文档介绍：Chapter 11
Adrenoceptor Blocking Drugs
Pharmacology
Instructor : Lei Linsheng 雷林生
The major pharmacologic effects of adrenoceptor blocking drugs are to occupy either α1,α2, or βreceptors outside the central nervous system and prevent their activation by catecholamines and related agonists.
Since these drugs block adrenergic receptors, they are also called sympatholytics or antiadrenergic drugs
α–Adrenoceptor blocking drugs
block α–receptor, antagonize the effects of α-agonists
after pretreatment with
α-antagonist -- Adr produces a decrease in BP– called “epinephrine reversal”
Adr
NA
ISO
Catech-lamine
control
After -blocker
After - blocker
200
100
0
200
100
0
200
100
0
Phenoxybenzamine 酚苄明
an agent related to the nitrogen mustards, forms a reactive ethyleneimonium 乙撑亚胺离子 intermediate that covalently binds to αreceptors.
乙撑亚胺
ethylenimine;
aziridine
亚胺 imine
亚胺离子
iminium
(immonium)
onium 鎓
分子中含有碳-氮双键的化合物。通式R2C=NR′,其中R和R′可以是烃基或氢。
binds to αreceptors producing irreversible blockade (14-48 hs)
long duration of action
slow onset of effect
Phenoxybenzamine 酚苄明
Pharmacological actions
antagonizes αreceptor
blocks vasoconstriction induced by catecholamines
but little fall in blood pressure in hypertension patients.
increases cardiac output
-- reflex effects
-- blockade of presynapticα2
Uses
Pheochromocytoma(嗜铬细胞瘤)
hypertensive crisis
A usually benign tumor of the adrenal medulla or the sympathetic nervous system in which the affected cells secrete increased amounts of epinephrine or norepinephrine.