new beta adrenoceptors block

8/3/2019 New Beta Adrenoceptors Block

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Drugs competitively

block adrenergicreceptors


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Relative affinity for 1and / or 2 receptors

Some of them have 'Intrinsicsympathomimeticactivity ISA


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Some have membranestabilizing effect ( LA orquinidine like effect )

Some have high lipid

solubility; with centraldepressant effect


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B-blockers

Non selectivePropranolol

Pindolol

Selective 1

Atenolol

Metoprolol

Combined & blocker

labetalol &carvedilol


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B-blockers

Lipophilic Hydrophilic


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Lipophylic Hydrophilic

oralabsorption

Complete Irregular

Livermetabolism

Yes No

T 1/2 Short Long

CNS side

effects

High low


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HydrophilicLipophylic

AtenololPropranolol

AcebutalolTimolol

Labetalol

Carvedilol


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The prototype of betablockers.

It has equal affinity for 1& 2

It has NO ISA . It possess local anesthetic

action


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Heart- ve chronotropic ,

- ve inotropic- ve dromotropic

COP, work & O2 consumption. automatcity & excitability


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vasoconstriction

( B2blocking) blood supply toorgans


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1. COP (1- blocking effect).2. Block rennin release, so Ag II &

aldosteron (1- effect).

3. NE release from Nerveterminals.

4. central sympathetic outflow.5.Ressetting of baroreceptor


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Bronchoconstriction in

susceptible patients(2- blocking effect).


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1. Hypoglycemia due todecrease both

glycogenolysis & glucagonsecretion

2. Inhibit lipolysis

3. Sodium retention : BP in renal perfusion Na+retention& plasma volume.


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Propranolol depresses

CNS reduce tremors

due to anxiety


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1.Hypertension.

2. Angina pectoris

3. Cardiac arrhythmia.

4. Myocardial infarction

5. Hyperthyrodism


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6. Open-angle Glaucoma(chronic): Timolol

7. Prophylaxis of Migraine

headache

8. Management of familial

tremors & anxiety9. Pheochromocytoma with

-blockers (never alone)


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1-Block of cardiac 1

-receptors:

-ve inotropic heart failure(treated by digitalis).

-ve chronotropic bradycardia(Treated by atropine).

-ve dromotropic heart failure.Hypotension.


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2. Blockade of2:Bronchospasm and asthma.

Hypoglycemia (symptomless

hypoglycemic coma).

Vasoconstriction (cold

extremities).Coronary vasoconstriction.


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Exacerbates angina,

tachycardia, maylead to arrhythmias

Rebound hypertension.


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Bronchial asthma.

Type I diabetes mellitus.

Peripheral vascular disease.

Heart block, severe HF,

massive MI.


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PharmacokineticInteractions

PharmacodynamicInteractions

1. Hepatic enzyme

inhibitors as:cimetidine & isoniazid

1. Anti-diabetic drugs

e.g. insulin.

2. Hepatic enzyme

inducers as:

barbiturates,

phenytoin, & rifampin

2. Verapamil (calcium

channel blocker)

3. Non-steroidal anti-

inflammatory drugs

Drug interactions

Drugs Selectivity PA LA activity Lipid T (h)


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Drugs Selectivity PAactivity

LA activity Lipidsolubility

T (h)

Propranolol 1 , 2 - + High 4-6

Pindolol 1 , 2 + Weak Moderate 3-4

Atenolol 1 - - Low 6-9

Acebutalol 1 + + Low 3-4

Labetalol 1, 1 + + Moderate 5

Carvedilol 1 ,

1 - - Moderate 6-8


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new beta adrenoceptors block

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