Drugs for Cardiac - act on SNS

Question 1

Drugs that act on SNS (sympathetic nervous system)

Answer 1

Alpha 1 blockers
Alpha 2 agonists
Beta blockers (BBs)

Question 2

Alpha 1 blockers - MOA

Answer 2

1. block alpha 1 receptors on arterioles and veins
   - vasodilate arterioles = ↓ SVR (systemic vasc. resistance)
   
   • vasodilate veins = ↓ preload (venous return)
2. block alpha 1 receptors in bladder & prostate
   
   • ↓ contraction of smooth muscle in bladder neck & prostate
     = treatment for Benign Prostate Hypertrophy (BPH)

Question 3

Benign Prostate Hypertrophy (BPH)

Answer 3

• causes urinary retention
• slow flow
• alpha 1 blockers ↓ contraction of smooth muscle to aid in voiding

Question 4

Alpha 1 blockers - Side Effects

Answer 4

• postural hypotension
  = venous dilation & blood pooling => ↓ cerebral blood flow => dizzyness
  [“first-dose effect” causes the dizzyness => small initial dose then gradually ⇡ dose & administer @ bedtime]
• reflex tachycardia
  = the vasodilation => stimulates baroreceptors which stimulates SNS => ⇡ HR

Question 5

Alpha 1 blockers

Answer 5

• zosin

Prazosin (Minipress)
Terazosin (Hytrin)
Doxazosin (Cardura)
Tamsulosin (Flomax)

Question 6

Prazosin (Minipress)

Answer 6

Alpha 1 blocker

• approved for HTN
• benefit men w/BPH (benign prostate hypertrophy)

Question 7

Terazosin (Hytrin)

Answer 7

Alpha 1 blocker

- approved for HTN and BPH

Question 8

Doxazosin (Cardura)

Answer 8

Alpha 1 blocker

- approved for HTN and BPH

Question 9

Tamsulosin (Flomax)

Answer 9

Alpha 1 blocker

• approved for only BPH
• not for HTN

Question 10

Alpha 2 agonist

Answer 10

Clonodine (Catapress)

Question 11

Clonodine (Catapress) - MOA and route

Answer 11

Alpha 2 agonist
MOA - acts on brainstem
- suppresses sympathetic outflow to heart/vessels => vasodilation => ↓ BP

Route: PO, transdermal patch

Question 12

Clonodine (Catapress) - side effects

Answer 12

• bradycardia (vasodilation)

- if discontinued abruptly, causes rebound tachycardia (better to taper off drug)

Question 13

beta blockers (BB)

Answer 13

• olol drugs

selective = affect only beta 1 receptors (heart)

nonselective = block both beta 1 and 2 (lungs and arterioles of skeletal muscle) receptors

Question 14

Non-selective beta blocker

Answer 14

Propranolol (Inderal)

Question 15

Selective beta blockers

Answer 15

Metoprolol (Lopressor)
Atenolol (Tenormin)
Labetalol (Trandate, Normodyne) - alpha and beta
Esmolol (Brevibloc)
Sotalol (Betapace)
Carvedilol (Coreg)

Question 16

Propanolol (Inderal)

Answer 16

nonselective bb
blocks beta 1 receptors
- ↓ HR, contractility => ↓ CO => ↓ BP
- ↓ AV conduction

blocks beta 2 in lungs

blocks beta 2 in liver
- suppresses glycognolysis => can be detrimental for diabetic pts

Indications: HTN, angina, dysrhythmias, MI, “stage fright”

Question 17

Propanolol (Inderal) - side effects

Answer 17

CV: slow HR and contractility
- if discontinued abrubtly, can cause rebound hypertension => best to taper off drug

Lungs: bronchospasm (not good for asthma pt)

CNS: readily crosses BBB = depressed

Metabolic: can mask S/Sx of hypoglycemic reaction (inhibits glycogenolysis)

others: fatigue, ↓ libido

Question 18

Metoprolol (Lopressor) - what type of drug?

Answer 18

beta 1 selective
Minimal effects on beta 2 => preferred for asthma pts
- doesn’t cause bronchospasm (except @ higher doses)
Can be used in diabetic pt, but still need to be careful

Question 19

Metoprolol (Lopressor) - NIs and pt. education

Answer 19

check pulse daily - call provider if < 50 bpm