Avoiding key challenges for testing on-body delivery systems

Chris Berry and Gareth Wynne, Smithers, discuss wearable on-body delivery systems, including some of the key challenges for laboratory testing and future trends in the physical and functional evaluation of these devices.

Why are we seeing a higher prevalence of On-Body Delivery Systems in recent years?  

The goal of On-Body Delivery Systems is to lessen the burden of treatment on the patient. These devices decrease the amount of time that patients must spend in clinical settings. This allows complex treatments to be brought directly into the user’s home.  

From the human element, they improve patient comfort. Due to the nature of bolus doses or medication with longer deliver times, patients previously were required to spend hours or days at a treatment facility. Now, On-Body Delivery Systems are attached to the patient, and they can go about their business in their own homes while staying on their medication schedule. 

What are the current testing standards for On-Body Delivery Systems? 

These devices follow a brand-new standard, ISO 11608 Part 6. Released in 2022, the new standard references previous guidance from the 11608 series, including Parts 1-5. Part 1 covers dose accuracy, general requirements, and defines sample size. Part 2 covers needles and Part 3 addresses containers. Part 4 covers the device’s electronics, and Part 5 covers the automated function of the device. By design, there is a requirement for On-Body Delivery Systems to fulfil needs from all the parts of the 11608 standard.  

Non-standard tests must also be considered. For example, if a device uses LED lights to indicate different stages of use for that device, you must test that those function correctly across various environments and use scenarios.  

Do you test for weather and waterproofing?   

The intended use of these devices will often be a user’s home environment, but laboratories should also be testing scenarios that mimic the most extreme or challenging environments that the device is likely to encounter. This can include testing under cold, dry, hot, and humid conditions. Testing should clearly show at what point these devices failed, and Smithers can assist in determining the likely cause of failure.  

These environmental conditions can impact the dose accuracy standard mentioned earlier. In addition, we can also conduct testing and simulated use in those environments in real time, combine this with exposure to free fall drops, and vibration conditioning and transport simulation.  

What are some risks that people might not think to test for?  

We have recently been specialising is occlusion testing, back pressure testing, and the evaluation of dose delivery profiles. These are complicated and time-consuming tests that many in-house laboratories find more convenient to test through independent laboratories like Smithers.  

Occlusion is particularly important for pump devices, in which there is a separate cartridge, and the product is delivered through a line to the patient. There is potential for the line to become blocked or occluded if the line becomes kinked or pinched, allowing the pump to create pressure within the line. Once that line is unblocked, the line could then deliver an unintended bolus.  

Orientation is also an element people do not always consider. It may impact the functionality of the device if the patient puts it on upside down. This may sound silly, but these devices are intended to become part of a patient’s daily routine. If that person is getting ready in the early morning or it is dark, it needs to be expected that these devices may be applied in unpredictable orientations.  

The more technology and functionality included in a device, the higher the number of potential risks. If the device has a pause function, for example, how does it interact with the dose accuracy? If the user pauses it for a second, it should give a zero dose. When the patient restarts, does the device continue and give an exact dose, as per the acceptance criteria, or does it give a little bit more, a little bit less. You must design your experiments to test for these scenarios. 

What unique challenges do miniaturisation pose for device testing? 

The device’s physical design, especially if it included ergonomics, can complicate testing, as it can impact the mounting or fixture of these devices. You want a skilled laboratory testing provider to ensure that they have the expertise and approaches necessary to customise the testing to meet that design. At Smithers, we use technologies like 3D printing to rapidly produce purpose-built fixtures to work with unique sizes and dimensions of devices.  

What does the future of testing On-Body Delivery Systems look like? 

Integration with more sensors is coming rapidly. You see this with the recent release of diabetes systems, with blood glucose monitoring systems working in tandem with insulin pumps. Now, patients can have a pump communicating with a separate sensor, measuring the blood glucose level, and automatically delivering the appropriate dose of insulin.  

The truth is that the industry has consistently increased the complexity of these devices over the years, so expertise in testing these devices is more important than ever. We are seeing an increase of in-house testing operations default to independent laboratories like ours because it is becoming harder to secure the expertise necessary to perform adequate testing of these devices.