Spray-drying nanocapsules in presence of colloidal silica as drying auxiliary agent: formulation and process variables optimization using experimental designs

Mediation of synergistic chemotherapy and gene therapy via nanoparticles based on chitosan and ionic polysaccharides

Nanoparticles (NPs)-based on various ionic polysaccharides, including chitosan, hyaluronic acid, and alginate have been frequently summarized for controlled release applications, however, most of the published reviews, to our knowledge, focused on the delivery of a single therapeutic agent. A comprehensive summarization of the co-delivery of multiple therapeutic agents by the ionic polysaccharides-based NPs, especially on the optimization of the polysaccharide structure for overcoming various extracellular and intracellular barriers toward maximized synergistic effects, to our knowledge, has been rarely explored so far. For this purpose, the strategies used for overcoming various extracellular and intracellular barriers in vivo were introduced first to provide guidance for the rational design of ionic polysaccharides-based NPs with desired features, including long-term circulation, enhanced cellular internalization, controllable drug/gene release, endosomal escape and improved nucleus localization. Next, four preparation strategies were summarized including three physical methods of polyelectrolyte complexation, ionic crosslinking, and self-assembly and a chemical conjugation approach. The challenges and future trends of this rapidly developing field were finally discussed in the concluding remarks. The important guidelines on the rational design of ionic polysaccharides-based NPs for maximized synergistic efficiency drawn in this review will promote the future generation and clinical translation of polysaccharides-based NPs for cancer therapy.

Optimization of Particle Properties of Nanocrystalline Solid Dispersion Based Dry Powder for Inhalation of Voriconazole

A one-step spray drying based process was employed to generate ready-to-use nanocrystalline solid dispersion (NCSD) dry powder for inhalation (DPI) of voriconazole (VRC). The solid dispersion was prepared by spray drying VRC, MAN (mannitol) and soya lecithin (LEC) from mixture of methanol-water. Various formulation and process related parameters were screened, including LEC, inlet temperature, total solid content and feed flow rate to generate particles of geometric size ≤5 µm. Aerosil® 200 was explored as the quaternary excipient either during spray drying or by physically mixing with the optimized ternary NCSD. The powders were extensively characterized for solid form, primary particle size, assay, embedded nanocrystal size, morphology, porosity, density and moisture content. Aerodynamic properties were studied using next generation impactor (NGI), while surface elemental composition and topography were investigated using SEM-EDS (scanning electron microscopy- energy dispersive spectroscopy) and AFM (atomic force microscopy), respectively. At selected inlet temperature of 120 ˚C, total solid content and feed flow rate significantly impacted the size of primary NCSD particles. Size of primary particles increased with increase in total solid content and feed flow rate of the solution. VRC nanocrystals were obtained in polymorphic Form B whereas the matrix of MAN consisted of mixture of polymorphic Forms α, β and δ. SEM-EDS analysis confirmed deposition of Aerosil® 200 on surface of spray dried particles. In addition to increased porosity and reduced density, increase in surface roughness of particles (evident from AFM topographic analysis) contributed to enhanced powder deposition at stages 3 and 4 in NGI. In comparison, physical blending of NCSD with Aerosil® 200 showed improvement in aerosolization due to flow enhancement property.

Characterization of nanoparticles made of ethyl cellulose and stabilizing lipids: Mode of manufacturing, size modulation, and study of their effect on keratinocytes

We have developed an ethyl cellulose-based nanoparticulate system for encapsulation of sparingly soluble active pharmaceutical ingredients. Cannabidiol (CBD) and curcumin (CUR) were selected as model active ingredients. Using the nanoprecipitation method, nanoparticles ranged between 150 nm and 250 nm were obtained with an entrapment efficiency of >80%. It has been shown that incorporation of stabilizing lipids significantly reduced aggregation, increased the yield and the active ingredient-to-polymer ratio. In this study, we have explored the influence of process parameters on the extent of new particle core formation: chemical properties of the active ingredients, polymer concentrations, non-solvent addition rate, and the volume of the organic solvent for nanoparticle size control. The relationship between the particle radius [R] and the polymer concentration [Pol] was defined by R ∝ [Pol]ⁿ when n < ⅓. The extent of polymer supersaturation was related to the value of n, when the high polymer supersaturation increased the formation rate of new particle cores while decreasing polymer layering on the existing cores and the nanoparticles size. The obtained nanoparticles have shown low toxicity in keratinocytes, however, higher loadings of CUR or CBD resulted in increased toxicity. The nanoparticles effectively internalized into keratinocytes, implying their applicability for dermal delivery.

Lyophilization of Nanocapsules: Instability Sources, Formulation and Process Parameters

Polymeric nanocapsules have gained more and more interest in the medical sciences. Their core-shell structure offers numerous advantages, especially regarding their use as drug delivery systems. This review begins by presenting the different intrinsic sources of the instability of nanocapsules. The physical and chemical potential instabilities of nanocapsules reduce their shelf-life and constitute a barrier to their clinical use and to their commercialization. To overcome these issues, lyophilization is often used as a process of choice in the pharmaceutical industry especially when labile compounds are used. The state of the art of lyophilization nanocapsules is reviewed. The formulation properties and the process parameters are discussed for a complete understanding of their impact on the stability and storage of the final dried product. To assess the quality of the dried product, various characterization methods are also discussed.

Evaluation of the microencapsulation of orange essential oil in biopolymers by using a spray-drying process

Essential oils are volatile compounds commonly used by several industries, easily degradable, which restrains their applications. Therefore, we developed and validated a methodology for producing microcapsules loaded with orange essential oil, using a spray-drying process. The experimental design results showed that the combination between a low flow transfer rate (0.15 L h⁻¹) of the colloidal suspension, a higher drying air flow rate (536 L h⁻¹), and an inlet air temperature of 150 °C to the spray-dryer were the most important parameters for the atomization efficiency. The method optimization resulted in microcapsules with powder recovery between 7.6 and 79.9% (w w⁻¹), oil content ranging from 8.9 to 90.4% (w w⁻¹), encapsulation efficiency between 5.7 and 97.0% (w w⁻¹), and particle sizes with a high frequency of distribution less than 4 μm. In these experiments, gelatin and lignin were evaluated as biopolymers of encapsulation. We also developed an analytical method using headspace gas chromatography. The matrix effects could be addressed by using matrix-matched calibration curves. The chromatographic analysis was linear and selective for d-limonene between 0.025 and 3.00 µg mL⁻¹, with correlation coefficients higher than 0.99. The analytical method had limits of detection and quantitation of 0.024 and 0.073 mg g⁻¹ for gelatin and 0.039 and 0.119 mg g⁻¹ for lignin, respectively.

Design and Characterization of Spray-Dried Chitosan-Naltrexone Microspheres for Microneedle-Assisted Transdermal Delivery

Naltrexone (NTX) hydrochloride is a potent opioid antagonist with significant first-pass metabolism and notable untoward effects when administered orally or intramuscularly. Microneedle (MN)-assisted transdermal delivery is an attractive alternative that can improve therapeutic delivery to deeper skin layers. In this study, chitosan-NTX microspheres were developed via spray-drying, and their potential for transdermal NTX delivery in association with MN skin treatment was assessed. A quality-by-design approach was used to evaluate the impact of key input variables (chitosan molecular weight, concentration, chitosan-NTX ratio, and feed flow rate) on microsphere physical characteristics, encapsulation efficiency, and drug-loading capacity. Formulated microspheres had high encapsulation efficiencies (70%-87%), with drug-loading capacities ranging from 10%-43%. NTX flux through MN-treated skin was 11.6 ± 2.2 µg/cm²·h from chitosan-NTX microspheres, which was significantly higher than flux across intact skin. Combining MN-assisted delivery with the chitosan microsphere formulation enabled NTX delivery across the skin barrier, while controlling the dose released to the skin.

Dry powder aerosols to co-deliver antibiotics and nutrient dispersion compounds for enhanced bacterial biofilm eradication

The purpose of this study was to formulate a dry powder for inhalation containing a combination treatment for eradication of Pseudomonas aeruginosa bacterial biofilms. Dry powders containing an antibiotic (ciprofloxacin hydrochloride, CH) and nutrient dispersion compound (glutamic acid, GA) at a ratio determined to eliminate the biofilms were generated by spray drying. Leucine was added to the spray dried formulation to aid powder flowability. A central composite design of experiments was performed to determine the effects of solution and processing parameters on powder yield and aerodynamic properties. Combinations of CH and GA eradicated bacterial biofilms at lower antibiotic concentrations compared to CH alone. Spray dried powders were produced with yields up to 43% and mass mean aerodynamic diameters (MMAD) in the respirable range. Powder yield was primarily affected by variables that determine cyclone efficiency, i.e. atomizer and solution flow rates and solution concentration; while MMAD was mainly determined by solution concentration. Fine particle fractions (FPF)<4.46μm and <2.82μm of the powders ranged from 56 to 70% and 35 to 46%, respectively. This study demonstrates that dry powder aerosols containing high concentrations of a combination treatment effective against P. aeruginosa biofilms could be developed with high yield, aerodynamic properties appropriate for inhalation, and no loss of potency.

Spray drying formulation of amorphous solid dispersions

Spray drying is a well-established manufacturing technique which can be used to formulate amorphous solid dispersions (ASDs) which is an effective strategy to deliver poorly water soluble drugs (PWSDs). However, the inherently complex nature of the spray drying process coupled with specific characteristics of ASDs makes it an interesting area to explore. Numerous diverse factors interact in an inter-dependent manner to determine the final product properties. This review discusses the basic background of ASDs, various formulation and process variables influencing the critical quality attributes (CQAs) of the ASDs and aspects of downstream processing. Also various aspects of spray drying such as instrumentation, thermodynamics, drying kinetics, particle formation process and scale-up challenges are included. Recent advances in the spray-based drying techniques are mentioned along with some future avenues where major research thrust is needed.

Combining a flow reactor with spray dryer to allow the preparation of food-grade quality sodium 2-polyhydroxyalkyl-1,3-thiazolidine-4-carboxylates with a low environmental impact

The 1,3-thiazolidine-4-carboxylic acid (TCA) and 2-substituted 1,3-thiazolidine-4-carboxylic acids (2S-TCAs) are used as additive prodrugs of cysteine and glutathione in agronomy and in the food and pharmaceutical industries.

Surfactant-free redispersible nanoparticles in fast-dissolving composite microcarriers for dry-powder inhalation

Spray-drying was investigated for the stabilization of surfactant-free nanoparticles as carriers for dry-powder inhalers. The microparticles rapidly dissolve after inhalation yielding dispersed nanoparticles. Nanoparticles were prepared by a solvent displacement technique avoiding any surfactants. Microcarriers were prepared by spray-drying nanoparticle suspensions with lactose, mannitol or α-cyclodextrin as stabilizers. Nanoparticle size and ζ-potential before and after spray-drying were analyzed with photon correlation spectroscopy and laser Doppler anemometry, respectively. Cell uptake into macrophages was studied using U 937 cells by confocal microscopy. Stabilization of nanoparticle suspensions by spray-drying with α-cyclodextrin yielded redispersible particles smaller than 200 nm. α-Cyclodextrin was a more efficient stabilizer than commonly used excipients. Microparticles with a mass median aerodynamic diameter of 4.3 μm showed properties suitable for dry-powder inhalation. The cell culture experiments with redispersed nanoparticles seem to suggest less interaction and uptake with macrophages compared to polymeric microparticles. In conclusion, nanoparticles can easily be transferred to dry-powders suitable for inhalation by spray-drying. This allows the pulmonary application of nanoparticles in high concentrations.

Scaling up the spray drying process from pilot to production scale using an atomized droplet size criterion

PURPOSE

The purpose of this study was to investigate the possibility of producing identical powders in pilot and production scale spray drying equipment by matching the droplet size distributions produced by two differently sized atomizers.

METHODS

Particles were prepared by spray drying solutions of acetaminophen and polyvinylpyrrolidone K-30. The success of the up-scaling was evaluated by comparing the powders in terms of particle size distribution (laser diffraction), crystallinity (XPRD) and morphology (SEM). Furthermore, the influence of process parameters on other product characteristics such as stability and residual volatile content was also evaluated.

RESULTS

The spray drying experiments resulted in spherical, amorphous particles with volumetric median diameters of typically 4-10 microm for pilot scale and 4-30 microm for production scale. The results showed that particles with similar morphology and crystallinity could be produced in the two applied spray dryers. However, scale-up based purely on matching droplet size distributions was not feasible.

CONCLUSIONS

The scale-up criterion did not account for the differences between the droplet-drying gas mixing and residence time distribution within the two spray dryers. Therefore, production scale experiments are required in order to obtain similar product characteristics as in pilot scale.

Pharmaceutical particle engineering via spray drying

This review covers recent developments in the area of particle engineering via spray drying. The last decade has seen a shift from empirical formulation efforts to an engineering approach based on a better understanding of particle formation in the spray drying process. Microparticles with nanoscale substructures can now be designed and their functionality has contributed significantly to stability and efficacy of the particulate dosage form. The review provides concepts and a theoretical framework for particle design calculations. It reviews experimental research into parameters that influence particle formation. A classification based on dimensionless numbers is presented that can be used to estimate how excipient properties in combination with process parameters influence the morphology of the engineered particles. A wide range of pharmaceutical application examples—low density particles, composite particles, microencapsulation, and glass stabilization—is discussed, with specific emphasis on the underlying particle formation mechanisms and design concepts.