Tamoxifen and antidepressant’s co-prescription: general practitioners and pharmacist’s alert

Abstract

Abstract Issue Well known drug-drug interaction with some antidepressants, especially selective serotonin reuptake inhibitors which reduce tamoxifen’s effectiveness and associated with an increased risk of death from breast cancer. Description of the problem To identify and characterize the exposure to antidepressants in women with breast cancer treated with tamofixen in a west french area. Retrospective population based cohort study; claims from the French Health insurance database. Women living in Pays de la Loire area, aged 20 years or older treated with tamoxifen for breast cancer in 2018 who had concomitant treatment with antidepressants. Call phone to general practitioner’s and meeting with pharmacist when a high or moderate level drug-drug interaction’s was identified. Results Of 4138 women treated with tamoxifen, 497 (12%) received an antidepressant treatment in 2018, corresponding to 571 co-prescriptions. Of them, 74 (13%) was moderate level drug-drug interaction, 66 (11.6%) high level and 307 (53.8%) weak level.70% of high level drug-drug interaction were due to paroxetine and 43% of moderate level due to duloxetine. For these co-prescriptions, concomitant patient’s exposure was for more than four months in 22% cases. 127 different general practitioners and 152 pharmacists (339 different dispensation’s date) were concerned by these drug-drug interactions. Lessons French health insurance medical department has contacted general practitioners or pharmacists concerned by these drug-drug interactions. We informed general practitioners to be aware about women treated with tamoxifen when co-prescription with an antidepressant is necessary, preference should be given to one of them that show little or no inhibition of cytochrome P450 2D6. Key messages Mediation medication and detection of drug-drug interaction by pharmacist. Preferential choice of antidepressant by general practitioner or women treat with co-prescription (tamoxifen and antidepressant).