Safety Alert: Tamoxifen
Select Antidepressants May Interact with Tamoxifen (Novaldex)
In a recent study, Indiana University School of Medicine and pharmacy benefit provider Medco Health Solutions, Inc. identified a possible drug interaction between tamoxifen (Novaldex) and the antidepressants paroxetine (Paxil), fluoxetine (Prozac), and sertraline (Zoloft). In this study, patients taking tamoxifen and one of these antidepressants (paroxetine, fluoxetine, or sertraline) experienced recurrent breast cancer at a higher rate than those who took tamoxifen alone.
Tamoxifen is prescribed to reduce the risk of breast cancer recurrence in patients with a history of breast cancer and for breast cancer prevention in high-risk women. Antidepressants are most commonly prescribed for depression and anxiety, but are also sometimes prescribed "off-label" to treat symptoms of menopause and/or the side effects of tamoxifen.
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What does this mean?
Since these results were presented without a full description of the study methods, it is important not to draw too many conclusions until the final study report is made available. That said, this new information adds to concerns from other studies suggesting that antidepressants like paroxetine (Paxil), fluoxetine (Prozac), and sertraline (Zoloft) can lower the amount of tamoxifen's active form in the bloodstream and reduce the effectiveness of tamoxifen. Not all antidepressants cause this problem - no greater breast cancer risk was seen in women taking the antidepressants citalopram (Celexa), escitalopram (Lexapro) or fluvoxamine (Luvox) with tamoxifen in this study. Although data are not available on other antidepressants such as duloxetine (Cymbalta), venlafaxine (Effexor), desvenlafaxine (Pristiq), or bupropion (Wellbutrin), these medicines have a different effect on metabolism and thus, may not impact the efficacy of Tamoxifen.
If you take tamoxifen and an antidepressant or if you are considering taking an antidepressant, please talk to your doctors about which one is best for you. It is always good practice to review your complete list of medicine with your doctor on a routine basis and anytime you receive a new prescription.
