia like phenylephrine - crosses over to alpha stimulation

Question 24

Why should beta blockers be continued throughout perioperative period?

Answer 24

prevent spontaneous endogenous sympathetic stimulation and increase HR, BP, workload, etc.

Question 25

Are beta blockers reversible?

Answer 25

yes - if enough beta agonist is given, it can reverse the effects of beta blockers

Question 26

What does chronic use of beta blockers do?

Answer 26

increase number of beta adrenergic receptors

Question 27

Net effects of beta 1 adrenergic stimulation?

Answer 27

increased inotropic, chronotropic, and dromotropic activity

Question 28

Percentages of beta receptors in heart?

Answer 28

B1 = 75% | B2 - 20%

Question 29

What 4 drugs are non-selective B1 and B2 antagonists?

Answer 29

propranolol, timolol, nadolol, and pindolol

Question 30

What drugs are cardio-selective B1 agonists?

Answer 30

metoprolol, esmolol, atenolol, bisoprolol, acebutolol, and betaxolol

Question 31

What is lost with big doses of beta blockers?

Answer 31

selectivity

Question 32

Why B1 antagonists with asthma?

Answer 32

no bronchoconstriction occurs with B1 antagonism

Question 33

B1 blockers drugs cause what effects on heart?

Answer 33

decreased ionotropic, chronotropic, and dromotropic properties

Question 34

When are B1 blocker effects most seen?

Answer 34

during activity - decreases myocardial oxygen consumption | (decreased ischemia and angina) and decreases workload of heart

Question 35

What is one major benefit with B1 blockers during activity?

Answer 35

slows HR - allows more coronary artery perfusion time

Question 36

What beta blocker is highly protein bound?

Answer 36

propranolol

Question 37

Why is nadolol unique?

Answer 37

prolonged duration (20-40 hours elimination half life) and permits once daily administration

Question 38

How is timolol (non-cardioselective B blocker) effective in treatment of glaucoma?

Answer 38

decreases aqueous humor production - decreases ICP

Question 39

Is timolol protein bound? what is the elimination half time?

Answer 39

Not much - 4 hour elimination half time

Question 40

What effects are seen with timolol with systemic absorption?

Answer 40

rapid absorption causing beta blockade leading to bronchoconstriction and bradycardia

Question 41

What prominent effect is seen with bisoprolol?

Answer 41

bradycardia (cardioselective B1 antagonist)

Question 42

What prominent effect is seen with nebivolol?

Answer 42

bradycardia and decreased BP (essential HTN) - is a cardioselective B1 antagonist

Question 43

How does betaxolol compare to timolol with bronchoconstriction?

Answer 43

Betaxolol (non-cardioselective B blocker) is given topically instead of timolol and does not have as much bronchoconstriction effect as timolol does

Question 44

What kind of acute patients should receive BB and why/why not?

Answer 44

Acute MI - decreases O2 consumption, workload, HR, contractility, etc. Should not be given with LV failure, bradycardia, or AV conduction delay/block

Question 45

Relative contraindications of B blockers?

Answer 45

Asthma, PVD, lung restrictive disease, and mental depression

Question 46

What endocrine patients need to be monitored with B blockade?

Answer 46

DM - mask signs of hypoglycemia

Question 47

What kind of patients having surgery should receive BB to avoid ischemia?

Answer 47

CAD, DM, LV hypertrophy, and positive stress test

Question 48

What is the single most potentially reversible factor for mortality and cardiovascular complications after surgery?

Answer 48

myocardial ischemia

Question 49

What do all beta blockers do?

Answer 49

decrease mortality

Question 50

Why is atenolol given 7 days preop and 7 days post op?

Answer 50

to prevent increased incidence of CV effects in CAD patients for up to 2 years post op

Question 51

Why give esmolol intraop?

Answer 51

wears off quickly

Question 52

What patients cannot receive beta 2 antagonists?

Answer 52

Restrictive lung disease and PVD patients