OBJECT DRUGS

Antiarrhythmics (CYP2D6 Substrates):

• Flecainide (Tambocor)
• Mexiletine (Mexitil)
• Propafenone (Rythmol, etc.)

PRECIPITANT DRUGS

Antidepressants:

• Bupropion (Wellbutrin, etc.)
• Duloxetine (Cymbalta)
• Fluoxetine (Prozac, etc.)
• Paroxetine (Paxil, etc.)

Comment:

These antidepressants inhibit CYP2D6, and can lead to accumulation of flecainide, mexiletine, or propafenone, and may increase the risk of toxicity. People with "normal" CYP2D6 activity (Extensive Metabolizers) are at the greatest risk.

Class 2: Use Only if Benefit Felt to Outweigh Risk

• Use Alternative:
• Antidepressant: Citalopram (Celexa), desvenlafaxine (Pristiq), escitalopram (Lexapro), and sertraline (Zoloft), are weak inhibitors of CYP2D6, and fluvoxamine and venlafaxine (Effexor) have little or no effect on CYP2D6.
• Monitor: Be alert for an increased effect of the antiarrhythmic if CYP2D6 inhibitors are coadministered. Monitoring of the antiarrhythmic plasma concentration is warranted.