alpha receptor blockers/ agonists

Question 1

Doxazosin (Cardura)

Answer 1

selective alpha-1 blocker
-leaves alpha-2 mediated feedback mechanism intact

• Used to treat hypertension and BPH
• long half life

Toxicity:
orthostatic hypotension “first dose phenomenon”

Question 2

Prazosin (Minipress)

Answer 2

selective alpha-1 blocker
-leaves alpha-2 mediated feedback mechanism intact

-Used to treat hypertension and BPH

Toxicity:
orthostatic hypotension “first dose phenomenon”

Question 3

Tamsulosin (FloMax)

Answer 3

selective alpha-1 blocker

• leaves alpha-2 mediated feedback mechanism intact
• selective alpha 1a receptor blocker (bladder)
• treats hypertension and BPH
  
  • daily dosing

Adverse effect:
impaired ejaculation

Toxicity
orthostatic hypotension “first dose phenomenon”

Question 4

Phentolamine

Answer 4

alpha 1 and 2 blockade

-short half life

-used to diagnose pheochromocytoma
-short term decrease of BP by 35/25 is
highly indicative of pheo.

Toxicity:
orthostatic hypotension

Question 5

Phenoxybenzamine

Answer 5

alpha 1 and 2 blockade

-very long half life

• used for pre-op treatment of pheochromocytoma removal
  
  • protects from excessive HTN from catecholamine leakage

Question 6

Phentolamine (OraVerse)

Answer 6

alpha 1 and 2 blockade

-short half life

-used to diagnose pheochromocytoma
-short term decrease of BP by 35/25 is
highly indicative of pheo.

Toxicity:
orthostatic hypotension

Question 7

Phenylephrine

Answer 7

selective alpha-1 agonist

Indications
IV: Pressor effects

Topical: mydriatic, hemorrhoid shrinkage

Oral: nasal congestion / rhinorrhea

Toxcity:
vasoconstriction
-induced necrosis if accidentally delivered
IM/Sub-Q

Question 8

Midodrine

Answer 8

selective alpha-1 agonist

Indications
1) Orthostatic hypotension

2) Urinary incontinence (1 clamps down on urinary sphincter)

Toxicity:
urine retention
piloerection