Impact of excipient choice on the aerodynamic performance of inhalable spray-freeze-dried powders.

Spray-freeze-drying (SFD) is a process in which a solution is dispersed into a freezing medium and dried by sublimation, resulting in lyophilized powders with spherical particles. This study aims at screening and evaluating the impact of the excipient choice and spray solution characteristics in SFD on the physico-chemical characteristics of lyospheres and rate their suitability for producing pulmonary applicable powders using a novel SFD method. A monodisperse droplet-stream was injected into a vortex of cold gas for the production of inhalable, uniform spherical lyophilisates with a narrow particle size distribution.

Jet-vortex spray freeze drying for the production of inhalable lyophilisate powders.

Spray-freeze-dried powders were suggested for nasal, epidermal (needle-free injection) or pulmonary application of proteins, peptides or nucleic acids. In spray-freeze-drying processes an aqueous solution is atomized into a refrigerant medium and subsequently dried by sublimation. Droplet-stream generators produce a fast stream of monodisperse droplets, where droplets are subject to collisions and therefore the initial monodispersity is lost and droplets increase in diameter, which reduces their suitability for pulmonary application.

Aerodynamic Droplet Stream Expansion for the Production of Spray Freeze-Dried Powders.

In spray freeze-srying (SFD), a solution is sprayed into a refrigerant medium, frozen, and subsequently sublimation dried, which allows the production of flowable lyophilized powders. SFD allows commonly freeze-dried active pharmaceutical ingredients (e.g.

Collisions and coalescence in droplet streams for the production of freeze-dried powders.

Streams of mono-disperse micro-droplets with diameters ranging from about 20 μm to 100 μm were produced from diluted aqueous solutions containing carbohydrates and proteins using a pinhole type piezoelectric generator with either a 20 μm or a 50 μm single-orifice diaphragm. Image sequences indicating droplet size, velocity, inter-droplet spacing at various distances from the nozzles as well as collision events and coalescence were recorded using a high-speed camera and analysed quantitatively. The size-dependent gradual deceleration of the droplets is superimposed by small scale random movements, which equally affect both large and small droplets and lead to early contacts and coalescence.

Pharmaceutical spray freeze drying.

Pharmaceutical spray-freeze drying (SFD) includes a heterogeneous set of technologies with primary applications in apparent solubility enhancement, pulmonary drug delivery, intradermal ballistic administration and delivery of vaccines to the nasal mucosa. The methods comprise of three steps: droplet generation, freezing and sublimation drying, which can be matched to the requirements given by the dosage form and route of administration. The objectives, various methods and physicochemical and pharmacological outcomes have been reviewed with a scope including related fields of science and technology.