A supplier at the recent AMI conference on Medical Grade Polymers (September 16-17, Philadelphia) commented that increasingly automotive plastics companies are starting to diversify into the medical device industry. The performance specifications are similarly demanding, however, this is an incredibly complex market to enter in terms of regulatory and quality controls.
Leisel Masson of Stryker Orthopaedics has described some of the problems that they have had with suppliers from wrong material grades being delivered (for example, flame retardant ABS instead of medical grade) to polymer found to have been contaminated from being stored in recycled oil drums at the suppliers. Her message to suppliers is that they must maintain the highest standards and communicate any forthcoming changes immediately to medical manufacturers, so that FDA approvals can be obtained well ahead of time. International regulatory bodies are commenting over and over again that companies are not obtaining enough data, making unsubstantiated claims and not always taking time to interpret test results (including not noticing failed tests). Suppliers need to understand the medical market to meet the needs - for example, a recent request for a plastic colorant resulted in an offer of a material so far only used in concrete and completely inappropriate.
NAMSA is one of the key contract laboratories for the medical device industry. It recommends using ISO 10993-18 to help choose the right polymer. The ISO standards may be expanded to cover specific device types. The FDA Code of Federal Regulations (CFR) specifies tests for total extractables, which are polymer specific. The United States Pharmacopoiea (USP), Chapter 661, currently covers PP, PE, PET and PETG and is looking at being expanded to include PC and possibly PU. Peter Solera of Ciba commented on current issues with leachables, such as the concerns in the US with bisphenol A and polycyclic aromatic hydrocarbons. As an analytical chemist, he would like the authorities to set detection limits rather than a blanket 'zero', which is an undefined target. His colleague, Rachel Dong, described the issues for extractables in drug delivery devices. Inhalation aerosols, injections and injectable suspensions are at highest risk of packaging interaction.
Ticona has extensive experience in supply engineering plastics into the drug delivery sector of the medical device industry. It has looked at the International Pharmaceutical Aerosol Consortium on Regulation and Science (IPAC-RS) good manufacturing practice (GMP) guide as an efficient way forward for companies. It would supply the basis for audit of Orally Inhaled and Nasal Drug Products (OINP). Laura MacDonald commented that some standards include training employees to understand the impact of change to pharma customers.
Dr Vinny Sastri of Winnovia LLC has carried out a survey of medical plastics from the device manufacturers' viewpoint. Trends include cost reduction, the need for cleanliness at suppliers, substitution of metal and glass, coatings, globalization, replacement of reusable devices and a huge trend in devices incorporating electronics. Manufacturers would like suppliers to customise products to their needs - they appreciate that there is a value versus volume issue here.
Chris Kaye of US Endoscopy is a design expert and encourages engineers to think outside the box, liaising with care givers and looking at current products to find ways to improve and add value. In the case of a polyp trap, visibility was improved, which can allow procedures to move on as the physician can see that he has the appropriate sample. The trap has a built in magnifying glass and ruler. Granta Design has material selection software including pricing and medical grade selection to facilitate the design process.
Bioabsorbable polymers are being tested by many companies for medical devices including Sahajanand, Terumo, Cordis, Biosensors, Abbot Vascular, Reva Medical, Igaki Medical Planning, Biotronic and Bioabsorbable Therapeutics. Dr Vipul Davé of Cordis has worked on stent materials that will resorb with time, allowing repeat procedures to be carried out by vascular surgeons. These stents are commonly used in drug delivery over specified periods time.
Bioabsorbable polyurethanes are under development by DSM. The company has created a new division, DSM Biomedical, headed by Steve Hartig, to supply plastics into the medical device market. Products include the Dyneema UHMWPE fiber for applications such as orthopaedic, and the ComfortCoat anti-microbial coating. It has recently acquired the Polymer Technology Group, where Bob Ward has extensive experience in polymer development: current research includes surface modification of materials to improve performance. In one experiment there was a 1000-fold decrease in platelet adhesion to a modified catheter.
Foster Corporation is a compounder supplying the medical industry. They have looked at the use of antimicrobials. Statistics show that over 1 million patients in the USA each year develop hospital acquired infections attributed to medical devices such as central venous catheters (CVCs), bladder catheters, endotracheal tubes, tracheostomy devices and surgical implants. Appropriate additives, such as silver, Triclosan and Chlorhexidine can help eliminate bacteria, although currently there are no standards to determine antimicrobial efficacy.
The RTP Company is has worked on conductive compounds to reduce static in devices such as inhalers, and reduce drug retention in the device from 20% t o 2%. This Permastat technology is available in over 20 resin systems. Dr Joel Bell has carried out extensive research on ABS systems initially.
Advanced transparent acrylics (Plexiglass) from Arkema show improved environmental stress-crack resistance and processability, and better performance after gamma sterilisation: very little yellow index increase and no light transmittance loss. Topas Advanced Polymers also has clear grades of materials - in this case, cyclic olefin copolymers (COC). Plastics offer a greater design freedom than with glass: one new development with COCs is a pre-filled syringe with a mixing chamber, which can store dry medicant and liquid diluent in the barrel and mix them just prior to drug delivery. An added benefit is very low adsorption of proteins such as interferon, compared to glass.
LyondellBasell is working on reliability of supply of its medical grade polyolefins, looking at back up plants that would also be qualified by its customers. This would assist in force majeure, for example, the hurricane in Houston closed plants this week and an alternative source located elsewhere would supply instead.
DuPont Engineering Polymers has semi-crystalline engineering plastics for non-implantable devices and has been extensively involved with applications such as surgical instruments and movable artificial limbs. The company hopes to release two new grades of acetal later this year with improved moulding properties. DuPont also has a new Metafuse metal/polymer hybrid technology where a 100 micron layer of nanocrystalline metal is added to a plastic to strengthen it and improve stiffness.
With the concerns surrounding the use of phthalates, companies such as Teknor Apex are offering thermoplastic elastomers as potential PVC substitutes, with lower density but less established in the marketplace. Also in the elastomer field, Rhodia Silicones was bought by the Bluestar group in China and is now Bluestar Silicones. Products include wound care soft adhesives.
Molding technology is advancing. Dr Mark Simon of Saint-Gobain has extensively studied two-shot molding with silicone and thermoplastics, examining adhesion and processing temperatures to ensure good bonding. Bondable substrates include PEEK, PC, polyimide, phenolic, polyester, polysulfone and ABS.
The message at this year's Medical Grade Polymers conference was that medical device manufacturers rate reliability, quality and communication as the key attributes of a good material supplier, together with a willingness to partner in new product development.