Drugs

Question 1

Phenoxybenzamine

Answer 1

noncompetitive (covalent)
LONG-LASTING

alpha1 and alpha 2 antagonist

a2 antagonism can inc. presynaptic NE release…increase CO…tempering BP lowering action

Question 2

Phenoxybenzamine indications

Answer 2

sympathetic excess secondary to pheochromocytoma, Raynaud’s phenomenon, frostbite, acrocyanosis

Question 3

Phenoxybenzamine pk

Answer 3

slow onset (several hours)
long duration (3-4 days)

Question 4

Phenoxybenzamine adverse effects

Answer 4

sinus-tach
nasal congestion
drowsiness, fatigue, weakness…
tachycardia…cardiac arrhythmias

Question 5

Phentolamine

Answer 5

short-acting
competitive antagonist
alpha1 and alpha 2 receptors

DOSE DEPENDENCY!!!!

Question 6

Phentolamine indications

Answer 6

pheochromocytoma and hypertensive emergency

Question 7

Phentolamine dose dependency

Answer 7

small dose…greater effect on a2 receptors–> increase in CV force b/c increase release of NE (positive inotropic effect dominates…inc BP

Large dose…greater effect on a1 receptors–> vasodilation and reduction BP

Question 8

Prominent feature of phentolamine

Answer 8

postural hypotension

Question 9

Phentolamine adverse effects

Answer 9

reflex tachycardia that precipitates cardiac arrhythmias

these efffects severely limit use for essential HTN