Conventional spray drying is a useful process but has its limitations. John Polidoro, Mark Ketner and Carl Sahi, Engineered BioPharmaceuticals, explain how the field of dry powder processing can be advanced by the newer technique of atmospheric spray freeze drying.
Scientists and engineers manufacture dry powder pharmaceuticals for many reasons, including increasing stability and shelf life of drug formulations; for storing at room temperatures; reducing weight and bulk; and for facilitating the development of novel self-administration methods of delivery, such as nasal and pulmonary delivery.
The mainstay method for liquid-to-dry-powder conversion is lyophilisation. Also known as freeze drying, lyophilisation involves freezing a bulk liquid solution and subliming off the solvent using temperature and vacuum. Pharmaceutical companies worldwide have used this method for decades to produce dry powder pharmaceuticals, even though it is slow, has significant energy requirements and often necessitates post processing to produce a powder suitable for its end-use application.
With pressure on pharmaceutical companies to increase manufacturing efficiency and produce products with higher activity and longer shelf lives, including the manufacture of complex and fragile dry powder biologics, bulk processing lyophilisation may have reached its limitations.
New methods exist that provide the reliability and performance of lyophilisation, yet offer the scientist and engineer a dashboard of opportunity to fabricate intricate features and properties into each particle. One of the advanced technologies leading the charge into ‘engineered’ dry powder pharmaceuticals is atmospheric spray freeze-drying (ASFD).
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