Packaging for Medical Devices

Medical device is best defined as the product items or component thereof which does not achieve any of its principal intended purposes through chemical action within or on the body of human or animals and not dependant on being metabolized for obtaining the intended objective. Thus the words chemical action and metabolized essentially miss between a drug and medical device. The medical devices are classified under three regulatory classes based on the significance and in assuring their safety. Theses fall under those regulatory classes:

• General Controls
• Special Controls
• Pre-Market Approval

Functional needs
In medical device packaging several functions are being inbuilt and to that extent packaging becomes an integral part of the development of the product or system. Besides being a container, a carrier for transport, protection and identification packaging in this instance also implies a sterile barrier in terms of protection from microorganism and other physical contamination. The packaging medium should possess inherent characteristics such as maximum pore size and pinhole freeness. The other significant feature expected is the package integrity ensuring no breaks or seal failure leak or openings that will affect product quality. Even atmospheric or environmental factors that would come into play should be considered in the material selection. This will include heat, light, stresses etc. What is thus expected is the total ability to keep the product safe and secure.

The package also is the information and identification source as a vehicle to carry messages related to product use, safety, storage, product identity, precautions etc. The print details should be legible, accurate and clear, misprint or misregistration should be avoided.

In medical device packaging the primary importance attached to is maintenance of sterility all through the distribution and till it is put to use. Peelable packaging which probably constitutes a major percentage of medical device packaging is typical of above needs. The medical device packaging also can have in-built added features such as measuring device, dispensing mechanism, stabilizing stand, disposal receptacle etc. This clearly emphasizes the multidimensional and multifunctional features through packaging.

Packaging forms
Various forms of packages are in use for medical devices. The form is often decided by the product characteristics, the physical features and dosage aspects. The commonly used types include thermoformed trays, flexible webs, flexible non formed pouches, bags and vented flexible bags, laminated and co-extruded structures formed though FFS systems, cartons and wraps. The use of glass and metals are very limited. Commercial availability of thermoformable plastics, high tech laminated and barrier structures and functionally sound and easily peelable lidding materials have helped a boon to medical device packaging. Nonwoven synthetic has revolutionsed disposables' packaging. Flexible webs as top or base layer have also added to sterilizable and easy openable packs. Flexible pouches are more common for single dose disposable items.

Sterility maintenance
While physical and dimensional stability, product package compatibility, shelf life, physical protection, and environmental preservation are of significant features to be identified with the package for medical devices, sterility, and sterilization get uppermost needs of the packaging system. The common methods of sterilization include ethylene oxide (ETO), radiation (gamma) sterilization, steam or autoclave, dry heat and plasma sterilization. The method of sterilization can have an effect on the packaging material used and possible package interaction. Hence selection of the packaging media is to be governed by the sterilization method to be adopted.

Factors like temperature, pre humidification, evacuation and gassing rate, cycle time, gas mix, quality of seal and chemical compatibility can affect seal integrity in the ETO sterilization. The key criteria of the packaging material will thus be porosity, compatibility, hot tack and moisture. Material degradation is the significant aspect to be considered in the gamma ray irradiation. Autoclave/ steam sterilization identified problems such as inconsistent peelability, poor control on seal film splitting, dimensional stability, distortion etc. Where steam sterilization is desired / selected the material characteristics to be looked into are porosity, high barrier for retort sterilization, resistance to microorganism, product compatibility, effective seal and yet easy openability, and economics. Materials used for dry heat sterilization should be able to withstand long hours of controlled elevated temperatures. Plasma sterilization has been on the increase since the recent years. Post/sterilization of prepacked OEM, medical devices are potential products for plasma sterilization besides in hospitals. Due to low toxicity of sterilization by products this technique is finding wide spread applications.