Freeze-drying is a crucial tertiary step when preparing many different products. Commonly associated with instant coffee and food preservation, there are freeze-drying processes well-suited for more sophisticated products. For example, lyophilization is an essential method of dehydrating pharmaceutical ingredients in bulk.
Image Credit: Powder Systems
This article will explore how freeze-drying works, as well as some of its benefits for microsphere formulation.
What is Freeze-Drying?
There is no discernible difference between lyophilization and freeze-drying; the former is merely a technical synonym for the latter. Lyophilization is a process of drying where a product is cooled in temperature below its triple point, where the product’s liquid, gas, and solid phases exist in a thermodynamic equilibrium.
The freezing process is deceptively complicated, as the goal is to maximize the formation of large ice crystals to expedite sublimation. Unlike melting, where ice transitions directly to vapor, the product undergoes sublimation when heated under vacuum conditions.
This method can lower residual moisture content down to as little as 1% and potentially shorten product drying times by a third. Undoubtedly, these advantages offer substantial cost savings for pharmaceutical manufacturers while potentially enhancing critical quality attributes of pharmaceutical ingredients.
Why are Pharma-Grade Microspheres Freeze-Dried?
Preparing pharmaceutical microspheres can present a formidable challenge. These minute components, commonly known as balls, beads, microbeads, or spheres, exhibit diverse compositions derived from an expanding array of candidate materials.
Drug manufacturers can fabricate high-performance microspheres using ceramics, glass, polymers, silicates, and other substances, offering versatile functionality for pharmaceutical applications and beyond. However, this variety contributes to a lack of uniformity when it comes to preparation and development; thus, there is no single consensus as to the best method of preparation.
Drying is a key process in microsphere formulation, and freeze-drying is one of the preferred methods. Microspheres lend themselves exceptionally well to freeze-drying, given that they must be prepared in a dry state to prevent premature release of the active component. Additionally, there are often certain stability issues with microspheres that can be overcome by freeze-drying.
How Freeze-Drying Fits into Microsphere Formulation
Microsphere formulation is a very complicated, multi-step workflow. The microspheres must first be synthesized, followed by harvesting. Polymeric microspheres–a preferred drug delivery vehicle in novel pharmaceuticals–are generally derived from coacervation, spray drying, or evaporation prior to refining via de-watering, washing, drying, blending, and–in many situations–freeze-drying.
Freeze-drying involves freezing the microspheres, followed by subjecting them to an ultra-low vacuum and gradually raising the temperature. This process transforms the microspheres into a flexible and porous solid state. Furthermore, freeze-dried microspheres are free from dust, exhibit exceptional flow properties, and achieve homogeneity.
The freeze-drying method is becoming more widespread in pharmaceutical manufacturing because of its benefits for biopharmaceutical molecules and compounds with poor solubility. There are also potential stability problems in the microspheres that can be resolved by freeze-drying.
All-in-one solutions that offer a combination of all preparation stages, from classification to recovery, have also made freeze-drying a better commercially viable option.
The Key Benefits of Freeze-Drying
- Fights poor solubility
- Increased stability
- Maintained physical shape
- Increased shelf life
- Ambient temperature storage
The MSR™ Microsphere Refiner
Powder Systems Limited has been manufacturing and designing advanced technology for pharmaceuticals and chemical processing for over 30 years. Its flagship product is the MSR™ MicroSphere Refiner, a piece of cGMP equipment that drug manufacturers and developers can use for highly reproducible and scalable microsphere development.
The MSR™ has continually offered users the ability to perform drying, classification, and sampling processes in one instrument, but the needs of the industry have since evolved.
Freeze-drying capabilities have thus been incorporated to address this, with an adjusted design and optimized critical ancillary systems. The highly engineered vacuum skid and more stringent temperature controls enable higher precision and automation capabilities for the tightest possible control of key process parameters.
PSL’s Quality-by-Design (QbD) approach ensures that each element of the instrument is optimized to meet vital industry challenges. This encompasses a thoroughly refined drying process with minimal product transfer needs, thus expediting the overall refining process while maintaining uncompromised quality.
About Powder Systems 
Powder Systems Limited (PSL) provides a full range of solid liquid separation solutions for filtration, drying, and processing from research and development activities up to larger commercial production scale.
Quality and innovation are central to everything they do. They are proud of their award-winning track record and have been working with industry partners for over 35 years.
PSL supports clients by developing solutions to overcome challenging manufacturing processes and provide first-class aftercare services.
Sponsored Content Policy: AZoLifeSciences publishes articles and related content that may be derived from sources where we have existing commercial relationships, provided such content adds value to the core editorial ethos of News-Medical.Net which is to educate and inform site visitors interested in medical research, science, medical devices and treatments.