The ageing of the population is associated with polypharmacy and the frequent use of potentially inappropriate medications, increasing the risks for patients in nursing homes (NHs). This thesis evaluates the implementation of three interventions aimed at optimising drug therapy for the older adults in Swiss nursing homes: QC-DeMo (Quality-Circle Deprescribing Module), IDeI (Individual Deprescribing Intervention) and MRNH (Medication Reviews in Nursing Homes). Observational studies using mixed-method approach through implementation research methodology have highlighted several factors that facilitate the implementation of these interventions, such as interprofessional collaboration, access to medical records and structured processes. Obstacles include resistance from residents and families, lack of time and staff turnover. To ensure the sustainability of these interventions, adapted strategies will be tested as part of a future project. This research contributes to a better understanding of the issues involved in implementing pharmaceutical services in geriatrics and provides guidelines for better implementing interventions aiming at safer and more rational prescribing in NHs.