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Adrenoceptor blocking drugs

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					                        Adrenoceptor blocking drugs
                             (Adrenoceptor antagonists)
                             Section 1 α-R antagonists
Basic actions
1.CVS effects
(1) α1-R antagonistic effects:
Endogenous CA blockage: Postural hypotension
Exogenous CA blockage: “adrenaline reversal”


 (2) α2-R antagonistic effects:
presynaptic 2 antagonism –NE release
2.other effects
(1) prostate α1-R antagonism: dilation
(2)insular α2-R antagonism: insulin release
[Classification]
 .
Ⅰ α1, α2-R antagonists
1.short-term acting: competitive antagonists
   Phentolamine(酚妥拉明), tolazoline (妥拉唑啉)
2. long-term acting: noncompetitive antagonists
   Phentoxybenzamine(酚苄明)


 .
Ⅱ α1-R antagonists: prazosine(哌唑嗪)
 .
Ⅲ α2-R antagonists: yohimbine(育亨宾)


α1, α2-R antagonists
phentolamine (酚妥拉明,苄胺唑啉,regitine,立其丁)
[pharmacological actions]
1.vessels : dilation; BP ↓
“reversion of adrenaline’s action”
Mechanism: (1) direct action
             (2) α1-R blockade
2.heart: excitation, CO ↑ HR ↑
3.other effects: cholinergic action
                  histamine-like action
[clinical uses]
1. peripheral vasospasmatic disorders:
eg.Raynaud’s syndrome(雷诺氏综合征), Buerger’s disease(伯格氏病,血管闭塞
性脉管炎)
2. local vasoconstrictor excess (eg, NA)
3. shock
4. CHF and AMI
5. diagnosis and treatment of pheochromocytoma
6.others: male sexual dysfuction
[adverse reactions]
1.cardiovascular reaction:
Postural    hypotension, tachycardia, angina, arrhythmia
2.gastrointestinal reaction: stomachache, diarrhea, vomiting, ulceration
3.histamine-like reaction


Tolazoline(妥拉唑啉)
Characteristics (compared with phentolamine )
      weaker in a antagonism,
      stronger in cholinergic and histaminergic effects.


phenoxybenzamine(酚苄明) Noncompetitive antagonism
[Pharmacokinetics]: Slow onset(1h), and long duration(3-4d)
[pharmacological actions]
1.α1-R antagonistic effects : slow, strong and long.
2. 5-HT and HA-R antagonistic effects
[clinical uses]
1. peripheral vasospasmatic disorders
2. pheochromocytoma
3. shock
4. Urinary obstruction caused by benign prostatic hyperplasia
[adverse reactions]
Postural hypotension, tachycardia (palpitation), arrhythmia, nasal congestion,
CNS inhibition


α1-R antagonists
Prazosin(哌唑嗪)
Terazosin(特拉唑嗪)
Doxazosin(多沙唑嗪)
【Clinical uses]
1. HBP
2. CHF
3. prostatic hyperplasia:


α2-R antagonists
Yohimbine (育亨宾)
uses
1. tool agent for research
2. impotence (阳痿):痿必治


                            Section 2 β-R antagonists
classification
1.β1,β2-R antagonist
   1A:Propranolol(普萘洛尔), Timolol(噻吗~)
   1B:pindolol(吲哚~)
2.β1-R antagonist
   2A:atenolol(阿替~) , metoprolol(美托~)
   2B:Acebutolol(醋丁~)
3. α, β -R antagonist
       Labetalol(拉贝~)
Intrisic sympathomimeticactivity, ISA; partial agonistic activity, PAA
[Characteristics of Pharmacokinetics]
[basic actions]
1. β-R blocking action:
1) cardiovascular effects:
      heart : depression
      vessels: contraction
      BP
2)bronchial smooth muscle
3)metabolism
4)renin release↓
2.intrinsic sympathominetic activity(ISA)
3.membrane stabilizing action: in large dose
4.other effects:
         antiplatelet aggregative(propranolol)
         ↓intraocular pressure (timolol)
[clinical uses]
1.arrhythmias
2. hypertension
3. angina pectoris, myocardial infarction
4.CHF
5.others: hyperthyroidism, glaucoma, pheochromocytoma
[adverse actions]
1.Common reactions
2. bronchial asthma
3. cardiovascular reaction
4. rebound phenomenon:
5. others


Some β-R antagonists
1A :nonselective, no ISA
    Propranolol(普萘洛尔),
1.pharmacokinetics: high liposolubility
2.actions:
3.uses: HBP, arrhythmia, CHF,
             myocardial ischemia, hyperthyroidism
    Timolol(噻吗洛尔)
1.actions: strongest
2.uses: glaucoma


1B:nonselective, ISA
    Pindolol(吲哚洛尔)
Actions: strong
Uses: HBP


2A: selective, no ISA
    Atenolol(阿替洛尔): long t1/2
       Metoprolol(美托洛尔)


3: α、β-R antagonists
    Labetolol(拉贝洛尔)
1.β-R blockage>α-R blockage
2. β-R blockage<propranlol
3.α-R blockage<phentolamine
4.ISA
5.used in HBP, angina pectoris
    Arotinolol (阿罗洛尔)
    1.β-R blockage<α-R blockage
    2. used in HBP, angina pectoris, supraventricular tachycardia

				
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