Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Aldose reductase inhibitor
Introduction
Aldose reductase inhibitors are a class of drugs being studied as a way to prevent eye and nerve damage in people with diabetes.
Mechanism
Mechanism
Their target, aldose reductase, is an enzyme that is normally present in many other parts of the body, and catalyzes one of the steps in the sorbitol(polyol) pathway that is responsible for fructose formation from glucose. Aldose reductase activity increases as glucose concentration rise in diabetes in those tissue that are not insulin sensitive, which includes the lenses, peripheral nerve and glomerulus. Sorbitol does not diffuse through cell membranes easily and therefore accumulates, causing osmotic damage which leads to retinopathy and neuropathy.
Diabetic cataract
Diabetic cataract
Diabetic cataract formation follows an increase in sugars in the lens. The excess sugar within the lens is reduced by aldose reductase to its alcohol, but the lens capsule is relatively impermeable to sugar alcohols. Because of the excess sugar alcohol (polyol), the lens imbibes water, causing osmotic imbalance. Eventually, increased sodium and decreased potassium levels and decrease glutathione levels lead to cataract formation. Topical administration of aldose reductase inhibitors have been shown to prevent the cataract in rats.[2]