A new study shows that for the same level of blood pressure control, Diovan (valsartan), the angiotensin II receptor blocker (ARB), is more effective than the calcium channel blocker amlodipine in reducing microalbuminuria (p<0.001), an early sign of diabetic kidney disease.

The results of the study, the Microalbuminuria Reduction with Valsartan (MARVAL) trial, suggest that Diovan lowers microalbuminuria through effects that are independent of blood-pressure-lowering. The lead author of the article was Giancarlo Viberti, MARVAL investigator, from the Department of Diabetes, Endocrinology & Internal Medicine, GKT School of Medicine, Guy's Hospital, King's College, London.

Current treatment guidelines from prestigious medical organisations including the American Diabetes Association (ADA) and National Kidney Foundation (NKF) already recommend ARBs such as Diovan as the initial agents of choice in hypertensive type 2 diabetes patients with microalbuminuria.

Microalbuminuria results when deteriorating kidneys allow protein to pass into the urine. Microalbuminuria is a major risk factor for progressive kidney disease as well as heart disease. Left untreated, microalbuminuria may progress to end-stage renal disease (ESRD), resulting in the need for dialysis or transplantation. Up to 40 per cent of people with type 2 diabetes develop ESRD and the annual cost of treating ESRD in the US alone is $14.5 billion. Heart disease remains the leading cause of death in diabetic patients and studies show risk for death from cardiovascular disease doubles in type 2 diabetes patients who have microalbuminuria.

MARVAL was a multi-centre, double-blind, randomised, parallel study in patients aged 35-75 with type 2 diabetes and microalbuminuria with normal or high blood pressure. As part of the study, both treatment groups had blood pressure controlled to the same level. Patients were randomised to receive valsartan 80 mg once-daily or amlodipine 5 mg once-daily over 24 weeks. The target blood pressure for all patients was 135/85 mm/Hg and if necessary, doses of active treatments were doubled at week 4, bendrofluazide (a thiazide diuretic) was added from week 8, and doxazosin (an alpha blocker) was added from week 12 to help patients attain this goal.

The study was designed to assess the blood-pressure-independent effects of Diovan vs. amlodipine on urinary albumin excretion rates (UAER), a measure of microalbuminuria. At week 24, there was a 44% reduction in UAER with valsartan (56% of baseline) vs. an 8% reduction with amlodipine (92% of baseline), a highly significant effect (p<0.001). Valsartan lowered UAER similarly in both the hypertensive and normotensive subgroups. More patients reversed to normoalbuminuria with valsartan (29.9% vs. 14.5%; p=0.001). Blood pressure reductions were similar between the two treatments (systolic/diastolic 11.2/6.6 mmHg for valsartan, 11.6/6.5 mmHg for amlodipine).

Diovan is supported by the world's largest clinical trial programme with an ARB. These trials include the recently completed Val-HeFT study, which was the largest study ever conducted in heart failure. Other major ongoing trials in the Diovan clinical trial programme are VALUE (high-risk patients with hypertension, including nearly 5,000 patients with diabetes), and VALIANT (15,000 post-myocardial infarction patients). Another major study is NAVIGATOR, which will be the largest study ever conducted in patients with impaired glucose tolerance at high risk for cardiovascular events.

Diovan is already approved for first-line treatment of high blood pressure in more than 80 countries, including the US, and is one of the fastest growing agents among the top 10 branded prescription medications for this condition. An estimated three million patients worldwide take Diovan for high blood pressure.