Blood pressure drugs slow eye problems in diabetes

By Gene Emery

BOSTON, July 1 (Reuters) - Two Merck (MRK.N) blood pressure drugs given to diabetics to prevent worsening kidney problems do not work in that way but may prevent diabetes-related eye problems, researchers reported on Wednesday.

The Vasotec brand of enalapril and the Cozaar brand of losartan slowed progression of diabetic eye damage in more than 65 percent of patients, the researchers found in a study partially funded by Merck.

Kidney disease known as diabetic neuropathy causes at least 45 percent of kidney failures in the United States. Diabetes is also the main cause of acquired blindness in adults.

The research, reported in the New England Journal of Medicine, was originally designed to see if early treatment with either drug, which affect the body's renin-angiotensin system that regulates renal function and blood pressure, would slow kidney deterioration in people with type-1 diabetes.

Neither drug helped the kidneys compared to a placebo. But shortly after the study began, the research team led by Dr. Michael Mauer of the University of Minnesota decided to include evaluations for diabetic retinopathy, in which blood vessels that leak in the eyes can damage vision.

After following 285 patients for five years, they discovered the eyes did benefit. Retinopathy progressed significantly in 38 percent of the volunteers getting a placebo compared to only 25 percent who took enalapril and 21 percent who got losartan.

"There is a benefit and the benefit appears to be a little bit more easy to detect in people with no or mild eye changes than in people with severe eye changes," Mauer said in a telephone interview.

"Inhibition of the renin-angiotensin system reduced the advancement of retinal changes by 60 to 70 percent as compared with placebo, mostly likely independent of blood-pressure reduction," a group of doctors led by Dr. Bruce Perkins of the University of Toronto wrote in a commentary.

Mauer said more research is needed before the drugs could be routinely given to diabetics who show no signs of kidney or eye problems, especially since they may cause birth defects if given to pregnant women.

"But there are some people whose blood sugars are very difficult to control, who are developing early eye changes. It might be quite reasonable, given what we know, to institute this kind of treatment," he said. (Editing by Alan Elsner and Maggie Fox)