Intended for healthcare professionals

Rapid response to:

Practice Therapeutics

Hormone replacement therapy

BMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e763 (Published 16 February 2012) Cite this as: BMJ 2012;344:e763

Rapid Response:

Re: Hormone replacement therapy

Please correct in abovementioned publication the statement that paroxetine and fluoxetine are CYP2D6 inducers. Instead these SSRI are inhibitors of the CYP2D6 enzyme which participates in the transformation of the prodrug tamoxifen to its active metabolite endoxifen. The combination of paroxetine with tamoxifen in patients treated for breast cancer has been shown to result in an increase risk of death of breast cancer with increasing dose of tamoxifen (1). The combination of fluoxetine with tamoxifen had not been extensively studied yet. But on grounds of this plausible interaction mechanism, the combination of paroxetine and tamoxifen should indeed be avoided since alternatives for both the SSRI and tamoxifen are available.

1 Kelley CM, Juurlink DN, Gomes T, Duong-Hua M, Prittchard KI, Austin PC, et al. Selective serotonin reuptake inhibitors and breast cancer mortality in women receiving tamoxifen: a population based cohort study. BMJ 2010;340;c693.

Competing interests: No competing interests

19 March 2012
Wilhelmina M.C. Mulder
clinical pharmacologist
Hospital Pharmacy, Academic Medical Center
Meibergdreef 9, Amsterdam, The Netherlands