Two-Drug Combo Reduces Diabetic Kidney Damage
WEDNESDAY June 4, 2008 -- A combination of two drugs used to combat some of the damaging effects of type 2 diabetes may also reduce the risk of diabetic kidney failure, a new Danish study has found.
But the researchers warn that testing the combination of losartan (Cozaar) and aliskiren (Tekturna) to block the activity of a molecule that damages renal arteries is still in the early stages.
Losartan is often prescribed for high blood pressure in diabetes. Aliskiren blocks the pathways that allow the vessel-damaging molecule -- angiotensin II -- to grow and expand.
The study, published in the June 5 issue of the New England Journal of Medicine, used 599 people with type 2 diabetes, the kind that generally develops in adults. In the six-month trial, half took losartan and aliskiren, while the others took losartan and a placebo. The double-dose treatment reduced the amount of protein in the urine by 50 percent or more in 24.7 percent of participants, compared to 12.5 percent of those who got the placebo.
"This is clearly a very exciting thing," said Dr. Matthew Weir, director of the division of nephrology at the University of Maryland School of Medicine. Kidney failure is a major problem in diabetes, and reducing the rate of failure would be a major achievement, he noted.
However, the results won't officially mean anything to the U.S. government. Weir said the U.S. Food and Drug Administration doesn't officially recognize reduction of proteinurea as a biomarker of success in preserving kidney function. And the trial lasted only six months, which means more studies are required, he added.
"The ultimate plan now would be to do a full renal [kidney] protection trial over, say, three years to show that this is a better strategy to prevent kidney failure," he said.
Weir himself is not waiting for such a trial to use the two-drug therapy. "I have been doing it for a while, because I have been aware of this study for a while," he said.
"Exciting" was a word also used by Dr. Robert Zimmerman, interim director of the Cleveland Clinic endocrinology department. "Certainly, this is pointing in the direction you want to see," he said.
Diabetes is probably the leading cause of kidney failure that leads to dialysis, Zimmerman added. "About 50 percent of dialysis is probably due to diabetes."
But he agreed with Weir that more work is necessary. "We clearly need to have more long-term data," Zimmerman said. "That would be the next stage, to see whether this truly proves to be a treatment that ought to be used more frequently."
Drugs such as ACE inhibitors, as well as losartan, now are used to help prevent kidney damage in diabetes, he said. "What this study seems to indicate is that using a renin inhibitor is another way of blocking the pathway that is associated with the increased risk of renal disease," Zimmerman said.
"This is an important study that is likely to change my practice," said Dr. Ajay K. Singh, an associate professor of medicine at Harvard Medical School and director of dialysis at Brigham and Womens Hospital. "Based on the results of this study, I am much more likely to use a direct renin inhibitor in addition to an angiotensin blocker in patients with Type 2 diabetes with kidney disease."
Posted: June 2008