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ARBs not equally effective at reducing blood pressure, UK study finds

By Lilian Anekwe

Candesartan is more effective at lowering blood pressure than losartan, according to a meta-analysis by UK researchers who estimate the difference could equate to a substantial reduction in coronary heart disease events and strokes.

It has been suggested that all ARBs lower blood pressure to a similar extent when administered at the recommended doses, but this position has been challenged by the results of the meta-analysis of hypertension trials.

The analysis of 13 randomised controlled trials covered 4,000 patients, and compared the mean changes in systolic and diastolic blood pressure for each drug alone - both in low-dose monotherapy, where 4 and 8mg candesartan and 25 and 50mg losartan were compared, and high-dose monotherapy, where 12, 16 and 32mg candesartan were compared with 100mg losartan, and in combination with hydrochlorothiazide.

All analyses showed statistically superior reductions in systolic and diastolic blood pressure with candesartan when compared with losartan, and on the basis of all data the weighted mean difference – of 3.2 mmHg systolic and 2.2 mmHg diastolic – favoured candesartan.

Dr Peter Meredith, senior lecturer in cardiovascular and medical sciences at the University of Glasgow, wrote in the Journal of Human Hypertension: ‘These findings are contrary to the suggestion that all ARBs lower blood pressure to a similar extent.'

‘The results of our analyses suggest that candesartan monotherapy could increase the diastolic blood pressure reduction by an additional 1.8 mmHg when compared with losartan… it can be shown that this additional blood pressure response could reduce coronary heart disease events by 32% and reduce stroke by 44%.'

‘On the basis of the differential in diastolic blood pressure with the combination therapy using hydrochlorothiazide, similar considerations predict that coronary heart disease events would be reduced by 41% and stroke by 55%.'

The researchers did call for caution to be exercised in the interpretation of their results, and pointed out that the study was limited by being based on the pooling of data from disparate trials, and cited a lack of data from randomised outcome trials.

But Dr Meredith concluded: ‘Given the consistency of the findings for both systolic blood pressure and diastolic blood pressure and with different doses of the two drugs, there is compelling evidence to indicate that candesartan provides superior blood pressure reductions when compared with losartan and is likely to be superior in CV protection.'

MSD, the manufacturer of losartan, was unavailable for comment.

Journal of Human Hypertension 24, 525-531 (August 2010)

Not all ARBs are equally effective at lowering blood pressure