How can the efficacy of auto-injectors be improved?

Cambridge, United Kingdom - Cambridge Design Partnership reports on how Incidences of allergic reactions are rising¹, with approximately 200 to 250 million people suffering with food allergies globally. Many rely on immediate treatment using adrenalin to deal with a severe allergic reaction². In the UK alone there are over 200,000 people using the drug, and most will carry auto-injectors for use in emergencies³.

However, a recent review by the European Medicines Agency (EMA) into the efficacy of this treatment highlighted a severe lack of studies in this area and potential issues with the injection⁴. This followed a report by the Medicine and Healthcare products Regulatory Authority (MHRA) which investigated the death of a teenager from a nut allergy despite her using an auto-injector⁵. These issues were recently highlighted on BBC Radio 4’s Inside Health program, which featured allergy specialist Dr. Robert Boyle, who uncovered significant problems with the devices through a study in 2013⁶.

So where did it all go wrong, or was it ever right?
The adrenaline auto-injector (or Epi-Pen as it is commonly known) was developed for civilian use following the success of the Combo Pen, designed to treat nerve gas attacks in the military[7]. It greatly simplified the injection process for the user, as the injection depth and dose volume are fixed, and the need to use a vial for filling the syringe is removed, speeding up the process considerably. The Epi-Pen concept has been so successful that there are now a multitude of drugs utilizing the auto-injector design.

However, adrenaline is invariably used in highly stressful situations, in order to treat a severe allergic reaction. As the auto-injector was originally designed for use in the military, the users were well trained to manage in these circumstances and the user group generally consisted of healthy adult males. Nowadays the devices are given to people of all ages, and with children suffering more from anaphylaxis than any other age group, the device has to be appropriate for a wide range of user groups.

On the recent BBC Radio 4 program Boyle highlighted how having to respond to a stressful situation can affect the person administering the drug. In his trial, more than half of the intensively trained parents were unable to correctly operate the devices in an emergency. He cited some of the common errors associated with auto-injectors: holding them the wrong way round, failing to remove the safety cap, and not pressing hard enough. They also discussed how little research into the efficacy of the device has been done because studies can cause severe allergic reactions in test subjects, plus real life situations are likely to occur in public and not in clinical settings. All of these issues have resulted in little drive to improve the devices over the last 50 years, leaving key issues unaddressed, such as the force applied by the user when operating the device or the angle of the auto-injector on insertion.

There are in fact numerous reasons why the adrenaline might not reach the right location in order for it to work effectively. Some users press harder than others, different people have thick or thin layers of fat, and some devices have different needle lengths to others. All of these factors can lead to an ineffective or even harmful injection. On top of this, the patients themselves may be confused, especially where they are taking multiple injected medicines, such as insulin injectors as well as adrenalin, as the locations and injection depth required will be different for each drug.

What are the solutions, and where do we go next?
The key recommendations from the MHRA and EMA reports covered patient advice, such as regularly checking expiry dates, carrying a spare injector, and remembering that the device is only part of the solution and medical services must be contacted immediately in all cases. It also suggested that manufacturers produce better training materials and encourage patients to practice with training devices regularly. Furthermore, new studies into the penetrating effects of adrenaline need to be undertaken by the device manufacturers, as there seems to be a significant knowledge gap. These studies will hopefully reveal key insights into how new devices can be designed to perform more effectively, but manufacturers must review and improve the usability of the devices that are currently on the market. The findings of research, such as the studies by Boyle, must be captured and transformed into design inputs for new devices.

Cambridge Design Partnership (CDP) knows the importance of usability and human factors when creating solutions for medical device design. We understand that it is essential from an early stage to recognize and consider the different use environments, together with the emotional and cognitive challenges encountered when using the device. In the case of adrenaline auto-injectors, the stressful situation when people need to use it has to be carefully considered, as do the different user groups and their varied needs. This can then be effectively documented in the requirements capture stage, something, which is often overlooked in industry.

As highlighted in an earlier blog[8] by our colleague Lucy, our product innovation approach at CDP includes validation testing, where the advantages of validating early and regularly combined with users interacting and contributing to the development process all allow a step-change in device performance. This approach should enable the next generation of adrenaline auto-injectors to more effectively meet the real needs of the users and be appropriate for their emotional state.

^{1 Allergy Statistics, Allergy UK https://www.allergyuk.org/allergy-statistics/allergy-statistics}

^{2 Food Allergy, a Rising Global Health Problem, by the World Allergy Organization http://www.worldallergy.org/UserFiles/file/WorldAllergyWeek2013final.pdf}

^{3 BBC Radio 4, Inside Health, Wed 7 October 2015 http://www.bbc.co.uk/programmes/b06flmg7}

^{4 Adrenaline auto-injectors, European Medicines Agency http://www.ema.europa.eu/ema/index.jsp?curl=pages/medicines/human/referrals/Adrenaline_auto_injectors/human_referral_000367.jsp&mid=WC0b01ac05805c516f}

^{5 Adrenaline auto-injector advice for patients, UK Gov.uk https://www.gov.uk/drug-safety-update/adrenaline-auto-injector-advice-for-patients}

^{6 Children with severe allergies at risk from incorrect use of adrenaline injector, Imperial College London http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_5-7-2013-15-18-45}

^{7 Epi-pen inventor helped millions and died in obscurity, Tampa Bay Times http://web.archive.org/web/20130201055705/http:/www.tampabay.com/news/humaninterest/epipen-inventor-helped-millions-and-died-in-obscurity/1038756}

^{8 Why validate concepts? By Lucy Sheldon http://www.cambridge-design.co.uk/news-and-articles/blog/why-validate-concepts-ask-wonderful-wizard-of-oz}

Source: Cambridge Design Partnership