Pharmacokinetic interactions between topiramate and pioglitazone and metformin.

•Interactions of topiramate and metformin or pioglitazone were evaluated.•Systemic exposure to metformin was increased by topiramate.•Systemic exposure to pioglitazone, M-IV and M-III were decreased by topiramate.•Pioglitazone did not affect the pharmacokinetics of topiramate.