Beta blockers
Also known as: beta-adrenergic blockers, the -olols
Medicines ending in -olol that shield the heart from adrenaline, slowing it and reducing its oxygen demand. Core treatment for angina, after heart attacks, in heart failure and for controlling fast rhythms.
- Biological target
- Beta-1 adrenergic receptor, Beta-2 adrenergic receptor
- Also called
- beta-adrenergic blockers, the -olols
Mechanism of action
Adrenaline and noradrenaline speed and strengthen the heart through beta-1 receptors. Beta blockers occupy the receptors so the heart beats more slowly and less forcefully, uses less oxygen and lets fewer atrial impulses through the AV node. Cardioselective members (bisoprolol, metoprolol, atenolol) mostly spare the beta-2 receptors in the airways; non-selective ones (propranolol) block both and can provoke asthma. In heart failure, protecting the heart from chronic adrenaline drive improves survival when started low and increased slowly.
Members of the class
Members with a page on this site are linked.
Conditions treated
Class effects
- Tiredness, cold hands and feet, slow pulse
- Vivid dreams, erectile dysfunction
- Masking of hypoglycaemia warning signs
Cautions
- Never stop suddenly: rebound angina and fast rhythms
- Asthma is a relative contraindication, especially for non-selective agents
- Not combined with verapamil or diltiazem
- Second- or third-degree heart block
Class warnings
- Can provoke bronchospasm in asthma (cardioselective agents only with specialist advice); avoid abrupt withdrawal after long use because of rebound angina and arrhythmia; mask the warning symptoms of hypoglycaemia in diabetes. UK
- Contraindicated in asthma with a history of bronchospasm, marked bradycardia, second- or third-degree heart block, cardiogenic shock and uncontrolled heart failure. UK
Class interactions
| With | Effect | Source |
|---|---|---|
| Verapamil and diltiazem | Additive bradycardia, heart block and heart failure; the combination is avoided. | UK |
| Insulin and sulfonylureas | Beta blockers mask hypoglycaemia and can prolong it. | UK |
| Other antihypertensives and alpha blockers | Additive hypotension and, with clonidine, rebound hypertension on withdrawal. | UK |
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