4CPS-273 Does Age Really Matter on the Prevalence of Drug–drug Interactions with Endovenous Chemotherapy?

Background and importanceCancer patients receive multiple medications, exposing them to an increased risk of drug–drug interactions (DDI). Moreover, DDIs represent an escalating concern for older adults. Screening for DDI is not generally performed with endovenous chemotherapy.Aim and objectivesThe aim of this study was to evaluate the influence of DDI in the elderly treated with endovenous chemotherapy (EVC).Material and methodsA retrospective study was performed in a tertiary hospital. Patients who initiated EVC during 2019 were included. All DDI were screened and categorised. Data collected were: demographic, cancer by site, chemotherapy treatment and concomitant drugs. DDI in patients aged ≥70 and < 70 years were analysed. Continuous data were expressed as mean (95% CI) and qualitative data as percentages. The Mann–Whitney U test for continuous variables and the χ2 test for qualitative data were used.Results679 patients were included. 65 (9.6%) presented 127 DDI (median 1.95 interactions/patient). Differences between groups are shown in table 1. The most implicated chemotherapy drug was paclitxel (104, 81.9%), interacting mainly with antihypertensive agents, enhancing a blood pressure lowing effect. For all category D DDI, six resulted in an increase in chemotherapy concentrations, potentially increasing toxicity, with two decreasing chemotherapy concentrations and one causing higher anticoagulant drug concentrations.Conclusion and relevanceOlder patients presented a higher number of DDI although they seemed to be less severe DDI than in younger patients. Future studies need to identify the relevant DDI with clinical implications to optimise medication safety in older adults.References and/or acknowledgementsConflict of interestNo conflict of interest