Anti-hypertension drugs: least effective ones prescribed

Healthfacts, Sept, 1997

Of all the drugs available for the treatment of hypertension, the most com- monly prescribed lack evidence of superiority. This finding, from a new study conducted at 48 European medical centers, confirms the results of earlier clinical trials (British Medical Journal, 19 July 1997). Calcium channel blockers and ACE inhibitors are two widely promoted classes of drugs which should not be a doctors first choice for the treatment of high blood pressure. These drugs do not have the proven track record of the two older drug classes, beta blockers and diuretics, which have been on the market for 30 and 40 years, respectively. Choosing the appropriate anti-hypertensive drug has taken on new relevance in the last few years as risks of certain calcium channel blocking drugs have been widely publicized in the general media.

The new European study is one of the first to compare the efficacy of all four treatments for high blood pressure. Thomas Phillipp, M.D., and colleagues, randomly assigned 868 people with hypertension to be treated with one the four classes of anti-hypertensive drugs. The superiority of the beta blocker was demonstrated eight weeks into the study and continued to its end at one year. People on the calcium channel blocker had the highest dropout rate, primarily due to headache, flushes, palpitations, and intolerable swelling.

The investigators concluded, "Our results do not provide any evidence for a superior anti-hypertensive effectiveness or superior tolerability of the new classes of antihypertensive products - namely, calcium channel blockers and angiotensin converting enzyme (ACE) inhibitors. As these new drugs are now widely accepted as treatments of first choice our results further emphasize the need for research to confirm that they do reduce morbidity and mortality, as has been shown for diuretics and beta blockers." (Thirteen different beta blocking drugs are available, each with several brand names, and there are many more versions of diuretics.) The limited efficacy of all antihypertensive drugs was demonstrated by this study. For example, blood pressure was con- trolled in nearly 64% of participants taking beta blockers, but by the study's end, the percentage had dropped to 48%. In other words, slightly more than half the people taking the best of the anti-hypertensive will not receive any benefit.

Blood pressure reduction is not the final goal of anti-hypertensive drug therapy. Rather, it is to reduce the odds of having a stroke or heart attack. However, long-term studies proving these benefits have been conducted only with participants taking beta blockers and/or diuretics. This explains why long-standing treatment guidelines from the National High Blood Pressure Program advise doctors to prescribe the newer classes of anti-hypertensive drugs, calcium channel blockers and ACE inhibitors, only when the older drugs fail to lower blood pressure.

This advice and the scientific evidence supporting it have been ignored by many doctors in the U.S. and Europe thanks to the promotional activities of the drug companies. New drugs generate higher profits as long as they remain under patent, usually for 17 years. Yet we rarely know whether a new drug is an improvement over the old. To gain FDA approval, a manufacturer must conduct two trials that demonstrate that its new drug can lower blood pressure and do it more effectively than a placebo. This can be done in studies lasting only a few months. A drug company, however, is not required to prove its new drug is more effective than those already on the market. Nor must it prove the long-term treatment goal, in this case, reduction of the rate of stroke and heart attack. Such studies are published years later, if ever.

The uninformed prescribing practices of American and European physicians have come under scrutiny in the last few years because a higher rate of heart attack, cancer, and gastrointestinal hemorrhage was found among people taking short-acting calcium channel blockers (see chart on page 3). While this is alarming, the finding has not always been consistent. Three studies, for exam- ple, found no increased incidence of death or complications with these drugs, according to The Medical Letter (14 February 1997). Still, this physician publication which has no drug company advertising advises doctors to avoid treating hypertension with any short-acting calcium channel blocker, especially Adalat and Procardia, until more studies have been done. The Medi- cal Letter advises this for people taking calcium channel blockers because other drugs have failed: "Patients with hypertension already controlled by a long-acting calcium channel blocker should stay on it."

Resource

To learn what kind of antihypertensive drug you are taking check the 1997 Physicians Desk Reference, which is available at most public libraries.