A literature review published in The Oncologist by Dan Hertz, PharmD, PhD, a recent graduate of the UNC Eshelman School of Pharmacy, and his PhD adviser, Howard McLeod, PharmD, helped inform the Food and Drug Administration’s recommendations regarding a potential interaction between the new menopause drug Brisdelle and the breast cancer drug tamoxifen.
Brisdelle, approved by the FDA on June 28, is the first nonhormonal treatment in the United States for moderate to severe hot flashes and night sweats associated with menopause. It contains paroxetine, a selective serotonin reuptake inhibitor (SSRI) that inhibits the enzyme CYP2D6. This could be problematic for one of Brisdelle’s potential target populations — women with a history or high risk of breast cancer — because they might be taking tamoxifen, which is a CYP2D6 substrate.
Hertz, who was a student in the Division of Pharmacotherapy and Experimental Therapeutics and is now a research assistant professor at the University of Michigan College of Pharmacy, and McLeod used their expertise in clinical pharmacology and oncology pharmacogenetics to interpret the complicated literature on the influence of CYP2D6 activity and tamoxifen efficacy. Their evidence-based review highlighted the possibility that CYP2D6 inhibition from concomitantly administered SSRIs could meaningfully affect the efficacy of tamoxifen.
Because of conflicting findings on the effect of paroxetine on tamoxifen, Brisdelle’s label recommends that prescribers of the drug weigh its benefits against the risk of possible decreased tamoxifen effectiveness and consider avoiding concomitant use of Brisdelle. The FDA cited the review by Hertz and McLeod in its July burst e-mail to members of the American Society Clinical Pharmacology Therapeutics, in which the agency explained the reason for the recommendations.