Human factors is now firmly established at the heart of medical device development, and that includes prefilled syringes. Regulators, and in particular the US Food and Drug Administration (FDA) have recently published guidance on human factors testing for manufacturers (UCM259760 ‘Human Factors for Medical Devices, published February 6th 2016).

FDA have also just published a list of medical devices that they regard as top priority for human factors, and autoinjectors are on the list. The message from the FDA is very clear; if you are intending to apply for pre-market approval in the US for any type of medical device, you will need to demonstrate that you comply with these requirements. And if you are developing an autoinjector, human factors (HF)  validation is mandatory. In essence, manufacturers are being asked to integrate human factors into their new product development, and to demonstrate that they understand the use-related risks for their device. Where to start? Three aspects are important; the intended uses, the intended users and the anticipated use environment. Have you clearly stated who the intended users are, and for what specific use your PFS is intended? Have you understood the environment in which your product is likely to be used?

The recommended approach is to adopt a systematic method for analysing and evaluating the usability of your product through early, small-scale formative testing. Product designers will recognise this phase as ‘design verification’. Once you have verified that the design of your product meets the needs of its intended users, you will then need to validate that it can be used safely and effectively. Typically this will mean running a human factors validation study in which you test the final ‘go-to-market’ version of your product. The validation study will need to use ‘simulated use’ scenarios in which a sample of patients will inject into a skin pad. The root cause of any use error or difficulty will need to be investigated so that you can demonstrate that you understand the causes of potential failures. Validation for products intended for the US will need to be carried out in the US with representative samples of the intended users. So for example, if your product is intended to treat rheumatoid arthritis (RA), your test sample must include people in the US with the right severity of RA, and with a mix of prior experience of injecting. Increasingly, PFS are being used for complex molecules and biologics, and in many cases the first injection might be performed by a healthcare professional in a clinical setting. This effectively means that HCPs are now an additional user group and should be included in the validation study.

On completion of your validation study, the results will need to be fed back into your use-related risk assessment. After a further review of the risks, you will need to demonstrate that you have reduced the level of use-related risk to the minimum possible level, and that it is not practical to reduce risk further. But what if you plan to use an existing PFS, perhaps one that has been used for a considerable time in one therapy area, but which you intend to develop for a different type of treatment? Do you need to go right back to square one and re-verify the design? Well, like the whole HF process, you are managing use-related risk. You may be aware of known use problems with the PFS (for example by reviewing customer complaints, or by reviewing the published literature). You may also perform an expert review to identify whether there are any ways in which risk could be reduced. But one thing is clear; if you are switching patient types to a very different therapy area, it is highly likely that FDA will ask you to revalidate the PFS in the new user group. Here at MDU we have built up considerable experience in human factors testing of medical devices, including PFS, pen injectors and autoinjectors. We test extensively in the US and EU and we work with some of the world’s leading pharmaceutical and medical device companies.