Pitfalls of Concomitant Use or Discontinuation of Cytochrome P450 2D6 Inhibitors The concomitant usage of tramadol hydrochloride tablets with all cytochrome P450 2D6 inhibitors (e.g., amiodarone, quinidine) may possibly cause an increase in tramadol plasma amounts as well as a reduce inside the levels of the active metabolite, M1.When naloxone will