Beta blockers are a class of drugs with complex cardiovascular effects including reduction in heart rate and oxygen demand in the heart muscle. Beta blockers target beta receptors found in the different parts of the body such as heart muscle, smooth muscles, blood vessels, airways and kidneys. Beta blockers work by inhibiting the release of neurotransmitters adrenaline and noradrenaline which transmit signals from nerve endings to muscles, blood vessels and heart.
Beta blockers are non-selective, ie without preference to any subtype of beta receptors (carvedilol, labetalol, propranolol, sotalol) or cardioselective, working mainly on heart tissue (atenolol, bisoprolol, metoprolol, nebivolol). Carvedilol, bisoprolol and sustained-release metoprolol can be used in heart failure patients.
Beta-blockers should not be stopped suddently due to the risk of rebound phenomenon (sudden deterioration in symptoms).
Beta blockers are contraindicated in asthma. They are normally well tolerated but especially the non-selective beta blockers may have side effects including dizziness and lightheadedness, fatigue, bradycardia (slow heart beat), cold hands and feet.