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Maverick: an emergency auto-injector designed for total patient safety

The Maverick emergency auto-injector merges Duoject Medical System’s design and development expertise with Stevanato Group’s contract manufacturing capabilities. Six Human Factor studies conducted over 150 patients show how the current configuration resulted from several design iterations, considering the patient’s intuitiveness and total safety.

When seconds are essential to saving lives, administering medications with a thoroughly reliable, easy-to-use, and safe auto-injector is critical.  The perfect emergency auto-injector (EAI) must incorporate enough fail-safe features to prevent any possible misuse and be accessible at all times by the largest range of users.  Achieving this “one device fits all” is a great challenge.

Due to the nature of treatments provided by EAIs, a strong approach to Human Factors (HF) is key to designing a product capable of delivering a life-saving dose of drugs even in the worst possible context of use.  HF studies evaluate user interactions with the device and whether the intended user population in the environment of use could safely and effectively use the device with the specified drug product. 

Because the level of user experience with emergency treatments can vary greatly from one another, an emergency administration device must be extremely intuitive. In an article from The Psychologist: Survival – Mind and Brain, Sarita Robinson and Nikola Bridges suggest that cognitive failures in emergency situations mean that actions taken can be ineffective at best and in some cases can actually reduce survival.  In other words, humans in life-threatening situations tend to demonstrate difficulties in making rational decisions that could transform even the simplest action into a complex one. This reaction to immediate stressful events is normal and can be minimized through training and experience. The designers of EAIs need to be aware of the fine balance between adding the right number of fail-safe features without complexifying the use of the device for experienced users. 

Maverick was designed with the end-user in mind.  Every learning from HF studies was analyzed and implemented and then verified again with real users.  Multiple HF studies early in the device development enabled significant improvements on the user interface, the design, and the instructions for use.

To test HF with EAIs in the most realistic context of use, many parameters must be considered. Throughout the HF testing of Maverick, Duoject’s HF specialists learned that the test environment and scenario can have a great impact on the experiment outcome.  The ideal test protocol will let every participant be exposed to the exact same experience.  This is crucial for comparing the experimentation results between participants and trials.  Similar to the medical device development work, obtaining an ideal test protocol is also an iterative process.  Over the course of subsequent Maverick’s HF studies, our team optimized the test protocols to generate the most reliable data.  The following are recommendations for HF studies with EAIs:

EAI users most probably will not have a lot of experience using such a device for a few reasons. First, patients prescribed with an EAI may never have to use it.  If the user has already used an EAI, chances are it is some time ago because emergencies do not happen often.  Second, during an emergency event, the patient (EAI owner) might not be able to self-administer the life-saving dose and may require the help of someone else.  The person administering the emergency drug to the patient might not have any experience with EAI.  For these reasons, the test population must integrate experienced and inexperienced users.

Using an actor to act as a patient (injection receiver) proved to be problematic as participants will not interact the same way with the actor (if the actor is a female or a male as an example). Moreover, we could not guaranty the actor would be available if subsequent experimentations were required.  For these reasons, in the two latest Maverick HF studies, the actor was replaced with a generic mannequin.  Our testing demonstrated that to minimize variability from a study to another and to control interactions between the participant and the patient, using a generic mannequin instead of a human actor is essential.

Another important aspect of HF studies with EAIs is the ability to reproduce a sense of urgency.  This is crucial to recreating a realistic context of use because most real-life interactions with EAIs will happen in an urgent situation.  Our team experimented with different ways of effectively reproducing such an emergency, without putting the test participant at risk.  Our team found that a constant loud alarm clock lasting for the whole experiment duration proved to be an efficient way of creating a sense of urgency.

Finally, to recreate the most realistic context of use and to challenge the limits of the device intuitiveness, no instructions or training can be provided to the participant other than what is available on the device itself.  It is the responsibility of the designer to create use steps that reduces the occurrence of errors to a minimum and provide easy-to-follow instructions.  The primary goal in the first HF studies was to validate the user experience. Subsequent studies aimed at validating the instructions.  The HF study protocol for EAIs must consider that user access to instructions is restricted, other than access to what is available on the device.

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Maverick offers unique improvements upon commercially available systems in terms of user experience and safety.  For example with marketed devices, nothing prevents the end-user from actuating the probe while holding the device upside-down, resulting in a loss of dose and/or delivery of the dose of epinephrine in the end-user’s thumb – potentially resulting in thumb amputation or death (if another dose is not provided promptly).

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Maverick is a novel auto-injector currently under development by Duoject, with a patented dual triggered needle activation preventing using the device in the wrong orientation and potentially wasting a life-saving dose.  The first trigger (black probe) is fully accessible and meant to be depressed by pressure applied to the injection site (thigh in this case) while the second trigger (red button) is shrouded and cannot be depressed by a large surface – only a finger can displace the button sufficiently to fire the injection.  The first trigger (black probe) requires some force to stay depressed which helps to reach IM injection because compressing the fat tissue decreases the skin-to-muscle distance.  Finally, the device’s user can rely on audible, visual, and tactile feedback. He/she is never exposed to sharp injuries throughout the intramuscular injection, as the needle retracts automatically after injection.

The Maverick EAI merges Duoject’s design and development expertise with Stevanato Group’s unique primary packaging, molding, tooling, and assembly capabilities. Maverick’s technology and design are patented in several countries. The device’s mechanical robustness is also provided by SG Nexa® glass cartridge, featuring an external anti-friction and anti-scratches silicone coating for improved container closure integrity and reduced breakages in fill/finish processes.  Stevanato Group streamlines the auto-injector supply chain under one point of contact, coordinating from the design and optimization of the glass container to injection molding and sub-assembly from fast prototyping to mass production.

For further information on Maverick, please visit our website.

We thank our partner Duoject Medical Systems for their contribution in writing this article and for sharing their experience in conducting HF studies on Maverick.

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