Answer
Potent CYP2D6 inhibitors, particularly paroxetine and fluoxetine, can reduce formation of active endoxifen and should be avoided where possible after clinical review.
Sources for this answer
- Tamoxifen 20 mg Tablets — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.