Medicines-access policy is commonly assessed through formulary inclusion, procurement, outlet availability, price or successful dispensing. These indicators are important, yet they can classify a medicine as accessible while an individual treatment episode is repeatedly disrupted. Stockouts may force patients to search across facilities or sectors; substitutions may preserve treatment or destabilize it depending on therapeutic fit and how the change is managed; medication information may fail to accompany the patient; and monitoring responsibilities may become disconnected from prescribing and dispensing. When health systems do not absorb these disruptions, patients and caregivers frequently perform the repair work. This commentary develops a longitudinal interpretation of medicines access centred on treatment continuity. Continuity is defined as preservation over time of access to a clinically appropriate medicine, including appropriately managed substitution where necessary, adequate medication-information transfer, required monitoring and follow-up, and a level of patient repair work that does not itself become a material access barrier. The argument does not assume that every shortage causes interruption or that every switch is harmful. Evidence from drug shortages, biosimilar switching, medication reconciliation and treatment-burden research instead indicates that the consequences of disruption depend on available alternatives, health-system organization, communication, information continuity, monitoring and patient capacity. Policy evaluation should therefore supplement point availability indicators with longitudinal measures capable of detecting whether treatment remains practically and clinically viable across repeated episodes of care.
