Microspheres are small spherical particles, having a required size range (typically 5μm, up to 250μm). These particles can be manufactured from various natural and synthetic materials such as polymer microspheres. New applications for microspheres are discovered every day from coating to cosmetics and cancer research. Powder Systems Ltd. (PSL) has developed process solutions for this type of drug delivery, as biodegradable polymer microspheres can work as miniature time release capsules for parenteral drugs, within pharmaceutical and biotechnology industries. Along with these types of processes, other industry requirements have evolved utilising the microsphere technology. Microsphere production is experiencing a fast growing demand due to its revolutionary characteristics and applications. Blue chip pharmaceutical companies around the world are adopting this formulation method, usually developed by laboratory development contract organisations and research universities. The first applications for the pharmaceutical sector were developed 10 years ago mainly in the United States, where PSL was already a pioneering equipment manufacturer providing small scale sterile filter dryers, specifically designed to suit the microsphere formulation. Suspended microspheres obtained from various micro encapsulation processes require unique handling that differ from a typical filtration and drying operation. Following the synthesis stage, microspheres require being washed, classified by size, filtered then dried under appropriate conditions to gain the final free flowing injectable or inhalation microsphere product. Microspheres are random in size and need to be filtered and classified into the micron size range desired before drying. PSL sterile filter dryers have been designed to meet these criteria from washing to classifying and drying. With PSL’s design, utilising side and bottom filtration, size classification is achieved. Classification being the most difficult task associated with microsphere production. Typically with microsphere processes, large liquid volumes with a small ratio of suspended solids have to be handled. Thus some processes require a scalping pre-filtration step in order to reduce the liquid volume and eliminate the oversized microspheres. This is achieved with the PSL Scalping Filter prior to transfer into the PSL Microsphere Filter Dryer. Most microsphere processes require sterility, PSL solutions have been designed with Steam-In-Place and drainability capabilities. The discharge is part of the sterility envelope. PSL Microsphere Sterile Filter Dryer is tiltable to accommodate a sterile discharge. PSL has completed a number of worldwide projects using microsphere filtration solutions from laboratory scale to commercial production. This complex process is now implemented more and more around the world by undisclosed pharmaceutical and biopharmaceutical companies.
