Dosage: The dosage of Sitagliptin & Metformin should be individualized on the basis of the patient's current regimen, effectiveness, and tolerability while not exceeding the maximum recommended daily dose of 100 mg sitagliptin and 2000 mg metformin. Initial combination therapy or maintenance of combination therapy should be individualized and left to the discretion of the health care provider.
Sitagliptin & Metformin should generally be given twice daily with meals, with gradual dose escalation, to reduce the gastrointestinal (GI) side effects due to metformin. The starting dose of Sitagliptin & Metformin should be based on the patient's current regimen. The recommended starting dose in patients NOT currently treated with metformin is 50 mg sitagliptin/500 mg metformin hydrochloride twice daily, with gradual dose escalation recommended to reduce gastrointestinal side effects associated with metformin.
The starting dose in patients already treated with metformin should provide sitagliptin dosed as 50 mg twice daily (100 mg total daily dose) and the dose of metformin already being taken. For patients taking metformin 850 mg twice daily, the recommended starting dose of Sitagliptin & Metformin is 50 mg sitagliptin/1000 mg metformin hydrochloride twice daily.
Co-administration of Sitagliptin & Metformin with an insulin secretagogue (e.g., sulfonylurea) or insulin may require lower doses of the insulin secretagogue or insulin to reduce the risk of hypoglycemia. No studies have been performed specifically examining the safety and efficacy of Sitagliptin & Metformin in patients
previously treated with other oral antihyperglycemic agents and switched to Sitagliptin & Metformin. Any change in therapy of type 2 diabetes should be undertaken with care and appropriate monitoring as changes in glycemic control can occur
Side effects: The most common adverse reactions reported in > 5% of patients simultaneously started on sitagliptin and metformin and more commonly than in patients treated with placebo were diarrhea, upper respiratory tract infection, and headache. Nasopharyngitis was the only adverse reaction reported in > 5% of patients treated with sitagliptin monotherapy. Hypoglycemia was also reported more commonly in patients treated with the combination of Sitagliptin and sulfonylurea, with or without Metformin, than in patients given the combination of placebo and sulfonylurea, with or without Metformin. The most common established adverse reactions due to initiation of metformin therapy are diarrhea, nausea/vomiting, flatulence, abdominal discomfort, indigestion, asthenia, and headache.