By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

The angiotensin receptor blockers (ARBs) are a very popular new class of blood pressure-lowering drugs, which are heavily marketed by pharmaceutical manufacturers. There are now six of them approved for use in the US, and their general properties are very similar. Claims have been made that some members of this class are more effective at lowering blood pressure than others. Most of these claims were based on relatively small studies.

An analysis of 43 studies in which the effectiveness of four of them was assessed in a total of more than 11,000 patients has looked at this question. The drugs were losartan (Cozaar) given in a dose of 50 or 100 milligrams a day, valsartan (Diovan- 80 to 160 milligrams), irbesartan (Avapro - 150 to 300 milligrams), and candesartan (Atacand- 8 to 16 milligrams). The average reduction of blood pressure for all of the drugs was 11 mm Hg for systolic pressure, and 8.5 mmHg for diastolic. These numbers were basically the same for all four drugs, and for each drug about 50% of patients were classified as “responders”(that is the drug lowered diastolic pressure to less than 90 mmHg or by 10 mmHg). When the doses were increased to its maximum level, this rate increased to 60%. Increasing the doses thus only produced a small additional fall of blood pressure.

When the four ARBs were given in combination with hydrochlorothiazide (a diuretic), the blood pressure decrease was bigger, being on average 18 mmHg for systolic and 12 mmHg for diastolic pressure. The responder rates were also higher, in the range of 60 to 70%.

Doctor’s comments

For some of the classes of blood pressure lowering drugs, such as the calcium channel blockers, there are substantial differences between the individual drugs, but for the ARBs this does not so far appear to be the case. The six drugs that are currently approved by the FDA have the same mode of action, and all have minimal side effects. They are all approved for once daily dosing, and although they do vary somewhat in their duration of action, this analysis provided no evidence that any one of them is more or less effective than the others. The analysis also emphasizes that most blood pressure lowering drugs only work in about 60% of patients, and that the response is better to combination drugs (in this case an ARB with a diuretic). Managed care companies often negotiate a deal with one pharmaceutical company to give a favorable price on their drug, and one implication of this analysis is that it is unlikely to make much difference if you are switched from one of these drugs to another.

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