Combination Treatment Effective Against Diabetic Retinopathy

A 2-drug combination reduced retinal cell death more effectively than a single drug therapy.

In a recent study, a 2-drug cocktail was observed to provide more protection against diabetic retinopathy than a single drug in rat models. The investigators said that this combination is a promising treatment for patients with diabetic retinopathy, which is a leading cause of vision loss in patients with diabetes.

Diabetic retinopathy damages the blood vessels in the retina, and causes vision loss or blindness. In 2016, the American Academy of Ophthalmology estimated that 4.2 million patients with diabetes age 40 and over had the condition.

Poor blood glucose control is a risk factor for patients who eventually develop diabetic retinopathy, therefore, improved disease management is important for controlling early cases of the disease. Certain drugs, such as Lucentis, have also been approved to treat the condition, but more advanced cases may require surgery.

According to a new study published in Investigative Ophthalmology & Visual Science, a multi-drug treatment effectively reduced symptoms of diabetic retinopathy in animals.

The study authors discovered that the 2-drug cocktail reduced capillary loss by 68%, compared with only 43% with a single-drug treatment. The combination treatment is comprised of an angiotensin receptor neprilysin inhibitor (ARNI) plus irbesartin, which is used to treat high blood pressure, and the diarrhea treatment thiorphan.

The investigators tested the ARNI against treatment with irbesartin monotherapy, an angiotensin receptor blocker.

While the 2-drug cocktail was not seen to reverse symptoms of diabetic retinopathy, it was observed to slow damage in the animals, according to the study. Notably, the study authors said that the ARNI was able to dramatically reduce inflammation, which is a main symptom of the condition.

"If you can decrease that inflammation, it protects the retinal cells and delays the progression of the disease," said study co-author Tuhina Prasad, PhD.

The ARNI was also observed to be more effective, compared with irbesartin, at reducing retinal cell death after 12 weeks of treatment in the rat models, according to the study. This treatment reduced cell death by 51%, while the single drug only reduced cell death by 25%.

These findings are significant for the development of novel drugs to treat diabetic retinopathy since it is strongly linked to prolonged diabetes, the authors wrote.

Prior to exploring the 2-drug cocktail in humans, the investigators must continue with animal studies to determine the potential long-term side effects of using a neprilysin enzyme inhibitors on the eye. Additionally, the long-term effects of neprilysin enzyme inhibitors are largely unknown.

However, the study authors concluded that the 2-drug combination may be a promising treatment option for the millions of patients with diabetic retinopathy.