Medical Device Link.

DESIGN

Triggers for change

The essence of packaging can be summarised in three points:

• Provision and maintenance of a sterile barrier for the finished medical device
• Protection of the medical device during shipment to the end-user
• Product identification, principally via labelling.

Feedback and comment from the field is vitally important and can provide suggestions on enhancements to pack design. Theatre staff in particular give important information on how the design works in their environment and how the packaging performs in reality compared with the theory.

Ease of package opening. This is of considerable importance to theatre staff; the operating nurse is seeking access to the implant or device as quickly and efficiently as possible. The small size of some products can mean that their removal from the pack during surgery is troublesome. A good solution is to have a customised container to accurately house each product and at the same time allow easy removal when required (Figure 1). Compatibility between the packaging container material and lidstock are the determining factors for easy peel-off when retrieving a medical device from its packaging.

Figure 1: Packaging component with product fitted. (click image to enlarge)

Package size reduction. Storage space is an issue in hospitals and the standardisation of packaging configuration will allow effective use of customer space. Standardisation is also beneficial to the manufacturing process. If the majority of product has the same packaging, this results in fewer part numbers, less changeovers and more flexibility with machine capacity. A minor design change to a packaging component allowed the company to consolidate its packaging and accommodate 80% of its product range in one design. The largest product by volume was skin-packed on a tray fabricated from polyethylene terephthalate glycol (PETG), and other products were also skin-packed using a PETG tray, but in a different profile. This required two different sets of tooling for each product set and limited machine availability because it required a dedicated skin-pack machine for each product type. The main reason for the different pack types was that one product set was bulkier and heavier, which raised questions about pack durability, that is, whether the tray surface could be pierced by the product during transit. To resolve this, a grooved pattern was designed on the base to reinforce the tray and to ensure that any pointed features of the product did not come into contact with the base (Figure 2).

A full validation of this was performed using trays of the largest size and the tray was qualified for use on all products, not just the large volume set. This also had a secondary benefit in that the associated packaging with this tray is smaller; the finished pack size (in field) will reduce from 2409.2 cm³ to 1825.2 cm³.

Communication with the customer provides the drive to review packaging design and materials. This communication is most often the initial trigger for a packaging design change. It demonstrates a positive response to the particular customer and design change can benefit all in the market place.

Design phase

Figure 2: Product inside packaging trays. (click image to enlarge)

The engineer can be faced with a design change to an existing packaging component or the requirement to design for a new product launch. Either way, the use of computer-assisted design is a significant tool at this stage, particularly when checking the geometric relationship between the product and the pack design. Once an idea has been conceived, further proving is the next step. This usually involves collaboration with a prospective supplier of the packaging components, whose knowledge can be helpful in assessing the design with regard to manufacture; it may be necessary to compromise the design before a prototype can be made.

On completion of a prototype, the design must provide a positive response to the following questions:

• Does the concept fulfil the original requirement that drove change?
• How compatible is the design with existing packaging components and the product?
• What implications will the design have on the existing packaging process?
• Will significant tooling costs be incurred?
• Can the design be produced in volume and at the right cost by the supplier?

It is here that it becomes evident why change can take months rather than weeks, the actual process of designing takes up a relatively small proportion of the design phase.

Validation

Quality assurance dictates that any change to a product or product-related components must be validated. For packaging this ensures that

• the change will have no adverse effect on the end-user
• the change is fully supported by rationale and data.

Validation provides the designer with the opportunity to define test criteria; these criteria must be rigorous enough to justify the design and satisfy an auditor. It should also determine the quality of the packaging component that has been designed and its performance within the manufacturing environment. The number of samples used is dependant on the range and scope of the validation, for example, does the packaging change affect just one product or a complete range? Packaging validation typically consists of two elements:

Seal validation. As stated previously, the essential feature of a package is to create a sterile barrier, in most cases this is achieved using a blister or a pouch. Because the sealing ability of the component is crucial in forming the barrier, the validation must obtain the optimal sealing parameters for the new design. The parameters are

• temperature
• time
• pressure; for most validations, pressure is usually a constant and the sealing machine manufacturers recommendations are used.

The validation must determine what operating window can be used for the new design to consistently produce acceptable seals. This involves testing a series of combinations of time and temperature and performing seal inspections to predefined acceptance criteria.

Package testing. Once the sealing of the packaging has been verified, the durability of the design is tested using distribution simulation testing. ASTM standards are employed: D999, Vibration Testing; and D775 and D880, Drop Testing of Loaded Containers by Free Fall (www.astm.org). This testing simulates the pack in transit and provides evidence that the pack can withstand vibration and drop testing. The success of the exercise is determined by post-test inspection whereby the sterile barrier is examined to ensure that the seal is still fully intact.

Validation provides the designer with a clear view on how the design will react in the factory environment and throughout shipping and distribution process. Unforeseen issues can arise such as sealability, fit with mating components and poor fit between components and product, which can cause product damage. If these setbacks do occur, the validation has still achieved its purpose in preventing potential risks to the customer/user. This will result in revisiting the design phase, or in some cases, examining the packaging process. Although valid-ation failure is painful and will affect project timelines, it provides a structured approach to a design evaluation.

Validation completion is an historical and sequential record of the company’s efforts to analyse and qualify the packaging design. The next phase is to inform customers in advance of the forthcoming change.

Regulatory requirements

Regulatory expertise is essential when informing the customer of any changes to product and ensures that the requirements are met prior to the introduction of the change. Again, the validation data is the documented evidence that the change has been qualified.

The value of change

Packaging design change can be a lengthy process because of the qualification requirements in the industry. The perspiration or inspiration of the design is only one step in a series of objectives that must be obtained prior to market introduction. Packaging design can provide a real opportunity to strengthen customer relations and can also be a major source of cost savings. Customers’ perception of their supplier is most clear when handling the products in their own environment as they employ their expertise. The chance to improve and enhance that image is presented by the packaging engineer’s ability to achieve change through packaging design.

David Slattery is a Packaging Engineer at a medical device manufacturing company.