Beta blockers

 

1- ß1 receptors:

– Myocardial cells

– Device juxtaglomerular

– Adipocytes

2- ß2 receptors:

– Blood vessels

– Bronchi

– Uterus

3- Common properties:

* On the cardiovascular system

+ Inotropic effects, chronotropic, and dromotropic bathmotropic negative

+ Decreased cardiac output of blood pressure with increase in total peripheral resistance.

* On the renin-angiotensin system -> reduction in plasma renin activity

* On the bronchi -> bronchoconstriction, bronchial hyperreactivity

* On metabolisms:

+ Reduction glycogenolysis and glucagon secretion => risk of worsening hypoglycemia

+ Decreased HDL => increased atherogenic risk

+ Increased triglycerides

* On the eye -> decrease in intraocular pressure and aqueous humor secretion.

4- properties depending on the type of beta-blockers:

A- cardioselective beta blockers:

Iles meet the bronchial and vascular receptors

B- Beta-blocker with intrinsic sympathomimetic activity:

It results in a smaller reduction in the frequency and cardiac contractility and decreased peripheral resistance.

C- membrane stabilizing effect:

Effect quinidine-like or anesthetic of the membrane, at very high doses in some products (propranolol)

5- Indications:

A- Cardiovascular:

– HTA

– Angina of effort

– Accident prevention after MI

– Hypertrophic cardiomyopathy

– Heart failure (carvedilol, bisoprolol, metoprolol)

B- Other:

– Prevention of migraine

– Essential tremor

– Hyperthyroidism

– Open angle glaucoma (timolol)

– Prevention of rebleeding in cirrhotic patients with PH

– Algoneurodystrophy

6- Contraindications:

A- Cardiovascular:

– Decompensated heart failure

– AVB 2nd and 3rd degree

– Raynaud’s Syndrome

– Severe arterial disease (stage III and IV)

B- Other:

– Asthma

– COPD

7- Beta blockers:

A- cardioselective:

– Acebutolol (SECTRAL®)

– Atenolol (Ténormine®)

– Metoprolol (Lopressor®)

– Esmolol

– Bisoprolol

B- Not cardioselective:

– Propranolol (Avlocardyl®)

– Pindolol (Visken®)

– Labetalol (Trandate®)

– Nadolol

– Sotalol

– Carvedilol (Kredex®)

C- intrinsic sympathomimetic activity:

– Acebutolol

– Pindolol

D- Effect quinidine-like:

– Propranolol

– Acebutolol

-> The sotalol also a class effect of Vaughan III (such as amiodarone)

-> Labetalol also has a property alphabloquante

-> The membrane stabilizing effect appears for doses higher than the therapeutic doses

E- Side effects:

– Bradycardia

– Raynaud’s Syndrome

– Central nervous disorders, insomnia

– Asthma

– Heart failure

– Disorders of atrioventricular conduction

– Severe hypoglycemia in diabetic patients (often masked by beta-blockers)

– Impotence

F- Precaution:

– Prescription cautious diabetic (prefer a cardioselective product)

– Period of 15 days between stopping treatment with an MAOI and early beta-blocker

– No association with calcium antagonists bradycardia except hypertrophic cardiomyopathy

– Very gradual cessation of therapy with beta-blockers (lesion rebound angina)

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