Pharmacist prescribing has been introduced to alleviate pressures on hospital services and improve timely access to treatment. However, implementation in inpatient settings remains highly variable, with pockets of excellent practice alongside areas where prescribing roles are limited or absent. Traditional effectiveness reviews have demonstrated positive impacts of pharmacist prescribing on clinical and service outcomes yet offer limited insight into how contextual conditions and underlying mechanisms interact to produce results in complex hospital inpatient environments. This realist review aims to develop and refine programme theory (PT) explaining how pharmacist prescribing in hospital inpatient settings works, for whom, why and in what circumstances, with particular attention to the factors that support or constrain successful implementation.

The review will follow Pawson’s six-stage realist synthesis process andRealist And Meta-narrative Evidence Syntheses: Evolving Standards guidance, moving iteratively between theory development, searching, selection, data extraction and synthesis. A multidisciplinary stakeholder advisory group and patient and public involvement group will work alongside the review team to feedback on the scope, refinement of context-mechanism-outcome configurations (CMOCs) and implementation recommendations. Initial programme theories will be developed and then refined using evidence from formal searches of MEDLINE, Embase, CINAHL and Scopus alongside grey literature. Data will be extracted into a descriptive spreadsheet and coded in NVivo using deductive, inductive and retroductive approaches to identify, test and refine CMOCs. The final output will be a refined PT and practical recommendations to inform design, implementation and scaling of pharmacist prescribing roles in hospital inpatient care with attention to equity and acceptability for patients and multidisciplinary teams.

Ethics approval is not required for this realist review as it involves secondary analysis of published articles and grey literature. Dissemination will include peer-reviewed publications, presentations to pharmacy departments and professional bodies, as well as co-produced accessible materials with patient and public groups to support knowledge mobilisation. The review protocol has been registered on PROSPERO.

CRD420261283633.