Beta-adrenoceptor blocking drugs

Beta blockers, also known as beta-adrenoceptor blocking agents, are pharmaceutical agents that act as competitive antagonists of the β-adrenoceptors, which are activated by the endogenous catecholamines epinephrine (adrenaline) and norepinephrine (noradrenaline), of the sympathetic nervous system. Beta blocking drugs used to treat conditions such as angina, heart failure, cardiac arrhythmias, edema and high blood pressure and can also be used in the management of glaucoma and anxiety.

Side-effects are generally not serious, and lessen as the body adjusts to treatment. Hypotensive effects (especially following first dose), tiredness, dizziness and cold hands and feet are quite common side-effects. In men, beta blocker use can cause erectile dysfunction.

Beta blockers are contra-indicated in patients suffering from asthma, cardiogenic shock, hypotension, marked bradycardia, metabolic acidosis, phaeochromocytoma (apart from specific use with alpha-blockers), Prinzmetal’s angina, second-and third-degree AV block, severe peripheral arterial disease, sick sinus syndrome or uncontrolled heart failure. Additionally, beta blockers, including those considered to be cardioselective, should be avoided where possible in patients with a history of asthma, bronchospasm or a history of obstructive airways disease. If there is no alternative, cardioselective beta blockers can be prescribed to patients under specialist care, with particular attention paid to the induction of bronchospasm. There is a risk of precipitating heart failure when beta blockers and the calcium channel blocker (antiarrhythmic), verapamil, are used together in established ischaemic heart disease.

LIke α-blockers, beta blockers can be selective or non-selective for β-adrenoceptor subtypes. β₁-selective drugs are considered to be cardioselective as the heart and kidneys are the main sites of β₁-adrenoceptor expression. β₂-adrenoceptors are expressed in the lungs, gastrointestinal tract, liver, uterus, vascular smooth muscle, and skeletal muscle, and β₃-adrenoceptors are found in fat cells.

Non-selective beta blockers

timolol (hypertension, angina, migraine prophylaxis, prophylaxis after myocardial infarction, glaucoma- reduces elevated intraocular pressure)

pindolol (hypertension, angina)

propranolol (hypertension, angina, anxiety, essential tremor, migraine prophylaxis, arrhythmias, prophylaxis after myocardial infarction, management of the symptoms of thyrotoxicosis)

levobunolol (glaucoma- reduces elevated intraocular pressure)

carteolol (hypertension, elevated intraocular pressure)

sotalol (cardiac arrythymias)

oxprenolol (angina, hypertension and cardiac arrythymias)

nadolol (angina, hypertension, migraine pain and tremor)

Selective beta blockers (β₁-selective, cardioselective)

atenolol (hypertension, angina, arrhythmias)

esmolol (tachycardia and hypertension in peri-operative period, short-term treatment of supraventricular arrhythmias)

metoprolol (hypertension, angina, arrhythmias, early intervention within 12 hours of infarction, migraine prophylaxis)

celiprolol (mild-moderate hypertension)

co-tenidone (hypertension), co-tenidone is a 4:1 mixture of atenolol and the carbonic anhydrase inhibitor, chlortalidone

bisoprolol (hypertension, angina)

acebutolol (hypertension, angina, arrhythmias)

nebivolol (essential hypertension, hypertension in patients with renal impairment, adjunct in stable mild to moderate heart failure)

betaxolol (hypertension, primary open-angle glaucoma) note that β₁ selectivity is not absolute, and some inhibitory effects on β₂-adrenoceptors is exhibited at higher doses.