What is the recommended dosage of Sitagliptin (DPP-4 inhibitor) and Metformin Hydrochloride (biguanide) 50 MG-1000 MG Oral Tablet, Extended Release?

Sitagliptin/Metformin ER 50 mg/1000 mg Dosing

The recommended dosage of Sitagliptin/Metformin ER 50 mg/1000 mg is one tablet once daily with the evening meal, with dose adjustments required based on renal function and glycemic response. 1, 2

Standard Dosing Regimen

• Administer one tablet (50 mg sitagliptin/1000 mg metformin ER) once daily with the evening meal to optimize absorption and minimize gastrointestinal side effects 2
• The extended-release formulation provides 24-hour glucose control with once-daily dosing, improving adherence compared to immediate-release formulations 2
• Maximum total daily dose of metformin should not exceed 2000 mg when using extended-release formulations 2

Dose Titration Strategy

• If initiating therapy, start with a lower strength tablet (e.g., 50 mg/500 mg) and titrate upward to minimize gastrointestinal adverse effects 2
• Increase by 500 mg metformin increments every 7 days until target dose is reached, monitoring for tolerability 2
• The 50 mg/1000 mg strength is appropriate for patients already tolerating metformin 1000 mg daily or higher doses 3

Critical Renal Function Adjustments

Renal function determines whether this specific dose strength can be used safely:

• eGFR ≥60 mL/min/1.73 m²: Continue standard dosing of 50 mg/1000 mg once daily 1, 2
• eGFR 45-59 mL/min/1.73 m²: Continue 50 mg/1000 mg but monitor closely for lactic acidosis risk factors 1, 2
• eGFR 30-44 mL/min/1.73 m²: Reduce total daily metformin dose to 1000 mg maximum - this 50 mg/1000 mg tablet would represent the entire daily dose; consider switching to 50 mg/500 mg twice daily instead 1, 2
• eGFR <30 mL/min/1.73 m²: Discontinue metformin entirely - this combination tablet is contraindicated 1, 2, 4

Sitagliptin-Specific Renal Adjustments

The sitagliptin component also requires dose reduction in renal impairment, which affects combination tablet selection:

• eGFR >50 mL/min/1.73 m²: Standard sitagliptin dose of 100 mg daily (use 100 mg/1000 mg or 100 mg/500 mg tablets, not the 50 mg strength) 1
• eGFR 30-50 mL/min/1.73 m²: Maximum sitagliptin dose of 50 mg daily - the 50 mg/1000 mg tablet is appropriate if metformin can be continued 1
• eGFR <30 mL/min/1.73 m²: Maximum sitagliptin dose of 25 mg daily, but metformin is contraindicated at this level 1

Important caveat: The 50 mg sitagliptin dose in this tablet is actually a reduced dose for moderate renal impairment (eGFR 30-50 mL/min/1.73 m²), not the standard 100 mg dose for normal renal function 1

Monitoring Requirements

• Check eGFR at least annually in patients with normal renal function 2
• Increase monitoring frequency to every 3-6 months when eGFR <60 mL/min/1.73 m² 2, 4
• Monitor vitamin B12 levels periodically, especially after 4 years of metformin therapy or if peripheral neuropathy or anemia develops 2, 4
• Assess glycemic response after 3 months; if HbA1c targets not achieved, add additional agent rather than exceeding maximum metformin dose 2

Common Pitfalls and How to Avoid Them

• Do not use this combination in patients with eGFR <30 mL/min/1.73 m² due to metformin contraindication and risk of fatal lactic acidosis 1, 4
• Temporarily discontinue before procedures with iodinated contrast, during hospitalizations, or when acute illness compromises renal or hepatic function 2, 4
• Do not exceed 2000 mg total daily metformin dose even if glycemic control is inadequate; instead add a second agent with proven cardiovascular benefit (SGLT2 inhibitor or GLP-1 agonist) 2
• Recognize that the 50 mg sitagliptin dose indicates this tablet is formulated for patients with moderate renal impairment, not for those with normal renal function who typically require 100 mg sitagliptin daily 1
• Start with lower metformin doses and titrate gradually if switching from immediate-release formulations to minimize gastrointestinal side effects 2, 5

Special Populations

Hospitalized Patients

• Discontinue this combination tablet in hospitalized patients and transition to insulin-based regimens for better glycemic control during acute illness 1
• Sitagliptin alone or with basal insulin may be considered for elderly hospitalized patients with mild-to-moderate hyperglycemia, but the combination tablet should be held 1

Elderly Patients

• Use with caution in older adults due to age-related decline in renal function 1, 4
• Monitor more frequently for vitamin B12 deficiency, which can worsen peripheral neuropathy 4
• Consider lower doses initially and titrate based on tolerability and renal function 4