Issue:June 2024

DEVICE STUDY - Putting Auto-Injector Interchangeability to the Test


In a crowded market, the right differentiator can hold the key to valuable competitive edge. But that can often be easier said than done when it comes to the pharma industry. Regulatory con­siderations and the patient experience pose unique challenges when it comes to innovation. The right approach, however, can turn challenges into opportunities that can benefit not just pharma companies but also patients and healthcare systems. The current growth in biosimilars is an example of this in action.

The expiry of many patents for biological medicines is lead­ing to an increase in biosimilars, with developers looking for ways to differentiate their new products from the originator versions.1 The choice of drug delivery device can be an obvious option to set a pharma company apart from its competitors. But it is not necessarily a straightforward route to success.

At the centre of any decision about which device to choose is the patient. They might be very young or an older person with dexterity issues. And they will almost certainly find it difficult to follow complicated instructions. They are also likely to have be­come used to whatever device they have been using for their medication in the previous months or years.

All these factors need to be taken into account when deciding whether patients can successfully switch to a different drug deliv­ery device. Because if patients struggle to cope with a new device, there is a risk they will miss out on vital doses of medication – particularly given the trend for self-administration at home with­out medical supervision.


The best way to discover how patients are likely to cope with a new device is to put it to the test – see how long it takes patients to work out how to use a new device and whether they can suc­cessfully carry out test injections. Yet there is a shortage of studies on the ease of switching devices.

To shed light on what happens when patients are asked to switch between two different auto-injectors, Owen Mumford Phar­maceutical Services (OMPS) commissioned an independent study to discover whether regular users of a market-leading three-step auto-injector were able to switch to a new two-step auto-injector and successfully perform injections.

The two devices used in the study were SHL Medical’s three-step, button-activated DAI® auto-injector and the two-step, spring-powered Aidaptus® device from OMPS, which uses pres­sure to activate the injection – instead of pushing a button, the patient just presses the device onto the injection site.

The study involved 52 participants, aged between 16 and 75, who had all been using the DAI auto-injector for at least 3 months. There were 34 women and 18 men, split between the US and the UK. The aim was to test their ability to switch from a familiar auto-injector to a new one – looking at how easily they could learn how to use the new Aidaptus device and whether they could successfully complete injections with it.

The participants had not seen the Aidaptus auto-injector be­fore the study – and they were not given any training, demon­strations, or coaching. They were given the devices in unopened original boxes containing their respective instructions for use (IFU) and asked to administer injections into an injection pad on a table – four injections in total, starting with the DAI auto-injector and then alternating with the Aidaptus. The facilitators were told to intervene only if there was a risk to the participants.


The primary measure was injection success. An injection was considered suc­cessful if the participant correctly delivered the injection into the pad – inserting and using the device as described in the IFU and not removing it until the contents had been fully delivered into the injection pad.

With multiple factors involved in any switch, more user studies are vital for a better understanding of the issues.

A secondary measure was injection time – calculated from when a participant placed the auto-injector on the injection pad and started the injection process through to when the device was removed from the pad.

Other secondary measures included whether the participant examined the de­vice and how long they took to examine it, whether the participant read the IFU, and their confidence in performing the injec­tions. Demographic factors – age, gender, left or right handedness, and geographical location – and their impact on the other measures were also recorded.

All the secondary measures were cal­culated by analyzing videos of participants throughout the test process. Ease of use was therefore calculated based on video analysis of the way in which participants handled and examined the device as well as the time taken for injections.


The study was not intended to be a di­rect comparison between the DAI and Aidaptus auto-injectors, as all participants were already familiar with the DAI device. The results, however, clearly showed that all participants were able to successfully switch from the three-step auto-injector to the two-step device, with no impact on in­jection success.

Participants used the two devices in a similar way, with injection times (measured as previously described) falling after each injection – indicating familiarization. Mean injection times were similar for both de­vices. Participants took more time to famil­iarize themselves with Aidaptus prior to the first injection – compared with the DAI – but this was to be expected, as all partici­pants were already familiar with the DAI.

The injection time across men and women was very similar. However, the men in both countries had a shorter injec­tion time across all Aidaptus injections. Gender, however, did not impact the suc­cess of injections and the ability to switch between the two devices. Left or right handedness also appears to have had no impact on injection success – and no sig­nificant impact on injection time.

Age also had no impact on injection success. Older users – participants over 40 – typically had longer mean injection times for both the three-step and the two-step auto-injectors, but all injections were suc­cessful, irrespective of injection times.

US participants completed their first Aidaptus injection around 30% (4.6 sec­onds) faster than UK participants – close to their speed when familiar with the de­vices. This could indicate a greater ability to switch between devices for this US pop­ulation, but further research would need to be conducted to confirm this.

All participants completed their first injection with Aidaptus successfully, re­gardless of whether they had read the IFU – which suggests they found both devices easy to use. US participants were more likely to examine the IFU and/or device than UK participants before both Aidaptus injections. Most participants needed to look at the IFU only once. They were able to switch between the two-step and three-step auto-injectors without constantly re­ferring back to the IFU.

The participants had not seen the Aidaptus auto-injector before the study – and they were not given any training, demonstrations, or coaching.


As the wider availability of biosimilars creates a significantly more competitive market, consideration of the most suitable devices for administering the new drugs is also crucial. That’s why pharma compa­nies need access to more data from human factors studies and other ease-of-use testing – to support regulatory appli­cations for interchangeability determina­tion. The FDA requires a regulatory application to provide evidence that the impact of switching between delivery de­vices has been assessed.

Ideally, the patient experience should be improved by any switch to a different drug delivery device – at the very least, it should not be adversely affected. With multiple factors involved in any switch, more user studies are vital for a better un­derstanding of the issues. But the OMPS study suggests patients can successfully switch from a three-step auto-injector to a two-step device without external interven­tion – a valuable step toward de-risking the device choice dilemma.


  1. Mulcahy A, Buttorff C, Finegold K, et al. Projected US savings from biosim­ilars, 2021 –2025. Am J Manag Care. 2022;28:329–335.

Alex Fong, MBA, is an experienced senior manager in the Insight, Analytics, and Strategy fields. He has applied these skills in a broad range of industries, including the FMCG/CPG, retail, telecoms, and management consulting sectors. He has worked and lived in several international markets throughout his career, including Hong Kong, the US, South Africa, and France.