Adrenoceptor antagonist drugsAdrenoceptor antagonist drugs
Department of pharmacology
Zhu ling (朱玲 )
2010.3
Adrenoceptor antagonist drugsAdrenoceptor antagonist drugs
Adrenoceptor antagonist drugs ( Adrenoceptor blocking drugs )
A kind of drugs that can combine to adrenoreceptor and have little or no mimic action of NA , but prevent the receptor activation by adrenergic transmitter and related agonist.
According to receptor selectivity, it can be classified to three groups.
Adrenoceptor antagonist drugsAdrenoceptor antagonist drugs groups drugs
αreceptor antagonist
α1 α2 R antagonist phentolamine phenoxybenzamine
α1 R antagonist Prazosin, terazosin
α2 R antagonist yohimbine
β receptor antagonist
β1 β2 R antagonist Propranolol, timolol, pindolol
β1 R antagonist Atenolol, metoprolol
β2 R antagonist butoxamine
αβ receptor antagonist labetalol
αreceptor antagonistαreceptor antagonist αreceptor antagonist may be reversible or irreversible
in their inter action with these receptor. classification : short-duration group phentolamine 酚妥拉明 tolazoline 妥拉唑啉 Prazosin and analogs
reversible antagonists
long-duration group phenoxybenzamine酚苄明 irreversible antagonist
αreceptor antagonistαreceptor antagonisteffect
1 blood vessels and blood pressure
block α receptor
direct relaxes blood vessels muscle
vasodilation blood pressure
epinephrine reversal
2 heart reflex cardiac stimulation
presynapseα2 R blocking , negative feedback
αreceptor antagonistαreceptor antagonist
3 others cholinomimetic and histamine-like effect (short-duration agents)
blocking Ach, histamine and serotonin (5-HT) receptors ( phenoxybenzamine )
αreceptor antagonistαreceptor antagonist
Therapeutic application :① peripheral vascular disease (raynaud’s
disease)② inadvertent infiltration of NA into
subcutaneous during intravenous administration
③ shock cardiac stimulation④ prostate hyperplasia⑤ preoperative management of patients with
pheochromocytoma ⑥ hypertensive emergencies
αreceptor antagonistαreceptor antagonist
Adverse reaction :① prostural hypotension
② reflex tachycardia, arrhythmia
③ diarrhea, gastrointestinal stimulation, etc
β β receptor antagonistreceptor antagonist
A kind of drugs share the common feature of antagonizing the effects of catecholamine at βadrenoceptors, high selectivity occupy β adrenoceptors and competitively reduce receptor occupancy by catecholamines and other βagonists.
pure antagonist partial antagonist
β receptor antagonistβ receptor antagonistthe process in the bodythe process in the body
high lipid-solubility low lipid-solubility
Propranolol metoprolol timolol
Atenolol pindolol nadolol acebutolol
Well absorption Limited absorption
Low bioavailability No obviously first-pass elimination
Half life short Half life long
Plasma concentrations: great individual variability
Plasma concentrations: relatively invariableness
hepatic metabolism Excreted unchanged in the urine
β β receptor antagonistreceptor antagonistPharmacodynamics1 β blockade effects
1) heart inhibition
2) blood vessels peripheral resistance↑
3) blood pressure chronically lower
β blockade – reduce cardiac output
presynaptic membranes β blockade effects
CNS β blockade effects
antagonize the release of renin
Adrenoceptor antagonist drugsAdrenoceptor antagonist drugs
4) bronchia smooth muscles contraction 5) metabolism inhibit sympathtic nervous system stimulation
of lipolysis , partially inhibit glycogenolysis (impair
recovery from hypoglycemia, great caution in insulin-dependent diabetic patients)
anti-hyperthyroid renin release decrease
β receptor antagonist
β β receptor antagonistreceptor antagonist
2 Intrinsic sympathomimetic activity(ISA)
except blockade effect, it has partial agonistic action
3 else
local anesthetic action (membrane-stabilizing action)
anti-platelet congregate
β receptor antagonistβ receptor antagonist Therapeutic application 1 cardiac arrhythmias (tachycardia) 2 hypertension 3 ischemic heart disease (angina,resulting in
decreased cardiac work and reduction in oxygen demand, slowing and regularization of the heart rate)
4 myocardial infraction (increase stroke volume in some patients with obstructive cardiomyopathy)
5 else hyperthyroidism and crisis, glaucoma (timolol), splitting headache (brow ague), cardiomyopathy
β β receptor antagonistreceptor antagonist
Adverse reaction
1 alimentary tract and CNS effects
2 worsening of preexisting bronchial asthma
3 heart inhibition , peripheral blood vessels spasm
4 rebound phenomenon (rapid withdraw can lead to supersensitivity of receptor)