A 1-Month Exploratory Combination Safety and Toxicity Study of Co-Administration of Sitagliptin and Telmisartan in Male Wistar Han Rats

Diabetes and hypertension often coexist and need complex pharmacological management. Sitagliptin, a dipeptidyl peptidase-4 inhibitor, is widely used for glycemic control, and telmisartan, an angiotensin II receptor blocker, is the preferred treatment for hypertension. Thus, we have conducted a 1-month exploratory combination safety and toxicity study in male Wistar Han rats. Animals were administered 100 mg/kg/day of sitagliptin or telmisartan individually, or in combination by oral gavage. We have evaluated effects on body weight, feed intake, clinical chemistry, and hematology parameters, and microscopic examination of liver, kidney, adrenal glands, heart, lungs, lymphatic organs, and gastrointestinal tract. The combination showed a decrease in body weight gain, feed intake, hematocrit, reticulocytes, WBCs, serum triglycerides, AST, total protein, globulin, and heart weight, and increased serum levels of urea, phosphorous, magnesium, potassium, and kidney weight. Co-administration showed an additive effect on decrease in WBC counts, potentiating the effects on decreased serum triglycerides and increased phosphorous levels and kidney weights, and a synergistic effect on serum AST levels. Sitagliptin attenuated the changes caused by telmisartan on reticulocyte counts, serum creatinine levels, and liver and thymus weights. Administration of the individual compounds caused a reduction in spleen weight, though the combination had no effect. Sitagliptin, telmisartan, or combination dosing showed no significant organ toxicity upon histopathological examination. It appears that co-administration of telmisartan and sitagliptin is well tolerated in rats. Three-month toxicity studies, in both genders, with full toxicokinetic profiling and thorough tissue examination, will be necessary to support the combination's toxicity profile.