Janumet 50/500 Dosing
Janumet 50/500 (sitagliptin 50 mg/metformin 500 mg) should be taken twice daily with meals, with the option to titrate up to a maximum of sitagliptin 50 mg/metformin 1000 mg twice daily based on glycemic response and tolerability. 1, 2
Standard Dosing Schedule
- Take Janumet 50/500 twice daily (morning and evening) with meals to reduce gastrointestinal side effects associated with metformin 1, 3
- The usual adult dose of sitagliptin is 100 mg daily (achieved with two 50 mg tablets in the combination product), which can be taken as 50 mg twice daily when combined with metformin 2
- Titrate metformin gradually from 500 mg twice daily up to 1000 mg twice daily if additional glycemic control is needed and the lower dose is well tolerated 3
Dose Titration Strategy
- Start with Janumet 50/500 twice daily for patients inadequately controlled on metformin monotherapy or those requiring combination therapy 1, 4
- If glycemic targets are not achieved after 2-3 months, increase to Janumet 50/1000 twice daily (sitagliptin 50 mg/metformin 1000 mg) 3
- The maximum effective metformin dose is 2000 mg daily (1000 mg twice daily), which provides optimal glucose-lowering efficacy 5, 3
Special Dosing Considerations
- For patients with moderate-to-severe renal impairment, reduce sitagliptin dose to 25-50 mg once daily and adjust metformin according to kidney function 2
- Metformin may be safely used in patients with estimated glomerular filtration rate as low as 30 mL/min/1.73 m² 5
- Discontinue metformin if patients experience nausea, vomiting, or dehydration to prevent lactic acidosis 5
Expected Efficacy
- Janumet 50/500-1000 twice daily reduces HbA1c by approximately 0.7-1.7% from baseline over 18-104 weeks 6, 3
- 55-60% of patients achieve HbA1c <7% with the combination therapy 6, 3
- The combination provides complementary and possibly additive glucose-lowering effects without increasing hypoglycemia risk 1, 4
Safety Profile
- Gastrointestinal side effects (abdominal pain, nausea, diarrhea) occur in up to 16% of patients, primarily attributable to metformin 2, 6
- Hypoglycemia incidence is low and similar to placebo when used without sulfonylureas or insulin 6, 3
- Body weight remains stable or decreases slightly with Janumet, unlike some other diabetes medications 6
Common Pitfalls to Avoid
- Do not start metformin at full dose (1000 mg twice daily) immediately, as this increases gastrointestinal side effects—start at 500 mg twice daily and titrate gradually 5
- Do not continue metformin in patients with eGFR <30 mL/min/1.73 m² due to increased risk of lactic acidosis 5
- Monitor vitamin B12 levels periodically in long-term metformin users, especially those with anemia or peripheral neuropathy 5