Parenteral drug autoinjector testing – higher throughput and less risk

ZwickRoell examines why autoinjector testing after the final fill and finish can be so challenging.

Autoinjectors represent an important growth driver. Testing these devices can present operational challenges, which are coming to the forefront as the scale of autoinjector manufacturing and testing continues to expand. 

Closely related to pen injectors in basic design and function, autoinjectors are typically used for infrequent, single-dose medications that are for subcutaneous or intramuscular injections. Pen injectors are more commonly used for patients with chronic health conditions like diabetes. They are designed to be re-filled and used multiple times. Pens are typically used for medications that are injected subcutaneously.

The growth in this market over the past three decades is likely to sustain itself for the foreseeable future with an ageing population and rising rates of chronic diseases and allergies. These devices were originally developed to support emergency self-administered dosing of liquid medications in applications such as: Epinephrine (adrenaline) injectors used to combat nerve gas in military applications, and morphine injectors used by emergency personnel requiring urgent pain relief.

Starting with FDA approval of the EpiPen in 1987, injection devices have rapidly become a frontline solution in a broader range of healthcare applications. Some early devices did function incorrectly, driving recalls—and the implementation of quality control standards employed today. As technological developments open new capabilities for these devices, autoinjector usage continue to climb. 

These devices are increasingly becoming the standard delivery platform for injectable drugs, providing a self-administration solution for substances that cannot be administered as a pill or tablet. By ensuring a proper, precise dose every time, autoinjectors can increase safety for both supervised and unsupervised applications. They provide dose-sized storage, and instead of visibly inserting a needle into the skin, patients hold a device against their skin while it injects the medication.

Testing these devices after performing a final “fill and finish,” can be challenging. They need to be precisely engineered to perform reliably while meeting strict regulations for protecting patient health - the FDA is focused on ensuring safety and precise function. As companies handle ever-higher production and testing volumes, there is a more pressing need to streamline.

All medical devices require some extra quality assurance, but injection devices particularly stand out for their precise engineering needs, strict requirements for testing and manufacturing, and need to perform consistently and safely in an unsupervised setting. 

When patients or healthcare providers use an injection device, they are counting on it to deliver a full, precisely measured dose of a potentially life-saving therapeutic; autoinjectors must perform their intended function every time.

Delivering the incorrect amount of medication can adversely affect patient health. Even patient comfort is at stake: injection time is a key testing attribute, intended to ensure patients do not need to leave the needle in their skin for long amounts of time while waiting for the injection to fully dispense. Injection device testing leaves no room for error. Because of the standards for autoinjector safety, a single failed test could mean that an entire lot of thousands of devices is lost. Autoinjector testing operations must catch potential deficiencies while also minimising the risk of false positives that could impose immense costs. The number of devices from each lot that must be tested vary depending on the risk factors of the relevant drug, but heightened safety concerns generally necessitate larger samples compared to other industries.

Manual testing processes can slow down the pace of required work with many facilities are still using them. Traditional manual testing processes can limit testing throughput, and the ability to keep pace with rapidly increasing production volumes for autoinjectors, which can lead to human errors in specimen handling, measurement, and data recording. 

Also, valuable but optional quality control tests may be skipped to save time. Fortunately, there are proactive options for streamlining autoinjector testing while reducing the risk of errors.

Any testing machine that can perform multiple tests without further handling or technician intervention can dramatically streamline testing. Integrated testing solutions reduce the overall need for hands-on supervision from technicians, minimise waiting times between tests, limit the need for additional costly testing solutions, and reduce the number of human-specimen touchpoints where errors can occur. Some production line machinery providers can add ad hoc measurement devices as a custom attachment to the line itself. They are typically provided by manufacturing firms with little expertise in materials and component testing and have some important limitations. Most importantly, they are usually designed for specific autoinjector platforms. 

This can be problematic as new autoinjector designs are continuously coming to market. Where possible, the most effective testing solutions should use flexible handling systems that can work with current autoinjector designs while offering the versatility needed to future-proof testing for new platform developments. Rigorous daily checks are imperative to ensure testing equipment is working properly. Well maintained sensors are essential for ensuring precise readings, preventing false positives, and promptly diagnosing testing issues if they do occur. 

Automated autoinjector testing solutions can even provide automatic daily checks. For manual testing, technicians need to ensure that this requirement is followed strictly. While it is generally recommended that daily checks are caried out, other approaches such as performing a check at every shift change or product changeover may be viable.

For ensuring accurate testing results, recording/reporting of testing data is as important as taking the measurements themselves. Seamless documentation and execution help protect data quality and avoid costly mistakes. The FDA is only increasing demands for meticulously documented, highly traceable testing results. This issue is even more complex for companies managing multiple sites for the same product. Technicians who may be working at different facilities on opposite sides of the world must follow precise, repeatable procedures for data entry. Semi-automated and automated testing solutions can provide integrated data reporting, with measurements automatically recorded and uploaded to the cloud. If manual testing procedures are in place, technician training needs to be aligned across all sites and completed and kept up to date by all technicians.

The move toward automation in injection device testing is a necessary consequence of the need for increased testing throughput alongside reduced human errors. But some companies are not confident true automated solutions are the right fit for their production facilities or budgets. “Semi-automated” machines are designed to provide a more flexible option. They offer many of the benefits of automation, like integrated data reporting and the ability to conduct many different tests on the same machine, while scaling back features like robotic specimen handling. This allows these solutions to be offered at a lower price point, and to fit into a broader variety of production facilities. Semi-automated solutions can cover a variety of required tests, and optional tests that can provide deeper data.

Semi-automation offers more flexibility than ever, but as testing volumes increase, the value proposition for automating as many aspects of the process as possible grows. True automated systems support capabilities including robotic specimen handling, 24/7 operation, and other key features designed to dramatically speed up testing while minimising the risk of human error. As injection device production continues to scale up, we expect to see true automated testing operations proliferate more widely.

ZwickRoell will be exhibiting at Med-Tech Innovation Expo on 7-8 June 2023 at the NEC, Birmingham. For more information, visit www.med-techexpo.com.