Safety of Hypertensive Drug Questioned

B O S T O N, Aug. 29, 2000 -- A new round of conflicting studies is once again fueling debate among hypertension experts and creating confusion among the millions of patients wondering whether the medication they are taking for high blood pressure is actually reducing their risk of having a heart attack.

A study today from the European Society of Cardiology meeting in Amsterdam shows calcium channel blockers, one class of hypertension medication, may increase the risk of heart attacks and heart failure compared to other high blood pressure drugs. The report comes just days after research presented at another scientific meeting in Chicago reached an opposite conclusion.

For the 24 million Americans who take these drugs, the arguments among scientists still have not answered the question: What drug should I take?

Diagnosis: High Blood Pressure High blood pressure, or hypertension, which affects one out of every four Americans, occurs when the blood presses too hard against the walls of the arteries, damaging blood vessels and possibly leading to heart attacks or strokes.

Medications to treat hypertension include these calcium channel blockers, such as Pfizer’s Norvasc and Procardia, as well as ACE-inhibitors, beta-blockers and diuretics. The drugs bring blood pressure down to a normal range using different mechanisms, such as relaxing the artery muscles or reducing the amount of fluid in the arteries.

The researchers decided to look at the safety of long-acting calcium channel blockers after having revealed five years ago that the shorter-acting ones posed significant risk. Today, few doctors prescribe these shorter-acting drugs.

In the latest study announced in Europe, the researchers, led by Dr. Marco Pahor at Wake Forest University in Winston-Salem, N.C., combined nine previously-conducted smaller studies, in what is called a meta-analysis of collected data from the medical literature, to reach a large pool of more than 27,000 patients. He worked with investigators at the Albert Einstein College of Medicine in New York City and the University of Washington in Seattle.

The team compared calcium channel blockers to the other antihypertensive medications and found that those using calcium channel blockers had a 27 percent higher risk of suffering a heart attack and a 26 percent higher risk of having heart failure.

Significantly, however, those using calcium channel blockers were not found to have a higher risk of stroke — or death.

Avoidable Heart Problems Still, the researchers estimated that of the 28 million people worldwide using the drug, 85,000 will suffer “unnecessary” heart problems that could be avoided by using other, often cheaper, medications, such as diuretics.

However, hypertension experts say the battle is far from over.

A competing group of researchers from Australia presented a similar, so-called meta-analysis earlier this week at the International Society of Hypertension in Chicago which included more than 70,000 patients worldwide, and found no significant differences among the medications, either in effectiveness or outcome.

The National Institutes of Health is also in the midst of an eight-year study called ALLHAT, or the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial, comparing the various antihypertensive medications.

If the NIH trial had found a significant risk for those taking the calcium channel blockers so far, it would have been stopped short, notes Tulane epidemiologist Dr. Paul Whelton, a member of the trial’s steering committee.

But the NIH final conclusions will not be reported until 2002, leaving doctors and consumers with no clear answer for the time being, says Dr. Jeffrey Cutler, project officer of the study.

Both meta-analyses agreed calcium-channel blockers were just as effective as all the other medications at lowering high blood pressure.

However, because each drug works differently, it is not surprising there might be a difference in outcomes in heart failure, notes co-researcher Dr. Michael H. Alderman of Albert Einstein College of Medicine.

Calcium Channel Blockers: Costlier Another concern about calcium channel blockers is their price, costing several hundred dollars a year, compared to the other medications.

“The overuse of these less-effective calcium channel blockers — which can cost 10 to 15 times more than diuretics — is a major avoidable clinical problem,” said co-researcher Dr. Curt Furberg, a Wake Forest professor of public health who is also helping conduct the NIH’s ALLHAT trial.

But patients should not take this new message about the safety and effectiveness of long-acting calcium channel blockers into their own hands, the researchers agree.

“Patients should consult their physicians about any potential changes in their antihypertensive therapy,” says Dr. Bruce M. Psaty, a co-researcher and professor of medicine at the University of Washington.