Overview of psychological theories relevant to understanding people’s beliefs and intentions toward reusing medicines

Background: Many factors can impact a person’s behaviour. When the behaviour is subject to prediction, these factors can include, for example, the perceived advantages and disad-vantages of performing the behaviour, normative beliefs, and whether the behaviour is thought to be achievable. This paper examines intentions to engage in medicines reuse; i.e. to accept medi-cines returned unused to a pharmacy to be reused. The paper aims to outline the validity of the Theory of Planned Behavior (TPB) for understanding people’s intentions to engage in medicines reuse by examining this against other long-standing health-related psychological theories of be-havioural change. Thus the Health Belief Model (HBM), Protection Motivation Theory (PMT), Trans-Theoretical Model of Health Behaviour Change (TTM/SoC), Theory of Reasoned Action (TRA), and TPB are examined for their application in the study of medicines reuse. Discussion: The HBM, PMT, TTM/SoC, TRA, and TPB were assessed for their relevance to examining medi-cines reuse as a behaviour. The validity of the TPB was justified for the development of a Medica-tion Reuse Questionnaire (MRQ) to explore people’s beliefs and intention toward reusing medi-cines. Conclusion: TPB has been widely used inside and outside of health-related research and was found to have more accurately defined constructs making it helpful in studying medicines reuse behaviour.