Aim:Our objective was to explore the processes and determinants leading physicians to integrate estimated glomerular filtration rate (eGFR) in their drug prescriptionsBackground:Access to patients’ eGFR would allow primary care pharmacists to optimise their role in the procedure of safe prescribing. Some rare physicians actively integrate eGFR in their prescriptions, in a sporadically and uncoordinated manner.Methods:Qualitative study using semi-directed interviews conducted among 12 French physicians who integrated eGFR in their drug prescriptions, (February 2016–April 2017). These voluntary participants were recruited through different means: Twitter®, forums, direct contact and snowball sampling. Data analysis was based on the grounded theory approach, underpinned by a comprehensive perspective of interactionist orientation.Findings:Residency and training, professional experience – including experiences of adverse drug reactions – and the membership in various communities of professionals were key drivers for the integration of eGFR in prescriptions. The theoretical aim was above all safe prescribing in order to reduce adverse drug reactions, with the control by a dispensing pharmacist and/or other healthcare professionals. Nevertheless, none of the physicians had received any feedback from any healthcare professionals. Despite their disappointment, the physicians remained convinced of the interest of integrating eGFR in their prescriptions and would continue to do so. Characteristics associated with integration of eGFR in drug prescriptions belong partly to Roger’s theory of innovations. If a widespread diffusion of this habit takes place, it will be necessary to evaluate its adoption by both physicians and pharmacists.