Alan Thomas, marketing at ZwickRoell, analyses the mechanical testing of wearable autoinjectors for drug delivery devices.
They are called on-body delivery systems (OBDS), wearable autoinjectors, or simply wearables. While their names may vary, they ultimately refer to the same thing, devices that automatically administer highly viscous biologic drugs, while attached to the patient’s body. In the fast-growing market for biotechnological applications, there is a requirement to test the functionality of these devices in accordance with the international standard ISO 11608-6.
People suffering from an illness are likely to recover faster in a familiar environment, in other words, at home. For chronically ill patients, shortening the healing process is of particular significance and autoinjectors worn on the body can help. They not only reduce the cost of long-term therapies, but they are also able to promote patient comfort by allowing them to set up and undergo treatment in their own surroundings. These systems reduce the need for frequent visits to a clinic or doctor’s surgery for essential injections that would otherwise have to be administered by qualified personnel.
The benefits provided by injection systems which are securely attached to the patient’s body (on-body delivery systems) are clear, they reduce possible risks that result from administration of medicines through more commonly used needle-based injection systems. In addition, they are capable of optimally dispensing drug volumes ranging from 2 ml to 20 ml, in different time intervals from as little as a few seconds up to several hours. This form of therapy is ideal for daily self-treatment and can be implemented without having to spend time in a medical facility. The adhesive side of the injection system is attached directly to the patient’s skin, and the injection is administered through a needle or cannula integrated in the device.
Typical OBDS testing system
All the while, in today’s OBDS market, which is growing over 20% annually, manufacturers face several challenges when it comes to developing large-volume injectors. More specifically, ISO 11608-6 requires them to test the forces that result during the injection process due to the viscosity of the drug, the high volume, the injection time, the internal diameter of the syringe and needle, the needle length, and the occurring frictional forces, including static friction.
Extensive collaboration with the pharmaceutical industry and autoinjector device manufacturers has resulted in the development of sequential testing solutions for on-body delivery systems. These solutions are based on standard, low force static testing machines. Incorporating several newly designed adaptations, these machines can measure the force required to trigger the actuation button, as well as the injection depth, injection time, and the amount of liquid delivered using high-resolution, camera-based measuring systems. An integrated camera can record the process to verify how the sequences of the display elements react and document the audible signals or clicking sounds, of the injection system via a microphone. Testing machines can optionally support additional tests, such as determining the adhesive properties of the device bonding surface.
Advanced software can document the obtained results and display them in a clearly presented format. For maximum transparency, secure traceability for validation, and quality control, machines can perform the tests reliably and according to the required standards. This is important because in the biotechnology sector and the pharmaceutical industry, it is imperative to know who did what, when and why, and who is responsible. Every action must be documented in a tamper-proof and traceable manner according to FDA CFR Part 11.
The latest testing systems provide invaluable device functionality data to assist in the development of autoinjectors for cancer treatment therapies, autoimmune diseases and neurological disorders which are ultimately of benefit to the patient.
