Breast Cancer and Antidepressant Use

Tamoxifen is an antiestrogen drug that is used for a variety of indications related to breast cancer. Patients with breast cancer may suffer from anxiety, depression, tamoxifen-related hot flashes, or other states that respond to antidepressant medications. Antidepressants such as paroxetine, fluoxetine, bupropion, and duloxetine inhibit CYP2D6, the enzyme that converts tamoxifen into its most important active metabolite, endoxifen. Given that tamoxifen is a prodrug, and that preventing its metabolism to its active metabolites will compromise its efficacy, clinicians should avoid prescribing CYP2D6 inhibitors to patients receiving tamoxifen. For such patients, safer antidepressants are those that have low to no CYP2D6 inhibitor activity. Examples of such antidepressants are mirtazapine, sertraline, citalopram, escitalopram, venlafaxine, and desvenlafaxine.