Making sense of CYP2D6 and CYP1A2 genotype vs phenotype

CYP1A2 induction

A variety of medications and environmental factors may induce CYP1A2.

Medications. Certain medications may induce CYP1A2, including carbamazepine, phenytoin, rifampin, and primidone.

Cigarette smoking. A significant increase in smoking after 1 to 3 weeks may decrease drug levels, whereas a significant decrease in smoking after 1 to 3 weeks may result in elevated drug levels.³ Nicotine is not the causative agent of induction, but rather hydrocarbons found in cigarette smoke.¹¹

Diet. An increase in daily dietary intake of certain vegetables for 6 days has been shown to result in induction.³ Brassica (Cruciferae) vegetables such as broccoli (2 cups), cauliflower (1 cup), cabbage (1 cup), and radish sprouts (1/2 cup) have been found to increase CYP1A2 activity by 18% to 37%.¹⁰ Grilled meat also plays a role in induction.¹⁰

Related Resource

• Ellingrod VL, Ward KM. Using pharmacogenetics guidelines when prescribing: What's available. Current Psychiatry. 2018;17(1):43-46.

Drug Brand Names

Amiodarone • Cordarone, Pacerone
Amitriptyline • Elavil, Endep
Aripiprazole • Abilify
Asenapine • Saphris
Atazanavir • Reyataz  
Brexpiprazole • Rexulti
Bupropion • Wellbutrin, Zyban  
Carbamazepine • Carbatrol, Tegretol  
Chlorpromazine • Thorazine  
Chloroquine • Aralen
Cinacalcet • Sensipar
Ciprofloxacin • Cipro
Citalopram • Celexa
Clozapine • Clozaril
Desipramine • Norpramin  
Desvenlafaxine • Pristiq
Diphenhydramine • Benadryl
Doxepin • Silenor
Duloxetine • Cymbalta
Escitalopram • Lexapro
Ethinyl estradiol • Estinyl
Fluoxetine • Prozac
Fluvoxamine • Luvox
Haloperidol • Haldol  
Iloperidone • Fanapt
Imatinib • Gleevec
Imipramine • Tofranil
Mirtazapine • Remeron
Nortriptyline • Pamelor
Olanzapine • Zyprexa
Paliperidone • Invega
Paroxetine • Paxil
Perphenazine • Trilafon
Phenytoin • Dilantin
Pimavanserin • Nuplazid
Primidone • Mysoline
Quetiapine • Seroquel
Quinidine • Cardioquin
Rifampin • Rifadin
Risperidone • Risperdal
Sertraline • Zoloft
Terbinafine • Lamisil
Thioridazine • Mellaril
Trazodone • Desyrel, Oleptro
Venlafaxine • Effexor
Vilazodone • Viibryd  
Vortioxetine • Trintellix
Ziprasidone • Geodon