Purity of medical devices in the manufacturing process

On November 26, the Fraunhofer IPA launched the industry consortium "Purity of Medical Devices in the Manufacturing Process according to VDI 2083 Sheet 21". (Source: Fraunhofer IPA/Photo: Rainer Bez)

The determination of the purity of medical devices has been uniformly regulated since October of this year: VDI Guideline 2083 Sheet 21 offers guidance on how manufacturers can determine whether purity limits are necessary for their products and how these can be derived and verified. The next, consistent step is being taken by the industry consortium launched at Fraunhofer IPA on November 26, 2019. Its task: to specify the derivation of limit values for product-specific purity requirements for particulate and chemical contaminants.

For hip prostheses just as for syringes, catheters, or bandages: medical devices must not harm the patient when used properly. Numerous legal and normative regulations are intended to ensure this, which medical technology companies must fulfill to bring their products to market. From such very general legal requirements, requirements for the purity of medical devices are directly derived.

In this context, it is problematic that neither purity limit values nor the testing techniques and analytical equipment to be used are sufficiently regulated by law or standards. At the same time, there is an increasing demand to consider the purity of medical devices and their supplier components more concretely. For example, the new EU regulation for medical devices, the Medical Device Regulation (MDR 2017/745), explicitly addresses the purity of medical devices, as does the quality management standard DIN EN ISO 13485 (2016-03), which is mandatory for the manufacture of medical devices. This includes, for example, particulate contaminants. However, no specific requirements are specified regarding which particular purity requirements apply to a medical device.

A standard for the purity determination of all medical devices

Until now, manufacturers have been left to their own devices. As part of the mandatory risk assessment, each company has proceeded at its own discretion, setting limit values, so-called acceptance criteria, for critical contaminants from the manufacturing process, and selecting testing methods. Now, general guidance can be found in the new guideline VDI 2083 Sheet 21 "Purity of Medical Devices in the Manufacturing Process," developed within an industry consortium led by Fraunhofer IPA. "The standard is applicable to all medical devices. It outlines ways for manufacturers to establish acceptance criteria for their medical devices and how these can be verified," summarizes IPA scientist Guido Kreck the benefit of the guideline.

Establishing acceptance criteria

The specific values for individual medical devices still need to be defined by the manufacturers themselves. Depending on the chosen approach, different acceptance criteria may result. "Legal and normative requirements have in common that they do not contain specific information on how to establish acceptance criteria or how to demonstrate them," explains Kreck. "Furthermore, it is challenging to establish product-specific standards for the broad spectrum of different medical devices that address relevant purity issues." The newly founded industry consortium, which was established on November 26 at Fraunhofer IPA, aims to find ways for companies to derive concrete acceptance criteria for their products despite these challenges.

Two directions of the industry consortium

The industry consortium primarily aims to further specify the derivation of acceptance criteria for product-specific purity requirements, which are generally described in the VDI guideline, for particulate and chemical contaminants.

The participating companies are to be provided with uniform and clear strategies on how to meaningfully and transparently derive acceptance criteria for medical devices, minimizing risks to patients while also considering the achievable purity levels in manufacturing. For this purpose, a study is also underway to determine the current state of purity, in which participating companies can provide their products for particulate purity analyses.

"A practical guide based on these results would be a significant step forward, because companies could then orient themselves on such a clear rationale in the future, thereby establishing a well-founded basis for dialogue with notified bodies as well as discussions with suppliers and service providers," says Kreck. "Currently, it is common practice for manufacturers to rely on standards that are not directly related to their medical device, such as those from the pharmaceutical sector, or to apply medical technology standards from other fields to their products."

Project start in 2020

On April 21, 2020, working groups will begin addressing these aspects. Initially, concrete product-specific standards in which purity requirements for medical devices are already explicitly defined will be researched and collected. This will provide a starting point for deriving acceptance criteria. Furthermore, meaningful and applicable derivation concepts for acceptance criteria from non-product-specific standards will be collected and evaluated using example products from the participant circle. A promising approach is to group medical devices based on purity considerations, forming clusters and deriving purity requirements for these groups. Finally, analyses of medical devices from the industry consortium participants will be conducted in anonymized form. These will form the data basis for the approach described in VDI 2083 for determining the current state, which also reflects the manufacturing-possible purity level.

Based on the results obtained, the industry consortium will agree on and propose a procedure for deriving acceptance criteria. This will be documented in the consortium's final paper, which will serve as the basis for further steps. Companies from the medical technology sector and their suppliers are invited to participate in this consortium.

What does VDI Guideline 2083 Sheet 21 regulate?

The new Sheet 21 of the VDI 2083 guideline series is a generally applicable and overarching standard for the purity of medical devices in the manufacturing process. The guideline contains a structured approach, e.g., which questions need to be answered to decide whether acceptance criteria for product purity are necessary—and if so, how these can be derived. It also presents suitable and meaningful analytical methods for different types of contaminants—biological, chemical, or particulate.