In a special global packaging online community, PMP News and DuPont Medical Packaging presented “Current Events in Healthcare Packaging,” and “Microbial Barrier Properties of Porous Sterile Barrier Systems: Does Selection of the Packaging Material Matter?” John Bamberger of DuPont Medical and Pharmaceutical Protection received several questions during the events. He provides written responses below.
Webcasts held so far in the community include “An Introduction to DuPont Tyvek,” “Fundamentals of Medical Package Engineering and Design,” and several updates on the DuPont Tyvek Transition. To view these Webcasts, visit
www.pmpnews.com/DuPontSeminars . Stay tuned for a full lineup of 2013 events.
Q: You mentioned that Tyvek has a superior tear strength and puncture resistance. What types of studies have been done to demonstrate this?
A: Tyvek styles for medical and pharmaceutical packaging applications were compared with medical-grade papers and synthetic fiber-reinforced paper using the Elmendorf Tear test (ASTM D1424 and EN 21974) and the Spencer Puncture test (ASTM D3420, procedure B). Data and additional information can be found in the DuPont Technical Reference Guide for Medical and Pharmaceutical Packaging located on the DuPont Medical Packaging Web site (www.
Q: Has there been any initial work or pilot studies with 3rd party molders to utilize post-use regrind?
A: Yes, work is ongoing to evaluate possible uses of post-use regrind in various applications.
Q: Is there a standard for storing medical products prior to product use?
A: ISO Standard 11607, Packaging for Terminally Sterilized Medical Devices–Part 1 Requirements for materials, sterile barrier systems, and packaging systems specifies the basic attributes required of materials and pre-formed systems intended for use in packaging systems for terminally sterilized medical devices, while considering a wide range of potential materials, medical devices, packaging system designs, and sterilization methods.
Q: What is the Tyvek Transition Project? Will the material change or just the testing of the current material?
A: This project is a plan to transition Tyvek 1073B and Tyvek 1059B to the latest flash-spinning technology and equipment. The objective of the development phases and the Transition Project itself is to demonstrate functional equivalence to the Tyvek you are currently using in terms of seal strength, microbial barrier and integrity of sterilized packages. Target properties for the styles produced on the newer lines, shown side-by-side with properties for the current styles, are posted on our Web site, www.MedicalPackaging.DuPont.com .
Q: What are the environmental storage requirements for Tyvek?
A: Tyvek should be stored at ambient temperature and humidity.
Q: Will studies from HPRC be available to non-members?
A: Information is available to members and non-members at the HPRC Web site, www.HPRC.org .
Responses to Questions from “ASTM F2638” Webinar
Q: What is FDA’s position on ASTM F2638 versus ASTM 1608 testing?
A: It is our understanding that the FDA Standards Program reviewed ASTM F2638 and has submitted its intent to have it included in the list of FDA Recognized Consensus Standards. To the best of our knowledge, ASTM F1608 is not on the list of FDA Recognized Consensus Standards. However, please note that the use of a standard— recognized or not—is voluntary and can be used to support claims as appropriate.
Q: Does ASTM F2638 only apply strictly to porous material or can it be used for materials like polyfoil (that are sterilized by gamma radiation) as opposed to EtO?
A: This test method is applicable to porous materials used to package terminally sterilized medical devices.
Q: ISO 11607 does not include ASTM F2638. Are there any efforts to work with ISO and include this standard?
A: Yes, at the time of the webinar there was an active ballot for ISO 11607, that included ASTM F2638 as part of the new standards in Annex B.
Q: Is this test method adopted by European laboratories?
A: At the time of the webinar, the only laboratory offering ASTM F2638 was U.S. based Nelson Laboratories. Work is ongoing to socialize the industry to ASTM F2638 and promote wider adoption of the test method.
Q: What is the sample size recommended when using this testing?
A: The area of the sample exposed to the aerosol is 100 mm in diameter. A sample of porous barrier material no less than 120 mm in any dimension is recommended to ensure the sample completely covers the O-ring in the lower half of the sample holder.
Q: Based on this information, can we still use F1608 to test microbial barrier?
A: Yes, F1608 can be used for microbial barrier testing. However, as stated, the test method operates at a defined flow rate well into the range where impaction is the dominant filtration mechanism. Because of this phenomenon, some porous materials appear to provide a much better microbial barrier than they actually do in real-world conditions (i.e., low flow rates.) You will need to define your risk tolerance to determine how confident you are with your decision.
Q: Can the F2638 test be used for other applications?
A: In addition to package validation testing, F2638 also lends itself to in-process quality testing for sterile barrier packaging material manufacturers.
Q: Can all porous packaging materials be tested using this method?
A: The intent of this test method is to determine the flow rate through a material at which maximum penetration occurs. The porous nature of some materials used in sterile packaging applications might preclude evaluation by means of this test method. The maximum penetration point of a particular material could occur at a flow rate that exceeds the flow capacity of the test apparatus. As such, this test method may not be useful for evaluating the maximum penetration point of materials with a Bendtsen flow rate above 4000 mL/min. But you need to ask yourself, if I am thinking of using a porous material of this type, is this material appropriate for my application?
Q: Why is the maximum penetration point important?
A: The point of maximum penetration is where the microbial barrier properties of a porous material are challenged to their limit. This is the flow rate at which neither diffusion nor impaction dominates. Because the arc of the curve (curve showing penetration as a function of flow rate) is dependent on the characteristics of the individual test material, the appropriate way to compare materials is to use the parameter that measures the maximum penetration through the material, i.e., the flow rate at which the most particles pass through the sample.
Q: You stated that packaging is the first line of defense during surgery. Is it possible hospitals will start asking more questions about microbial barrier?
A: It is not only possible, it is probable. Healthcare-Associated Infections (HAI) are a global concern. As hospitals implement infection prevention protocols, they are looking at all areas of potential infection. Early efforts have focused on the most obvious causes, such as hygiene, training, etc., since these are low-hanging fruit. As understanding becomes more evolved, hospitals will begin to focus on secondary and tertiary areas of concern. Packaging’s role in the prevention of HAIs will be critical since packaging is the first line of defense during surgery. Regulators may also begin to look at this area more closely.
Q: What if I do not know the typical flow rates and contamination levels during distribution, handling, and storage?
A: Lack of information is not uncommon. This is where you need to apply your particular risk tolerance. Remember, risk of contamination can be assessed as a probability. Once you test materials for microbial barrier and rank their performance, you can determine the materials that meet your criteria based on the data set available. For package design, there are other factors that should be considered, including adhesion between materials, the presence or absence of secondary or tertiary packaging, and the nature of the device within the package.
Q: Is this new test method for a “whole package” or just the material itself?
A: ASTM F2638 is used to test the porous barrier material. It should be noted ISO 11607 states that in the absence of applicable validated tests (for the complete package), microbial barrier performance characteristics can be established by testing the microbial barrier properties of materials and the integrity of the seals and closures.
Q: What porous material temperature effects can be detected by this test?
A: It is important to understand the temperature profile your packages will endure during the life cycle of the package (distribution, handling, storage, etc.). It is recommended you include at least one test at worst case conditions to determine the aerosol filtration performance of porous packaging materials.