Intratracheal Administration of Dry Powder Formulation in Mice

In the development of inhalable dry powder formulations, it is essential to evaluate their biological activities in preclinical animal models. This paper ...

Establishment and Evaluation of a Porcine Vein Graft Disease Model

Venous graft disease (VGD) is the leading cause of coronary artery bypass graft (CABG) failure. Large animal models of CABG-VGD are needed for the ...

The University of Hong Kong

the First Affiliated Hospital of Jinan University

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.

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

Pulmonary delivery of messenger RNA (mRNA) has considerable potential as therapy or vaccine for a range of lung diseases. Inhaled dry powder formulation of mRNA is particularly attractive as it has superior stability and dry powder inhaler is relatively easy to use. A safe and effective mRNA delivery vector as well as a suitable particle engineering method are required to produce a dry powder formulation that is respirable and mediates robust transfection in the lung. Here, we introduce a novel RNA delivery vector, PEGKL4, in which the synthetic cationic KL4 peptide is attached to a monodisperse linear PEG of 12-mers. The PEGKL4 formed nano-sized complexes with mRNA at 10:1 ratio (w/w) and mediated effective transfection on human lung epithelial cells. PEGKL4/mRNA complexes were successfully formulated into dry powder by spray drying (SD) and spray freeze drying (SFD) techniques. Both SD and SFD powder exhibited satisfactory aerosol properties for inhalation. More importantly, the biological activity of the PEGKL4 /mRNA complexes were successfully preserved after drying. Using luciferase mRNA, the intratracheal administration of the liquid or powder aerosol of PEGKL4 /mRNA complexes at a dose of 5μg mRNA resulted in luciferase expression in the deep lung region of mice 24h post-transfection. The transfection efficiency was superior to naked mRNA or lipoplexes (Lipofectamine 2000), in which luciferase expression was weaker and restricted to the tracheal region only. There was no sign of inflammatory response or toxicity of the PEGKL4 /mRNA complexes after single intratracheal administration. Overall, PEGKL4 is an excellent mRNA transfection agent for pulmonary delivery. This is also the first study that successfully demonstrates the preparation of inhalable dry powder mRNA formulations with in vivo transfection efficiency, showing the great promise of PEGKL4 peptide as a mRNA delivery vector candidate for clinical applications.

Effective mRNA pulmonary delivery by dry powder formulation of PEGylated synthetic KL4 peptide.

The development of small interfering RNA (siRNA) formulation for pulmonary delivery is a key to the clinical translation of siRNA therapeutics for the treatment of respiratory diseases. Most inhalable siRNA powder formulations published to date were limited by the siRNA content which was often too low to be clinically relevant. This study aimed to prepare inhalable siRNA powder formulations that contained high siRNA loading of over 6% w/w by spray drying, with human serum albumin (HSA) investigated as a dispersion enhancer to improve the aerosol performance. The effect of siRNA, HSA and solute concentrations in the formulations were evaluated systemically using factorial analyses. All the spray dried siRNA powders exhibited excellent aerosol performance with fine particle fraction (FPF) consistently over 50% in all the formulations. An enrichment of HSA on the particle surface was observed. Surface corrugation was more prominent as HSA composition increased. Importantly, the bioactivity of siRNA was successfully preserved upon spray drying as demonstrated in the in vitro transfection study, and up to 78% of intact siRNA retained in the spray dried powder. Overall, HSA is an effective dispersion enhancer and spray drying is an appropriate technique to produce inhalable dry powder with high siRNA loading for further investigation.

High siRNA loading powder for inhalation prepared by co-spray drying with human serum albumin.

Spray freeze drying is a particle engineering technique that allows the production of porous particles of low density with excellent aerosol performance for inhalation. There are a number of operating parameters that can be manipulated in order to optimise the powder properties. In this study, a two-fluid nozzle was used to prepare spray freeze dried formulation of voriconazole, a triazole antifungal agent for the treatment of pulmonary aspergillosis. A full factorial design approach was adopted to explore the effects of drug concentration, atomisation gas flow rate and primary drying temperature. The aerosol performance of the spray freeze dried powder was evaluated using the next generation impactor (NGI) operated with different inhaler devices and flow rates. The results showed that the primary drying temperature played an important role in determining the aerosol properties of the powder. In general, the higher the primary drying temperature, the lower the emitted fraction (EF) and the higher the fine particle fraction (FPF). Formulations that contained the highest voriconazole concentration (80% w/w) and prepared at a high primary drying temperature (-10 °C) exhibited the best aerosol performance under different experimental conditions. The high concentration of the hydrophobic voriconazole reduced surface energy and cohesion, hence better powder dispersibility. The powders produced with higher primary drying temperature had a smaller particle size after dispersion and improved aerosol property, possibly due to the faster sublimation rate in the freeze-drying step that led to the formation of less aggregating or more fragile particles. Moreover, Breezhaler®, which has a low intrinsic resistance, was able to generate the best aerosol performance of the spray freeze dried voriconazole powders in terms of FPF.

Qiuying Liao

Department of Pharmacology and Pharmacy,
LKS Faculty of Medicine,
Department of Pharmacology and Pharmacy, LKS Faculty of Medicine

The University of Hong Kong

Intratracheal Administration of Dry Powder Formulation in Mice

Establishment and Evaluation of a Porcine Vein Graft Disease Model

Qiuying Liao

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Pharmacology and Pharmacy,LKS Faculty of Medicine,Department of Pharmacology and Pharmacy, LKS Faculty of Medicine

The University of Hong Kong

Intratracheal Administration of Dry Powder Formulation in Mice

Establishment and Evaluation of a Porcine Vein Graft Disease Model

Department of Pharmacology and Pharmacy,
LKS Faculty of Medicine,
Department of Pharmacology and Pharmacy, LKS Faculty of Medicine