Magazine article Drug Topics

Combination Drug Offers New Option for Diabetes

Magazine article Drug Topics

Combination Drug Offers New Option for Diabetes

Article excerpt


Patients with Type 2 diabetes whose blood glucose is not adequately controlled with metformin or sitagliptin (Januvia, Merck) alone will now have a new option. Last month, the Food & Drug Administration approved a two-in-one product from Merck. Janumet, containing both metformin and sitagliptin, is also for use in patients already taking the two drugs separately.

Janumet improves glycemie control by three mechanisms. The dipeptidyl peptidase4 (DPP-4) inhibitor sitagliptin works on the incretin pathway to increase circulating levels of incretin hormones, said Holly S. Divine, PharraD., CGP, CDE, associate professor at University of Kentucky College of Pharmacy. In this way, she said, sitagliptin "increases insulin release and decreases glucagon release in a glucose-dependent manner. Metformin primarily decreases hepatic glucose production." According to Merck, the metformin component also improves insulin sensitivity by increasing uptake and utilization of glucose by muscles and tissues.

Although no clinical efficacy studies were conducted with Janumet before its approval, bioequivalence with sitagliptin and metformin administered as separate tablets was demonstrated. A total of 701 patients took part in a 24-week study to evaluate the efficacy of the two drugs together. In combination with metformin, sitagliptin provided significant improvements in A^sub 1C^/ fasting plasma glucose, and two-hour postprandial glucose. More than twice as many patients on the combination therapy reached the A^sub 1C^ goal of < 7% compared with those patients on metformin alone.

"There are advantages and disadvantages to combination drug therapy," Divine said. Potential advantages include taking one tablet versus two and one copayment instead of two. "Disadvantages include lack of flexibility when dosage change of one drug are needed or when the cost of the combination drug product is higher than the cost of the two individual drugs, although this is not necessarily the case with Janumet." According to the manufacturer, the price of twice-daily Janumet will be $4.86 per day.

Janumet, like metformin, is dosed twice daily with meals. The starting dose should be individualized and based on the patient's current regimen. However, the recommended initial dosage for patients not on prior metformin therapy and not adequately controlled on sitagliptin is 50 mg sitagliptin/500 mg metformin. …

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