Threats of Concomitant Use or Discontinuation of Cytochrome P450 2D6 Inhibitors The concomitant use of tramadol hydrochloride tablets with all cytochrome P450 2D6 inhibitors (e.g., amiodarone, quinidine) may possibly result in a rise in tramadol plasma levels along with a decrease from the levels of the active metabolite, M1.Reserve concomitant pre