Antihypertensive drugs

Antihypertensive drugs are medicines that help lower blood pressure in peoplewhose blood pressure is too high. Blood pressure is a measurement of the force with which blood moves through the body's system of blood vessels. Although everyone's blood pressure goes up and down in the course of a typical day,some people have blood pressure that stays high all the time. This conditionis known as hypertension. Hypertension is not the same as nervous tension. People who have high blood pressure are not necessarily tense, high-strung, ornervous. They may not even be aware of their condition. Being aware of high blood pressure and doing something to control it are extremely important, however. Untreated, high blood pressure can lead to diseases of the heart and arteries, kidney damage, or stroke, and can shorten life expectancy.

Treatments for high blood pressure depend on the type of hypertension. Most cases of high blood pressure are called essential or primary hypertension, meaning that the high blood pressure is not caused by some other medical condition. For most people with primary hypertension, it is difficult to figure outthe exact cause of the problem. However, such hypertension usually can be controlled by some combination of antihypertensive drugs and changes in daily habits(such as diet, exercise, and weight control). Controlling primary hypertension is however a lifelong commitment. Although people may be able to reducethe amount of medicine they take as their blood pressure improves, they usually must continue taking it for the rest of their lives.

In people with secondary hypertension, the high blood pressure may be due tomedical problems such as kidney disease, narrowing of certain arteries, or tumors of the adrenal glands. Correcting these problems often cures the high blood pressure, and no further treatment is needed.

Many different types of drugs are used, alone or in combination with other drugs, to treat high blood pressure. The major categories are:

  • Angiotensin-converting enzyme (ACE) inhibitors, such as benazepril (Lotensin), captopril (Capoten), enalapril (Vasotec), lisinopril (Prinivil, Zestril), quinapril(Accupril), and ramipril (Altace). ACE inhibitors work by preventing a chemical in the blood, angiotensin I, from being converted into a substance that increases salt and water retention in the body. These drugs also make blood vessels relax, which further reduces blood pressure.
  • Angiotensin II receptor antagonists, such as losartan (Cozaar) and losartan with hydrochlorothiazide (Hyzaar). These drugs act at a later step in the same process that ACE inhibitors affect. Like ACE inhibitors, they lower blood pressure by relaxingblood vessels.
  • Beta blockers, such as atenolol (Tenormin), metoprolol(Lopressor), nadolol (Corgard), propranolol (Inderal), and timolol (Blocadren). Beta blockers affect the body's response to certain nerve impulses. This,in turn, decreases the force and rate of the heart's contractions, which lowers blood pressure.
  • Blood vessel dilators (vasodilators), such as hydralazine (Apresoline) and minoxidil (Loniten). These drugs lower blood pressure by relaxing muscles in the blood vessel walls.
  • Calcium channel blockers, such as amlopidine (Norvasc), diltiazem (Cardizem), isradipine (DynaCirc), nifedipine (Adalat, Procardia), and verapamil (Calan, Isoptin, Verelan).Drugs in this group slow the movement of calcium into the cells of blood vessels. This relaxes the blood vessels and lowers blood pressure.
  • Diuretics, such as chlorthalidone (Hygroton), furosemide (Lasix), hydrochlorothiazide (Esidrix, HydroDIURIL), and metolazone (Zaroxolyn). These drugs control blood pressure by eliminating excess salt and water from the body.
  • Nerve blockers, such as alpha methyldopa (Aldomet), clonidine (Catapres), guanabenz (Wytensin), guanadrel (Hylorel), guanethidine (Ismelin), prazosin(Minipress), rauwolfia derivatives (Reserpine), and terazosin (Hytrin). These drugs control nerve impulses along certain nerve pathways. This allows blood vesselsto relax and lowers blood pressure.

The recommended dosage depends on the type, strength, and form of antihypertensive drug. Check with the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage. Always take antihypertensive drugs exactly as directed. Never take larger or more frequent doses, and do not miss any doses. Some antihypertensive drugs may take several weeks to noticeably lower blood pressure. Once it begins to work and symptoms improve, continuing to take the medicine is just as important. Stopping some hypertensive drugs suddenly may cause serious problems. Check with the physician who prescribed the medicine to find out if it is necessary to gradually taper down before stopping the medicine completely.

Antihypertensive drugs will not cure high blood pressure, but will help control the condition. To avoid the serious health problems that high blood pressure can cause, patients may have to take medicine for the rest of their lives.Furthermore, medicine alone may not be enough. People with high blood pressure also may need to avoid certain foods and keep their weight under control.The health care professional who is treating the condition can offer advice on what measures may be necessary.

Anyone taking antihypertensive drugs should not take any other prescription or over-the-counter medicine without first checking with his or her physician.Some medicines may increase blood pressure. Most patients who take antihypertensive drugs are not bothered by side effects. However, antihypertensive drugs may interact with many other medicines. When this happens, the effects ofone or both of the drugs may change or the risk of side effects may be greater. Anyone taking antihypertensive drugs should not take any other prescription or nonprescription (over-the-counter)medicine without first checking with his or her physician.

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