Sitagliptin Approved As Add-on To Insulin

Sitagliptin (known as Januvia) has been approved by the European Commission as an add-on to insulin (with or without metformin) for people with Type 2 diabetes who cannot control their condition effectively with a combination of diet, physical activity and insulin. Sitagliptin is a once-daily DPP-4 inhibitor that works by blocking the action of DPP-4, an enzyme which destroys the hormone incretin.

Incretins help the body produce more insulin only when it is needed and reduce the amount of glucose being produced by the liver when it is not needed.

Further option for people with Type 2 diabetes

“We welcome this announcement that sitagliptin will be made available, as it can offer people with Type 2 diabetes a further option to help them achieve good glycaemic control,” said Caroline Butler, Care Advisor at Diabetes UK.

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General Information
Januvia is an orally-active inhibitor of the dipeptidyl peptidase-4 (DPP-4) enzyme. The DPP-4 enzyme inactivates incretin hormones, which are involved in the physiologic regulation of glucose homeostasis. By inhibiting DPP-4, Januvia increases and prolongs active incretin levels. This in turn increases insulin release and decreases glucagon levels in the circulation in a glucose-dependent manner.

Januvia is specifically indicated for the improvement of glycemic control in patients with type II diabetes mellitus as monotherapy or combination therapy with metformin or a peroxisome proliferatoractivated receptor gamma (PPAR) agonist (e.g., thiazolidinediones) when the single agent does not provide adequate glycemic control.

Januvia is supplied as 25 mg, 50 mg or 100 mg tablets designed for oral administration. The recommended initial dose of the drug is 100 mg once daily.

Clinical Results

FDA Approval
FDA approval of Januvua was based on the pooled results of two double-blind, placebo controlled monotherapy studies and two double-blind, placebo controlled combination therapy studies.

Monotherapy Trials

The Januvia monotherapy trials had one with an 18 week duration and one with a 24 week duration. In the 18-week study, 521 subjects were randomized to placebo, Januvia 100 mg, or Januvia 200 mg, and in the 24-week study 741 subjects were randomized to placebo, Januvia 100 mg, or Januvia 200 mg. In both trials subjects went under a 7 week washout period then completed a 2-week, single-blind, placebo run-in period, before receiving treatment. Treatment with Januvia at 100 mg daily provided significant improvements in A1C, FPG, and 2-hour PPG compared to placebo. In the 18-week study, 9% of patients receiving Januvia 100 mg and 17% who received placebo required rescue therapy. In the 24-week study, 9% of patients receiving Januvia 100 mg and 21% of patients receiving placebo required rescue therapy. The 200 mg daily dose did not provide greater glycemic efficacy than the 100 mg daily dose in either trial.

Combination Therapy Trials

The first randomized, double-blind, placebo-controlled trial enrolled 701 subjects. It was designed to compare Januvia in combination with metformin as treatment for 24 weeks. Subjects already on metformin at a dose of at least 1500 mg per day were randomized after completing a 2-week single-blind placebo run-in period. Subjects on metformin and another antihyperglycemic agent and subjects not on any antihyperglycemic agents (off therapy for at least 8 weeks) were randomized after a run-in period of approximately 10 weeks on metformin (at a dose of at least 1500 mg per day) in monotherapy. Subjects were randomized to the addition of either 100 mg of Januvia or placebo, administered once daily. This combination provided significant improvements in A1C, FPG, and 2-hour PPG compared to placebo with metformin. Rescue glycemic therapy was used in 5% of those treated with Januvia 100 mg and 14% of those treated with placebo.

The second randomized, double-blind, placebo-controlled trial enrolled 353 subjects. It was designed to evaluate Januvia in combination with pioglitazone as treatment for 24 weeks. Patients on any oral antihyperglycemic agent in monotherapy or on a PPAR agent in combination therapy or not on an antihyperglycemic agent (off therapy for at least 8 weeks) were switched to monotherapy with pioglitazone (at a dose of 30-45 mg per day), and completed a run-in period of approximately 12 weeks in duration. After the run-in period on pioglitazone monotherapy, patients were randomized to the addition of either 100 mg of Januvia or placebo, administered once daily. This combination therapy demonstrated significant improvements in A1C and FPG compared to placebo with pioglitazone. Rescue therapy was used in 7% of patients treated with Januvia 100 mg and 14% of patients treated with placebo.

Side Effects

Adverse events associated with the use of Januvia may include, but are not limited to, the following:

  * Upper Respiratory Tract Infection
  * Nasopharyngitis
  * Headache.

Mechanism of Action

Januvia is an an orally-active inhibitor of the dipeptidyl peptidase-4 (DPP-4) enzyme. The DPP-4 enzyme inactivates incretin hormones, which are involved in the physiologic regulation of glucose homeostasis. Januvia slows the inactivation of incretin hormones and thus increases and prolongs their action. By inhibiting DPP-4, Januvia increases and prolongs active incretin levels. This in turn increases insulin release and decreases glucagon levels in the circulation in a glucose-dependent manner

Source
Diabetes UK