Pharmaceutical applications spray-dried systems

The advent of biotechnology, bioengineering and pharmaceutical delivery systems has increased the requirements for solubility and stability of macromolecules under a variety of versatile and unique conditions and subsequently the use of non-aqueous solvents. Specihc applications include a) isolation, purification, precipitation and crystallization of biopharmaceuticals, b) processing methods such as spray drying and microencapsulation, and c) formulation of proteins for delivery systems requiring high concentrations and prolonged stability, such as implants and depots. 

The most widely used spray-drying process layout is the open-cycle layout in which the air is drawn from the atmosphere, passed through the drying chamber, and exhausted back to the atmosphere. This layout is used for aqueous feedstock and employs air as the drying gas. There are numerous variations of open-cycle layout systems, two of which are common in pharmaceutical applications (Fig. 7) (10). The most common and cost-effective layout utilizes a high-efficiency cyclone and scrubber (Fig. 7A). In this layout, the loss of very fine particles to the atmosphere eannot be prevented. If the desired particle size of the spray-dried product is too small to be reeovered by eyelone and scrubber systems then the use of a layout employing a bag filter is recommended (Fig. 7B). 

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