Dosing Time-Dependent Difference in the Suppressive Effect of Empagliflozin on the Development of Mechanical Pain Hypersensitivity in Diabetic Mice.

A problem for patients with diabetes is the rise of complications, such as peripheral neuropathy, nephropathy, and retinopathy. Among them, peripheral neuropathy, characterized by numbness and/or hypersensitivity to pain in the extremities, is likely to develop in the early stages of diabetes. Empagliflozin (EMPA), a sodium-glucose cotransporter-2 inhibitor, exerts hypoglycemic effects by preventing glucose reabsorption in proximal tubular cells. EMPA can improve cardiovascular and renal outcomes in diabetic patients, but its suppressive effect on the development of diabetic neuropathy remains unclear. In this study, we demonstrated that optimizing the dosing schedule of EMPA suppressed the development of pain hypersensitivity in streptozotocin (STZ)-induced diabetic model mice maintained under standardized light/dark cycle conditions. A single intraperitoneal administration of STZ to mice induced hyperglycemia accompanied by pain hypersensitivity. Although EMPA did not exert anti-hypersensitivity effect on STZ-induced diabetic mice after the establishment of neuropathic pain, the development of pain hypersensitivity in the diabetic mice was significantly suppressed by daily oral administration of EMPA at the beginning of the dark phase. On the other hand, the suppressive effect was not observed when EMPA was administered at the beginning of the light phase. The hypoglycemic effect of EMPA and its stimulatory effect on urinary glucose excretion were also enhanced by the administration of the drug at the beginning of the dark phase. Nocturnal mice consumed their food mainly during the dark phase. Our results support the notion that morning administration of EMPA may be effective in suppressing the development of peripheral neuropathy in diabetic patients. SIGNIFICANCE STATEMENT: Empagliflozin, a sodium-glucose cotransporter-2 inhibitor suppressed the development of neuropathic pain hypersensitivity in streptozotocin-induced diabetic model mice in a dosing time-dependent manner.