Beetablokaatoreid

Beetablokaatoreid, also known as beta-blockers, are a class of medicines that block beta-adrenergic receptors. In Estonian medical terminology they are usually called beetablokaatorid; beetablokaatoreid may appear as an alternative spelling. They affect the cardiovascular system by reducing the actions of adrenaline and related chemicals on the heart and vessels.

The mechanism of action involves antagonism of beta-adrenergic receptors, primarily the beta-1 receptors in the heart. This leads to lowered heart rate, reduced myocardial contractility, slower conduction through the atrioventricular node, and decreased cardiac output. They also reduce renin release from the kidneys, which can lower blood pressure. Some nonselective agents can affect beta-2 receptors in the airways and blood vessels, potentially causing bronchoconstriction and peripheral effects. Lipid and glucose effects are usually modest but may complicate diabetes or lipid management in some patients. Abrupt withdrawal can cause rebound tachycardia and hypertension.

Beta-blockers are categorized as cardioselective (primarily beta-1) or nonselective (beta-1 and beta-2). Common examples include metoprolol, atenolol, and bisoprolol (cardioselective), and propranolol and nadolol (nonselective). Short-acting agents like esmolol are used in acute settings; others such as carvedilol have additional alpha-blocking activity.

Indications include hypertension, angina pectoris, certain arrhythmias, and heart failure with reduced ejection fraction. They are also used for myocardial infarction prevention, thyrotoxic symptoms, essential tremor, and migraine prophylaxis in select cases. Caution is advised in asthma or COPD, diabetes, or significant conduction disorders; they should not be stopped abruptly. Adverse effects include bradycardia, fatigue, dizziness, and, with nonselective types, bronchospasm.