Beta-blockers are antagonists at the ß-adrenoceptor, thereby blocking sympathetic nervous system effects of increasing heart rate and blood pressure. The initial effects reduce cardiac output, but this returns to normal with blood pressure remaining low due to an unknown mechanism.
Oral. Intravenous use may be needed rarely.
- Bronchospasm
- Bradycardia
- Hypotension
- Tiredness
- Cold peripheries
- Nightmares
Beta-blockers have been associated with an increase in the incidence of diabetes in some clinical trials, leading to the advice that they should not be first line treatment for hypertension unless there are other indications (e.g. angina).
Beta-blockers should be used with care in combination with other drugs which lower blood pressure (although this may be the intended effect).
Beta-blockers have been noted to cause bronchospasm and are therefore contraindicated in asthma.
Verapamil should not be used with beta-blockers due to the risk of heart block.
Avoid using Sotalol in combination with other drugs that prolong the QT interval.
Beta-blockers should not be stopped abruptly as they can cause rebound tachycardia and hypertension, which may even lead to myocardial infarction.
Beta-blockers differ in lipid solubility and in cardioselectivity. Those which are more lipophilic are more rapidly metabolised and excreted. They may also cross the blood brain barrier causing central adverse effects.
No beta-blocker is completely cardioselective and therefore all have the potential to cause bronchospasm in patients with asthma.
Some beta-blockers also have partial agonist (sympathomimetic) activity.
Cardioselective beta-blockers may have less adverse effects.
