PDA Block 1 Adrenergic Antagonists (Sympatholytics) Adrenergics Blockers

Question 1

Reserpine

Note: Lipophilic= can penetrate CNS and PNS

Answer 1

Receptor: Adrenergic neuron blocker
Target Organ: CV, CNS
Effects: Depletes Adrenergic nerves NTs by inhibiting vesicular mono amines transporters 2VMAT2
= dopamine not sequestered in vesicles.
Uses: Anti-HTN (not commonly used)
Side Effect: Orthostatics hypotension
sexual dysfunction
CNS depression (suicidal)

Question 2

Phenoxybenzamine

Shorten duration of soft tissue anesthesia produced by local anesthetic or Sypathomimetics

Answer 2

Receptor: blocks a1, a2
Target Organ: CV
Effects: irreversible antagonist= long duration (days) vasodilation
Vasodilation proportional to SNS tone.

Use : Pheochromocytoma (hormone secreting tumor of adrenal gland)
Side Effect: Tarchycardia and Salt/water retention
Orthostatic Hypotension

Question 3

Phentolamine

Answer 3

Receptor: blocks a1, a2
Target Organ: CV
Effects: reversible antagonist= short duration vasodilation
Block can be overcome by increase agonist

Use : Pheochromocytoma (hormone secreting tumor of adrenal gland)
HTN
Side Effect: Tarchycardia and Salt/water retention
Orthostatic Hypotension

Question 4

Prazosin

Answer 4

Receptor: blocks a1
Target Organ: CV, prostate & Bladder
Effects: Selective competitive antagonist
Decrease Vascular Resistance, decrease Capacitance of Vein
Produce favorable Lipid profile (low LDL, high HDL)

Use : HTN short term
CHF tx. Decrease preload and after load
Benign Prostate Hyperplasia (BPH)- relax a1 mediated contraction of prostate and bladder neck.

Side Effect: minimal Tarchycardia (does not block a2)
First Dose Phenomena (hypoten,& syncope)
Orthostatic Hypotention and salt/water retention

Question 5

Guanadrel

Similar drug- guanethidine bretylium (IV)

Answer 5

Receptor: Adrenergic Neurons Blocker
Target Organ: CV
Effect: Taken up via NE transporter (NET), depletes NE from storage
Use: Anti-HTN (essential)

Side Effect: Orthostatic Hypotension, sexual dysfunction
Interaction: cocaine,
Tricyclics anti-depressants- blockade of NET inhibits action

Question 6

Tamsulosin

Silodosin: a1A> a1B- use for BPH

Answer 6

Receptor: blocks a1 ( a1A antagonist)
Target Organ: Prostate & Bladder
Effects: tx. BPH with little effect on BP

Use : BPH
Side Effect: N/A