desvenlafaxine will increase the level or outcome of codeine by influencing hepatic enzyme CYP2D6 metabolism. Use Caution/Check. Desvenlafaxine inhibits CYP2D6; with increased desvenlafaxine doses (ie, 400 mg) lessen the CYP2D6 substrate dose by approximately fifty%; no dosage adjustment needed with desvenlafaxine doses 7 consecutive times instantl… Read More