desvenlafaxine will improve the degree or result of codeine by impacting hepatic enzyme CYP2D6 metabolism. Use Warning/Check. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) lessen the CYP2D6 substrate dose by nearly fifty%; no dosage adjustment essential with desvenlafaxine doses seven consecutive days promptly ahead … Read More