Psychotropic Medications Metabolized by Cytochromes P450 (CYP) 2D6 Enzyme and Relevant Drug Interactions

Psychotropic medications metabolized by cytochromes P450 (CYP) 2D6 are reviewed, and the possible relevance of this metabolism to drug-drug interactions is discussed. CYP2D6 is a member of the cytochrome P450 super family and it plays a primary role in the metabolism of more than 70 substrate medications, belonging to classes such as antidepressants, antipsychotics, mood stabilizers, antiarthemics, beta blockers antiemetics, opoid and Sedative/ hypnotics. It is responsible for the metabolism of about 25% of the commonly prescribed drugs. CYP2D6 Primarily metabolizes four of the typical antipsychotic medications, such as haloperidol, chlorpromazine, thioridazine and perphenazine, and risperidone from second generation antipsychotics. Nortriptyline, paroxetine, fluoxetine, venlafaxine and desipramine are antidepressants which are primarily metabolized by CYP2D6. Propranolol, metoprolol, timolol and alperolol are among the common beta blockers which are primarily metabolized by CYP2D6. Drugs which are metabolized by CYP2D6 may inhibit or induce the action of the enzyme. Drugs that inhibit CYP2D6 will predictably increase the plasma concentrations of the medications or decrease in clearance of substrates. Drugs such as bupropion, Fluoxetine, Paroxetine, norethindrone Citalopram, Escitalopram, Sertraline, Fluvoxamine, Nefazodone, Venlafaxine, clomipramine, cocaine, quinidine, and ranitidine are inhibiters of CYP2D6 enzyme. Unlike CYP1A2, CYP2C9, CYP2C19, CYP3A4 and CYP3A5 enzymes which together with CYP2D6 metabolizes 90 percent of drugs CYP2D6 has no significant inducers.