Autonomic Antagonists

Question 1

What is atropine?

Answer 1

Competitive antagonist for muscarinic receptor’s ACh binding site (ie parasympathetic antagonist)

Question 2

What does atropine do to the HR?

Answer 2

inc

Question 3

What does atropine do to the AVN refractory pd

Answer 3

dec

Question 4

What does atropine do to arteriolar vasodilation

Answer 4

dec

Question 5

What do we use atropine clinically for?

Answer 5

• Interrupt or prevent a vagal rxn
• Restore AV conduction in disorders that cause prolonged AV nodal refractoriness
• ->inferior wall MI
• ->Digitalis intoxication

Question 6

What would a beta 1 antagonist do?

Answer 6

• Dec HR
• Dec velocity, inc refractoriness
• Dec myocardial intotropy and metabolic rate
• Inhibit renin release

Question 7

What is prazosin?

Answer 7

Competitive alpha 1 antagonist (with a little alpha 2)

-inhibits vasoconstriction decreasing PVR and BP

Question 8

Side effect of prazosin?

Answer 8

postural hypotension

Question 9

What are doxazosin and terazosin

Answer 9

pure alpha 1 antag that have a slower onset and longer duration than prazosin

Question 10

Why does a greater lipid solubility of a drug matter?

Answer 10

Greater lipid sol=more readily penetrates BBB

Question 11

Which beta blockers are lipophilic?

Answer 11

propranolol, metoprolol (abs in GI, metab by liver, short T1/2)

Question 12

What beta blockers are hydrophilic?

Answer 12

Atenolol (longer T1/2, renal metab)

Question 13

What is propranolol?

Answer 13

Non selective beta blocker with high lipid solubility, short half life and hepatic elimination and low bioavailability

Question 14

What is metoprolol?

Answer 14

Beta 1 antagonist with moderate lipid solubility, high bioavailability and hepatic elimination

Question 15

What is atenolol

Answer 15

Beta 1 blocker with low lipid sol, 40% bioavailability and renal elimination

Question 16

What is carvedilol?

Answer 16

Non selective beta blocker with additional alpha 1 blockade, moderate lipid sol, hepatic elimination

Question 17

What CV conditions do we use beta blockers for?

Answer 17

HF, MI, Angina, Arrhythmias, hyperT

–>don’t give with complete heart block or cardiogenic shock

Question 18

Adverse effects of beta blockers

Answer 18

• Sinus bradycardia, sinus arrest AV block
• Reduced LV contractility in severe symptomatic HF
• Bronchoconstriction
• Fatigue, mental depression, nightmares, sexual dysfxn
• Raynaud’s precipitation
• Worsening of limb ischemia with severe PVD
• Withdrawal (tachy arrhythmias, angina etc because beta1 receptors become upregulated with chronic use)
• Inc TGs, dec HDL
• Can mask symptoms of hypoglycemia in diabetes

Question 19

Do we use beta blockers for cardiogenic shock?

Answer 19

NO WAY! He has to do whatever he can to maintain output, including very increased HR.

Question 20

Who are the ideal pts for beta blocker use?

Answer 20

• Physical activity induces attacks of angina
• Coexistent hyperT
• Hx of supraventricular or ventricular arrhythmias
• Previous MI
• Left ventricular systolic dysfxn
• Mild to moderate HF symptoms
• Prominent anxiety state

Question 21

Poor candidates for beta blockers

Answer 21

• asthma/lung disease
• SEVERE LV dysfxn with HF
• Hx of depression
• Raynauds
• Symptomatic peripheral vascular disease
• Brittle diabetes
• Severe bradycardia or heart block