Pentoxifylline, a drug used to treat patients with circulation problems, may also benefit those with kidney disease caused by diabetes and other conditions. Specifically, pentoxifylline decreases proteinuria, the abnormal leakage of protein into the urine, according to two articles in the September issue of the American Journal of Kidney Diseases, the official journal of the National Kidney Foundation.
"When kidneys are healthy, very little or no protein appears in the urine," says Dr. Kerry Willis, Senior Vice President for Scientific Activities at the National Kidney Foundation. "Protein in the urine is an early sign that the kidney's filters have been damaged by disease, allowing protein to leak into the urine."
Pentoxifylline makes red blood cells more flexible to improve circulation in the smallest blood vessels of the body. It also has anti-inflammatory properties. Several small clinical trials have suggested that the drug decreases proteinuria caused by diabetes.
A research team at the Kidney Research Centre and the Ottawa Health Research Institute in Ontario, Canada, combined data from 10 of these studies to get a better idea of just how effective pentoxifylline is in diabetic patients.
A total of 476 patients were treated for approximately 6 months. Pentoxifylline substantially reduced proteinuria, particularly in patients with the highest levels of urine protein.
According to lead author Dr. Brendan B. McCormick, "Proteinuria is a strong risk factor for kidney failure, and by decreasing proteinuria, pentoxifylline may help in reducing the likelihood that a diabetic patient will end up needing dialysis."
In two of the trials, pentoxifylline was as effective as captopril, a type of drug called an ACE inhibitor used to treat high blood pressure and to protect kidneys in diabetic patients. This property may be particularly beneficial in patients who cannot take ACE inhibitors because of their side effects.
In the second paper, Dr. Tun-Jun Tsai and colleagues at National Taiwan University Hospital in Taipei took this concept even further, looking at how well pentoxifylline worked in concert with losartan, another ACE inhibitor. The 85 patients had advanced kidney disease due to diabetes and to glomerulonephritis, a group of diseases that cause inflammation and damage to the kidney's filtering units.
After one year, proteinuria was reduced by an additional 40%.
An additive effect between pentoxifylline and ACE inhibitors is important, Dr. Tsai's group points out, because ACE inhibitors and drugs like them often lose their effects over time, and pentoxifylline represents a nontoxic option for boosting their effectiveness.
Authors of both reports call for larger trials to confirm their findings, and to see if pentoxifylline actually stops kidney disease progression.
"A positive finding in this context would be of profound significance because it would provide a novel and inexpensive therapy for the growing global epidemic of diabetic nephropathy," Dr. McCormick's team concludes.
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