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Defining and demystifying medical grade polymers

The healthcare and medical device industry is heavily regulated to ensure quality, sustainability and most importantly safety of human life. Hence, device development is a long and complex undertaking, with strict compliance regulations, long-term tests, quality checks and certifications.

Nonetheless, one seemingly simple question has not been universally defined: What is a “medical grade” polymer? The Association of German Engineers, VDI, embarked on defining and describing what is considered a medical-grade plastic and have published their guideline (VDI 2017: 2019-07) as a very useful reference for polymer producers and medical device manufacturers alike.

From orthopedic and surgical instruments to diagnostic equipment, drug-delivery systems and implants to vision aids, polymers have been used in the healthcare and medical industry for decades. Meeting constantly new requirements like weight and size reduction, easier processing, flexibility, biocompatibility, stricter sanitation or the need for single-use instruments would be practically impossible without the use of polymers. Hence, it comes as no surprise, that an estimated 50 percent of all materials used in medical device manufacturing consist of plastics. 
By: Siobhan Bastiansen
Medical & Market Manager at IMCD Germany
However, when it comes to the right polymer choice for a specific medical or pharmaceutical application, things can get complicated. Despite strict international and national regulations as well as demanding requirements for medical polymers, one extra difficulty in this choice is the fact that there has been no universally accepted definition of “medical-grade” polymers so far.

The challenges of the past

In recent years, the so-called “PIP scandal”, where the French implant device manufacturer Poly Implant Prothèse (PIP) used industrial silicone instead of surgical-grade silicone for breast implants, affected the medical industry, with far-reaching financial, judicial and personal consequences for PIP, the material suppliers, Notified Bodies and for the patients. The scandal came to light in 2010 after high rates of rupturing were reported. To this day, this case keeps the courts busy. Only in February 2017, the European Union Court of Justice decided in the case of TÜV Rheinland that whilst Notified Bodies do have to protect end-users of medical devices, they are not legally liable. The PIP scandal from 2010 is only the most recent of the failures that took place in the past decades causing great outcry throughout the industry. 

It once again showed the extent of unresolved questions and uncertainties on all sides. In the 1990s, many polymer suppliers decided to withdraw from the medical market as a consequence of similar affairs. To stop the drying-up of the market in the United States, the US Congress passed “The Biomaterials Access Assurance Act of 1998”, which stipulated that raw material suppliers were not to be held liable for any product failure as long as they “meet applicable contractual requirements or specifications”. Since then, medical device manufacturers have had to invest heavily to make sure their products comply with regulatory requirements and are safe for the intended application. However, a national or international definition of “medical-grade” polymer or plastic is yet to be put into place.

Application restrictions as self-protection for polymer suppliers

Following several high-profile and costly litigations in the '90s, companies that actively market their polymers for medical applications typically have developed policies regarding restricted or permitted applications. “There is a wide variety of ‘rules’ from polymer producers concerning which applications are allowed. Often the restrictions may not be related to expected performance of the polymer in the target application, but rather reflect the corporate environment and legal department’s decisions. The restrictions can have much more to do with perceived risk exposure to litigation down the line. Some examples of guidelines are: 

  • not permitted to be used in medical applications
  • skin contact only
  • no direct contact with fluids entering the blood stream
  • maximum 24 hours inside the body
  • maximum 29 days inside the body

Of course, it is very challenging for medical device manufacturers and OEMs, especially the specialised small and medium-sized businesses, to keep track of all the different and complex policies and disclaimers. As a specialist medical polymer distributor, we see our role as the critical bridge between our polymer principals and our customers, the device manufacturers, to make the right polymer choice process a safe, successful, sustainable and convenient one. For instance, currently, there are very few polymer choices for medical device manufacturers designing products to remain in the body longer than 30 days, and where the customer wants the confidence and support of the raw material supplier. “Our partner Lubrizol Life Science- Health is one of the very few polymer suppliers who do not restrict the use of their TPUs to 30 day implants but instead have a disclaimer reminding that the choice of polymer is up to the device manufacturer. 

Medical device designers are free to select from a wide TPU portfolio the most suitable grades to be tested and considered for each specific application. But on the other hand, if we have a customer who has very low volume demand for a coloured material for a non-invasive device, we can offer a range of options advising MOQs of coloured resins direct from the producer, or assist in finding a long-term sustainable solution with our medical compounding partner IPC.

MDR and its impact for medical device manufacturers

While polymer producers have determined their own individual set of characteristics to define what a medical grade is, medical device manufacturers have been theoretically free to choose any polymer, as long as they followed existing regulations, while carrying the risks involved with product liability. Many device manufacturers have relied on compliance with applicable standards such as USP Class VI and ISO 10993, with regard to biocompatibility when choosing the material for their application.

The European Union Medical Device Regulation 2017/745 (MDR), which came into force on 25th May 2017 and will be mandatory from May 26th 2021, places a strong emphasis on risk management and safety. Compared with previous medical device guidelines as MDD 93/42/EEC, that the new MDR will replace, it comprises 100 additional articles and two more appendices, new classification rules as well as extra surveillance and safety reports. It also reinforces the position of notified bodies, “with regard to their right and duty to carry out unannounced on-site audits and to conduct physical or laboratory tests on devices to ensure continuous compliance by manufacturers after receipt of the original certification.”

This is especially relevant for many small and medium-sized medical device manufacturers, the new, more demanding law may sound the death knell, as it will make the market entry for their products extremely difficult and expensive. Still, when it comes to an industry-wide, standard definition for medical-grade polymer, the new MDR, like MDD before, remains silent. Hence, there is no compulsory use of medical polymers for medical applications, as long as conformity with existing regulations is given.

First steps towards a definition of medical grades

In Germany, things are moving. The Association of German Engineers, VDI created the VDI 2017 Guideline for Medical Grade Plastics, As VDI stated, “The aim is to define the requirements for the polymers for use in medical devices and thus to develop a standard that can be used as a guideline for raw material producers and manufacturers of medical devices.

The directive covers development, logistics, procurement and purchasing equally." We are fully supportive of the VDI initiative and think that by highlighting consistency in formulation, quality, biocompatibility and supply security, this will bring more reliability, stability and long-term commitment for all sides. This is what polymer manufacturers and medical device producers alike need.

Change management and long-term committment are key differentiators

In the meantime, specialised medical polymer producers have already taken the opportunity to create indispensable value for medical plastics processors and OEMs. To understand the peculiarity, one has to recall that only up to three percent of the worldwide polymer production ends up in medical and healthcare applications, but this is really a drop in the ocean. For many polymer suppliers that serve diverse high-volume industries like automotive, food, packaging, construction etc., it may make no economic sense to invest in a market with such small potential volumes.

However, several of these ‘industrial grade’ resins have made their way into products that are considered as medical devices and as such are subject to MDR or FDA conformity. For medical device manufacturers, on the other hand, this holds several risks and challenges; once they have carefully chosen and tested a material to comply with all the complex laws and guidelines for medical plastics, and to meet the requirements for their specific application, they need to rely on long-term supply and predictability. Sudden delivery stops or changes in the raw material production without notification of the device manufacturer, that are common in the industrial polymer sector, can be fatal as the medical device producers may have to repeat the whole complicated and expensive gauntlet of tests, qualification and certification processes that can take years.

Polymer suppliers that develop and provide specialised polymers for medical applications have discovered a significant gap in this complicated situation to add value for the manufacturer. Suppliers we have been cooperating with for many years have already put transparent mechanisms into place to ease the process of change control for the OEMs and to also secure a long-term supply. This way, both parties benefit from a close cooperation with mutual insight and knowledge exchange and protect their business and products from expensive failures.

Change is constant

Therefore, it is important for these manufacturers to understand the “landscape” of typical polymer producers. In chemical plants producing hundreds of thousands of tonnes of widely used polymers such as PP and PE, their daily business is to attain continuous improvement in efficiencies, quality, innovation and economics. This means that CHANGE is constant with a dynamic grade choice, new grades replace older grades and offer advantages to industrial customers. For medical customers though, these changes can be huge.

In the polyolefin world, product stewardship is key – controlling consistency and a no-change-lock across all departments within the polymer manufacturers business. So knowing your supplier and being sure that they know you and your application is the ideal scenario”, sums up Siobhan Bastiansen from IMCD. “They can give the right support, advise you and be there for the long term, which is crucial for success across the lifetime of the product. This is even more true with regard to the regulations of the new MDR”

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