This article is part of PharmTech's supplement "Bioprocessing and Sterile Manufacturing 2010."
The biopharmaceutical and vaccine industries are embracing single-use technologies more and more as alternatives to fixed stainless-steel equipment. Although the technologies still have limitations of mass and heat transfer, the generally mild process conditions in biopharmaceutical operations are conducive to using a disposable plastic film surface as the product-contact layer. Disposable components also eliminate the need for surface cleaning to avoid contamination and cross-contamination.
Several factors enable the disposable plastic bags used for solution preparation, storage, and product-generation steps to promise potential cost advantages. Because single-use systems can provide sufficient volume (i.e., currently 2000–3000 L, depending on the application) to accommodate the capacity requirements of most commercially produced vaccine and biopharmaceutical products (including those whose quantities have been raised by yield increases from new cell lines), the use of disposables is posed to grow in the next decade.As any biopharmaceutical-industry professional will probably testify, no two projects are alike. It can therefore be difficult to make general estimates about potential cost advantages. However, when making early estimates regarding technology concepts, it is practical and acceptable to put some rough criteria to use.
NNE Pharmaplan (Soborg, Denmark) uses a modular approach to designing and engineering processes and production facilities. The company breaks down the project's scope into modules for structured engineering activities. Process modules are typically combinations of process equipment (e.g., one bioreactor with three associated feed tanks) so that they can be seen as the main building blocks of the production process.
This modular approach allows an overview of the factors that affect a project, and process modules also can be the basis for the calculations that obtain cost-related criteria for the application of single-use technologies. Although experience has shown that these quick estimates can be remarkably accurate, this approach is clearly rough and should only be seen as an estimate.
Investment costs are probably the biggest and most obvious source of the cost advantages of single-use components over fixed, steel systems. The difference arises mainly because single-use systems require less instrumentation and fewer utilities. Because sterilization and cleaning processes are eliminated, installation and support systems are reduced.
This advantage clearly allows a manufacturer to purchase more capacity for a limited startup budget, but also has an effect on the variable costs because a much lower investment sum has to be amortized, compared with that of fixed steel systems. In fact, it is the low up-front investment cost, which lowers variables costs, that typically tips the scales in favor of single-use systems.
Single-use systems have fewer utility requirements, and they also can be stacked or moved in certain volume ranges. These systems thus occupy a small footprint because of their improved designs and mobility, as well as their decreased demand for piping, valves, instrumentation, and the related maintenance space required. To be sure, single-use systems do require room for manipulation, transport, and waste removal, but even with these space requirements, they occupy less space than do fixed systems. To manipulate or maintain the equipment—which already occupies less space—it is possible to push the equipment aside to allow access. In this way, the process modules can share each other's footprints to a certain degree.