Sympatholytic pharmacology Flashcards
(62 cards)
orthosteric
site where NE binds directly to block the ability of the agonist to bind
allosteric
not binding directly to site where NE binds, but blocks binding at another site
side effects of alpha1 receptor antagonists
orthostatic hypotension, inhibition of ejaculation, nasal stuffiness, tachycardia
What kind of agonist is Phenoxybenzamine (Dibenzyline)?
non-selective alpha receptor antagonist
What else does Phenoxybenzamine block?
acetylcholine, histamine, and serotonin receptors
What kind of antagonist is Phenoxybenzamine?
irreversible antagonist resulting from covalent modification of receptor
When would you use Phenoxybenzamine?
not used anymore
historically was used in HTN crisis and pheochromocytoma
What type of antagonist is Phentolamine (Regitine)
non-selective alpha receptor antagonist
competitive/reversible blocker
muscarinic and histamine receptor agonist
What kind of effects does Phentolamine produce?
potent vasodilation, but induces pronounced reflex tachycardia
What does Phentolamine block?
blocks presynaptive alpha2 receptors (may promote release of NE) and 5-HT receptors
Quinazolines
Prazosin, Terazosin, and Doxazosin
What kind of antagonists are quinazolines?
alpha-1 adrenergic receptor antagonists
What do quinazolines do?
vasodilators, relaxation of smooth muscle in enlarged prostate and in bladder base
How do the three quinazolines vary?
Vary in half-life:
Prazosin - 3 hours
Terazosin - 12 hours
Doxazosin - 20 hours
Describe the “first dose” effect of quinazolines
orthostatic hypotension occurs with the first dose, but you’ll become tolerant over the first 24 hours
What kind of receptor antagonist is Yohimbine (Yocon)?
alpha2-adrenergic receptor antagonist
What does Yohimbine do?
blockade of alpha2 receptors increases sympathetic discharge, off the market, doesn’t really do anything, used in herbal supplements
Aryloxypropanolamines are what kind of drugs?
beta blockers
Propranolol
non-selective beta blocker, lipophilic (CNS penetration), local anesthetic properties (Na+ channel blocker), first gen but still used a lot
Therapeutic uses for beta-adrenergic receptor antagonists
hypertension, angina, cardiac arrhythmias, migraine, stage fright, thyrotoxicosis, glaucoma, congestive heart failure (types II and III)
Pharmacological effects of beta blockers
decreased cardiac output and heart rate, reduced renin release*, increase VLDL, decrease HDL, inhibit lipolysis, increase bronchial airway resistance, inhibit compensatory glycogenolysis and glucose release in response to hypoglycemia
Non-selective beta-adrenergic receptor antagonists
Propranolol, Nadolol, Timolol, (Pindolol, and Carteolol)
Uses of Nadolol
hypertension, angina, migraine
How is Nadolol different from propranolol?
less lipophilic than propranolol
