Drug interactions
Metformin + Zonisamide
Severity: Moderate
Metformin and Zonisamide: 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
Zonisamide is a weak carbonic anhydrase inhibitor and can cause non-anion gap metabolic acidosis. Metformin carries a risk of lactic acidosis, so combined use may compound acid-base disturbance, especially in renal impairment.
What this interaction means in plain words
Metformin and Zonisamide 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.
Metformin belongs to Endocrine; Zonisamide belongs to Central Nervous System.
Why it happens
Carbonic anhydrase inhibition by zonisamide lowers bicarbonate, adding to metformin-associated lactic acidosis risk.
What to do
Check serum bicarbonate at baseline and periodically, and assess renal function. Reduce or stop one drug if persistent acidosis develops.
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 Zonisamide
- Zonisamide + Zuranolone Major
- Acetazolamide + Zonisamide Moderate
- Amisulpride + Zonisamide Moderate
- Amobarbital + Zonisamide Moderate
- Apalutamide + Zonisamide Moderate
- Asenapine transdermal + Zonisamide Moderate
Other interactions of Metformin
Frequently asked questions
Can I take Metformin with Zonisamide?
MediHelp rates the interaction as moderate. Metformin and Zonisamide 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. Zonisamide is a weak carbonic anhydrase inhibitor and can cause non-anion gap metabolic acidosis. Metformin carries a risk of lactic acidosis, so combined use may compound acid-base disturbance, especially in renal impairment.
How serious is the interaction between Metformin and Zonisamide?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check serum bicarbonate at baseline and periodically, and assess renal function. Reduce or stop one drug if persistent acidosis develops.
What other medicines interact with Zonisamide?
MediHelp also lists interactions of Zonisamide with, for example, Zuranolone, Acetazolamide, Amisulpride. The full list is on the Zonisamide page.
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