OBJECT DRUGS
PRECIPITANT DRUGS
Antidepressants:
- Bupropion (Wellbutrin, etc.)
- Duloxetine (Cymbalta)
- Fluoxetine (Prozac, etc.)
- Paroxetine (Paxil, etc.)
Comment:
Tamoxifen is a prodrug that is converted to active metabolites by CYP2D6. Evidence from studies in patients with breast cancer have shown that patients on potent CYP2D6 inhibitors have reduced concentrations of active tamoxifen metabolites, and reduced survival. People with "normal" CYP2D6 activity ("Rapid Metabolizers") will be at the greatest risk.
Class 2: Use Only if Benefit Felt to Outweigh Risk
- Use Alternative:
- Antidepressant: Given the severity of the potential interaction, every effort should be made to avoid the above antidepressants in patients receiving tamoxifen. Alternative antidepressants have less effect on CYP2D6: 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: If CYP2D6 inhibitors are used with tamoxifen, be alert for evidence of reduced tamoxifen effect.