desvenlafaxine will improve the stage or impact of codeine by influencing hepatic enzyme CYP2D6 metabolism. Use Warning/Keep an eye on. Desvenlafaxine inhibits CYP2D6; with better desvenlafaxine doses (ie, four hundred mg) reduce the CYP2D6 substrate dose by approximately fifty%; no dosage adjustment necessary with desvenlafaxine doses seven consec