Potentiation of the antidepressant-like effects of dextromethorphan by quinidine.

<p>A single dose of the CYP2D6 inhibitor quinidine (30 mg/kg, i.p.) administered concomitantly with dextromethorphan (0–30 mg/kg, i.p.) significantly potentiated the decrease in immobility time for dextromethorphan at 10 mg/kg (A). In contrast, in the locomotor study, dextromethorphan in combination with quinidine had no stimulatory effects (B). Data shown are expressed as mean ± S.E.M. ***<i>P</i><0.001, compared with the saline-treated group; one-way ANOVA followed by <i>post-hoc</i> Tukey's tests. QND, quinidine. DM, dextromethorphan.