Microsphere formulation with the PSL Microsphere Refiner

Filtration solutions for microsphere formulation, from small-scale processes to production

The Microsphere Refiner

Microspheres are small spherical particles with 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.

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 the pharmaceutical and biotechnology industries. Along with these types of processes, other industry requirements have evolved that use microsphere technology.

Microsphere production is experiencing growing demand due to its revolutionary characteristics and applications. Blue Chip pharmaceutical companies around the world are adopting this formulation method, usually developed by contract research organisations and universities. The first applications for the pharmaceutical sector were developed 10 years ago, mainly in the US, where PSL was already a pioneering equipment manufacturer providing small-scale sterile systems, specifically designed to suit the microsphere formulation.

Suspended microspheres obtained from various micro encapsulation processes require unique handling that differs from a typical filtration and drying operation. Following the synthesis stage, microspheres need to be washed, classified by size, filtered then dried 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 Microsphere Refiners have been designed to meet these criteria from washing to classifying and drying.

Formulation Lab Development Microsphere Refiner with tiltable discharge

With PSL’s unique design, using side and bottom filtration, size classification is achieved. PSL says classification is the most difficult task associated with microsphere production, where typically large liquid volumes with a small ratio of suspended solids have to be handled. Thus some processes require a scalping pre-filtration step 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 Refiner.

Most microsphere processes also require sterility and PSL solutions have been designed with steam-in-place and drainability capabilities. The discharge is part of the sterility envelope. The PSL Microsphere Refiner is tiltable to accommodate a sterile discharge.

PSL has completed a number of worldwide projects using microsphere filtration solutions from lab scale to commercial production. Pharmaceutical and biopharmaceutical firms across the world are now implementing this complex process more frequently.