Inhalable budesonide porous microparticles tailored by spray freeze drying technique

A Comprehensive Review of the Latest Trends in Spray Freeze Drying and Comparative Insights with Conventional Technologies

Spray freeze drying (SFD) represents an emerging drying technique designed to produce a wide range of pharmaceuticals, foods, and active components with high quality and enhanced stability due to their unique structural characteristics. This method combines the advantages of the well-established techniques of freeze drying (FD) and spray drying (SD) while overcoming their challenges related to high process temperatures and durations. This is why SFD has experienced steady growth in recent years regarding not only the research interest, which is reflected by the increasing number of literature articles, but most importantly, the expanded market adoption, particularly in the pharmaceutical sector. Despite its potential, the high initial investment costs and complex operational requirements may hinder its growth. This paper provides a comprehensive review of the SFD technology, highlighting its advantages over conventional drying techniques and presenting its latest applications focused on pharmaceuticals. It also offers a thorough examination of the principles and the various parameters influencing the process for a better understanding and optimization of the process according to the needs of the final product. Finally, the current limitations of SFD are discussed, and future directions for addressing the economic and technical barriers are provided so that SFD can be widely industrialized, unlocking its full potential for diverse applications.

A Review on Micro and Nanoengineering in Powder-Based Pulmonary Drug Delivery

Pulmonary delivery of drugs has emerged as a promising approach for the treatment of both lung and systemic diseases. Compared to other drug delivery routes, inhalation offers numerous advantages including high targeting, fewer side effects, and a huge surface area for drug absorption. However, the deposition of drugs in the lungs can be limited by lung defence mechanisms such as mucociliary and macrophages' clearance. Among the delivery devices, dry powder inhalers represent the optimal choice due to their stability, ease of use, and absence of propellants. In the last decades, several bottom-up techniques have emerged over traditional milling to produce inhalable powders. Among these techniques, the most employed ones are spray drying, supercritical fluid technology, spray freeze-drying, and thin film freezing. Inhalable dry powders can be constituted by micronized drugs attached to a coarse carrier (e.g., lactose) or drugs embedded into a micro- or nanoparticle. Particulate-based formulations are commonly composed of polymeric micro- and nanoparticles, liposomes, solid lipid nanoparticles, dendrimers, nanocrystals, extracellular vesicles, and inorganic nanoparticles. Moreover, engineered formulations including large porous particles, swellable microparticles, nano-in-microparticles, and effervescent nanoparticles have been developed. Particle engineering has also a crucial role in tuning the physical-chemical properties of both carrier-based and carrier-free inhalable powders. This approach can increase powder flowability, deposition, and targeting by customising particle surface features.

Spray freeze drying to solidify Nanosuspension of Cefixime into inhalable microparticles

PURPOSE

Spray-freeze drying (SFD) incorporating diverse carbohydrates and leucine was employed to obtain dried nanosuspension of cefixime with improved dissolution profile, good dispersibility, and excellent inhalation performance.

METHODS

Nanoprecipitation was utilized to prepare nanoparticles (NPs). Nanosuspensions of cefixime were solidified via SFD to access inhalable microparticles. The aerosolization efficiencies were evaluated through twin stage impinger (TSI). Laser light scattering and scanning electron microscopy (SEM) provided assistance to determine the particle size/size distribution and morphology, respectively. Amorphous/ crystalline states of materials were examined via differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Release profiles of candidate preparations were evaluated.

RESULTS

The fine particle fraction (FPF) ranged from 18.96 ± 0.76 to 79.28 ± 0.45%. The highest value resulted from trehalose with NP/carrier ratio of 1:1 and leucine 20%. The particle size varied from 5.24 ± 0.97 to 10.17 ± 1.01 μm. The most and the least size distribution were achieved in mannitol and trehalose containing formulations, respectively. The majority of samples demonstrated ideally spherical morphology with diverse degrees of porosity and without needle-shaped structure. Percentages of release in F₇ and F₈ were 89.33 ± 0.88% and 93.54 ± 1.02%, respectively, via first 10 min.

CONCLUSION

SFD of nanosuspensions can be established as a platform for the pulmonary delivery of poorly water-soluble molecules of cefixime. Trehalose and raffinose with a lower ratio of NP to the carrier and higher level of leucine could be introduced as favorable formulations for further respiratory delivery of cefixime.

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.

Preparation and evaluation of vancomycin spray-dried powders for pulmonary delivery

The aim of the current study was to achieve a dry powder formulation of vancomycin by spray drying whilst evaluating the effect of pH and excipient type and percentage used in formulation on particle characteristics and aerosolization performance. A D-optimal design was applied to optimize the formulation comprising vancomycin and two main excipient groups; a carbohydrate bulking agent (lactose, mannitol or trehalose) and a second excipient (hydroxypropyl beta-cyclodextrin or L-leucine) at pH 4 and 7. The physicochemical properties of particles (size, morphology, crystallinity state, residual moisture content), stability, and aerosolization characteristics were investigated. Using the combination of two excipients increased the fine particle fraction of powder emitted from an Aerolizer^® device at a flow rate of 60 L/min. Hydroxypropyl beta-cyclodextrin showed more potential than L-leucine in aerosolization capabilities. Stability studies over 3 months of storage in 40 °C and 75% relative humidity suggested a good physical stability of the optimized formulation containing 17.39% hydroxypropyl beta-cyclodextrin along with 29.61% trehalose relative to the amount of drug at pH 4. Use of two excipients including trehalose and hydroxypropyl beta-cyclodextrin with a total weight ratio of 47% relative to the amount of drug is appropriate for the preparation of vancomycin dry powder formulation for inhalation.

Immunogenicity of glycine nanoparticles containing a chimeric antigen as Brucella vaccine candidate

Purpose

Brucellosis as a worldwide zoonotic illness affect domestic animals and humans doesn't have any vaccine for the prevention of infection in humans yet. The aim of this study was to evaluate the specific immune response following the administration of glycine nanoparticles as adjuvant and delivery system of a chimeric antigen contained trigger factor, Omp31, and Bp26 in murine model.

Materials and Methods

The chimeric antigen of Brucella was cloned and expressed in Escherichia coli (E. coli) BL21 (DE3). Purification and characterization of recombinant protein was conducted through Ni-NTA (nickel-nitrilotriacetic acid) agarose, SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis), and Western blot. Nanoparticle characteristics including morphology, particle size distribution, zeta potential, protein retention rate, and release rate were measured in vitro. Subsequently, nanoparticle contained antigen was administered to mice and blood sample was taken to measured the antibody level.

Results

The protein retention in the nanoparticles was successfully done and the nanoparticle characteristics were appropriate. The average size of glycine particles containing antigen was about 174 nm, and the absorption of protein was approximately 61.27% of the initial value, with a release rate of approximately 70% after 8 hours. Enzyme-linked immunosorbent assay result proved that the immunized sera of mice which were administered with nano-formula contains high levels of antibodies (immunoglobulin G) against recombinant chimeric antigen and also a high level of mucosal antibody (immunoglobulin A) in the oral group, which showed a desirable immunity against Brucella.

Conclusion

The results showed that chimeric antigen-loaded glycine nanoparticles can act as a vaccine candidate for inducing the cellular and humoral immune response against brucellosis.

Recent advances in the development of microparticles for pulmonary administration

Pulmonary drug delivery offers several benefits for the management of various conditions over other conventional routes. Inhalation of drugs can also be useful for targeting alveolar macrophages and for maintaining a higher drug concentration in the lung tissues to improve the efficacy of drugs and shorten the duration of treatment, thereby reducing drug toxicities. Thus, such an approach is useful in the treatment of various pulmonary and nonpulmonary diseases. Newer techniques and delivery devices have been used for the formulation of inhalable microparticles. Here. we not only focus on advances in inhalation therapy and in the preparation of microparticles, but also address the clinical development and regulatory aspects of such therapies.

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.

Supercritical Fluid-Assisted Porous Microspheres for Efficient Delivery of Insulin and Inhalation Therapy of Diabetes

Pulmonary delivery of drugs has attracted increasing attention in healthcare, as the lungs are an easily accessible site for noninvasive systemic delivery of drugs. Although pulmonary inhalation of porous microparticles has been shown to sustain drug delivery, there are limited reports on efficient delivery of insulin and inhalation therapy of diabetes based on supercritical carbon dioxide (SC-CO₂ ) technology. Herein, this study reports the fabrication of insulin-loaded poly-l-lactide porous microspheres (INS-PLLA PMs) by using the SC-CO₂ technology, and their use as an inhalation delivery system potentially for diabetes therapy. Biocompatibility and delivery efficiency of the PLLA PMs in the lungs are investigated. The PLLA PMs show negligible toxicity to lung-derived cells, resulting in no significant reduction in cell viability, as well as levels of various inflammatory mediators such as interleukin (IL)-6, IL-8, and tumor necrosis factor-α, compared with the negative control group. INS-PLLA PMs are further efficiently deposited in the trachea and the bronchi of superior lobes of the lungs, which exhibit pronounced hypoglycemic activity in induced diabetic rats. Together, the results demonstrate that the INS-PLLA PMs have a strong potential as an effective strategy for inhalation treatment of diabetes.

Supercritical Fluid-Assisted Decoration of Nanoparticles on Porous Microcontainers for Codelivery of Therapeutics and Inhalation Therapy of Diabetes

The impact of nanotechnology and its advancements have allowed us to explore new therapeutic modalities. To this end, we designed nanoparticles-inlaid porous microparticles (NIPMs) coloaded with small interfering RNA (siRNA) and glucagon-like peptide-1 (GLP-1) using the supercritical carbon dioxide (SC-CO₂) technology as an inhalation delivery system for diabetes therapy. siRNA-encapsulating chitosan (CS) nanoparticles were first synthesized by an ionic gelation method, which resulted in particles with small sizes (100-150 nm), high encapsulation efficiency (∼94.8%), and sustained release performance (∼60% in 32 h). These CS nanoparticles were then loaded with GLP-1-dispersed poly-l-lactide (PLLA) porous microparticles (PMs) by SC-CO₂-assisted precipitation with the compressed antisolvent (PCA) process. The hypoglycemic efficacy of NIPMs administered via pulmonary route in mice persisted longer due to sustained release of siRNA from CS nanoparticles and the synergistic effects of GLP-1 in PMs, which significantly inhibited the expression of dipeptidyl peptidase-4 mRNA (DPP-4-mRNA). This ecofriendly technology provides a convenient way to fabricate nanoparticle-microparticle composites for codelivery of a gene and a therapeutic peptide, which will potentially find widespread applications in the field of pharmaceutics.

Drying Technologies for the Stability and Bioavailability of Biopharmaceuticals

Solid dosage forms of biopharmaceuticals such as therapeutic proteins could provide enhanced bioavailability, improved storage stability, as well as expanded alternatives to parenteral administration. Although numerous drying methods have been used for preparing dried protein powders, choosing a suitable drying technique remains a challenge. In this review, the most frequent drying methods, such as freeze drying, spray drying, spray freeze drying, and supercritical fluid drying, for improving the stability and bioavailability of therapeutic proteins, are discussed. These technologies can prepare protein formulations for different applications as they produce particles with different sizes and morphologies. Proper drying methods are chosen, and the critical process parameters are optimized based on the proposed route of drug administration and the required pharmacokinetics. In an optimized drying procedure, the screening of formulations according to their protein properties is performed to prepare a stable protein formulation for various delivery systems, including pulmonary, nasal, and sustained-release applications.

A review on recent technologies for the manufacture of pulmonary drugs

This review discusses recent developments in the manufacture of inhalable dry powder formulations. Pulmonary drugs have distinct advantages compared with other drug administration routes. However, requirements of drugs properties complicate the manufacture. Control over crystallization to make particles with the desired properties in a single step is often infeasible, which calls for micronization techniques. Although spray drying produces particles in the desired size range, a stable solid state may not be attainable. Supercritical fluids may be used as a solvent or antisolvent, which significantly reduces solvent waste. Future directions include application areas such as biopharmaceuticals for dry powder inhalers and new processing strategies to improve the control over particle formation such as continuous manufacturing with in-line process analytical technologies.

Nanosizing techniques for improving bioavailability of drugs

The poor solubility of significant number of Active Pharmaceutical Ingredients (APIs) has become a major challenge in the drug development process. Drugs with poor solubility are difficult to formulate by conventional methods and often show poor bioavailability. In the last decade, attention has been focused on developing nanocrystals for poorly water soluble drugs using nanosizing techniques. Nanosizing is a pharmaceutical process that changes the size of a drug to the sub-micron range in an attempt to increase its surface area and consequently its dissolution rate and bioavailability. The effectiveness of nanocrystal drugs is evidenced by the fact that six FDA approved nanocrystal drugs are already on the market. The bioavailabilities of these preparations have been significantly improved compared to their conventional dosage forms. There are two main approaches for preparation of drug nanocrystals; these are the top-down and bottom-up techniques. Top-down techniques have been successfully used in both lab scale and commercial scale manufacture. Bottom-up approaches have not yet been used at a commercial level, however, these techniques have been found to produce narrow sized distribution nanocrystals using simple methods. Bottom-up techniques have been also used in combination with top-down processes to produce drug nanoparticles. The main aim of this review article is to discuss the various methods for nanosizing drugs to improve their bioavailabilities.

Large porous particles for respiratory drug delivery. Glycine-based formulations

Large porous particles are becoming increasingly popular as carriers for pulmonary drug delivery with both local and systemic applications. These particles have high geometric diameters (5-30μm) but low bulk density (~0.1g/cm³ or less) such that the aerodynamic diameter remains low (1-5μm). In this study salbutamol and budesonide serve as model inhalable drugs with poor water solubility. A novel method is proposed for the production of dry powder inhaler formulations with enhanced aerosol performance (e.g. for salbutamol-glycine formulation the fine particle fraction (FPF≤4.7μm) value is 67.0±1.3%) from substances that are poorly soluble in water. To overcome the problems related to extremely poor aqueous solubility of the APIs, not individual solvents are used for spray freeze-drying of API solutions, but organic-water mixtures, which can form clathrate hydrates at low temperatures and release APIs or their complexes as fine powders, which form large porous particles after the clathrates are removed by sublimation. Zwitterionic glycine has been used as an additive to API directly in solutions prior to spray freeze-drying, in order to prevent aggregation of powders, to enhance their dispersibility and improve air-flow properties. The clathrate-forming spray freeze-drying process in the multi-component system was optimized using low-temperature powder X-ray diffraction and thermal analysis.

Design and pharmaceutical applications of porous particles

Porous particles have been developed as a novel carrier to improve drug delivery, dissolution, tableting, and so on, which can be prepared by many methods.

Hydroxypropylcellulose as matrix carrier for novel cage-like microparticles prepared by spray-freeze-drying technology

The objective of this study is to design novel dissolution-enhanced microparticles loaded poorly soluble drug nanocrystals used a low viscosity of hydroxypropylcellulose (HPC) as matrix carrier. An interesting approach combined homogenization and the spray-freeze-drying technique was developed. The results demonstrated that the ratio of HPC to drug played an important role in size-reduction efficiency of drug during homogenization. And the formation of cage-like structure of the composite particles depended on ratio of HPC to drug. The spray-freeze-dried composite particles with HPC ratio of 1:2, 1:1 and 2:1 possessed excellent redispersibility, which attributed to its porous matrix and large surface area (3000m²/g). The dissolution of spray-freeze-dried composite particles with higher ratios of HPC (1:2 and 1:1) was significantly enhanced, which attributed to the particle size reduction of drug. The HPC could immobilize drug nanocrystals in its cage-like structure and prevent it from the subsequent agglomeration during storage. In conclusion, the prepared cage-like microparticles is a promising basis for further formulation development.

Amorphous powders for inhalation drug delivery

For inhalation drug delivery, amorphous powder formulations offer the benefits of increased bioavailability for poorly soluble drugs, improved biochemical stability for biologics, and expanded options of using various drugs and their combinations. However, amorphous formulations usually have poor physicochemical stability. This review focuses on inhalable amorphous powders, including the production methods, the active pharmaceutical ingredients and the excipients with a highlight on stabilization of the particles.