11 - Adrenoreceptor blockers Flashcards
Adrenoreceptor antagonist classification
a blockers
- non selective
- –irreversible (phenoxybenzamine)
- –reversible (phentolamine)
- a1 selective (prazosin)
- a2 selective (yohimbine)
beta blockers
- nonselective (propanolol)
- b1 selective (atenolol)
- b2 selective (butoxamine)
PHENOXYBENZAMINE class similar drug MOA uses SE
- adrenergic antagonist a-nonselective
- none
- irrerversibly blocks a adrenergic receptors a1>a2
- pheochromocytoma (presurgical)
- orthostatic hypotension, reflex tachycardia, gi irritation, MI
forms covalent bonds with a receptors (effect lasts for several days)
PHENTOLAMINE, TOLAZOLINE class similar drug MOA uses SE
- adrenergic antagonist a-nonselective
- none
- reversibly blocks a adrenergic receptors a1>a2
- pheochromocytoma (presurgical), antidote to a1 agonist overdose, rebound hypertension
- orthostatic hypotension, reflex tachycardia, gi irritation
PRAZOSIN class similar drug MOA uses SE
- adrenergic antagonist a1 selective
- doxazosin, terazosin, tamsulosin, sildosin, alfuzosin
- selectively blocks a1 adrenergic receptors
- BPH, hypertension
- first dose orthostatic hypotension, reflex tachycardia (less chance)
tamsulosin is most selective for prostatic smooth muscle
What is the pharmacologic advantage of a1 selectivity?
reflex tachycardia is less common and less severe
isoproerenorol is NOT a beta blocker. it is a:
non-selective beta agonist
PROPANOLOL class similar drug MOA uses SE
- adrenergic antagonist b nonselective
- pindolol, timolol, labetalol, carvedilol, nadolol, levobunolol, metipranolol
- blocks b1 and b2 receptors. blocks sympathetic effects on heart and BP, reduces renin release
- angina prophylaxis, hypertension, arrhythmias, migraine, performance anxiety, hyperthyroidism
- bronchospasm, av block, heart failure, cns sedation, erectile dysfunction
masks symptoms of hypoglycemia in diabetics
carvedilol and labetalol has combined a and b blockade (may be used for pheochromocytoma)
beta blockers in diabetic patients
- masking of premonitory symptoms of hypoglycemia from insulin overdosage (tachycardia, tremor, anxiety)
- impaired hepatic mobilization of glucose
intrinsic sympathomimetic activity
- partial agonist activity
- advantage in treating patients with asthma because these drugs are less likely to cause bronchospasm
- acebutolol, pindolol, carteolol, bopindolol, oxprenolol, celiprolol, penbutolol
beta blockers with intrinsic sympathomimetic activity
pindolol, acebutolol
local anesthetic activity
- membrane stabilizing activity
- disadvantage when beta blockers are used topically in the eye
- – decreases protective reflexes
- – increases the risk of corneal ulceration
- absent from timolol and betaxolol making them useful for glaucoma
non selective beta blocker with longest half-life
nadolol
ATENOLOL class similar drug MOA uses SE
- adrenergic antagonist b1 selective
- betaxolol, esmolol, acebutolol, metoprolol, alprenolol, nebivolol
- selectively blocks b1 receptors, blocks sympathetic effects on heart and BP
- angina, hypertension, heart failure, SVT (esmolol only)
- bronchospasm (less chance), av block, heart failure, cns sedation, erectile dysfunction
masks symptoms of hypoglycemia in diabetics
selective beta blocker with shortest half-life
esmolol
flow of acqueous humor
ciliary body posterior chamber anterior chamber angle pupil anterior chamber trabecular meshwork canal of schlemm uveoscleral veins