Medication-safety interventions are often judged by whether they are implemented and remain present, yet continued existence is an incomplete account of sustainability. Safer practice has to be reproduced through recurrent work: routines enacted, exceptions managed, knowledge transferred, conditions monitored, and adaptations kept compatible with the safety functions they are meant to protect. This article develops a Practice-Theory Persistence–Erosion Model explaining how medication-safety improvements can persist, adapt, stabilize, or gradually erode after implementation. The model distinguishes recurrent enactment from maintenance effort, separates staff turnover from the knowledge loss that may follow it, and differentiates adaptive maintenance, drift, and workaround formation. Persistence is sustained reproduction of safety-relevant functions under changing conditions; erosion is cumulative weakening or displacement of those functions when losses and modifications outpace replenishment, learning, and repair. Sustainability is therefore treated as a dynamic organizational accomplishment with multiple trajectories, generating testable implications for longitudinal monitoring, workforce continuity, adaptation assessment, and organizational learning.
