Pharmacologic class:

Antidiabetic (dipeptidylpeptidase-4 inhibitor)

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Active ingredient:

Sitagliptin (as phosphate) 25 mg, 50 mg, 100 mg; tabs.


Adjunct to diet and exercise in type 2 diabetes, as monotherapy or in combination with either metformin or a thiazolidinedione.


Incretins, such as glucagonlike peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide, are hormones that play a role in the regulation of glucose homeostasis. They increase insulin synthesis and release from pancreatic beta cells in response to normal or elevated blood glucose levels.

GLP-1 also acts to lower glucagon secretion from the pancreas. Incretins are inactivated by an enzyme known as dipeptidylpeptidase-4 (DPP-4). Sitagliptin inhibits the activity of DPP-4, thereby increasing and prolonging the activity of the incretins. This causes an increase in the release of insulin and a reduction in circulating glucagon levels in a glucose-dependent manner. In patients with type 2 diabetes, the use of sitagliptin results in lower fasting glucose levels and reduced postprandial glucose (PPG) elevations.

Clinical trials:

Four randomized, placebo-controlled studies involving 2,316 patients with type 2 diabetes were conducted to evaluate the effect of sitagliptin on glycemic control. Treatment with sitagliptin resulted in significant improvements in hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), and two-hour PPG compared with placebo.

To evaluate the safety and efficacy of sitagliptin as monotherapy, an 18-week study and a 24-week study were conducted involving a total of 1,262 patients with type 2 diabetes. Following a diet, exercise, and drug washout period, patients with inadequate glucose control were randomized to receive sitagliptin 100 or 200 mg/day, or placebo. Treatment with sitagliptin 100 mg/day resulted in significant improvements in HbA1c, FPG, and two-hour PPG compared with treatment with placebo. Another monotherapy study was conducted that established the safety and efficacy of this drug (given at a reduced dose) in patients with chronic renal insufficiency.

The effect of sitagliptin use on serum lipid levels was similar to placebo.The efficacy of sitagliptin in combination with metformin was established in a trial involving 701 patients. Significant improvements in HbA1c, FPG and two-hour PPG levels were seen in patients given sitagliptin in addition to metformin compared with those given placebo with metformin.

In combination with pioglitazone, sitagliptin was shown to provide significant improvements in HbA1c and FPG compared with placebo in a study involving 353 patients.


100 mg once daily. Renal insufficiency: Creatinine clearance (CrCl) ≥30-<50 mL/min: 50 mg once daily; CrCl <30 mL/min or on dialysis: 25 mg once daily.


<18 years: not recommended. Geriatric considerations: Monitor renal function.


Not for the treatment of type 1 diabetes or diabetic ketoacidosis.


Monitor renal function before starting therapy, then periodically. Severe hepatic insufficiency. Pregnancy (Cat. B). Nursing mothers.


Monitor digoxin.

Adverse reactions:

Nasopharyngitis, upper respiratory tract infection, headache.

How supplied:

Tabs — 30, 90, 100.

For more information, call 866.637.2500, or visit