Venlafaxine

Pharmacogenomic Information in the Context of the FDA-Approved Drug Label*

Venlafaxine (Effexor) is an inhibitor of neuronal serotonin and norepinephrine reuptake and weak inhibitor of dopamine reuptake used in the treatment of depression.

The FDA recommends, but does not require, genetic testing prior to initiating or reinitiating treatment with Venlafaxine.

Excerpt from the Venlafaxine (Effexor) drug label:
"Plasma concentrations of venlafaxine were higher in CYP2D6 poor metabolizers than extensive metabolizers. Because the total exposure (AUC) of venlafaxine ... was similar in poor and extensive metabolizer groups, however, there is no need for different venlafaxine dosing regimens for these two groups."

"CYP2D6 Inhibitors: In vitro and in vivo studies indicate that venlafaxine is metabolized to its active metabolite, ODV, by CYP2D6, the isoenzyme that is responsible for the genetic polymorphism seen in the metabolism of many antidepressants. Therefore, the potential exists for a drug interaction between drugs that inhibit CYP2D6-mediated metabolism of venlafaxine, reducing the metabolism of venlafaxine to ODV, resulting in increased plasma concentrations of venlafaxine and decreased concentrations of the active metabolite. CYP2D6 inhibitors such as quinidine would be expected to do this, but the effect would be similar to what is seen in patients who are genetically CYP2D6 poor metabolizers."

For the complete drug label text with sections containing pharmacogenetic information highlighted, see the Venlafaxine (Effexor) drug label PDF.