Properties of Materials Used in Single-Use Flexible Containers: Requirements and Analysis

Nov 02, 2006

The adoption of single-use containers in the biopharmaceutical industry is becoming more frequent as the popularity and availability of the technologies increase. The choice of a solution for storage in single-use containers clearly depends on the application and the inherent risks associated with the application. A "one fits all" single-use system cannot respond to all the requirements of a particular step in a biopharmaceutical process, much less to all the steps of a process. The needs of an application will lead to very specific single-use solutions.

The physical properties of the film, such as the gas barrier, water loss, tensile strength, and temperature resistance, depend not only on the fluid contact surface, but on the overall composition of the film. A critical analysis of these physical properties is fundamental and cannot be taken at face value. And in all cases, the film is just one component of a single-use system, and all the components must be evaluated as a whole. This evaluation must include compatibility between the container and its contents (chemical resistance, extractables, and leachables) and an evaluation of the physical properties of the film under the appropriate operating conditions, based on a pertinent risk analysis of the manufacturing process. The type and amount of tests required are directly dependent on this risk analysis.

Overview of single-use technology


Single-use technology eliminates the risk of cross contamination, which is of growing concern because the industry increasingly is moving from dedicated single-product plants to multiproduct facilities. Eliminating cleaning and cleaning validation is another key reason for moving to single-use technology; cleaning is not a perfect science and the number of FDA warning letters containing remarks about cleaning procedures, analytical methods used, or indeed lack of validation of cleaning procedures, has grown in recent years.1 Single-use systems also can help companies achieve their manufacturing improvement goals, by offering faster turnaround and thus higher throughput, as well as high flexibility, which facilitates the implementation of process improvements. Several studies in recent years have demonstrated that significant savings in investment and cost of goods can be achieved as a result of implementing single-use technology.2 Disposables also can shorten the time needed to validate new facilities by several months by reducing cleaning and steaming validation requirements.

Table 1. The classical applications of single-use technologies
Table 1 lists the classical applications in which single-use technology has been adopted and has shown to benefit the companies that have implemented it.

Material properties of films used in single-use technologies

General description of a multilayer film structure

Monolayer film structures such as PVC and EVA have been widely used for many years for blood storage and parenteral nutrition. The properties that are required in film structures today, however, cannot always be achieved by a monolayer structure. As a result, polymeric structures are now more common. The minimum barrier structure features at least three layers:

  • A structural layer (e.g., PA, PET, LDPE) that determines the overall mechanical behavior of the film
  • A barrier layer (e.g., EVOH, PVDC, PA) that determines the structure's permeability behavior
  • The fluid contact layer (e.g, ULDPE, EVA, PP), which must combine inertness and good sealing properties.

The interaction of the layers is important in the overall performance of the film. For example, even though PE has better barrier properties than EVA, a film with an EVA contact layer may have better barrier properties than a film with a PE contact layer if the EVA-based film contains an EVOH layer and the PE-based film does not.

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