Janumet (Sitagliptin/Metformin) Dosing Guidelines
Janumet should be dosed at 50/500 mg or 50/1000 mg twice daily with meals, with a maximum recommended daily dose of 100 mg sitagliptin/2000 mg metformin. 1
Standard Dosing Regimen
- Initial dosing: Start with 50/500 mg twice daily with meals (breakfast and dinner)
- Dose titration: After 5-7 days, if no gastrointestinal side effects occur, can increase to 50/1000 mg twice daily 2
- Maximum daily dose: 100 mg sitagliptin/2000 mg metformin (as 50/1000 mg twice daily)
Dosing Based on Renal Function
Janumet dosing must be adjusted based on renal function:
| eGFR Level | Dosing Recommendation |
|---|---|
| ≥60 ml/min/1.73 m² | Standard dosing (up to 50/1000 mg twice daily) |
| 45-59 ml/min/1.73 m² | Consider dose reduction in some patients |
| 30-44 ml/min/1.73 m² | Maximum metformin component 1000 mg daily (e.g., 50/500 mg twice daily) [2] |
| <30 ml/min/1.73 m² | Contraindicated - do not use [2] |
Monitoring Requirements
Renal function:
- Monitor eGFR at least annually in all patients
- Every 3-6 months in patients with eGFR <60 ml/min/1.73 m² 2
- More frequently during illness that may affect renal function
Vitamin B12 levels:
Administration Considerations
- Always administer with meals to reduce gastrointestinal side effects 2
- If GI side effects occur when increasing the dose, return to the previous lower dose and try to advance more slowly 2
- Temporarily discontinue during procedures requiring radiocontrast agents or during acute illness that may affect renal function
Special Populations
- Elderly patients: Start at the lower end of the dosing range due to potential for decreased renal function
- Patients with poor glycemic control (HbA1c >10%): May require more rapid titration to maximum dose, but still follow the gradual titration process to minimize GI side effects
Common Side Effects and Management
Gastrointestinal effects: Nausea, vomiting, diarrhea, abdominal discomfort
- Management: Take with food, start with lower dose, gradual titration
Hypoglycemia risk: Lower than sulfonylureas but can occur, especially when combined with other glucose-lowering medications
- Management: Monitor blood glucose regularly, adjust other diabetes medications if needed
Important Warnings
Lactic acidosis: Rare but serious complication associated with metformin component
- Risk factors: Renal impairment, hepatic disease, excessive alcohol intake, dehydration
Acute kidney injury: Temporarily discontinue during conditions that may affect renal function
Vitamin B12 deficiency: Long-term use of metformin may reduce vitamin B12 absorption
Janumet combines the complementary mechanisms of action of sitagliptin (DPP-4 inhibitor) and metformin to improve glycemic control without significant weight gain 4, 5. The fixed-dose combination tablet has been shown to be bioequivalent to co-administration of the individual components 4, making it a convenient option for patients requiring dual therapy.