Taking the hype out of hypertension.

Few Americans today are unaware that high blood pressure can lead to heart attacks, strokes, or kidney failure. However, with the array of antihypertensive drugs now available, we may be thoroughly confused as to which one may be best in our own particular case.

Whatever particular medication that one's physician recommends, one should also employ other measures to reduce blood pressure--and thus possibly decrease (or even eliminate altogether) the need for drugs. These include exercise, diet (including weight reduction and salt restriction), reduction of alcohol intake, and stress management. All of these should be given a fair trial before medication is begun, unless the hypertension is so severe that the physician is unwilling to chance a sudden complication.

What, however, are the options if the drug-free approaches fail? The dozens of agents now available to treat hypertension are divided into four different classifications by their methods of action: diuretics, beta blockers, ACE inhibitors, and calcium-channel blockers.

Diuretics ("water pills") cause the kidneys to excrete more sodium and chloride. This in turn draws more water from the bloodstream, thereby reducing blood volume and causing blood vessels to dilate slightly. The most common of these are the thiazide diuretics, such as Diuril, Esidrix, and HydroDIURIL. Afro-Americans and the elderly seem to benefit most from these drugs, but diabetics and gout-prone persons can be adversely affected by them. Weakness and low potassium are other possible side effects.

Beta blockers are now second in popularity to diuretics. By interfering with the effect of adrenaline on the heart, they slow heart rate and lower the heart's blood output. However, beta blockers may cause wheezing among persons susceptible to pollens and other irritants that constrict the lung's breathing passages, which are dilated by adrenaline. They may also adversely affect diabetics by preventing the adrenaline surge that warns them that insulin has caused too sharp a drop in blood sugar.

This sudden increase in adrenaline speeds up the heart and causes sweating, thus alerting the diabetic patient to an insulin reaction. Without that surge, the diabetic may pass out before he can raise his blood sugar by drinking orange juice or eating candy. The most commonly used beta blockers include Inderal, Lopressor, and Tenormin.

ACE (angiotensin-converting enzyme) inhibitors, including Capoten, Vasotec, Prinivil, and Zestril, cause blood vessels to dilate. They have fewer side effects than diuretics or beta blockers, but they commonly produce a dry cough and may build up excess potassium in the blood.

Calcium-channel blockers also dilate blood vessels and, like beta blockers, are useful for treating angina, as well as hypertension. Flushing and swelling of legs are these drugs' most common side effects. Cardizem CD, Calan SR, and Procardia XL are sustained-release forms of these agents and need to be taken only once a day.

A variety of older drugs have been used for treating hypertension, although some have fallen out of favor for various reasons. One of them, reserpine (Serpasil), is an ancient, very inexpensive, naturally-occurring drug from India that needs to be taken only once a day. Reserpine acts on the central nervous system and may produce depression in a very small percentage of patients.

Methyldopa (Aldomet) is another "old-timer" that also acts on the brain. Drowsiness, impotence, and dry mouth are side effects that cause many patients to stop using it. Another older drug, clonidine (Catapres), also became unpopular because of these side effects. However, it has recently made a comeback with the development of the clonidine patch, which delivers the drug through the skin, thus eliminating the need for taking pills daily.

Opinions vary as to which class of drug should be tried first. Many patients will not respond adequately to their first-prescribed drug, even if the dosage is increased. Adding a second drug from another classification will then often achieve the desired results. Juggling the therapy in this manner requires a close working relationship between doctor and patient until a satisfactory maintenance program is worked out. The patient can then usually look forward to a comfortable and productive life.