Beta blockers Beta blockers are effective in the treatment of hypertension, as they reduce the risk of stroke and myocardial infarction. They also reduce the rate at which the heart works and hence the blood output. They relax smooth muscle in the arteries which reduces the peripheral resistance to blood flow, and they also reduce cardiac response to stress and exercise. Beta blockers should not be used for patients suffering from asthma, chronic bronchitis, emphysema or other respiratory diseases because they may narrow the airways in the lungs. Where there is an indication that a beta blocker is the preferred drug, it is important for additional treatment to be available, eg an inhaler, to deal with any breathing problems that might arise in affected patients.
Beta blockers slow down the heart rate, which means less oxygen is required.
This may produce adverse reactions in cases of heart failure or heart block. They also reduce the flow of blood to extremities causing patients to suffer cold hands and feet. A combination of diuretics and beta blockers remains the first choice of drug therapy in most patients for the treatment of hypertension. Angiotensin II has a vasoconstrictor action, stimulating the synthesis and release of aldosterone which reduces the extraction of salt and water from the blood. Ace inhibitors are generally well tolerated.