Drug interactions
Metformin-sitagliptin + Sulfamethoxazole
Severity: Moderate
Metformin-sitagliptin and Sulfamethoxazole: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Sulfamethoxazole, usually given with trimethoprim, can raise metformin levels because trimethoprim inhibits renal tubular cation transporters. Higher metformin exposure may increase the risk of lactic acidosis, particularly in patients with reduced renal function.
What this interaction means in plain words
Metformin-sitagliptin and Sulfamethoxazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Trimethoprim inhibits OCT2 and MATE transporters, reducing renal tubular secretion of metformin.
What to do
Monitor renal function and for signs of lactic acidosis, and consider reducing the metformin dose in patients with impaired renal function.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Metformin-sitagliptin
Frequently asked questions
Can I take Metformin-sitagliptin with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Metformin-sitagliptin and Sulfamethoxazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Sulfamethoxazole, usually given with trimethoprim, can raise metformin levels because trimethoprim inhibits renal tubular cation transporters. Higher metformin exposure may increase the risk of lactic acidosis, particularly in patients with reduced renal function.
How serious is the interaction between Metformin-sitagliptin and Sulfamethoxazole?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor renal function and for signs of lactic acidosis, and consider reducing the metformin dose in patients with impaired renal function.
What other medicines interact with Metformin-sitagliptin?
MediHelp also lists interactions of Metformin-sitagliptin with, for example, Clozapine, Contrast media, Diatrizoate meglumine / diatrizoate. The full list is on the Metformin-sitagliptin page.
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