Development of Biodegradable Polycation-Based Inhalable Dry Gene Powders by Spray Freeze Drying

Stability of Naked Nucleic Acids under Physical Treatment and Powder Formation: Suitability for Development as Dry Powder Formulations for Inhalation

A number of functional nucleic acids, including plasmid DNA (pDNA) and small interfering RNA (siRNA), have been attracting increasing attention as new therapeutic modalities worldwide. Dry pDNA and siRNA powder formulations for inhalation are considered practical in clinical applications for respiratory diseases. However, physical stresses in the powder-forming process may destabilize nucleic acids, particularly when vectors with stabilizing effects are not used. We herein compare the stability of naked pDNA and siRNA through various physical treatments and two powder-forming processes. The structural and functional integrities of pDNA were markedly reduced via sonication, heating, and atomization, whereas those of siRNA were preserved throughout all of the physical treatments investigated. Spray-dried and spray-freeze-dried powders of siRNA maintained their structural and functional integrities, whereas those of pDNA did not. These results demonstrate that siRNA is more suitable for powder formation in the naked state than pDNA due to its higher stability under physical treatments. Furthermore, a spray-freeze-dried powder with a high content of naked siRNA (12% of the powder) was successfully produced that preserved its structural and functional integrities, achieving high aerosol performance with a fine particle fraction of approximately 40%.

Engineering Inhalable Therapeutic Particles: Conventional and Emerging Approaches

Respirable particles are integral to effective inhalable therapeutic ingredient delivery, demanding precise engineering for optimal lung deposition and therapeutic efficacy. This review describes different physicochemical properties and their role in determining the aerodynamic performance and therapeutic efficacy of dry powder formulations. Furthermore, advances in top-down and bottom-up techniques in particle preparation, highlighting their roles in tailoring particle properties and optimizing therapeutic outcomes, are also presented. Practices adopted for particle engineering during the past 100 years indicate a significant transition in research and commercial interest in the strategies used, with several innovative concepts coming into play in the past decade. Accordingly, this article highlights futuristic particle engineering approaches such as electrospraying, inkjet printing, thin film freeze drying, and supercritical processes, including their prospects and associated challenges. With such technologies, it is possible to reshape inhaled therapeutic ingredient delivery, optimizing therapeutic benefits and improving the quality of life for patients with respiratory diseases and beyond.

Aerosolizable Plasmid DNA Dry Powders Engineered by Thin-film Freezing

PURPOSE

This study was designed to test the feasibility of using thin-film freezing (TFF) to prepare aerosolizable dry powders of plasmid DNA (pDNA) for pulmonary delivery.

METHODS

Dry powders of pDNA formulated with mannitol/leucine (70/30, w/w) with various drug loadings, solid contents, and solvents were prepared using TFF, their aerosol properties (i.e., mass median aerodynamic diameter (MMAD) and fine particle fraction (FPF)) were determined, and selected powders were used for further characterization.

RESULTS

Of the nine dry powders prepared, their MMAD values were about 1-2 µm, with FPF values (delivered) of 40-80%. The aerosol properties of the powders were inversely correlated with the pDNA loading and the solid content in the pDNA solution before TFF. Powders prepared with Tris-EDTA buffer or cosolvents (i.e., 1,4-dioxane or tert-butanol in water), instead of water, showed slightly reduced aerosol properties. Ultimately, powders prepared with pDNA loading at 5% (w/w), 0.25% of solid content, with or without Tris-EDTA were selected for further characterization due to their overall good aerosol performance. The pDNA powders exhibited a porous matrix structure, with a moisture content of < 2% (w/w). Agarose gel electrophoresis confirmed the chemical integrity of the pDNA after it was subjected to TFF and after the TFF powder was actuated. A cell transfection study confirmed that the activity of the pDNA did not change after it was subjected to TFF.

CONCLUSION

It is feasible to use TFF to produce aerosolizable pDNA dry powder for pulmonary delivery, while preserving the integrity and activity of the pDNA.

Effects of L-leucine on the properties of spray-dried swellable microparticles with wrinkled surfaces for inhalation therapy of pulmonary fibrosis

Swellable microparticles (SMs) provide a potential strategy for achieving sustained inhalation therapy. However, spray dried SMs are highly hygroscopic, exhibiting poor flowability and dispersibility properties. This study aimed at determining whether L-leucine (LL) can improve aerosolization performance of SMs with wrinkled surface and its potential mechanisms. Cryptotanshinone was co-spray dried with chitosan and LL (0-40%, mass fraction in carrier materials), after which the production yield, particle size, density, encapsulation efficiency, morphology, cohesion, crystallinity, surface LL distribution, hygroscopicity, water content and in vitro aerosolization performance of the developed formulations were characterized. In addition, we determined whether LL, as a hydrophobic amino acid, would impair swellability and macrophage phagocytosis of SMs. The possible impact of LL on in vitro drug release, cytotoxicity and anti-fibrosis effects on MRC-5 cells was also investigated. As the LL content increased, LL began to crystallize. At 7.5% LL, water content and hygroscopicity of the SMs were at their lowest. Moreover, at 7.5% LL, surface enrichment increased rapidly after which it achieved a comparatively complete coverage at 20-40% LL. However, LL ≥ 20% caused the formation of over-wrinkled, even dimpled or hollow particles, which significantly deteriorated powder properties. Optimum aerosolization performance was obtained at 10% LL, irrespective of its crystallization behavior, accompanied by the lowest cohesion, optimal flowability and production yield, and without impaired swellability, macrophage uptake and anti-fibrosis efficacy. The optimal formulation did not exhibit optimum surface LL coverage, implying that improvement of aerosolization performance of wrinkled SMs by LL not simply depended on its surface enrichment, but its significant influence on morphology and on related powder properties as well.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

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.

Preservation of DNA for data storage

The preservation of DNA has attracted significant interest of scientists in diverse research fields from ancient biological remains to the information field. In light of the different DNA safekeeping requirements (e.g., storage time, storage conditions) in these disparate fields, scientists have proposed distinct methods to maintain the DNA integrity. Specifically, DNA data storage is an emerging research, which means that the binary digital information is converted to the sequences of nucleotides leading to dense and durable data storage in the form of synthesized DNA. The intact preservation of DNA plays a significant role because it is closely related to data integrity. This review discusses DNA preservation methods, aiming to confirm an appropriate one for synthetic oligonucleotides in DNA data storage. First, we analyze the impact factors of the DNA long-term storage, including the intrinsic stability of DNA, environmental factors, and storage methods. Then, the benefits and disadvantages of diverse conservation approaches (e.g., encapsulation-free, chemical encapsulation) are discussed. Finally, we provide advice for storing non-genetic information in DNA in vitro. We expect these preservation suggestions to promote further research that may extend the DNA storage time.

The bibliography includes 99 references.

Pulmonary siRNA delivery for lung disease: Review of recent progress and challenges

Lung diseases are a leading cause of mortality worldwide and there exists urgent need for new therapies. Approval of the first siRNA treatments in humans has opened the door for further exploration of this therapeutic strategy for other disease states. Pulmonary delivery of siRNA-based biopharmaceuticals offers the potential to address multiple unmet medical needs in lung-related diseases because of the specific physiology of the lung and characteristic properties of siRNA. Inhalation-based siRNA delivery designed for efficient, targeted delivery to specific cells within the lung holds great promise. Efficient delivery of siRNA directly to the lung, however, is relatively complex. This review focuses on the barriers that impact pulmonary siRNA delivery and successful recent approaches to advance this field forward. We focus on the pulmonary barriers that affect siRNA delivery, the disease-dependent pathological changes and their role in pulmonary disease and impact on siRNA delivery, as well as the recent development on the pulmonary siRNA delivery systems.

Present Situation and Future Progress of Inhaled Lung Cancer Therapy: Necessity of Inhaled Formulations with Drug Delivery Functions

Inhaled lung cancer therapy is promising because of direct and noninvasive drug delivery to the lungs with low potential for severe systemic toxicity. Thus chemotherapeutic drugs have been administered clinically by nebulization of solution or suspension formulations, which demonstrated their limited pulmonary absorption and relatively mild systemic toxicity. In all these clinical trials, however, there was no obviously superior anticancer efficacy in lung cancer patients even at the maximum doses of drugs limited by pulmonary toxicity. Therefore methods that deliver both higher anticancer efficacy and lower pulmonary toxicity are strongly desired. In addition to the worldwide availability of pressured metered dose inhalers (pMDIs) and dry powder inhalers (DPIs) to treat local respiratory diseases, recent innovations in medicines and technologies are encouraging next steps toward effective inhaled lung cancer therapy with new therapeutic or drug delivery concepts. These include the discovery of target cells/molecules and drug candidates for novel cancer therapy, the development of high-performance inhalation devices for effective pulmonary drug delivery, and the establishment of manufacturing technologies for functional nanoparticles/microparticles. This review highlights the present situation and future progress of inhaled drugs for lung cancer therapy, including an overview of available inhalation devices, pharmacokinetics, and outcomes in clinical trials so far and some novel formulation strategies based on drug delivery systems to achieve enhanced anticancer efficacy and attenuated pulmonary toxicity.

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.

Dry Powder for Pulmonary Delivery: A Comprehensive Review

The pulmonary route has long been used for drug administration for both local and systemic treatment. It possesses several advantages, which can be categorized into physiological, i.e., large surface area, thin epithelial membrane, highly vascularized, limited enzymatic activity, and patient convenience, i.e., non-invasive, self-administration over oral and systemic routes of drug administration. However, the formulation of dry powder for pulmonary delivery is often challenging due to restrictions on aerodynamic size and the lung’s lower tolerance capacity in comparison with an oral route of drug administration. Various physicochemical properties of dry powder play a major role in the aerosolization, deposition, and clearance along the respiratory tract. To prepare suitable particles with optimal physicochemical properties for inhalation, various manufacturing methods have been established. The most frequently used industrial methods are milling and spray-drying, while several other alternative methods such as spray-freeze-drying, supercritical fluid, non-wetting templates, inkjet-printing, thin-film freezing, and hot-melt extrusion methods are also utilized. The aim of this review is to provide an overview of the respiratory tract structure, particle deposition patterns, and possible drug-clearance mechanisms from the lungs. This review also includes the physicochemical properties of dry powder, various techniques used for the preparation of dry powders, and factors affecting the clinical efficacy, as well as various challenges that need to be addressed in the 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.

Physical stability of dry powder inhaler formulations

Introduction: Dry powder inhalers (DPIs) are popular for pulmonary drug delivery. Various techniques have been employed to produce inhalation drug particles and improve the delivery efficiency of DPI formulations. Physical stability of these DPI formulations is critical to ensure the delivery of a reproducible dose to the airways over the shelf-life.Areas covered: This review focuses on the impact of solid-state stability on aerosolization performance of DPI drug particles manufactured by powder production approaches and particle-engineering techniques. It also highlights the different analytical tools that can be used to characterize the physical instability originating from production and storage.Expert opinion: A majority of the DPI literature focuses on the effects of physico-chemical properties such as size, morphology, and density on aerosolization. While little has been reported on the physical stability, particularly the stability of engineered drug particles for use in DPIs. Literature data have shown that different particle-engineering methods and storage conditions may cause physical instability of dry powders for inhalation and can significantly change the aerosol performance. A systematic examination of physical instability mechanisms in DPI formulations is necessary during formulation development in order to select the optimum formulation with satisfactory stability. In addition, the use of appropriate characterization tools is critical to detect and understand physical instability during the development of DPI formulations.

Stabilization of Deformable Nanovesicles Based on Insulin-Phospholipid Complex by Freeze-Drying

Deformable nanovesicles have been extensively investigated due to their excellent ability to penetrate biological barriers. However, suffering from serious physical and chemical instabilities, the wide use of deformable nanovesicles in medical applications is still limited. Moreover, far less work has been done to pursue the lyophilization of deformable nanovesicles. Here, we aimed to obtain stable deformable nanovesicles via freeze-drying technology and to uncover the underlying protection mechanisms. Firstly, the density of nanovesicles before freeze-drying, the effect of different kinds of cryoprotectants, and the types of different reconstituted solvents after lyophilization were investigated in detail to obtain stable deformable nanovesicles based on insulin-phospholipid complex (IPC-DNVs). To further investigate the underlying protection mechanisms, we performed a variety of analyses. We found that deformable nanovesicles at a low density containing 8% lactose and trehalose in a ratio of 1:4 (8%-L-T) have a spherical shape, smooth surface morphology in the lyophilized state, a whorl-like structure, high entrapment efficiency, and deformability after reconstitution. Importantly, the integrity of IPC, as well as the secondary structure of insulin, were well protected. Accelerated stability studies demonstrated that 8%-L-T remained highly stable during storage for 6 months at 25 °C. Based on in vivo results, lyophilized IPC-DNVs retained their bioactivity and had good efficacy. Given the convenience of preparation and long term stability, the use of combined cryoprotectants in a proper ratio to protect stable nanovesicles indicates strong potential for industrial production.

Formulation of RNA interference-based drugs for pulmonary delivery: challenges and opportunities

With recent advances in the field of RNAi-based therapeutics, it is possible to make any target gene 'druggable', at least in principle. The present review focuses on aspects critical for pulmonary delivery of formulations of nucleic acid-based drugs. The first part introduces the therapeutic potential of RNAi-based drugs for the treatment of lung diseases. Subsequently, we discuss opportunities for formulation-enabled pulmonary delivery of RNAi drugs in light of key physicochemical properties and physiological barriers. In the following section, an overview is included of methodologies for imparting inhalable characteristics to nucleic acid formulations. Finally, we review one of the bottlenecks in the early preclinical testing of inhalable nucleic acid-based formulations, in other words, devices suitable for pulmonary administration of powder-based formulations in rodents.

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.

Moisture-Resistant Co-Spray-Dried Netilmicin with l-Leucine as Dry Powder Inhalation for the Treatment of Respiratory Infections

Netilmicin (NTM) is one of the first-line drugs for lower respiratory tract infections (LRTI) therapy, but its nephrotoxicity and ototoxicity caused by intravenous injection restrict its clinical application. Dry powder inhalation (DPI) is a popular local drug delivery system that is introduced as a solution. Due to the nature of NTM hygroscopicity that hinders its direct use through DPI, in this study, L-leucine (LL) was added into NTM dry powder to reduce its moisture absorption rate and improve its aerosolization performance. NTM DPIs were prepared using spray-drying with different LL proportions. The particle size, density, morphology, crystallinity, water content, hygroscopicity, antibacterial activity, in vitro aerosolization performance, and stability of each formulation were characterized. NTM DPIs were suitable for inhalation and amorphous with a corrugated surface. The analysis indicated that the water content and hygroscopicity were decreased with the addition of LL, whilst the antibacterial activity of NTM was maintained. The optimal formulation ND₂ (NTM:LL = 30:1) showed high fine particle fraction values (85.14 ± 8.97%), which was 2.78-fold those of ND₀ (100% NTM). It was stable after storage at 40 ± 2 °C, 75 ± 5% relative humidity (RH). The additional LL in NTM DPI successfully reduced the hygroscopicity and improved the aerosolization performance. NTM DPIs were proved to be a feasible and desirable approach for the treatment of LRTI.

Using two-fluid nozzle for spray freeze drying to produce porous powder formulation of naked siRNA for inhalation

Spray freeze drying is an attractive technology to produce powder formulation for inhalation. It can be used to generate large porous particles which tend to aerosolize efficiently and do not aggregate readily. It also avoids material to be exposed to elevated temperature. In this study, we reported the use of two-fluid nozzle to produce spray freeze dried powder of small interfering RNA (siRNA). The effect of atomization gas flow rate and liquid feed rate were inspected initially using herring sperm DNA (hsDNA) as nucleic acid model. The atomization gas flow rate was found to have a major impact on the aerosol properties. The higher the atomization gas flow rate, the smaller the particle size, the higher the fine particle fraction (FPF). In contrast, the liquid feed rate had very minor effect. Subsequently, spray freeze dried siRNA powder was produced at various atomization gas flow rates. The particles produced were highly porous as examined with the scanning electron microscopy, and the structural integrity of the siRNA was demonstrated with gel electrophoresis. The gene-silencing effect of the siRNA was also successfully preserved in vitro. The best performing siRNA formulation was prepared at the highest atomization gas flow rate investigated with a moderate FPF of 30%. However, this was significantly lower than that obtained with the corresponding hsDNA counterparts (FPF ∼57%). A direct comparison between the hsDNA and siRNA formulations revealed that the former exhibited a lower density, hence a smaller aerodynamic diameter despite similar geometric size.

Intratracheal Administration of siRNA Dry Powder Targeting Vascular Endothelial Growth Factor Inhibits Lung Tumor Growth in Mice

Inhalation therapy using small-interfering RNA (siRNA) is a potentially effective therapeutic strategy for lung cancer because of its high gene-silencing effects and sequence specificity. Previous studies reported that intratracheal administration of siRNA using pressurized metered dose inhalers or nebulizers could suppress tumor growth in murine lung metastatic models. Although dry powder inhalers are promising devices due to their low cost, good portability, and preservability, the anti-tumor effects of siRNA dry powder have not been elucidated. To evaluate the gene-silencing and anti-tumor effects of intratracheally delivered siRNA dry powder, vascular endothelial growth factor-specific siRNA (VEGF-siRNA) dry powder was administered intratracheally to mice with metastatic lung tumors consisting of B16F10 melanoma cells or Lewis lung carcinoma cells. A single intratracheal administration of VEGF-siRNA dry powder reduced VEGF levels in both bronchoalveolar lavage fluid and lung tumor tissue. Furthermore, repeated intratracheal administration of VEGF-siRNA dry powder suppressed the number of visible metastatic foci on the lung surface and tumor area in lung tissues. Taken together, intratracheal administration of siRNA dry powder could be a novel therapeutic strategy for lung cancer through the suppression of specific genes expressed in lung tumor tissue.

Development of spray-freeze-dried siRNA/PEI powder for inhalation with high aerosol performance and strong pulmonary gene silencing activity

In the present study, a novel dry small interfering RNA (siRNA) powder for inhalation, containing polyethyleneimine (PEI) as a delivery vector, was produced by spray freeze drying (SFD). The powder had spherical and highly porous structure of approximately 10 μm in diameter with high aerosol performance for emission and lung delivery. The reconstituted siRNA/PEI complex after dissolution of the powder had almost the same physicochemical properties and in vitro gene silencing activity as the original one constituted in the sample solution before SFD, showing that the integrity of the siRNA was maintained. In in vivo studies of intratracheal administration into lung metastasis mice and healthy mice, powder with a low dose of 3 μg siRNA exhibited strong and specific gene silencing activity against tumors metastasized to the lungs, whereas it caused no significant histological changes, lactate dehydrogenase leakage, or inflammatory cytokine induction in the lungs. These results strongly indicated that inhalable dry siRNA/PEI powders can provide effective pulmonary gene silencing without severe lung injury and that SFD can be applied to the production of such powders.

Development and evaluation of Chitosan nanoparticles based dry powder inhalation formulations of Prothionamide

Prothionamide (PTH), a second line antitubercular drug is used to administer in conventional oral route. However, its unpredictable absorption and frequent administration limit its use. An alternate approach was thought of administering PTH through pulmonary route in a form of nanoparticles, which can sustain the release for several hours in lungs. Chitosan, a bio-degradable polymer was used to coat PTH and further freeze dried to prepare dry powder inhaler (DPI) with aerodynamic particle size of 1.76μm. In vitro release study showed initial burst release followed by sustained release up to 96.91% in 24h. In vitro release further correlated with in vivo study. Prepared DPI maintained the PTH concentration above MIC for more than 12h after single dose administration and increased the PTH residency in the lungs tissue more than 24h. Animal study also revealed the reduction of dose in pulmonary administration, which will improve the management of tuberculosis.

[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.

Development of Dry Powder Inhaler Containing Prothionamide-PLGA Nanoparticles Optimized Through Statistical Design: In-vivo Study

Objective:

The objective of the present work was to formulate Prothionamide (PTH) nanoparticles using Poly lactic co-glycolic acid (PLGA), optimized by Box-Behnken Design and further modification to dry powder inhaler followed byin-vivostudy.

Methods:

Poly-lactic co-gycolic acid (PLGA), a biodegradable polymer was used to coat Prothionamide by solvent evaporation technique. Formulation was optimized using Box-Behnken Design. Response surface curve and desirability factors helped in the selection of optimum formulation of PTH nanoparticles. Dry powder inhaler was prepared by adding inhalable grade lactose to optimize PTH nanoparticles. Mass median aerodynamic diameter (MMAD) was carried out using Andersen Cascade Impactor (ACI) to demonstrate its suitability in the pulmonary administration.In-vitrodrug release of dry powder inhaler was carried out in simulated lungs fluid. Correlationin-vitrotoin-vivowas established after performing animal experiment.

Results:

FTIR study reveals no chemical interaction between PTH, lactose and PLGA as the principle peaks was retained with same intensity in the physical mixture. Scanning electron microscope showed the spherical shape and aerodynamic particle size was found to be 1.69µm. Drug release study showed initial burst release followed by zero order release.In-vivomodel confirmed the presence of PTH after 24h. Aerodynamic particle size and the release profile revealed the suitability of PTH loaded nanoparticles containing dry powder inhaler for the pulmonary administration.

Conclusion:

Prepared DPI containing PTH nanoparticles can improve in the management of tuberculosis by increasing PTH residency in the lungs tissue for prolong period of time.

Preservation of DNA Nanostructure Carriers: Effects of Freeze-Thawing and Ionic Strength during Lyophilization and Storage

DNA nanostructures have attracted wide interest in biomedical applications, especially as nanocarriers for drug delivery. Therefore, it is important to ensure the structural integrity of DNA nanostructures under ambient temperature storage. In this study, we examined lyophilization-based preservation of DNA nanostructures by investigating the structural integrity of different DNA nanostructures reconstituted from lyophilization. We demonstrated that lyophilization under appropriate ionic strength is amenable to the storage of DNA nanostructures. Compared with that stored in liquid solution, DNA nanostructure carriers reconstituted from lyophilization showed significantly better structural integrity after an accelerated aging test equivalent to 100-day room-temperature storage.

Comparative Study on Different Drying Methods of Fish Oil Microcapsules

Microencapsulation is widely used to minimize the oxidation of fish oil products. This study compared the effects of different drying methods, for example, spray drying (SD), freeze drying (FD), and spray freeze drying (SFD) on the microencapsulation of fish oil. Spray drying (SD) is the most common method for producing fish oil microcapsules, and it has low operation cost and short processing time, while the product yield and quality are poor. Freeze drying (FD) can be used to produce oil microcapsules with high quality, but it takes long time and high overall cost for drying. Spray freeze drying (SFD) is a new method for the preparation of microcapsules, which combines the SD and FD processes to obtain high quality powder. The yield of powder reached 95.07% along with porous structure by SFD. The stability and slow-release property of SFD products were better than those of SD and FD, which showed that SFD improved product storage stability and potential digestibility.

In vivo pharmacokinetics, biodistribution and the anti-tumor effect of cyclic RGD-modified doxorubicin-loaded polymers in tumor-bearing mice

In our previous study, we successfully produced and characterized a multifunctional drug delivery system with doxorubicin (RC/GO/DOX), which was based on graphene oxide (GO) and cyclic RGD-modified chitosan (RC). Its characteristics include: pH-responsiveness, active targeting of hepatocarcinoma cells, and efficient loading with controlled drug release. Here, we report the pharmacokinetics, biodistribution, and anti-tumor efficacy of RC/GO/DOX polymers in tumor-bearing nude mice. The objective of this study is to assess its targeting potential for tumors. Pharmacokinetic and biodistribution profiles demonstrated that tumor accumulation of RC/GO/DOX polymers was almost three times higher than the others, highlighting the efficacy of the active targeting strategy. Furthermore, the tumor inhibition rate of RC/GO/DOX polymers was 56.64%, 2.09 and 2.93 times higher than that of CS/GO/DOX polymers (without modification) and the DOX solution, respectively. Anti-tumor efficacy results indicated that the tumor growth was better controlled by RC/GO/DOX polymers than the others. Hematoxylin and eosin (H&E) staining showed remarkable changes in tumor histology. Compared with the saline group, the tumor section from the RC/GO/DOX group revealed a marked increase in the quantity of apoptotic and necrotic cells, and a reduction in the quantity of the blood vessels. Together, these studies show that this new system could be regarded as a suitable form of DOX-based treatment of the hepatocellular carcinoma.

Non-viral gene therapy: Gains and challenges of non-invasive administration methods

Gene therapy is becoming an influential part of the rapidly increasing armamentarium of biopharmaceuticals for improving health and combating diseases. Currently, three gene therapy treatments are approved by regulatory agencies. While these treatments utilize viral vectors, non-viral alternative technologies are also being developed to improve the safety profile and manufacturability of gene carrier formulations. We present an overview of gene-based therapies focusing on non-viral gene delivery systems and the genetic therapeutic tools that will further revolutionize medical treatment with primary focus on the range and development of non-invasive delivery systems for dermal, transdermal, ocular and pulmonary administrations and perspectives on other administration methods such as intranasal, oral, buccal, vaginal, rectal and otic delivery.