Crystal Lake, IL
At the onset of a project it seems there are a myriad of things that an engineer or packaging professional should consider when choosing an effective material combination for their medical device. In actuality, there are a few main driving factors that should be considered in order to make an informed decision to obtain the best possible material options in order to meet the demands of validation.
The ISO 11607 document is a great guidance tool but, to simplify the process, you can narrow down your choices by asking a few key questions of your materials supplier.
The first thing to consider is the sterilization method. The key attributes of various materials can either lend them to being a good fit or deem them nonfunctional for a variety of sterilization cycles. A very basic example of this would be the obvious need for a breathable material to allow gas or steam to penetrate the package during an EtO (ethylene oxide) or autoclave cycle. (See Figure 1) This would lead one to consider medical-grade papers or medical-grade Tyvek® for an option.
So we have answered one of our questions for material requirements. However, if one were to take the exercise a step further and look at autoclave on its own, there is a dividing line where one material may be successful and another would not be.
Taking Your Temperature
To explain, medical-grade Tyvek is capable of going through 121°C autoclave cycles, but not 135°C cycles. So, in the case of the higher temperature cycle, Tyvek would not be a viable option for the application, but the paper would be. This is just one example of how certain materials can be functional within certain sterilization options. All the various types of sterilization methods will impose limits on which materials can and cannot be used, as well as to what levels they can be processed, especially when considering a method like radiation.
Another key variable, which is often overlooked, concerns the physical requirements of the package. With an increased focus on shipping studies and the actual rigors of distribution, one should carefully consider the physical properties and material performance needs of the package.
One should take into account the size and shape of the device, and determine whether sharp points or radii may create potential puncture issues. There are a variety of materials and thicknesses that can be used to tailor a package to hold even the most difficult of devices from a puncture standpoint. Shape and size of the finished packaging also will play a part in this, allowing for enough space to properly fill and handle the package while not leaving an exorbitant amount of head space, which can cause flex or product shifting through distribution. (See Figure 2)
Extending Shelf Life
Another key component to consider is the shelf life of the device. Various devices will require different shelf life requirements and different moisture and oxygen barrier properties to make sure they maintain their effectiveness. (See Figure 3)
When choosing a material, one should consider the Moisture Vapor Transmission Rate (MVTR) and Oxygen Transmission Rate (OTR) properties of the material as an indication of the shelf life one might achieve when selecting these types of materials. There are other options as well that can combine long-term barrier materials with breathable vent strips to allow for sterilization using gas or steam while still achieving a required shelf life, or the consideration of a secondary barrier material may be required.
These represent a few of the key variables that should be considered when starting the process of choosing the proper packaging configuration for your device, but these do not wholly encompass the requirements that should be considered.
Ask your packaging supplier to work through these with you, and consider samples and some preliminary testing to make sure that you are working in the right direction. Proper preparation up front can save valuable time and dollars down the line when performing final validation of your product. Your packaging supplier should be a resource for these questions and consulted when processing this information.
This article was written by Brian Rosenburg, Vice President Sales & Marketing at Technipaq, Inc., Crystal Lake, IL. For more information, Click Here .