Medical Device Packaging: Evaluating And Upgrading To Clean
An AeroPackaging White Paper
By Stephen W. Van Someren
Quality Control Manager, AeroPackaging
A substantial amount of time, labor, and money is invested in producing ultra-clean medical devices. To ensure that the products arrive at the customer’s site in the same pristine condition, however, the packaging must also be carefully, routinely evaluated and upgraded.
Taking an existing product to cleaner and cleaner levels can be more complicated than starting from scratch with a new product. Any time a change is made to a medical product, the “Change” becomes an issue throughout the organization.
“Why are we changing?” asks the marketing department.
“What was wrong with the old package?” customers wonder.
Validation managers, meanwhile, need to know how to present the improvement in a substantiated presentation.
And you wonder why it’s necessary to go through all of this when the old package wasn’t causing any problems.
The answer: Because it’s the right thing to do.
The process of choosing cleanroom packaging for medical devices includes:
Evaluating the requirements of the device being packaged;
Matching those requirements to the capabilities of the cleanroom packaging films available; and
Specifying the parameters of the package to ensure that the chosen vendor clearly understands the requirements of the job.
While any packaging change — however trivial it may seem at first — adds additional complexity to the first step, it can ultimately provide a deeper understanding of the product as one comes to understand that product’s cumulative packaging history.
Step 1: Evaluating Requirements
Let’s assume, for the sake of discussion, that the product being packaged is a small, lightweight filter that has been in production for some time and is a leader in its application. Like most precision products, it has been steadily and substantially improved over the years.
Associated with these changes have been improvements to the environment in which the product is produced and a growing awareness that the product’s packaging must keep pace not only with improvements to the product itself, but with rising market expectations.
Again for discussion, let’s assume that our product has historically been packed in a heavyweight poly/Mylar-laminated bag (a takeoff from a military packaging film), chosen for its clarity and stiffness, and probably heavier than the product itself. The poly/Mylar film was made for general use, with its performance maximized for ease of sealing.
It has one major drawback, however: the inner sealing layer has seal enhancing additives, usually EVA (ethyl vinyl acetate), a low-melt temperate polymer that outgasses heavily. The inner film also has heavy levels of “anti-block” and “slip” additives to give it good processing characteristics.
Under normal, non-clean packaging circumstances the presence of these additives would not be a problem. In a move to cleaner packaging, however, the presence of additives will cause problems. The vinyl component of our filter’s packaging, for example, will outgas chlorides, contaminants most users need to avoid in any concentration. The other additives can migrate, acting as “wild cards” in terms of ionic and contact transfer contamination.
One of the engineering goals for any cleanroom packaging material is consistency of formula and the consistency of performance that follows. With commercial films — i.e., those not designed “clean” — this consistency is less important. Normal polymer blending and film extrusion isn’t a ppb industry: while this isn’t an evil plot, it is symptomatic of an industry that measures profit in fractions of pennies per pound, and one of the reasons for the considerable difference in price between “cleanroom packaging” and “commercial packaging.”
Our hypothetical product is packaged in a pouch style bag with a three-sided seal system that adds to the problem of contamination control. So our upgrade project, therefore, must not only include consideration of alternative materials, but also examination of other forms of bag fabrication that might offer a lower risk of contamination and, thereby, lower cost — even if the bag material is initially more expensive!
Step 2: Matching Requirements
Let’s also assume that the manufacturer of our hypothetical product has a long history of working with a clean manufacturing mindset. Because of this experience, the manufacturer feels that its established company standard for cleanroom packaging bags (NASA, JSCM 5322, Level 100) is reasonable and expectable for this product.
Chosen for its detail and repeatability even with relatively inexpensive equipment, the NASA standard provides a standard that all suppliers can understand and makes it clear that a rigid standard will be enforced. The specification also places important demands on vendors for record keeping and lot traceability, a feature those in the medical field recognize.
This manufacturer also established certain standards for the non-testable parameter of visible anomalies, which are found in all films. These standards are also set out in testable, measurable form-an important feature for vendors working to meet a manufacturer’s needs.
Most applications require consideration of nonvolatile residue (NVR). For this application, NASA JSCM 5322’s Level A (1 mg/sq. ft. film) was considered acceptable. While not an extremely low level for today’s high performance films, it is well within the tolerance of the product being packaged.
While some customers would like to set higher standards for their products than are required, each level beyond the real level of need required just adds cost without producing a direct return. The requirements of cleanroom packaging alone add enough cost without taking a product to levels of protection that cannot reward such an investment with a measurable return.
Ionic contamination and the product’s tolerance of different levels of ionic contamination must be investigated with accuracy and great concern, especially in applications involving electronics and high purity metals.
Fortunately, the plastic-based product under discussion here is not that critical, and the confidence provided by the NVR standards will assure that it won’t suffer from outgassing contamination or contact transfer to which other materials might be susceptible. High levels of performance from a point of very low outgassing and low ionic contamination are not as hard to meet as they used to be and normally don’t require the high cost films of the past.
In this project, the lack of an anti-static performance requirement for the product package is really a windfall because of the surface transfer contamination most anti-static additives would create. The use of anti-static packaging materials for any intimate contact situation must be approached with great caution; not only can the additives contaminate by contact transfer, but outgassing of volatile components could cause chemical changes to the plastics and leave visible surface marking on a very white filter surface.
As in all medical packaging challenges, moisture protection for the product must be considered. In this application the levels of protection offered by most packaging films are sufficient. But this is not always the case for medical devices, and each product must be examined for moisture-caused degradation from the standpoint of keeping a product from performing to its intended expectations.
The test standard for measuring moisture, moisture transmission rate (MVTR), is expressed in grams of moisture passing through 100 sq. in. of material in 24 hr. Almost all polymers offer some amounts of protection, but the amount of protection may vary greatly.
If the challenge is writing a specification for a moisture-sensitive product, a packaging engineer can help with formulas and packaging processes to help achieve the protection standards needed. In any packaging project, it is as important to be able to express your needs in a specification as it is to develop them.
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