Rationale: In current clinical practice, polypharmacy and patient empowerment are critical yet often overlooked. Polypharmacy, the chronic use of five or more drugs, poses risks such as adverse drug reactions and decreased medication adherence, especially in elderly and multimorbid patients. Despite the interconnected nature of drug-drug and drug-gene pro inter-actions, they are considered separately. Ignoring these interactions can be hazardous, yet clinical trials to investigate them are infeasible due to fast-growing complexity, variability among patients, high costs associated with large-scale studies, and ethical and logistical chal-lenges. Consequently, there is a substantial knowledge gap in managing complex medication regimens in real-life scenarios and providing guidelines to enhance patient empowerment and drug safety. The SafePolyMed project aims to develop a patient-centred framework to define, assess and manage drug-drug, drug-gene and drug-drug-gene interactions. This framework, a web-based medication management centre, will support patients in managing their therapy-related health data, enhancing education and empowerment, and improving patient safety.

Objective: To assess the impact of the developed medication management centre on patient empowerment in polypharmacy patients, thereby improving drug safety. Secondary objec-tives are to explore if the tool is able to identify patients at risk for a drug-drug-gene interaction and lower the adverse drug event rate.

Study design: The study is a proof of concept study conducted at four institutes located in Germany, Greece, Slovenia and The Netherlands. Polypharmacy patients will use the medi-cation management centre (MMC), which provides curated, patient-specific information about drug interactions and PGx. To assess patient empowerment, patients will receive ques-tionnaires during a 12 week follow-up period.

Study population: 120 subjects with polypharmacy (defined as the chronic use of 5 or more drugs) of at least 18 years of age, with a first prescription for one of 10 index drugs. The study will be performed at 4 different sites (Leiden (NL), Patras (GR), Ljubljana (SL), Aachen (DE)) to represent different clinical settings across Europe. Each site will recruit 30 patients.

Intervention: The MMC that provides patient centred information on drug-drug interactions and pharmacogenetics affecting personal polytherapy. The MMC will show a selection of high quality publicly available information such as details on different types of medications, includ-ing their uses, side effects and instructions for use, in the language of the patient. This infor-mation is targeted at an individual patient's medication profile to inform patients to better un-derstand and deal with their personal health information, with regard to drug therapy. Patients in the Netherlands, Slovenia and Greece also will receive their PGx profile to further personal-ise the MMC experience.

Main study parameters/endpoints: The primary outcome is the sense of empowerment and health literacy for participants before and after use of the MMC. Secondary outcomes include an evaluation of the drug-drug-gene interactions and adverse drug events in the study popula-tions compared to matched historical controls.

Nature and extent of the burden and risks associated with participation, benefit, and group relatedness: Patients are exposed to the regular treatment. In addition, patients will receive questionnaires at baseline, two, and twelve weeks regarding the use and experience of the medication management centre, and a close-out interview at week twelve. In addition, 10ml of blood will be collected during a venipuncture for pharmacogenetic analyses.

Benefits include having access to the medication management centre for the duration of the study. Additionally, patients will receive their PGx profile. This can be used to individualize drug treatment, based on the Dutch Pharmacogenetics Working Group (DPWG) guidelines.

Overall, minimal risks are expected for subjects as they will receive normal clinical care. In-formation from the MMC will be a curation of existing publicly available data. Any information regarding DDIs and DGIs will be supplemented with a disclaimer that the patient should not adjust their treatment without talking to a healthcare provider.

In order to be eligible to participate in this study, a subject must meet all of the following crite-ria:

• Polypharmacy defined as the use of 5 or more drugs
• Start usage of at least one index drug according to the list in table 3.
• Subject must be ≥ 18 years old
• Subject is able and willing to take part and be followed-up for at least 12 weeks
• Subject is able to donate blood or saliva
• Subject has signed informed consent

A potential subject who meets any of the following criteria will be excluded from participation in this study:

• Pregnancy or lactating
• Life expectancy estimated to be less than three months by treating clinical team
• Unable to consent to the study
• Unwilling to take part
• Subject has no fixed address
• Subject has previously been genotyped for PGx genes
• Subject has no current general practitioner
• Subject is, in the opinion of the Investigator, not suitable to participate in the study
• Estimated glomerular filtration rate (MDRD) of less than 15 ml/min per 1,73m2
• Patients with advanced liver failure (stage Child-Pugh C)