Major
Fluoxetine × Tamoxifen
Selective serotonin reuptake inhibitors×Selective estrogen receptor modulator (SERM)
Mechanism
Fluoxetine is a strong CYP2D6 inhibitor. Endoxifen falls 60%.
Symptoms
Tumour progression on long-term use.
Management
Alternative – sertraline, escitalopram or venlafaxine.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Sources
- FDA: Nolvadex (tamoxifen) prescribing information – CYP2D6 metabolism and antidepressant interactions (2018)– FDA Nolvadex label, Clinical Pharmacology §12.3 and Drug Interactions §7
- Journal of Clinical Oncology: CYP2D6 metabolism and patient outcomes in the tamoxifen adjuvant trial (2018)– Goetz MP, Suman VJ, Hoskin TL, et al. J Clin Oncol 2018;36(16):1610-1618
- FDA: Nolvadex (tamoxifen) prescribing information (2018)