The influences of CYP2D6 genotypes and drug interactions on the pharmacokinetics of venlafaxine: exploring predictive biomarkers for treatment outcomes

Rationale Two biomarkers: concentration ratio of O-desmethylvenlafaxine/venlafaxine and concentration sum of venlafaxine + O-desmethylvenlafaxine were adopted to indicate venlafaxine responses, but neither is validated.