Adrenergic Blockers

Question 1

Propranolol

Answer 1

mainly blocks B1 in heart
also blocks renin release (juxtaglomerular cells have B1)
variation in effect in large individuals (26 +/- 10% gets into blood)

Question 2

Timolol

Answer 2

doesn’t block Na+ channels

Question 3

Pindolol

Answer 3

partial agonist

less decrease in HR and BP

Question 4

Atenolol and metoprolol

Answer 4

less effects on lungs
popular
metoprolol especially good asthma and in preventing cardiovascular problems
metoprolol is excreted in urine; half life of 5h
atenolol metabolized in liver with half life of 6h

Question 5

uses of beta blockers

Answer 5

angina (decrease HR and force –> decrease work)
hypertension (initially decrease BP and CO; no postural hypotension)
cardiac arrhythmias
pheochromocytoma (during surgery)
prophylaxis of migraine (decrease pulse pressure; mainly seen in women)
prevent recurrence of heart attack
hyperdynamic circulatory states (stressful situations)

Question 6

Glaucoma

Answer 6

B blockers are well tolerated b/c they inhibit formation of aqueous humor
mostly B2 receptors in eye

However, prostaglandin analogs are drug of choice for glaucoma b/c they increase outflow through accessory uveoscleral pathway

Question 7

Precautions of B blockers

Answer 7

Asthma (not so bad with B1 specific drugs)
CNS depression - with pindolol and prpranolol (high lipid solubility) DONT USE WITH Hx OF DEPRESSION
Poor circulation - DONT USE IN PREGNANCY
Diabetes - blocks B2 to inhibit mobilization of liver glycogen; increase effect of insulin
Rebound tachycardia upon cessation of drug

Question 8

Alpha blockers

Answer 8

MOA: competitive A1 blocker; some block A2

Question 9

clinical use of alpha blockers

Answer 9

prostatic hypertrophy --> improve urine outflow
use tamulosin (Flomax) - specific for A1 receptors 

also used for high BP by dilating the arteries and veins 
use prasosin (half life of 3h) or terazosin (half life of 12h

Question 10

Phentolamine

Answer 10

A1/A2 = 4/1
can cause tachycardia
used to stop necrosis after injection of sympathomimetics that get into subcutaneous

Question 11

Precautions and side effects of alpha blockers

Answer 11

postural hypotension
nasal stufiness
impaired sex function (can’t ejaculate)
urinary incontinence

Question 12

Ergot alkaloids discovery

Answer 12

1st known adrenergic blocker
from Claviceps purpurea
can cause gangrene, angina, hallucinations, and abortions

Question 13

Ergot alkaloids activity

Answer 13

have partial agonist activity on A1 and 5HT1D receptors
Main effect is prolonged contraction of smooth muscle; acts mainly on capacitance of blood vessels

can also cause uterine smooth muscle contraction

Question 14

What are ergot alkaloids used for

Answer 14

migraines - relieved painful throbbing with each heart beat (ergotamine efficacy increased with caffeine)

Mild migraine - take aspirin
moderate - take ergot
severe - take beta blocker

also used in post partum bleeding (use ergonovine)