desvenlafaxine will increase the level or impact of codeine by influencing hepatic enzyme CYP2D6 metabolism. Use Warning/Keep track of. Desvenlafaxine inhibits CYP2D6; with bigger desvenlafaxine doses (ie, four hundred mg) lessen the CYP2D6 substrate dose by around fifty%; no dosage adjustment needed with desvenlafaxine doses 7 consecutive days ins