Recent advances in bioresorbable materials for stent and drug-delivery applications and the unique processing, sterilization, and storage challenges raised by these materials will be a featured topic at a LearningLabs session on Feb. 12 during PLASTEC West in Anaheim, CA. PlasticsToday spoke with Kurt Breitenkamp, PhD, from Exponent Inc., who will chair the two-hour session and present a paper on tailoring polymer properties.
While bioresorbables were developed some time ago and Abbott's Absorb Bioresorbable Vascular Scaffold is being used in many parts of the world (and is in clinical trials in the United States), there is still much to learn about these materials, their properties, and how they should be processed. That's where Breitenkamp comes in.
"The LearningLabs session will explore how the products behave in the field, how material properties affect degradation, and how we can predict these material and product behaviors, among other things" says Breitenkamp. "One of the things I really want to focus on, though, is testing. New testing methods are being developed by ASTM [American Society for Testing and Materials] in concert with FDA," he adds. Getting a product right the first time is, of course, crucial when developing an implantable medical device for a therapeutic purpose. Cost considerations are another factor: these materials can run into the tens of thousands of dollars per pound. All the more reason to carefully choreograph the processing, sterilization, and storage of these materials.
Bioresorbable polymers typically are based on polylactic acid (PLA) compounded with polylactide-co-glycolide (PGA). Once the device has done its job, the material breaks down into water and CO2. This elegant solution for evacuating unneeded devices in vivo creates a set of processing problems, however. "Sterilization issues are huge," says Breitenkamp, "as are storage considerations. Controlling humidity and temperature prior to use of the device is vital."
It's important to remember that bioresorbable materials are sensitive to aqueous degradation in—and outside of—the body. Storage of the raw materials, the processing environment, and the packaging and storage of the finished product must be taken into careful consideration. Just opening the nitrogen-sealed pouch, in which PLA/PGA pellets are stored, and slightly exposing them to ambient conditions can trigger the degradation process.
Ensuring that proper traceability and vigilance procedures are in place throughout the production and distribution cycles will also be discussed during the two-hour session. An expert on polymer science and materials chemistry, Breitenkamp works for Exponent, which has a background in providing expert witness testimony when product failures occur. Over the past 10 years, the company has emphasized a more proactive approach, says Breitenkamp, "by helping companies to develop products using scientific testing and validation methods so that they don't fail."
At the LearningLabs session, Breitenkamp will be joined by SuPing Lyu, Senior Principal Scientist, Medtronic Cardiac Rhythm Disease Management, who will discuss the use of processing technologies to increase strength in bioresorbable polymers.
For more information on the LearningLabs program and to register to attend, go to the LearningLabs website.