Drug Treatment of High Blood Pressure
Drugs that are used in the treatment of high blood pressure are called antihypertensives. With the wide variety of antihypertensives available, high blood pressure can be controlled in almost anyone, but treatment has to be tailored to the individual. (See also High Blood Pressure.) Treatment is most effective when the person and doctor communicate well and collaborate on the treatment program.
Different types of antihypertensives reduce blood pressure by different mechanisms, so many different treatment strategies are possible. For some people, doctors use a stepped approach to drug therapy: They start with one type of antihypertensive and add others as necessary. For other people, doctors find a sequential approach is preferable: They prescribe one antihypertensive, and if it is ineffective, they stop it and prescribe another type. For people with blood pressure at or above 140/90 mm Hg, usually two drugs are started at the same time. In choosing an antihypertensive, doctors consider such factors as
A majority of people (more than 74%) ultimately require two or more drugs to reach their blood pressure goal.
Most people tolerate their prescribed antihypertensive drugs without problems. But any antihypertensive drug can cause side effects. So if side effects develop, a person should tell the doctor, who can adjust the dose or substitute another drug. Usually, an antihypertensive drug must be taken indefinitely to control blood pressure.
Adrenergic blockers include alpha-blockers, beta-blockers, alpha-beta blockers, and peripherally acting adrenergic blockers. These drugs block the effects of the sympathetic division, the part of the autonomic nervous system that can rapidly respond to stress by increasing blood pressure.
Beta-blockers are the most commonly used adrenergic blockers. They are particularly useful for whites, young people, and people who have had a heart attack. They are also useful for people who have a rapid heart rate, angina pectoris (chest pain due to inadequate blood supply to the heart muscle), or migraine headaches. The risk of side effects is higher for older people.
Alpha-blockers are no longer used as the main therapy because they do not decrease the risk of death. Peripherally acting adrenergic blockers are usually only used if a third or fourth type of drug is needed to control blood pressure.
Angiotensin-converting enzyme (ACE) inhibitors lower blood pressure in part by dilating arterioles. They dilate arterioles by preventing the formation of angiotensin II, a chemical produced in the body that causes arterioles to constrict. Specifically, these inhibitors block the action of angiotensin-converting enzyme, which converts angiotensin I to angiotensin II (see figure Regulating Blood Pressure). These drugs are particularly useful for people with coronary artery disease or heart failure, whites, young people, people with protein in their urine because of chronic kidney disease or diabetic kidney disease, and men who develop sexual dysfunction as a side effect of another antihypertensive drug.
Angiotensin II receptor blockers (ARBs) lower blood pressure by a mechanism similar to the one used by angiotensin-converting enzyme inhibitors: They directly block the action of angiotensin II, which causes arterioles to constrict. Because the mechanism is more direct, angiotensin II receptor blockers may cause fewer side effects.
Calcium channel blockers cause arterioles to dilate by a completely different mechanism. They are particularly useful for blacks and older people. Calcium channel blockers are also useful for people who have angina pectoris, certain types of rapid heart rate, or migraine headaches. Calcium channel blockers may be short-acting or long-acting. Short-acting calcium channel blockers are not used to treat high blood pressure. Reports suggest that people using short-acting calcium channel blockers may have an increased risk of death due to heart attack, but no reports suggest such effects for long-acting calcium channel blockers.
Direct vasodilators dilate blood vessels by another mechanism. A drug of this type is almost never used alone; rather, it is added as a second drug when another drug alone does not lower blood pressure sufficiently.
A thiazide or thiazide-type diuretic (such as chlorthalidone or indapamide) may be the first drug given to treat high blood pressure. Diuretics can cause blood vessels to widen (dilate). Diuretics also help the kidneys eliminate sodium and water, decreasing fluid volume throughout the body and thus lowering blood pressure.
Thiazide diuretics cause potassium to be excreted in the urine, so potassium supplements or a diuretic that does not cause potassium loss or that causes potassium levels to increase (a potassium-sparing diuretic) sometimes must be taken with a thiazide diuretic. Usually, potassium-sparing diuretics are not used alone because they do not control blood pressure as well as thiazide diuretics do. However, the potassium-sparing diuretic spironolactone is sometimes used alone.
Diuretics are particularly useful for blacks, older people, obese people, and people with heart failure or chronic kidney disease.