Non-selective

Non-selective Beta Blockers

Non-selective beta blockers are a class of medications that inhibit the action of the sympathetic nervous system by blocking both beta-1 and beta-2 adrenergic receptors. These medications are used in the treatment of various cardiovascular conditions, as well as other medical conditions.

Pharmacology

Non-selective beta blockers work by antagonizing the effects of catecholamines, such as epinephrine and norepinephrine, on beta-adrenergic receptors. There are three types of beta receptors:

• Beta-1 receptors: Primarily located in the heart, they increase heart rate and contractility when stimulated.
• Beta-2 receptors: Found in the lungs, vascular smooth muscle, and other tissues, they mediate vasodilation and bronchodilation.

By blocking these receptors, non-selective beta blockers reduce heart rate, decrease myocardial contractility, and cause bronchoconstriction, among other effects.

Clinical Uses

Non-selective beta blockers are used to treat a variety of conditions, including:

• Hypertension: By reducing cardiac output and inhibiting renin release from the kidneys.
• Angina pectoris: By decreasing myocardial oxygen demand.
• Arrhythmias: Such as atrial fibrillation, by slowing conduction through the AV node.
• Heart failure: In certain cases, to reduce the workload on the heart.
• Migraine prophylaxis: By preventing vasodilation in cerebral vessels.
• Glaucoma: By reducing intraocular pressure.

Side Effects

The use of non-selective beta blockers can lead to several side effects, including:

• Bronchoconstriction: Particularly in patients with asthma or COPD, due to beta-2 receptor blockade.
• Bradycardia: Excessive slowing of the heart rate.
• Fatigue: Due to reduced cardiac output.
• Cold extremities: Resulting from peripheral vasoconstriction.
• Hypoglycemia: Masking of hypoglycemic symptoms in diabetic patients.

Examples of Non-selective Beta Blockers

Some common non-selective beta blockers include:

• Propranolol: One of the first beta blockers developed, used for a wide range of indications.
• Nadolol: Used for hypertension and angina.
• Timolol: Often used in the treatment of glaucoma.

Mechanism of Action

Non-selective beta blockers bind to both beta-1 and beta-2 adrenergic receptors, preventing the binding of endogenous catecholamines. This leads to a decrease in heart rate, myocardial contractility, and conduction velocity through the AV node, as well as bronchoconstriction and vasoconstriction.

Contraindications

Non-selective beta blockers are contraindicated in patients with:

• Asthma or severe COPD: Due to the risk of bronchospasm.
• Bradycardia: As they can further slow the heart rate.
• Heart block: Particularly second or third-degree AV block.

Also see

• Selective beta blockers
• Adrenergic receptor
• Hypertension
• Arrhythmia
• Glaucoma

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A

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B

• Brown atrophy of the heart

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• Ebb Cade
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E

• Eisenmenger's syndrome
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H

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I

• Idiopathic giant-cell myocarditis
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K

• Keshan disease

L

• Loeffler endocarditis

M

• Mydicar
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N

• Nonbacterial thrombotic endocarditis

O

• OLR1
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P

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T

• Traumatic cardiac arrest

V

• Ventricular aneurysm
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W

• Waon therapy