Norvasc better than beta blockers for lowering blood pressure

Nov 14 2005

According to a study presented at a meeting of the American Heart Association, Norvasc, was more effective at reducing blood pressure near the heart than standard, older treatments such as beta blockers.

Norvasc, produced by drug company Pfizer was better in lowering central pressure than the atenolol-based conventional recommended treatment, says lead researcher Bryan Williams, a professor at the University of Leicester School of Medicine.

The researchers also say that the results indicate that blood pressure near the heart, or central aortic blood pressure, may be a better predictor of heart attack and stroke risk than a traditional blood pressure measurement taken from the arm using the standard inflated arm cuff.

Norvasc belongs to a class of drugs known as calcium channel blockers, while atenolol is a beta blocker.

Williams says the study found that measuring blood pressure in the arm appeared to underestimate the efficacy of drugs such as amlodipine (Norvasc) and overestimate the efficacy of the beta blocker atenolol.

He regards the results of the study as clear-cut, dramatic and potentially very important.

The study was in fact a part of a major blood pressure study known as ASCOT unveiled earlier this year.

The Conduit Artery Function Evaluation (CAFE) study has helped explain why Norvasc was shown to reduce cardiac death compared with atenolol.

Professor Williams was given permission from Pfizer to do an independent review of about 10 percent, or 2,199, of the patients involved in the ASCOT study, checking their aortic blood pressure as well as the standard blood pressure measurement taken via the arm.

Williams explains that while the ASCOT study found Norvasc reduced adverse heart events, including a 14 percent reduction in cardiac death, compared to the beta blocker, the blood pressure reduction appeared to be about the same when measured in the conventional way.

The researchers hypothesized that the death rate difference might be related to blood pressure differences closer to the heart that were not reflected by a standard arm cuff reading.

The researchers say they were astonished when they saw there were such big differences, about 4 millimeters to 5 mm difference in mercury pressure in the central artery, which from a patient perspective is pretty big.

They say they found a significant relationship between how high the central blood pressure was and the likelihood of an adverse clinical outcome independent of what was measured in the arm.

The aortic blood pressure of patients was measured at least three times over the course of four to five years using a noninvasive device called SphygmoCor made by Sydney, Australia-based AtCor Medical Holdings.

Williams is not suggesting that patients routinely ask doctors to check their aortic blood pressure, but more research is needed into what different types of drugs that are routinely used are doing to functions of our large arteries and pressure in the arterial system.