Alpha-beta blockers are medications that contain both an alpha blocker and a beta blocker, combining the effects of the two medications. They belong to a class of medications called "adrenergic inhibitors," which act on nerve transmitters related to certain hormones essential to the body. These combination therapies are most commonly used to treat hypertension, the condition more commonly known as high blood pressure.
The critical mechanism of action of alpha-beta blockers lies in the combination of two distinct drug classes. The first, known as alpha blockers or alpha-adrenergic antagonists, work by relaxing certain vascular muscles and blocking the tightening action of the hormone norepinephrine. This keeps the walls of the veins and small arteries open, allowing better blood flow. When the blood is able to flow freely, a lower rate of blood pressure can be maintained. The muscle-relaxant function of these drugs also makes alpha blockers a good treatment option for older men with prostate problems because it helps improve urine flow.
The second class, known as beta blockers or beta-adrenergic blocking agents, work by blocking the effects of epinephrine, commonly referred to as adrenaline. These medications help the heart beat more slowly and with less force, which in turn reduces blood pressure. Beta blockers also improve blood flow and may be used to treat glaucoma and migraines.
Together, alpha-beta blockers work by preventing the cells in the smooth muscle of the blood vessels, heart and brain from receiving catecholamine, a chemical that narrows the arteries. Preventing the catecholamine from reaching these organs relaxes the blood vessels, allowing blood to flow more easily and reducing blood pressure.
Patients taking alpha-beta blockers need to take certain precautions, as faintness or dizziness can occur while taking the medications. These side effects commonly occur during a sudden change in position, such as standing up after lying down for a period of time. In case of side effects, patients should not stop taking alpha-beta blockers without getting a doctor's advice, as abrupt cessation can cause chest pain or lead to a heart attack.
Other possible side effects of alpha-beta blockers include depression, diarrhea, slow heart rate, and swelling of the legs and feet. Sexual dysfunction, depression, fatigue, and skin rashes may also occur. Those suffering from asthma may notice wheezing or shortness of breath while taking alpha-beta blockers. In some cases, the electrical system of the heart can be affected, although the patient will be unaware as such side effects do not cause noticeable symptoms.
Alpha-beta blockers can cause drowsiness, and alcohol can increase this side effect. Patients should not drive or operate heavy machinery until they know how these medications affect them. Patients should inform their physicians of any other medications, vitamins, or herbal supplements they are using before taking alpha-beta blockers, as some medications can interfere with their effectiveness or cause serious side effects.