Blood Pressure Drugs - Confusing but Crucial.
By Judy Foreman
03/11/03

[NOTE: See corrections re Lotrel in blue below 4/29/03]

In December, a study of more than 42,000 white and black Americans found that old-fashioned, cheap diuretics – “water pills” – work at least as well and sometimes better than more expensive drugs to treat high blood pressure and certain heart problems.  The study, dubbed ALLHAT, was published in JAMA, the Journal of the American Medical Association

In February, a study of more than 6,000 mostly white Australians came to a different conclusion - that drugs called ACE inhibitors were better than diuretics, although only for men (for unclear reasons). This study was published in the New England Journal of Medicine.

Between now and May, it falls to Dr. Aram Chobanian, dean of the Boston University School of Medicine, and his committee of experts picked by the National Heart Lung and Blood Institute to reconcile the studies and tell America’s 50 million hypertensives what to do.

Their conclusions are crucial. Hypertension doubles the risk of heart attack and is the leading risk factor for stroke and heart failure. One in four adult Americans has hypertension - defined as a reading of 140/90 millimeters of mercury or higher.

(The top number is the systolic pressure, taken as the heart muscle contracts. The lower number is the diastolic, as the heart relaxes. Normal blood pressure is 120/80, but even readings of 130/ 85 should be considered a red flag.) 

High blood pressure is so common, especially among older people,  that many patients don’t’ take it as seriously as they should. “High blood pressure doesn’t make you feel bad,” says Dr. Michele Hamilton, co-director of the heart failure program at the University of California, Los Angeles. This makes it harder for people to change their diets (and reduce salt), lose weight, reduce stress and take medications.

High blood pressure is also tricky for doctors because they usually don’t know what causes it. In 5 percent of cases, it’s caused by kidney and adrenal problems, or legal and illegal substances such as prednisone, cocaine, ephedrine, even licorice. But 95 percent of hypertension is deemed “essential” or “primary” because the cause is unknown.

Basically, blood pressure is a matter of hydraulics. If the pressure inside artery walls is too low, a person can go into shock and die. If the pressure is too high, because vessels are too narrow or rigid or the heart beats too hard, a person can develop heart and kidney failure and stroke. 

With age, the risks get worse because blood vessels become more rigid. Indeed, data from the Framingham Heart Study show that a person who has a normal blood pressure at 55 has a 90 percent chance of developing high blood pressure eventually.

Regulation of blood pressure is complex. Short term fluctuations are controlled by the nervous system, specifically hormones such as adrenalin and noradrenalin. Longer term, a key player is angiotensin II, a kidney hormone that makes vessels constrict.

If you have hypertension, the first remedy to try is behavioral: exercise and nutrition. This means losing weight if you’re heavy, adopting the DASH diet and restricting salt. Even losing just 10 pounds can lower blood pressure significantly.

It’s not fully clear whether consuming too much salt actually causes hypertension. But age-related increases in blood pressure can be minimized by reducing salt (sodium) intake to about  2.4 grams of sodium a day. (This equals 6 grams, about 1 teaspoon, of salt.)  In practice, this means not adding salt when cooking or eating and avoiding many canned and fried foods, including foods containing soy sauce.

The DASH diet, plus salt restriction, clearly lowers blood pressure. The DASH diet is rich in fruits, vegetables, lowfat diary foods, potassium, calcium, magnesium, fiber and protein. It’s low in total and saturated fat, red meat, sweet foods and sugary drinks.

Stress reduction helps, too. Dr. Thomas Graboys,  chairman of the Lown Cardiovascular Foundation, asks patients two questions: Do you look forward to going to work? And, do you look forward to going home at night? “If someone says no to either,” he says, stress may be contributing to that person’s problems.

To combat stress, Dr. Herbert Benson, president of the Mind/Body Medical Institute and associate professor of medicine at Harvard Medical School, recommends the “relaxation response.” That means taking 10 to 20 minutes a day to meditate, pray or quiet the mind and body through focused concentration. Stress reduction, he says, can minimize the “vicious cycle” in which people panic about their hypertension, making it worse.

If you’ve done all this and still have high blood pressure, you probably need medication. And that’s where doctors disagree – not on whether medication is needed, but on which drugs to try first. If hypertension is stubborn, you’ll probably need several drugs, and there are many to choose from.

Diuretics such as hydrochlorothiazide (Hydrodiuril) or chlorthalidone (Hygroton) flush excess water and salt from the body, allowing the heart to work less hard. One reason diuretics fared well in the ALLHAT study is that 32 percent of participants were black. Blacks, perhaps for genetic reasons, tend to be sensitive to salt and hence, highly responsive to diuretics.

Beta-blockers such as propanolol (Inderal) are another staple. They reduce nerve impulses to the heart and blood vessels, making the heart beat more slowly and with less force.

A similar class of drugs is the alpha blockers such as doxazosin (Cardura), which also reduce nerve impulses to blood vessels. But the Doxazosin arm of the ALLHAT study was stopped early because those patients had higher rates of cardiac problems.

ACE-inhibitors such as lisinopril (Zestril) relax blood vessels by blocking the formation of angiotensin II. (A newer class of drugs called angiotensin antagonists such as losartan (Lotrel Cozaar) act differently, by blocking receptors for angiotensin II in vessels.)

And then there are the calcium channel blockers (CCBs), drugs such as amlodipine  a combination of amlodipine and benazepril (Lotrel). They lower pressure by blocking calcium, which causes vessels to constrict.

Granted, it’s a bit confusing. But it’s “very reassuring” that the ALLHAT study found diuretics to be so effective, says Dr. Sid Smith, past president of the American Heart Association and professor of medicine at the University of North Carolina at Chapel Hill.

And because diuretics are cheap – about 13 cents a pill versus 10 times that for other medications - “there is no cost-quality tradeoff,” as Dr. Lawrence J. Appel, a hypertension specialist at Johns Hopkins Medical Institutions noted in a JAMA editorial.

As to which drug to start with, stay tuned for the findings from Chobanian’s committee. In the meantime, work with your doctor until you find a drug, or combination of drugs, that get your blood pressure out of the danger zone.

Judy Foreman is a freelance columnist who can be contacted at foreman@globe.com.