Stability of chitosan–pDNA complex powder prepared by supercritical carbon dioxide process

Single step nanospray drying preparation technique of gabapentin-loaded nanoparticles-mediated brain delivery for effective treatment of PTZ-induced seizures

In the present study, gabapentin (GBP)-loaded chitosan nanosized particles were fabricated applying the nanospray drying technique. Different preparation parameters (spray mesh diameter, chitosan concentration and presence of D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) were studied while fixing other parameters (spraying rate, inlet temperature and gas flow rate). An optimized formulation with a particle size 107 ± 13 nm was obtained upon spraying 0.1% (w/v) chitosan solution containing 0.05% (w/v) of TPGS utilizing the small nozzle (4 μm spray mesh hole size). Drug entrapment efficiency and yield were as high as 95% and 83%, respectively. A 98.1 ± 6.1% (w/w) cumulative drug release was recorded after 2 h. Confocal laser scanning microscopy showed higher fluorescent dye penetration into brain tissue following intranasal administration of Rhodamine B labeled spray dried chitosan nanoparticles (NPs) as compared to Rhodamine B solution. Pentylenetetrazole (PTZ) was used to induce convulsions in rats through elevating seizure stages, releasing neuroinflammatory mediators and reducing excitatory amino acid transporter 2 (EAAT 2) and γ-aminobutyric acid (GABA) brain contents. Nanospray dried GBP-loaded chitosan NPs reduced seizure score, neuroinflammation; TNF-α and TGF-β, elevated EAAT 2 and GABA as well as decreased degeneration in pyramidal neurons compared to marketed product Conventin® capsules. Thus, it can be concluded from the aforementioned data that nanospray dried GBP-loaded chitosan NPs could comprise an appropriate treatment of epilepsy.

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.

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.

Inhaled Micro/Nanoparticulate Anticancer Drug Formulations: An Emerging Targeted Drug Delivery Strategy for Lung Cancers

Local delivery of drug to the target organ via inhalation offers enormous benefits in the management of many diseases. Lung cancer is the most common of all cancers and it is the leading cause of death worldwide. Currently available treatment systems (intravenous or oral drug delivery) are not efficient in accumulating the delivered drug into the target tumor cells and are usually associated with various systemic and dose-related adverse effects. The pulmonary drug delivery technology would enable preferential accumulation of drug within the cancer cell and thus be superior to intravenous and oral delivery in reducing cancer cell proliferation and minimising the systemic adverse effects. Site-specific drug delivery via inhalation for the treatment of lung cancer is both feasible and efficient. The inhaled drug delivery system is non-invasive, produces high bioavailability at a low dose and avoids first pass metabolism of the delivered drug. Various anticancer drugs including chemotherapeutics, proteins and genes have been investigated for inhalation in lung cancers with significant outcomes. Pulmonary delivery of drugs from dry powder inhaler (DPI) formulation is stable and has high patient compliance. Herein, we report the potential of pulmonary drug delivery from dry powder inhaler (DPI) formulations inhibiting lung cancer cell proliferation at very low dose with reduced unwanted adverse effects.

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.

Supercritical Fluid Technology: An Emphasis on Drug Delivery and Related Biomedical Applications

During the past few decades, supercritical fluid (SCF) has emerged as an effective alternative for many traditional pharmaceutical manufacturing processes. Operating active pharmaceutical ingredients (APIs) alone or in combination with various biodegradable polymeric carriers in high-pressure conditions provides enhanced features with respect to their physical properties such as bioavailability enhancement, is of relevance to the application of SCF in the pharmaceutical industry. Herein, recent advances in drug delivery systems manufactured using the SCF technology are reviewed. We provide a brief description of the history, principle, and various preparation methods involved in the SCF technology. Next, we aim to give a brief overview, which provides an emphasis and discussion of recent reports using supercritical carbon dioxide (SC-CO2 ) for fabrication of polymeric carriers, for applications in areas related to drug delivery, tissue engineering, bio-imaging, and other biomedical applications. We finally summarize with perspectives.

Recent advances in chitosan-based nanoparticulate pulmonary drug delivery

The advent of biodegradable polymer-encapsulated drug nanoparticles has made the pulmonary route of administration an exciting area of drug delivery research. Chitosan, a natural biodegradable and biocompatible polysaccharide has received enormous attention as a carrier for drug delivery. Recently, nanoparticles of chitosan (CS) and its synthetic derivatives have been investigated for the encapsulation and delivery of many drugs with improved targeting and controlled release. Herein, recent advances in the preparation and use of micro-/nanoparticles of chitosan and its derivatives for pulmonary delivery of various therapeutic agents (drugs, genes, vaccines) are reviewed. Although chitosan has wide applications in terms of formulations and routes of drug delivery, this review is focused on pulmonary delivery of drug-encapsulated nanoparticles of chitosan and its derivatives. In addition, the controversial toxicological effects of chitosan nanoparticles for lung delivery will also be discussed.

Stability studies of chitosan-DNA-FAP-B nanoparticles for gene delivery to lung epithelial cells

A successful gene delivery system requires efficiency and stability during storage. Stability studies are imperative for nanomedicines containing biotechnological products such as plasmids and targeting peptides. Chitosan-DNA-FAP-B nanoparticles are novel non-viral vectors for specific gene delivery to the lung epithelial cells. In this study, the storage stability of chitosan-DNA-FAP-B nanoparticles at -20, 5 and 24 °C was examined. Size, zeta potential and transfection efficiency of these nano-particles in storage were also evaluated. Stability studies showed that chitosan-DNA-FAP-B nanoparticles were stable after 1 month when stored at -20 °C and retained their initial size, zeta potential and transfection efficiency. However, their stability was not desirable at 5 and 24 °C. Based on these results, it can be concluded that chitosan-DNA-FAP-B nanoparticles can be a promising candidate for gene delivery to lung epithelial cells with good storage stability at -20 °C during 1 month.

Pulmonary gene delivery using polymeric nonviral vectors

Pulmonary delivery provides an easy and well tolerated means of access for the administration of biomacromolecules to the pulmonary epithelium and could therefore be an attractive approach for local and systemic therapies. A growing number of reports, which are summarized in this review, mirror the viability of pulmonary gene delivery. Special attention has been paid to the biological barriers in the lung that must be overcome for successful delivery, and which can be divided into anatomic, physical, immunologic, and metabolic barriers. In light of these barriers, successful nonviral polymer-based formulations of therapeutic genes are presented depending on the chemical nature of the polymer. In addition to polyethyleneimine-based nonviral vectors, which have been most intensively studied for pulmonary gene delivery in the past, other polymeric, dendritic, and targeted materials are also described here, including novel and biodegradable polymers. As new materials need in vitro or ex vivo testing before in vivo application, sophisticated models for all three approaches have been illustrated. Although pulmonary siRNA delivery enjoys popularity in clinical trials, pulmonary gene delivery has so far not been translated into clinical applications. With this review, potential hurdles are demonstrated, but novel approaches that may lead to optimized systems are described as well.

Propellant-based inhalers for the non-invasive delivery of genes via oral inhalation

In this work we describe the development of a propellant-based, portable oral inhalation platform for the pulmonary delivery of genes. A core-shell strategy is utilized to efficiently disperse cationic-polymer-DNA nanoparticles in hydrofluoroalkane propellants, and to generate aerosols from the corresponding pressurized metered-dose inhaler formulations (pMDIs) that have excellent aerosol characteristics, suitable for deep lung deposition. The engineered polyplexes and core-shell structures were fully characterized, and their ability to transfect model lung alveolar epithelium cells in vitro was demonstrated. We also show that the propellant does not affect the biological activity of the plasmid DNA, and that the core-shell formulations have no in vitro cytotoxicity. The relevance of this work stems from the fact that pMDIs are the least expensive and most widely used portable oral inhalation devices, and are thus promising platforms for targeting genes to the lungs for the treatment of medically relevant diseases including asthma, cystic fibrosis, chronic obstructive pulmonary disease, and lung cancer.

Surface characterisation of bioadhesive PLGA/chitosan microparticles produced by supercritical fluid technology

PURPOSE

Novel biodegradable and mucoadhesive PLGA/chitosan microparticles with the potential for use as a controlled release gastroretentive system were manufactured using supercritical CO(2) (scCO(2)) by the Particle Gas Saturated System (PGSS) technique (also called CriticalMix(TM)).

METHODS

Microparticles were produced from PLGA with the addition of mPEG and chitosan in the absence of organic solvents, surfactants and crosslinkers using the PGSS technique. Microparticle formulations were morphologically characterized by scanning electron microscope; particle size distribution was measured using laser diffraction. Microparticle surface was analyzed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to evaluate the presence of chitosan on the surface. Mucoadhesiveness of the microparticles was evaluated in vitro using a mucin assay employing two different kinds of mucin (Mucin type III and I-S) with different degrees of sialic acid contents, 0.5-1.5% and 9-17%, respectively.

RESULTS

The two analytical surface techniques (XPS and ToF-SIMS) demonstrated the presence of the chitosan on the surface of the particles (<100 μm), dependent on the polymer composition of the microparticles. The interaction between the mucin solutions and the PLGA/chitosan microparticles increased significantly with an increasing concentration of mucin and chitosan.

CONCLUSIONS

The strong interaction of mucin with the chitosan present on the surface of the particles suggests a potential use of the mucoadhesive carriers for gastroretentive and oral controlled drug release.

Chitosan-based formulations for delivery of DNA and siRNA

Among non-viral vectors, chitosan and chitosan derivatives have been developed in vitro and in vivo for DNA and siRNA delivery systems because of their cationic charge, biodegradability and biocompatibility, as well as their mucoadhesive and permeability-enhancing properties. However, the transfection efficiency of chitosan is too low for clinical application. Studies indicated that the transfection efficiency depends on a series of chitosan-based formulation parameters, such as the Mw of chitosan, its degree of deacetylation, the charge ratio of chitosan to DNA/siRNA (N/P ratio), the chitosan salt form used, the DNA/siRNA concentration, pH, serum, additives, preparation techniques of chitosan/nucleic acid particles and routes of administration. In this paper, chitosan-based formulations for the delivery of DNA and siRNA were reviewed to facilitate the process of chitosan vector development for clinical application. In addition to formulation optimization, chitosan structure modification or additive incorporation is an effective way to improve the stability of the polyplex in biological fluids, enhance targeted cell delivery and facilitate endo-lysosomal release of the complex. In summary, the transfection efficiency of chitosan-based delivery systems can be adjusted by changing formulation-related parameters.

Micronization and Polymorphic Conversion of Tolbutamide and Barbital by Rapid Expansion of Supercritical Solutions

Rapid expansion of supercritical solutions (RESS) was applied to tolbutamide and barbital. The solubility in supercritical CO2 was determined to estimate the extraction efficiency roughly by a simple method and accurately by a direct spectrophotometric technique. The latter revealed that the solubility of tolbutamide was a function of applied pressure and temperature and was proportional to the pressure. No significant difference in solubility between polymorphic Forms I and II of tolbutamide was detected. Tolbutamide and barbital particles produced by the RESS were characterized by size distribution measurement, polymorph identification and morphological evaluation. Significant size reduction to micron or sub-micron level with narrow size distribution was achieved, while conventional mechanical grinding had only slight effect. The particle size was greatly affected by both extraction and expansion conditions. The lower the extraction temperature was, the smaller was the mean particle size. Higher extraction pressure resulted in smaller mean particle size when compared at the same extraction temperature. The mean particle size was reduced by lowering the spray nozzle temperature, by lowering the expansion chamber temperature, by increasing the CO2 amount per spray, and by increasing the exhaust gas flow rate. The RESS processing realized the polymorphic conversion as well. As for tolbutamide, three polymorphs (Forms I, II, and IV) out of four could be produced by changing the extraction conditions, and in the case of barbital, one polymorph (Form II) out of three was produced consistently.

Application of supercritical fluid to preparation of powders of high-molecular weight drugs for inhalation

The application of supercritical carbon dioxide to particle design has recently emerged as a promising way to produce powders of macromolecules such as proteins and genes. Recently, an insulin powder for inhalation was approved by authorities in Europe and the USA. Other macromolecules for inhalation therapy will follow. In the 1990s proteins were precipitated with supercritical CO(2) from solutions in an organic solvent such as dimethylsulfoxide, which caused significant unfolding of protein. Since 2000, aqueous solutions of proteins and genes have generally been used with a cosolvent such as ethanol to precipitate in CO(2). Operating conditions such as temperature, pressure, flow rates, and concentration of ingredients affect the particle size and integrity of proteins or genes. By optimizing these conditions, the precipitation of proteins and genes with supercritical CO(2) is a promising way to produce protein and gene particles for inhalation.

Biodegradable particle formation for drug and gene delivery using supercritical fluid and dense gas

Recent developments in biodegradable particle formation using supercritical fluids and dense gases have been reviewed with an emphasis on studies of micronizing and encapsulating poorly-soluble pharmaceuticals and gene. General review articles published in previous years have then been provided. A brief description of the operating principles of some types of particle formation processes is given. These include the rapid expansion of supercritical solutions (RESS), the particles from gas-saturated solution (PGSS) processes, the gas antisolvent process (GAS), and the supercritical antisolvent process (SAS). The papers have been reviewed under two groups, one involving the production of particles from pure biodegradable substances, and the other involving coating, capsule, and impregnation that contain active components, especially those that relate to pharmaceuticals. This review is a comprehensive review specifically focused on the formation of biodegradable particles for drug and gene delivery system using supercritical fluid and dense gas.

Supercritical carbon dioxide processing of active pharmaceutical ingredients for polymorphic control and for complex formation

Supercritical fluid technique have been exploited in extraction, separation and crystallization processes. In the field of pharmaceutics, supercritical carbon dioxide (scCO(2)) has been used for the purpose of micronization, polymorphic control, and preparation of solid dispersion and complexes. Particle design of active pharmaceutical ingredients is important to make the solid dosage forms with suitable physicochemical properties. Control of the characteristic properties of particles, such as size, shape, crystal structure and morphology is required to optimize the formulation. For solubility enhancement of poorly water-soluble drugs, preparation of the solid dispersion or the complexation with proper drugs or excipients should be a promising approach. This review focuses on aspects of polymorphic control and complexation behavior of active pharmaceutical ingredients by scCO(2) processing.

Preparation of Polymeric Submicron Particle-Containing Microparticles Using a 4-Fluid Nozzle Spray Drier

PURPOSE

We studied a novel method for preparing polymeric submicron particle-containing microparticles using a 4-fluid nozzle spray drier.

METHOD

Ethylcellulose (EC) and poly(lactic-co-glycolic acid) (PLGA), either alone or in combination with polyethylenimine (PEI), were used as polymers to produce submicron particles, and mannitol (MAN) was used as a water-soluble carrier for the microparticles. The polymer and MAN solutions were supplied through different liquid passages of a 4-fluid nozzle and then dried to obtain MAN microparticles containing EC or PLGA submicron particles. The polymer/MAN ratio was controlled by changing the concentration of the polymer and MAN solutions. EC or PLGA microparticles were observed via scanning electron microscopy, and the size of microparticles was determined by image analysis. The particle size distribution of EC or PLGA submicron particles was measured with a super dynamic light scattering spectrophotometer.

RESULTS

The method generated submicron-sized (<1 microm) particles of EC and PLGA. The mean diameters of EC and PLGA particles at a polymer/MAN ratio of 1:10 were 631 and 490 nm, respectively. The mean diameter of PLGA particles decreased as the PLGA/MAN ratio was reduced, reaching approximately 200 nm at a PLGA/MAN ratio of 1:100. The mean diameter of PLGA/PEI particles at PLGA/PEI/MAN ratios of 1:0.5:10 and 1:0.5:100 were 525 and 223 nm, respectively, and their zeta potentials were +50.8 and +58.2 mV, respectively. The size of EC submicron particles could be controlled by varying the spray conditions.

CONCLUSIONS

This study demonstrated that it is possible to prepare polymeric submicron particles dispersed in MAN microparticles in a single process using the 4-fluid nozzle spray drying method. Cationic PLGA particles with a diameter of approximately 200 nm could be prepared by adding PEI, suggesting the possibility of its use as a carrier for delivering DNA into cells. The precipitation of EC may occur by the mutual dispersion and mixing of solvents after collision of EC and MAN mists by antisolvent effect, thereby producing MAN microparticles containing EC submicron particles.

Particle engineering techniques for inhaled biopharmaceuticals

Formulation of biopharmaceuticals for pulmonary delivery is faced with the challenge of producing particles with the optimal properties for deep lung deposition without altering the native conformation of these molecules. Traditional techniques such as milling are continuously being improved while newer and more advanced techniques such as spray drying, spray freeze drying and supercritical fluid technology are being developed so as to optimize pulmonary delivery of biopharmaceuticals. While some of these techniques are quite promising, some are harsh and impracticable. Method scale up, cost-effectiveness and safety issues are important factors to be considered in the choice of a technique. This paper reviews the presently developed techniques for particle engineering biopharmaceuticals.

Micronization of Phenylbutazone by Rapid Expansion of Supercritical CO2 Solution

Rapid expansion of supercritical solutions (RESS) technique was applied for the preparation of phenylbutazone fine particles. The operating temperature and pressure affected the yield of the drug fine particles, which was evaluated by dissolving the sprayed product of drug into ethanol. Effect of pre- and post-expansion conditions on the particle size distribution of phenylbutazone was investigated and the smallest sample (mean particle size: 1.59 microm) was obtained when the RESS method was operated at a pressure of 26 MPa combined with a temperature of 32 degrees C. Physicochemical properties of the fine particles were investigated by powder X-ray diffraction and differential scanning calorimetry. It was found that the phenylbutazone fine particles obtained were meta-stable beta form under the experimental conditions tested, suggesting polymorphic transformation during the RESS process.