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.
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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
Advantages
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
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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.
