New material offerings are critical to medical device manufacturers as they provide new opportunities in the development of cutting edge technologies. This round-up features three new materials that are impacting medical device manufacturing in the areas of adhesives/coatings, molding, and extrusion.
Extrusion Material Focus
By Mathew Bills and Robert LaDuca
Natural colored PebaSlix resin alongside yellow colored PEBA resins, as well as a variety of extruded catheter tubing configurations and molded componentsWith today’s medical catheters becoming increasingly smaller and more complex, it has become nearly impossible to meet new product performance requirements capable of enabling the next generation clinical applications without the development of new materials and the integration of those materials with existing manufacturing processing technologies. For example, the competing requirements for flexibility, ultrathin walls, torque response, and kink resistance are often combined with the need for lubricity—allowing the passage of other devices or motion between catheter surfaces.
The use of PTFE, FEP, or HDPE as a liner has been effective at lowering friction. These materials are often specified for catheter designs despite their limitations. For example the use of PTFE limits sterilization options, increases stiffness, has higher cost, and requires reflow processing complexities. Attempts to meet low friction requirements while avoiding the limitations of using existing material options in catheters has led to the development of hydrophilic coatings for interior lumens and the tubing’s exterior. This alternative, however, poses additional issues such as the requirement for an aqueous environment, which is not always present in many applications.
Other attempted solutions to the friction problem have been to add lubricious agents into the base resin of the tubing being produced. Several possibilities have been explored, from PTFE particles to erucamide additives. The PTFE particles may be distributed throughout the thermoplastic. However, due to the melting point difference between the fluoropolymer and the thermoplastic, the PTFE particles do not fully disperse into the thermoplastic resin, creating a less than optimal result. Adding erucamide to a base polymer will reduce the co-efficient of friction but, over a short period of time, it will leach to the surface of the tube, leaving a chalk-like contaminant substance that becomes source of particulation.
In seeking a solution to these problems, Duke Empirical has developed a class of new materials that are being introduced into the market called PebaSlix and PolySlix. These new materials are lubricious and have low friction by a proprietary patent pending process that combines certain additives with the backbone of PEBA and/or polyurethane. The additives are fully dispersed into the thermoplastic, utilizing the full benefit of the additive without changing the mechanical properties, processability, or sterilization methods. PebaSlix and PolySlix with their non-leaching, fully dispersed properties can be bonded and processed in the same manner as traditional PEBA and urethane and are available in a variety of durometers. Material biocompatibility testing is underway and master file data will soon be made available for customer’s regulatory applications. The chart shows the reduced coefficient of friction of PebaSlix compared to standard Pebax, as well as other, traditionally considered low-friction materials such as PTFE, FEP, and HDPE.
Mathew Bills is the director of extrusion technologies at Duke Extrusion, a division of Duke Empirical. Robert LaDuca is the founder and CEO of Duke Empirical.
Adhesives/Coatings Material Focus
By Jennifer Hooker
Improved medical grade silicone formulations have been instrumental in the development of new medical electronic devices. These compounds feature easy application, convenient cure schedules, sterilization resistant properties, biocompatibility, and are environmentally friendly. They offer unmatched flexibility, temperature resistance, and cost effectiveness. Medical electronic devices are now available in smaller sizes, lighter weight, and have enhanced performance properties. Silicone systems have played a vital role in meeting the increasing challenging requirements of the medical device industry and expand future possibilities.
Optically clear MS 151Med has a low viscosity, a convenient cure schedule, and is easy to apply.One such material offering is the two component, room temperature curingMaster Bond MasterSil 151Med—a medical grade, potting and encapsulation silicone. Since flexibility is of vital importance in the design of medical devices subjected to vibration, impact, shock, and thermal cycling, this material is formulated to withstand such exposures. With a low viscosity of 1,500 cps, it is ideal for use in applications with complicated contours in very complex configurations. It is an excellent electrical insulator with a volume resistivity of 1x1015 ohm cm and can handle service over the wide temperature range of -65 to 400°F.
MasterSil 151Med cures optically clear with a refractive index of 1.43, making it well suited for use as a protective coating in optical and fiber optic applications. Cures can be accomplished at room temperature, or faster at elevated temperatures. Shrinkage upon cure is less than 0.1%. When cured, MasterSil 151Med has a Shore A hardness of 45 and an elongation at break of 160%. Even though it has such high elasticity, its tensile strength is still a favorable 880 psi at73°F. Mix ratio is 10 to 1 by weight. MasterSil 151Med fully meets USP Class VI requirements for medical applications.
Jennifer Hooker is a technical editor with Master Bond Inc. She has been reporting on new technology for over 7 years, both in the consumer and industrial markets.
Molding Material Focus
By Scott Young, Ph.D.
Novel products for individual therapies, such as imaging for diagnostics, new antibody treatments, biomarkers, tissue engineering, nanocarriers, and gene-based and stem-cell therapies, may reach the market by 2020.1 For many of these advanced pharmaceutical technologies, glass may not be the logical or preferred choice for containment and/or delivery. Technological advancements in therapeutics and diagnostics should be matched by innovations in containment and delivery systems.
The Daikyo Crystal Zenith polymer can be molded into containment systems suitable for a drug product’s life cycle.Glass as a primary contact material for pharmaceutical and biopharmaceuticals has hurdles to overcome with respect to suitability. The need for silicone lubricants, breakage, particles, and leachables are among the major concerns. To combat the risks associated with glass, modern polymeric materials should be considered. The manufacture and processing of polymers allows for flexibility in molding and forming throughout a drug product’s lifecycle. Qualification of such materials is dependent on intended use, and risk assessments should be considered early to support development and protection of the drug product throughout its lifecycle.
The Daikyo Crystal Zenith cyclic olefin polymer (COP) is a class of polyolefins in which the performance characteristics are enhanced. The synthesis allows for better control of the molecular structure with fewer side reactions and less need for performance additives. Precision molding can be optimized for the intended use and once the materials are qualified, forming can be adapted as needed. This class of polymer has few ingredients and offers the desired properties of transparency and break resistance. It also provides a strong moisture barrier and is easy to sterilize.
Cyclic olefin polymers are high-performance materials possessing the valuable properties necessary to manufacture, store, protect, and deliver drug products without many of the weaknesses inherent to glass. It is especially suitable for biologic applications since many of the COP’s quality attributes specifically meet the challenging needs of this market.
Scott G. Young, Ph.D. is a senior director at West Pharmaceutical Services. He is responsible for the development and commercialization of the Daikyo Crystal Zenith Platform, including syringes, vials, API containers, and novel delivery systems.
1 Breakage and Particle Problems in Glass Vials and Syringes Spurring Industry Interest in Plastics. IPQ in the News 7, August 2011.
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