1, 7.2) ]. Hazards of Concomitant Use or Discontinuation of Cytochrome P450 2D6 Inhibitors The concomitant use of Promethazine with Codeine Oral Remedy with all cytochrome P450 2D6 inhibitors (eg., amiodarone, quinidine) could result in an increase in codeine plasma concentrations along with a decre