Which antidepressants are cautioned for tamoxifen interaction due to potential cancer recurrence?

• A. Bupropion
• B. Fluoxetine
• C. Paxil
• D. All of the Above

Answer: (D)

Tamoxifen must be metabolized by the enzyme CYP2D6 to form endoxifen, the active compound that contributes to its anti-cancer effects. When a drug strongly inhibits CYP2D6, the conversion to endoxifen is reduced, which can lessen tamoxifen’s effectiveness and potentially increase the risk of cancer recurrence.

Certain antidepressants are known to block CYP2D6. Fluoxetine and paroxetine (Paxil) are potent inhibitors, meaning they can substantially cut endoxifen levels. Bupropion can also inhibit CYP2D6, though typically considered a weaker inhibitor than the SSRIs mentioned, it still has the potential to interfere with endoxifen production. Because of these interactions, all of these antidepressants are cautioned choices for patients taking tamoxifen.

Thus, selecting an antidepressant with minimal CYP2D6 inhibition is preferred in this context to preserve tamoxifen activation and its therapeutic effect.