**Preface to "Medicines Reuse"**

This is a book about 'medicines reuse'. In a pharmacy setting, medicines reuse is about redispensing unused medication returned by one patient for use by another. The 'reuse' of dispensed medicines instead of the disposal of the medication as waste is preferable where possible. Disposal as waste is the current practice that takes place in many parts of the world, including in the UK. A number of related or alternative terminologies also exist to describe the concept of medicines reuse, including re-dispensing, recycling, redistributing and reverse flow. Medicines reuse is gaining popularity around the world, either as an existing scheme or as an idea to be explored for implementation in the future. The contributing authors were motivated to write this book because medicines reuse has the potential to help reduce the waste and environmental pollution created by unused medicines, reduce the depletion of material resources and/or help save money and provide medicines to people who cannot otherwise afford them. Medicines reuse might also help deal with the problem of drug shortages or assist with the creation of new medicines using extracted and repurposed pharmaceutical ingredients. This can facilitate greater responsiveness and recovery in times of supply chain disruption when shortages occur. Yet, perhaps for historical reasons, this subject remains under-investigated. Our aim was to bring together leading authors in the field to help create a comprehensive and contemporary account of medicines reuse research. The intended audience for this book includes academics, health professionals, policy-makers, researchers and students, and indeed anyone else with an interest in making medicines use more sustainable by learning from research within the emerging field of medicines reuse. This book brings together over 20 authors from graduate students to Professors from the UK and the US working within a breadth of specialisms including Biomedical Engineering, Biosensors, Computer and Human Interaction, Health Psychology, Health Service Operations, Pharmacy Practice, and Technology Management and Circular Economy.

Paper one outlines a Circular Pharmaceutical Supply Chain and explains how it could be considered and tested as a sustainable supply chain proposition.

Paper two examines the different therapeutic classes and dosage forms making up medication waste around the world, to inform potential reuse practice.

Paper three describes medications stored in US households, gauging their risk to minors, pets, and the environment, while estimating the costs of unused medications.

Paper four draws on stakeholder meetings to detail the range of views expressed on medication waste and the potential for medicines reuse within a UK context.

Paper five reports on public attitudes towards medicinal waste and medicines reuse within a 'free prescription' healthcare system in Wales, UK.

Paper six examines the validity of the Theory of Planned Behaviour (TPB) for understanding people's intentions to engage in medicines reuse as a behaviour.

Paper seven reports on a TPB model which predicts behavioural intentions showing how people could embrace medicines reuse via practical measures.

Paper eight illustrates people's perceptions of medicines as common commodities to explain their pro-medicines-reuse beliefs and desire for these to be recycled.

Paper nine shows how sensing technologies applied to pharmaceutical packaging could enlist medicines to the Internet of Things to facilitate medicines reuse.

Paper ten gauges the effect of quality indicators, including sensing technology applied to packaging, on people's beliefs about medicines reuse in an experiment.

This is a unique, indispensable collection of papers whose publication coincides with the NHS's ambition to be the world's first net-zero national health service. With medicines accounting for 25% of the carbon emissions within the NHS (20% rooted in the medicines manufacturing and freight within the supply chain), medicines reuse could be the key to reducing emissions and helping the NHS and other health services globally to reach net zero status.

We are grateful to Elsa Wang at MDPI for facilitating the publication of this collection. We are indebted to all research participants and to all workplaces hosting the contributors.

**Parastou Donyai**

*Editor*

*Review*
