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)