Dry powder pharmaceutical biologics for inhalation therapy

Therapeutic biologics such as genes, peptides, proteins, virus and cells provide clinical benefits and are becoming increasingly important tools in respiratory medicine. Pulmonary delivery of therapeutic biologics enables the potential for safe and effective treatment option for respiratory diseases due to high bioavailability while minimizing absorption into the systemic circulation, reducing off-target toxicity to other organs. Development of inhalable powder formulation requires stabilization of complex biological materials, and each type of biologics may present unique challenges and require different formulation strategy combined with manufacture process to ensure biological and physical stabilities during production and over shelf-life. This review examines key formulation strategies for stabilizing proteins, nucleic acids, virus (bacteriophages) and bacterial cells in inhalable powders. It also covers characterization methods used to assess physicochemical properties and aerosol performance of the powders, biological activity and structural integrity of the biologics, and chemical analysis at the nanoscale. Furthermore, the review includes manufacture technologies which are based on lyophilization and spray-drying as they have been applied to manufacture Food and Drug Administration (FDA)-approved protein powders. In perspective, formulation and manufacture of inhalable powders for biologic are highly challenging but attainable. The key requirements are the stability of both the biologics and the powder, along with the powder dispersibility. The formulation to be developed depends on the manufacture process as it will subject the biologics to different stresses (temperature, mechanical and chemical) which could lead to degradation by different pathways. Stabilizing excipients coupled with the suitable choice of process can alleviate the stability issues of inhaled powders of biologics.

Inhalation delivery technology for genome-editing of respiratory diseases

The clustered regulatory interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system has significant therapeutic potentials for lung congenital diseases such as cystic fibrosis, as well as other pulmonary disorders like lung cancer and obstructive diseases. Local administration of CRISPR/Cas9 therapeutics through inhalation can achieve high drug concentration and minimise systemic exposure. While the field is advancing with better understanding on the biological functions achieved by CRISPR/Cas9 systems, the lack of progress in inhalation formulation and delivery of the molecule may impede their clinical translation efficiently. This forward-looking review discussed the current status of formulations and delivery for inhalation of relevant biologics such as genes (plasmids and mRNAs) and proteins, emphasising on their design strategies and preparation methods. By adapting and optimising formulation strategies used for genes and proteins, we envisage that development of inhalable CRISPR/Cas9 liquid or powder formulations for inhalation administration can potentially be fast-tracked in near future.

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.

Efficient optimization of high-dose formulation of novel lyophilizates for dry powder inhalation by the combination of response surface methodology and time-of-flight measurement

Inhalation of proteins/peptides has recently received attention as various biopharmaceuticals have emerged on the market. Novel lyophilisates for dry powder inhalation (LDPIs), which are aerosolized by air impact, have been reported and LDPIs are considered an attractive option for the pulmonary administration of biopharmaceuticals. However, desirable disintegration and aerosolization properties have been unavailable in high-dose formulations, which has been a critical issue. This study aimed to investigate high-dose LDPIs and their optimization. In the present study, lysozyme (Lysoz) was used as a stable model protein and formulated with various amino acids. Furthermore, response surface methodology (RSM) and time-of-flight measurement were applied for efficient optimization. Superior disintegration and aerosolization properties were confirmed in the LDPIs with phenylalanine (Phe) and leucine (Leu). RSM results revealed that 0.5 mg/vial of Phe and 1.0 mg/vial of Leu are the optimal quantities for high-dose formulation. Based on these optimum quantities, high-dose LDPI formulations were prepared and the maximum formulable quantity of Lysoz with acceptable inhalation performance was confirmed to be 3.0 mg/vial. The results suggest that LDPI can cover the milligram-order pulmonary administration of proteins/peptides. LDPIs are expected to have biopharmaceutical applications.

Naked pDNA Inhalation Powder Composed of Hyaluronic Acid Exhibits High Gene Expression in the Lungs

Gene therapy is a breakthrough treatment strategy against several intractable and lethal diseases that previously lacked established treatments. Viral and nonviral vectors have been studied to realize higher gene transfection efficiencies and to suppress the degradation of gene by nucleolytic enzymes in vivo. However, it is often the case that the addition of a vector results in adverse effects. In this study, we identified formulations of dry naked plasmid DNA (pDNA) powders with no vector showing significantly higher gene expression than pDNA solutions including vectors such as polyethylenimine (PEI) in the lungs of mice. We prepared the naked pDNA powders by spray-freeze-drying with various excipients. The gene expression of naked pDNA powders exceeded those of pDNA solutions containing PEI, naked pDNA solution, and reconstituted pDNA powder. Gene expression of each naked pDNA powder was dependent on the composition of excipients. Among them, the mice that were administered the pDNA powder composed of low-molecular-weight hyaluronic acid (LHA) as an excipient showed the highest gene expression. The lactate dehydrogenase activity and concentration of inflammatory cytokines in bronchoalveolar lavage fluid were comparable to those caused by ultrapure water. The results suggest that useful dry naked nucleic acid powders for inhalation could be created by optimizing the excipients, offering new insights into the development of pulmonary gene therapy.

[Development of Inhalable Dry Powder Formulations Loaded with Nanoparticles Maintaining Their Original Physical Properties and Functions]

 Functional nanoparticles, such as liposomes and polymeric micelles, are attractive drug delivery systems for solubilization, stabilization, sustained release, prolonged tissue retention, and tissue targeting of various encapsulated drugs. For their clinical application in therapy for pulmonary diseases, the development of dry powder inhalation (DPI) formulations is considered practical due to such advantages as: (1) it is noninvasive and can be directly delivered into the lungs; (2) there are few biocomponents in the lungs that interact with nanoparticles; and (3) it shows high storage stability in the solid state against aggregation or precipitation of nanoparticles in water. However, in order to produce effective nanoparticle-loaded dry powders for inhalation, it is essential to pursue an innovative and comprehensive formulation strategy in relation to composition and powderization which can achieve (1) the particle design of dry powders with physical properties suitable for pulmonary delivery through inhalation, and (2) the effective reconstitution of nanoparticles that will maintain their original physical properties and functions after dissolution of the powders. Spray-freeze drying (SFD) is a relatively new powderization technique combining atomization and lyophilization, which can easily produce highly porous dry powders from an aqueous sample solution. Previously, we advanced the optimization of components and process conditions for the production of SFD powders suitable to DPI application. This review describes our recent results in the development of novel DPI formulations effectively loaded with various nanoparticles (electrostatic nanocomplexes for gene therapy, liposomes, and self-assembled lipid nanoparticles), based on SFD.

Biodegradable Poly(Amino Ester) with Aromatic Backbone as Efficient Nonviral Gene Delivery Vectors

The development of gene delivery vectors with high efficiency and biocompatibility is one of the critical points of gene therapy. Two biodegradable poly(amino ester)s were synthesized via ring-opening polymerization between low molecular weight (LMW) PEI and diepoxide. The molecular weights of poly(amino ester)s were measured by GPC. Agarose gel retardation assays showed that these materials have good DNA-binding ability and can retard the electrophoretic mobility of plasmid DNA (pDNA) at a weight ratio of 1. The formed polyplexes have proper sizes of around 200 nm and zeta-potential values of about 30-40 mV for cellular uptake. In vitro experiments revealed that polymer P2 gave higher transfection efficiency than PEI 25KDa and Lipofectamine 2000 with less toxicity, especially in 293 cells. Results demonstrate that such a type of degradable poly(amino ester) may serve as a promising non-viral gene vector.