Aliskiren and valsartan are both renin inhibitors. In a randomised controlled trial of almost 1,800 people, combined treatment lowered diastolic BP by 12.2 mmHg.
In contrast, the decrease was just 4.1 mmHg for placebo, 9.0 mmHg for aliskiren alone and 9.7 mmHg for valsartan alone, it is reported in the Lancet.
But in tandem, the drugs cause a potentially life-threatening side-effect, high blood potassium. This means the treatment is unlikely to be suitable for use in general practice or primary prevention in specialist care, say Dr Willem Birkenhager, from Rotterdam in the Netherlands, and Dr Jan Staessen, from the University of Leuven in Belgium, in an accompanying editorial.
Biochemical monitoring would be needed if these drugs were to be given, they explained.
Lancet 2007; 370: 221-229
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