Can I switch from Farxiga (dapagliflozin) to Xigduo (dapagliflozin and metformin)?

Switching from Farxiga to Xigduo

Yes, you can switch from Farxiga (dapagliflozin) to Xigduo (dapagliflozin/metformin fixed-dose combination), and this is a straightforward transition that simply adds metformin to your existing dapagliflozin therapy. 1, 2

Understanding the Medication Switch

Xigduo is essentially Farxiga plus metformin in a single tablet. 2 Farxiga contains only dapagliflozin, while Xigduo combines dapagliflozin with metformin extended-release in fixed doses. 1, 3 This switch represents intensification of diabetes therapy by adding metformin to your SGLT2 inhibitor regimen. 4

Clinical Rationale for This Switch

• Metformin is the preferred foundational therapy for type 2 diabetes and should be initiated at diagnosis unless contraindicated. 4

• Combination therapy with dapagliflozin and metformin provides complementary mechanisms of action: dapagliflozin increases urinary glucose excretion while metformin reduces hepatic glucose production and improves insulin sensitivity. 5, 3

• The fixed-dose combination can improve medication adherence compared to taking multiple separate pills, which may enhance glycemic control. 3

• Clinical trials demonstrate that dapagliflozin plus metformin reduces HbA1c by up to 2%, produces weight loss of 2-3 kg, and modestly lowers systolic blood pressure by 3-5 mmHg. 3

How to Make the Switch

Simply stop Farxiga and start Xigduo at the appropriate dose based on your current dapagliflozin dose and renal function. 6, 1

Dosing Algorithm:

• If you are taking Farxiga 10 mg daily and have eGFR ≥45 mL/min/1.73 m²: Start Xigduo XR 10 mg/1000 mg once daily with the evening meal. 1, 3

• If you are taking Farxiga 5 mg daily and have eGFR ≥45 mL/min/1.73 m²: Start Xigduo XR 5 mg/1000 mg once daily with the evening meal. 1

• If your eGFR is 30-44 mL/min/1.73 m²: Metformin dose should be limited to maximum 1000 mg/day, so use lower-dose Xigduo formulations. 6

• If your eGFR is <30 mL/min/1.73 m²: Do not use Xigduo, as metformin is contraindicated at this level of renal function. 4, 6

Critical Pre-Switch Assessment

Check your renal function (eGFR) before making this switch. 6 Metformin has specific renal dosing requirements and is contraindicated when eGFR <30 mL/min/1.73 m². 4, 6

Renal Function Checklist:

• eGFR ≥60 mL/min/1.73 m²: No metformin dose adjustment needed; proceed with standard Xigduo dosing. 6

• eGFR 45-59 mL/min/1.73 m²: Consider reducing metformin to half the maximum dose; monitor renal function every 3-6 months. 6

• eGFR 30-44 mL/min/1.73 m²: Limit metformin to maximum 1000 mg/day; monitor renal function every 3 months. 6

• eGFR <30 mL/min/1.73 m²: Metformin is contraindicated; do not use Xigduo. 4, 6

Important Safety Considerations

• The combination of dapagliflozin and metformin has low hypoglycemia risk when used without sulfonylureas or insulin, so no preemptive dose reductions of other medications are typically needed. 6

• Metformin may cause gastrointestinal side effects (bloating, abdominal discomfort, diarrhea) in up to 30% of patients; these can be mitigated by gradual dose titration and taking the medication with food. 4, 3

• Continue the same sick-day management rules for dapagliflozin: Hold Xigduo during acute illness with reduced oral intake, fever, vomiting, or diarrhea to prevent volume depletion and ketoacidosis. 6

• Withhold Xigduo at least 3 days before major surgery or procedures requiring prolonged fasting to prevent postoperative ketoacidosis. 6

• Monitor for genital mycotic infections (approximately 6% incidence with SGLT2 inhibitors); maintain good genital hygiene to reduce risk. 6

• Long-term metformin use is associated with vitamin B12 deficiency; periodic measurement of B12 levels should be considered, especially if anemia or peripheral neuropathy develops. 4

Monitoring After the Switch

• Recheck eGFR within 1-2 weeks after starting Xigduo, as both dapagliflozin and metformin can affect renal function. 6

• Monitor HbA1c every 3 months to assess glycemic response to the combination therapy. 4

• If eGFR ≥60 mL/min/1.73 m²: Recheck renal function annually. 6

• If eGFR 45-59 mL/min/1.73 m²: Recheck renal function every 3-6 months. 6

When NOT to Make This Switch

Do not switch to Xigduo if:

• eGFR <30 mL/min/1.73 m² (metformin contraindicated). 4, 6

• History of lactic acidosis (metformin contraindicated). 4

• Severe hepatic impairment (metformin contraindicated). 4

• Acute or chronic metabolic acidosis (metformin contraindicated). 4

• Current acute illness with risk of tissue hypoxia (hold metformin temporarily). 4

Cardiovascular and Renal Benefits Are Preserved

The cardiovascular and renal protective effects of dapagliflozin are maintained when combined with metformin. 6, 7 Dapagliflozin reduces cardiovascular death or heart failure hospitalization by 29% and slows kidney disease progression regardless of whether it is used alone or with metformin. 6