Medical packaging design has become increasingly important in helping to ensure medical part integrity, and in preventing injury to patients and health professionals. Quite often it is up to hospital staff and those responsible for administering sterilized drugs to determine package integrity and evidence of tampering. The need for security and quality control of medical supplies has led to numerous innovations in the medical packaging industry. Different methods of sealing, improved materials to ensure toughness, and different tamper evident designs are employed to maintain package integrity throughout distribution and handling.

Ensuring tamper evidence

An example of tamper-evident packaging, made of XT polymer 375TE acrylic-based multipolymer compound

Significant costs are incurred in the medical device industry from manufacturer to end-user due to package failure, but greater risks occur when package failure goes undetected. Breeches can occur in shipping or handling that contaminate the package contents. Persons illegally retrieving pharmaceuticals will attempt to have any tampering go unnoticed. Package tampering must be readily and easily detectable by hospital and medical staff. However, external seals can be opened, removed and discarded without trace evidence, and some packaging materials can be cut open or punctured with little evidence of failure, requiring close scrutiny. As a result, tamper-evident packaging has become an important component of the medical and pharmaceutical industry.

"One of the biggest issues of healthcare providers is maintaining sterility," said Alexis Swan, corporate contract coordinator for Yale-New Haven Hospital in New Haven, CT, who discusses packaging integrity issues with medical and surgical supplies. "You want to be able to open a package and introduce products into a sterile field, making sterilization reliability very important. Healthcare providers assume that packages have appropriate levels of integrity, so if a package fails, that failure must be obvious." She adds that hospital personnel inspect packages thoroughly to ensure that sterile fields have not been compromised. "We must be able to see any type of failure in the package immediately," she said.

Visual confirmation
Rigid packaging trays used for sterilized medical devices and pre-filled pharmaceutical syringes require a higher level of tamper evidence, especially when packaging narcotics. Readily available packaging materials have been designed to instantly show evidence of failure so that the judgment of sterile reliability can be made quickly and easily.

Engineered compounds such as some acrylic-based multi-polymer extrusion compounds are formulated to make tampering readily apparent. Rigid packaging derived from these compounds present evidence of tampering in two ways. First, if the tray itself is tampered with by tearing or cutting into it with a knife, or even sticking a needle through a sidewall, the material turns from a transparent blue tint to a highly visible, opaque white where the breach occurred. Second, once sealed, if the lidding stock is separated from the tray, the optical properties of the thermoformed compound make that seal separation evident by an apparent color change. The color change is a result of the seal’s color depth when viewed through a specialized packaging compound.

Gamma irradiation
Optical clarity for packaging is important for a number of reasons. An optically clear package conveys a level of confidence in the integrity of its contents for the user. A package that has been crushed, is misshapen, or off color will incur more scrutiny by the user and delay procedures. It is important that packaging not be affected by sterilization methods. For the benefit of healthcare professionals, packaging materials should not yellow or become brittle after sterilization. Yellow packaging will cause hospital personnel to examine packaging integrity more closely and delay procedures. Materials may show some yellowing depending on thickness and the material makeup. Tamper evident acrylic-based compounds may slightly yellow in packages 0.040" thick, but thinner gauges will show very little color change, if any. Radiation sterilization can affect mechanical properties of plastic compounds, but acrylic compounds exhibit no changes in mechanical properties up to five MRads or 50 kGrays of radiation.

An additional benefit associated with tamper evident acrylic-based compounds is post-package sterilization. Once thermoformed, acrylic-based polymer trays can be filled and sealed before final sterilization of the contents and the package. A sealed acrylic-based package can be sterilized using Gamma radiation, E-beam radiation, or EtO sterilization methods. This method of sealed package sterilization ensures both the contents and the packaging are free of contamination. Furthermore, the material’s compatibility with the various sterilization methods ensures packaging integrity without color change, warping, or embrittlement.

Acrylic-based thermoformed trays can easily withstand typical hospital EtO sterilization cycles. However, EtO sterilization temperatures can deform package shapes if materials with deflection temperatures below 75º C are used, making it appear as though integrity has been compromised. Compounds that can endure EtO sterilization in addition to gamma or E-beam sterilization methods provide greater flexibility for packaging systems.

It is also important that medical packaging retain its impact strength and optical clarity through the rigors of storage and transportation. Recent studies demonstrate that acrylic-based compounds exhibit 100 percent property retention during heat aging in both sterilized and unsterilized samples. PETG suffered significant property changes, notably embrittlement. Retained strength of rigid medical packages is important for adequate protection for the duration of its proposed shelf life.

The ability of some compounds to be thermoformed over a wide temperature range allows the flexibility to use higher temperatures in order to obtain good definition on intricate parts without losing melt strength. Thermoformed rigid trays with deep draw designs require a material with relatively high melt strength. Where deep draws can be limited with polyesters or crystalline materials due to their low melt strength, tamper evident acrylic-based compounds can easily be thermoformed to draw ratios of 7:1 with good quality.

Counterfeit-proof packaging and holographic stamping
Package decoration and design is an important component of validation and anti-counterfeit techniques. Printing and decorating techniques can be used for a number of identification, information, or instructional purposes on thermoformed trays. Some thermoformed trays contain lubricants that can interfere with printing processes. Acrylic trays do not require lubricants and therefore can be clearly printed and decorated. Standard pad printing, screen-printing, and hot stamping techniques can be used with many extruded plastics to clearly identify the contents, and provide instructions on use.

Acrylic-based thermoformed compounds also offer the advantage of embossing an anti-counterfeiting holographic stamp into the packaging, letting medical staff quickly recognize its authenticity. Holographic embossing offers visual anti-counterfeiting validation for medical and pharmaceutical devices without adversely affecting the material’s tamper evident or sterilization properties. Decorative holograms allow fast product identification and avoid counterfeit products from overseas markets into medical distributors and hospitals.

Healthcare professionals should ensure that medical devices in their employ have levels of tamper evidence that are easily recognizable and detectable. Medical personnel should be able to quickly realize any signs of tampering with packaged devices. With an increasing number of disposable hospital equipment and devices, medical personnel will rely more and more on safe, sterile packaging stability. Fast reliable packaging validation in medical offices and hospitals will save professionals and administrators time and effort by easily identifying tampered and compromised medical and pharmaceutical products. HPN