Spray Freeze-Drying for inhalation application: Process and Formulation Variables

High porous particles with specific aerodynamic properties were processed by the spray freeze-drying (SFD) method. Comprehensive knowledge about all aspects of the SFD method is required for particle engineering of various pharmaceutical products with good flow properties. In this review, different types of the SFD method, the most frequently employed excipients, properties of particles prepared by this method, and most recent approaches concerning SFD are summarized. Generally, this technique can prepare spherical-shaped particles with a highly porous interior structure, responsible for the very low density of powders. Increasing the solubility of spray freeze-dried formulations achieves the desired efficacy. Also, due to the high efficiency of SFD, by determining the different features of this method and optimizing the process by model-based studies, desirable results for various inhaled products can be achieved and significant progress can be made in the field of pulmonary drug delivery.

Spray Freeze-Drying as a Solution to Continuous Manufacturing of Pharmaceutical Products in Bulk

Pharmaceutical manufacturing is evolving from traditional batch processes to continuous ones. The new global competition focused on throughput and quality of drug products is certainly the driving force behind this transition which, thus, represents the new challenge of pharmaceutical manufacturing and hence of lyophilization as a downstream operation. In this direction, the present review deals with the most recent technologies, based on spray freeze-drying, that can achieve this objective. It provides a comprehensive overview of the physics behind this process and of the most recent equipment design.

Porous and highly dispersible voriconazole dry powders produced by spray freeze drying for pulmonary delivery with efficient lung deposition

Systemic administration of antifungal agents for the treatment of pulmonary aspergillosis is limited by the poor lung deposition and severe adverse effects. In contrast, pulmonary delivery allows a higher amount of drug to be delivered directly to the infection site and therefore a lower dose is required. This study aimed to develop porous and inhalable voriconazole dry powder with good lung deposition by spray freeze drying (SFD), using tert-butyl alcohol (TBA) as a co-solvent. A three-factor two-level full factorial design approach was used to investigate the effect of total solute concentration, drug content and co-solvent composition on the aerosol performance of the SFD powder. In general, the SFD voriconazole powder exhibited porous and spherical structure, and displayed crystalline characteristics. The analysis of factorial design indicated that voriconazole content was the most significant variable that could influence the aerosol performance of the SFD powders. The formulations that contained a high voriconazole content (40% w/w) and high TBA concentration in the feed solution (70% v/v) displayed the highest fine particle fraction of over 40% in the Next Generation Impactor study in which the powder was dispersed with a Breezhaler® at 100 L/min. In addition, the fine particle dose of the SFD powder showed a faster dissolution rate when compared to the unformulated voriconazole. Intratracheal administration of SFD voriconazole powder to mice resulted in a substantially higher drug concentration in the lungs when comparing to the group that received an equivalent dose of liquid voriconazole formulation intravenously, while a clinically relevant plasma drug concentration was maintained for at least two hours. Overall, an inhalable voriconazole dry powder formulation exhibiting good aerosol property and lung deposition was developed with clinical translation potential.

Biomimetic hollow mesoporous hydroxyapatite microsphere with controlled morphology, entrapment efficiency and degradability for cancer therapy

Hollow mesoporous carbonated hydroxyapatite microspheres produced via sodium dodecyl sulfate assisted precipitation can target cancer cells through acidic dependent release of loaded CDDP.

Hollow and porous hydroxyapatite microspheres prepared with an O/W emulsion by spray freezing method

Microspheres with hollow and/or porous structures have been widely used in various applications. A new method of spraying and freezing emulsions was developed to prepare hollow HA (hydroxyapatite) microspheres with interconnected pores by using PVA (polyvinyl alcohol) as emulsifiers and binders. The relationships between viscosity and shear time or rates were tested and the dispersing stability of oil in water (O/W) emulsions was characterized with comparison to suspensions without the addition of oil phase. The effects of solid loadings of HA and the volume ratio between oil and water on the morphologies of microspheres were investigated. Hollow HA microspheres with particle diameter of ~20μm and pore size of ~0.6μm were successfully obtained by spray freezing method. Besides, drying and sintering processes were crucial to the formation of hollow and porous structures, respectively. The gentamicin loading and releasing of HA porous microspheres with different hollow volumes were tested.

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.

Spray freeze-dried porous microparticles of a poorly water-soluble drug for respiratory delivery

Particles of poorly water-soluble drugs were prepared to develop a dry powder inhaler (DPI). Spray freeze-drying (SFD) technique using a four-fluid nozzle (4N), which has been developed by authors, was applied in this research. Ciclosporin and mannitol were used as a poorly water-soluble model drug and a dissolution-enhanced carrier, respectively. The organic solution of ciclosporin and aqueous solution of mannitol were separately and simultaneously atomized through the 4N, and the two solutions were collided with each other at the tip of the nozzle edge. The spray mists were immediately frozen in liquid nitrogen to form a suspension. Then, the iced droplets were freeze-dried to prepare the composite particles of the drug and carrier. tert-Butyl alcohol (t-BuOH) was used as the organic spray solvent due to its relatively high freezing point. The resultant composite particles with varying drug content were characterized depending on their morphological and physicochemical properties. The particles contained amorphous ciclosporin and δ-crystalline mannitol. The characteristic porous structure of SFD particles potentially contributed to their good aerodynamic performance. A series of particles with a similar size distribution and different drug content revealed that the incorporation of mannitol successfully improved the cohesive behavior of ciclosporin, leading to enhanced aerosol dispersion. The dissolution test method using low-volume medium was newly established to simulate the release process from particles deposited on the surface of the bronchus and pulmonary mucosa. The composite with hydrophilic mannitol dramatically improved the in vitro dissolution behavior of ciclosporin in combination with the porous structure of SFD particles.