Popular Blood Pressure Medicine May Do More Harm Than Good

Aug. 29, 2000 (Amsterdam) -- A highly popular but expensive type of blood pressure medication may be responsible for an excessive number of heart attacks and cases of heart failure. Although the drugs, known as long-acting calcium channel blockers, effectively lower blood pressure as well as less expensive alternatives, a new study shows that they do not prevent the cardiovascular complications of high blood pressure.

Use of any of the long-acting calcium channel blockers leads to about 40,000 "unnecessary or excess" heart attacks in the U.S. each year and about 85,000 "excess events" worldwide, Marco Pahor, MD, tells WebMD. Pahor, a professor of medicine at Wake Forest University School of Medicine in Winston-Salem, N.C., headed the team of researchers who wrote the new study.

There are several different brands of these drugs on the market, but among the better known are Procardia XL, Norvasc, Cardizem CD, and Adalat CC. The annual cost of high blood pressure treatment with these drugs, which are taken daily, ranges from $740 to $990 a year. That, says Pahor, is much more expensive than treatment with another kind of drug called a diuretic that can cost only about $60 a year.

One of the reasons for the big difference in cost is that long-acting calcium channel blockers are only available as brand-name drugs, while the other, more effective blood pressure drugs -- diuretics, beta-blockers, and ACE inhibitors -- are available in generic formulations, says Pahor.

The researchers analyzed data from nine studies that compared the outcomes of patients taking a calcium channel blocker to the outcomes of patients treated with other drugs to treat high blood pressure. All 27,743 patients included in the nine studies had high blood pressure (also called hypertension), meaning a blood pressure of more than 140/90.

They found that people taking long-acting calcium channel blockers had a "27% higher risk of heart attack and 26% higher risk of congestive heart failure than did persons taking diuretics, beta-blockers, or ACE inhibitors," Pahor says.

The findings were presented Tuesday at an international cardiology meeting in Amsterdam, the Netherlands, by Pahor's colleague, Curt D. Furberg, MD, PhD, who is a professor of public health at Wake Forest University School of Medicine.

Pahor and Furberg say the calcium channel blockers were as effective at lowering blood pressure as the other medicines, but the findings suggest that the other drugs may offer some additional advantages over the calcium channel blockers in "the way they lower the blood pressure."

Pahor says many doctors believe that simply obtaining a reduction in blood pressure can predict the risk of future heart attacks or strokes. But, he says, even though calcium channel blockers do "lower the [blood pressure] number," the drugs may affect the body in other ways that "offset the benefit of a lowered blood pressure." Another possibility, he says, is that the other blood pressure-lowering agents, like beta-blockers, "offer some non-blood pressure action that by itself is protective."

Furberg says the findings provide clear evidence that calcium channel blockers should not be the first drug that patients get for their high blood pressure. "We now have a large body of evidence from large, randomized trials and the evidence speaks for itself," Furberg tells WebMD.

"Our recommendation is that [the other blood pressure-lowering medicines] ... diuretics, beta-blockers, and ACE-inhibitors, remain the clear choice for ... hypertension. Due to their clinical inferiority and high costs, calcium channel blockers should be considered when [other standard] drugs have failed or cannot be tolerated. A few large, ongoing trials may modify the findings, but it is unlikely they will reverse them," Furberg says.

Milton Packer, MD, says that before we assume that all calcium channel blockers are inferior to other antihypertensives, more studies need to be performed. "I think Dr. Furberg has presented data here today that raise a concern about the use of [calcium channel blockers]. The definitive answer is not in place ... I think this is the first step in an evolving process to find out what truly represents first ... therapy [for hypertension]." Packer, a professor of medicine at the Columbia University College of Physicians and Surgeons in New York, did not participate in the study.

Robert Temple, MD, associate director of medical policy at the FDA's Center for Drug Evaluation and Research, tells WebMD that the FDA does not plan any immediate action on long-acting calcium channel blockers.

"At the moment, we don't know what studies are included in ... [this] analysis and don't know what the individual results were. When one looks at this, it may be that the results are largely driven by the results of one study, so we don't have the answers yet ... We just can't act on rumors," he says, adding that the FDA will await publication of the results before acting.

"There have been lots of claims about calcium channel blockers in the past," Temple tells WebMD, but those claims, he says, "were based on observational data which were absolutely unreproducible." Pahor and his colleagues also did those studies. Pahor says the criticism of those early trials prompted the decision to do this more extensive analysis.

"I would hate to think that these drugs would be stopped because people think there is something wrong with the drugs, or because they think the drugs are dangerous," says Temple.

Medical experts agree and urge caution to patients considering stopping their blood pressure medicine due to this one study. In a press release from Wake Forest, Bruce M. Psalty, MD, PhD, a co-author of the new study and a professor of medicine, epidemiology, and health services at the University of Washington, said: "In all instances, patients should consult their physicians about any potential changes in their antihypertensive therapy. If patients are not taking a proven therapy such as low-dose diuretics, it is reasonable for them to ask their physicians, 'Why not?'"