Beta blockers, also known as beta-adrenergic blocking agents, are drugs that block the uptake, and therefore the effects, of epinephrine, also known as adrenaline, in the body. Epinephrine is a hormone produced by the adrenal gland that circulates in the bloodstream and transmits signals to various parts of the body in response to stress. These signals are transmitted when molecules of epinephrine bind to tiny epinephrine receptors in different areas of the body, such as the heart, lungs, and muscles. Some of the effects of epinephrine include causing the heart to beat faster and strengthening the force of each beat, opening the airways in the lungs, increasing blood sugar, and other effects.
Beta blockers work by binding to the epinephrine receptors. This prevents epinephrine in the bloodstream from binding to the receptor sites and transmitting the signals that cause increased heart rate and other effects.
Most often, beta blockers are used to treat high blood pressure, glaucoma, and migraines. However, in patients with chronic obstructive pulmonary disease (COPD), beta blockers may reduce the number of exacerbations patients have and reduce the severity of those exacerbations that do occur. They may work especially well for COPD patients who also have cardiovascular disease.
Beta blockers had not been used to treat COPD until relatively recently, as it was believed that they might cause the airways to constrict. However, recent studies have shown beta blockers to be safe for patients with COPD, though patients with certain conditions in addition to COPD, such as pulmonary hypertension and cor pulmonale, should not use them.