Methotrexate (MTX) is a cornerstone therapy in the management of rheumatoid arthritis (RA) and other autoimmune diseases. At low doses, MTX functions as a disease-modifying antirheumatic drug (DMARD), effectively reducing inflammation, pain, and joint damage, and slowing disease progression. Beyond rheumatology, MTX is also used in higher doses as a chemotherapeutic agent for certain cancers, reflecting its broad pharmacological utility. In current clinical practice, MTX for rheumatologic conditions is frequently administered as subcutaneous injections to improve adherence and minimise gastrointestinal side effects associated with oral formulations. However, these injections are typically prepared from multi-dose vials in hospital pharmacies, requiring aseptic aliquoting into individual syringes for each patient. This process not only increases pharmacy workload and prolongs patient waiting time but also limits flexibility for patients who require regular self-administration at home. Since the stability of MTX after aliquoting into secondary containers has not been clearly defined, most hospitals enforce short beyond-use dates, leading to medication wastage and inefficiencies in dose preparation and scheduling. This project seeks to establish the physicochemical and microbiological stability profile of methotrexate injection when stored in prefilled plastic syringes under varying temperature and light conditions. Stability testing will be conducted in accordance with ICH guidelines, assessing parameters such as MTX concentration, pH, appearance, particulate formation, and sterility over time. In addition, kinetic analysis using the Arrhenius equation will be applied to model degradation behaviour and predict long-term stability based on accelerated data. By defining the acceptable storage duration and conditions for prefilled methotrexate syringes, the study aims to support a safe, standardised approach to advance preparation in hospital settings. Establishing evidence-based stability data will enable hospitals to provide prefilled, patient-ready syringes suitable for self-administration at home without compromising safety or efficacy. This improvement can streamline pharmacy operations, reduce patient waiting times, and enhance continuity of care for individuals with chronic rheumatologic conditions. Ultimately, this project contributes to optimising methotrexate therapy delivery through the development of validated stability guidelines for prefilled syringes—promoting patient convenience, reducing hospital burden, and ensuring consistent treatment quality. The program is of 2 months attachment at Yuan Ze University, with a monthly allowance of not more than 20,000 NTD. Postgraduate students who are currently pursuing a tertiary research program in Science and Chemical Engineering or any relevant fields are welcomed to apply.