Minor
Suspected
Description
Memantine may compete with metformin for renal tubular cationic secretion, potentially increasing metformin plasma concentrations modestly.
Mechanism
Memantine and metformin are both organic cation transporter (OCT) substrates and are eliminated via renal tubular secretion; competition at OCT2 may reduce metformin clearance.
Clinical Significance
The interaction is generally minor but may be relevant in patients with renal impairment where both drug accumulations could be additive.
Management
Monitor renal function and blood glucose in patients taking both drugs, especially if renal function declines.