one, 7.2) ]. Pitfalls of Concomitant Use or Discontinuation of Cytochrome P450 2D6 Inhibitors The concomitant utilization of Promethazine with Codeine Oral Answer with all cytochrome P450 2D6 inhibitors (eg., amiodarone, quinidine) may possibly result in a rise in codeine plasma concentrations plus a reduce in Energetic metabolite morphine plasma f