Stability studies in pharmaceutical 3D printing: a scoping review protocol

Pharmaceutical three-dimensional (3D) printing is increasingly recognized as a key enabling technology for personalized medicine. While substantial advances have been achieved in the development of patient-specific dosage forms, the successful translation of these technologies into clinical practice depends on the generation of robust evidence supporting product stability, quality, and shelf life. Despite recent regulatory initiatives, including guidance issued by the European Medicines Agency, no harmonized framework currently defines stability-testing expectations across the diversity of pharmaceutical 3D-printing applications, raising concerns regarding the regulatory readiness of the field. This scoping review aims to systematically map the literature reporting stability studies of pharmaceutical products manufactured using any 3D printing technology. Specifically, it seeks to characterize current stability assessment practices, evaluate their alignment with established regulatory and pharmacopeial principles, and examine whether the available stability evidence supports progression from toward clinical implementation and point-of-care use. The present protocol was developed according to Joanna Briggs Institute (JBI) guidance and will be conducted and reported following JBI and PRISMA-ScR recommendations. Original research articles evaluating the stability of drug-loaded 3D-printed products over a minimum period of 24 hours will be identified through searches in MEDLINE, Embase, and Web of Science. Two independent reviewers will perform study selection and data charting. Extracted data will include formulation characteristics, printing technologies, storage conditions, study duration, analytical endpoints, pre-print stability assessments, and references to regulatory guidance. No critical appraisal will be undertaken. By providing the first comprehensive overview of stability-testing methodologies in pharmaceutical 3D printing, this review aims to identify methodological gaps, assess the depth of stability characterization of the evidence base, and inform future efforts toward regulatory harmonization and clinical translation.