The influence of mannitol on morphology and disintegration of spray-dried nano-embedded microparticles

Nano-Formulations for Pulmonary Delivery: Past, Present, and Future Perspectives

With the development of nanotechnology and confronting the problems of traditional pharmaceutical formulations in treating lung diseases, inhalable nano-formulations have attracted interest. Inhalable nano-formulations for treating lung diseases allow for precise pulmonary drug delivery, overcoming physiological barriers, improving aerosol lung deposition rates, and increasing drug bioavailability. They are expected to solve the difficulties faced in treating lung diseases. However, limited success has been recorded in the industrialization translation of inhalable nano-formulations. Only one relevant product has been approved by the FDA to date, suggesting that there are still many issues to be resolved in the clinical application of inhalable nano-formulations. These systems are characterized by a dependence on inhalation devices, while the adaptability of device formulation is still inconclusive, which is the most important issue impeding translational research. In this review, we categorized various inhalable nano-formulations, summarized the advantages of inhalable nano-formulations over conventional inhalation formulations, and listed the inhalable nano-formulations undergoing clinical studies. We focused on the influence of inhalation devices on nano-formulations and analyzed their adaptability. After extensive analysis of the drug delivery mechanisms, technical processes, and limitations of different inhalation devices, we concluded that vibrating mesh nebulizers might be most suitable for delivering inhalable nano-formulations, and related examples were introduced to validate our view. Finally, we presented the challenges and outlook for future development. We anticipate providing an informative reference for the field.

Green Extraction of Antioxidant Fractions from Humulus lupulus Varieties and Microparticle Production via Spray-Drying

The formulation of polymeric microparticles to encapsulate bioactive compounds from two hop varieties (Nugget and Perle) using sequential green extraction processes was performed. The technologies used were ultrasound-assisted extraction (UAE) and pressurized hot water (PHW) extraction. Liquid phases were analyzed for total phenolic content (~2%), antioxidant activity (IC50, DPPH: 3.68 (Nugget); 4.46 (Perle) g/L, TEAC (~4-5%), FRAP (~2-3%), and reducing power (~4%)), protein content (~1%), oligosaccharide content (~45%), and for structural features. The fractions obtained from UAE were selected to continue with the drying process, achieving the maximum yield at 120 °C (Perle) and 130 °C (Nugget) (~77%). Based on these results, the formulation of polymeric microparticles using mannitol as the carrier was performed with these fractions. The production yield (~65%), particle size distribution (Perle: 250-750 µm and Nugget: ~100 µm), and rheological features (30-70 mPa s at 0.1 s-1) were the parameters evaluated. The UAE extracts from hop samples processed using a sustainable aqueous treatment allowed the formulation of microparticles with a suitable yield, and morphological and viscosity properties adequate for potential food and non-food applications.

Modulation of engineered nanomaterial interactions with organ barriers for enhanced drug transport

The biomedical use of nanoparticles (NPs) has been the focus of intense research for over a decade. As most NPs are explored as carriers to alter the biodistribution, pharmacokinetics and bioavailability of associated drugs, the delivery of these NPs to the tissues of interest remains an important topic. To date, the majority of NP delivery studies have used tumor models as their tool of interest, and the limitations concerning tumor targeting of systemically administered NPs have been well studied. In recent years, the focus has also shifted to other organs, each presenting their own unique delivery challenges to overcome. In this review, we discuss the recent advances in leveraging NPs to overcome four major biological barriers including the lung mucus, the gastrointestinal mucus, the placental barrier, and the blood-brain barrier. We define the specific properties of these biological barriers, discuss the challenges related to NP transport across them, and provide an overview of recent advances in the field. We discuss the strengths and shortcomings of different strategies to facilitate NP transport across the barriers and highlight some key findings that can stimulate further advances in this field.

Investigation of Physico-Chemical Stability and Aerodynamic Properties of Novel "Nano-in-Micro" Structured Dry Powder Inhaler System

Pulmonary drug transport has numerous benefits. Large surface areas for absorption and limited drug degradation of the gastrointestinal system are provided through the respiratory tract. The administration is painless and easy for the patient. Due to their better stability when compared to liquid formulations, powders have gained popularity among pulmonary formulations. In the pharmaceutical sector, quality assurance and product stability have drawn a lot of attention. Due to this, it was decided to perform a long-term stability study on a previously developed, nanosized dry powder inhaler (DPI) formulation that contained meloxicam. Wet milling was implemented to reduce the particle size, and nano spray-drying was used to produce the extra-fine inhalable particles. The particle diameter was determined using dynamic light scattering and laser diffraction. Scanning electron microscopy was utilized to describe the morphology. X-ray powder diffraction and differential scanning calorimetry were applied to determine the crystallinity. In an artificial lung medium, the in vitro dissolution was studied. The Andersen Cascade Impactor was used to investigate the in vitro aerodynamic characteristics. The stability test results demonstrated that the DPI formulation maintained its essential qualities after 6 and 12 months of storage. Consequently, the product might be promising for further studies and development.

Formulation of Polymeric Microparticles Using Eco-Friendly Extracted Crude Fucoidans from Edible Brown Seaweed Undaria pinnatifida

Several bioactive compounds that hold a potential interest in the food industry as phenolic compounds, polysaccharides, proteins and vitamins, among others, are present in seaweeds. Green extraction technologies are the preferred way to obtain these compounds. Pressurized hot water extraction, from 160 to 220 °C, was tested to achieve high yields of these components from the edible brown seaweed, Undaria pinnatifida. The maximum fucoidan content was recovered at 160 °C, while the phloroglucinol content and antioxidant activity were maximum at 220 °C. The possibility of encapsulating these bioactive fractions using mannitol was assessed. The highest production yield of the polymeric particles was found using the 220 °C fraction (close to 75%). In order to formulate microparticles with bioactive potential, several ratios of liquid phases were assessed, 3:1, 1:1 and 1:3 (w:w), using the liquid fractions obtained at 160 °C and 220 °C. The yield production was always above 67%, being in the 1:3 ratio (160 °C:220 °C) and close to 75%. The rheological results indicated that the presence of microparticles enhanced the apparent viscosity of the aqueous dispersions with non-Newtonian profiles, achieving the highest viscosity for those formulated with microparticles from 160 °C:200 °C (3:1).

Preparation and Characterization of Ibuprofen Containing Nano-Embedded-Microparticles for Pulmonary Delivery

A fatal hereditary condition, cystic fibrosis (CF) causes severe lung problems. Ibuprofen (IBU), a non-steroidal anti-inflammatory drug, slows the progression of disease without causing significant side effects. Considering the poor water-solubility of the drug, IBU nanoparticles are beneficial for local pulmonary administration. We aimed to formulate a carrier-free dry powder inhaler containing nanosized IBU. We combined high-performance ultra-sonication and nano spray-drying. IBU was dissolved in ethyl acetate; after that, it was sonicated into a polyvinyl alcohol solution, where it precipitated as nanoparticles. Mannitol and leucine were added when producing dry particles using nano-spray drying. The following investigations were implemented: dynamic light scattering, laser diffraction, surface tension measurement, scanning electron microscopy, X-ray powder diffraction, differential scanning calorimetry, Fourier-transform infrared spectroscopy, in vitro dissolution test, and in vitro aerodynamic assessment (Andersen Cascade Impactor). The particle diameter of the IBU was in the nano range. The spray-dried particles showed a spherical morphology. The drug release was rapid in artificial lung media. The products represented large fine particle fractions and proper aerodynamic diameters. We successfully created an inhalable powder, containing nano-sized IBU. Along with the exceptional aerodynamic performance, the ideal particle size, shape, and drug-release profile might offer a ground-breaking local therapy for CF.

Spray-dried Pneumococcal Membrane Vesicles are Promising Candidates for Pulmonary Immunization

Pneumococcal infections represent a global health threat, which requires novel vaccine developments. Extracellular vesicles are secreted from most cells, including prokaryotes, and harbor virulence factors and antigens. Hence, bacterial membrane vesicles (MVs) may induce a protective immune response. For the first time, we formulate spray-dried gram-positive pneumococcal MVs-loaded vaccine microparticles using lactose/leucine as inert carriers to enhance their stability and delivery for pulmonary immunization. The optimized vaccine microparticles showed a mean particle size of 1-2µm, corrugated surface, and nanocrystalline nature. Their aerodynamic diameter of 2.34µm, average percentage emitted dose of 88.8%, and fine powder fraction 79.7%, demonstrated optimal flow properties for deep alveolar delivery using a next-generation impactor. Furthermore, confocal microscopy confirmed the successful encapsulation of pneumococcal MVs within the prepared microparticles. Human macrophage-like THP-1 cells displayed excellent viability, negligible cytotoxicity, and a rapid uptake around 60% of fluorescently labeled MVs after incubation with vaccine microparticles. Moreover, vaccine microparticles increased the release of pro-inflammatory cytokines tumor necrosis factor and interleukin-6 from primary human peripheral blood mononuclear cells. Vaccine microparticles exhibited excellent properties as promising vaccine candidates for pulmonary immunization and are optimal for further animal testing, scale-up and clinical translation.

Particle Engineering by Nano Spray Drying: Optimization of Process Parameters with Hydroethanolic versus Aqueous Solutions

Nano spray drying has emerged as an outstanding platform for engineering micro- and nanoparticles, with growing applications in various areas of drug delivery. As a new technology involving distinct technical design, parameters of the nano spray drying process are not fully elucidated. In a quality-by-design approach, the aim of the current study was to gain thorough understanding of critical determinants of product characteristics in the Büchi Nano Spray Dryer B-90. Following a factorial experimental design, a series of spray drying experiments were conducted to gain new insights into the influences of the inlet temperature, the spray solvent, and the solute concentration in the spray solution on the yield, the moisture content, and the particle size of the nano spray-dried powder material. Special consideration was given to the potential of using hydroethanolic in comparison with aqueous solvent systems and to particle engineering for pulmonary drug delivery. Lactose and mannitol, widely used as excipients in dry powder inhalation formulations, were used as model materials. Lactose and mannitol are known to spray dry in amorphous and crystalline forms, respectively. The yields of spray drying of lactose and mannitol amounted generally to 71.1 ± 6.6% w/w and 66.1 ± 3.5% w/w, respectively. The spray-dried materials exhibited generally a number-weighted median particle diameter of 1.6 ± 0.2 μm and a volume-weighted median particle diameter of 5.1 ± 1.0 μm. A detailed analysis of the results improved understanding of the interplay between process parameters in the Nano Spray Dryer. The results demonstrate that optimization of spray generation is the key to yield optimization. On the other hand, particle size is determined by the spray mesh pore size and the spray solution degree of saturation. Selection of an appropriate spray solvent and using spray solution additives could optimize spray flow. In parallel, the spray solvent and the solute concentration in the spray solution determine the degree of saturation. Guidance on optimization of particle engineering by nano spray drying is provided.

Complete Protection Against Yersinia pestis in BALB/c Mouse Model Elicited by Immunization With Inhalable Formulations of rF1-V10 Fusion Protein via Aerosolized Intratracheal Inoculation

Pneumonic plague, caused by Yersinia pestis, is an infectious disease with high mortality rates unless treated early with antibiotics. Currently, no FDA-approved vaccine against plague is available for human use. The capsular antigen F1, the low-calcium-response V antigen (LcrV), and the recombinant fusion protein (rF1-LcrV) of Y. pestis are leading subunit vaccine candidates under intense investigation; however, the inability of recombinant antigens to provide complete protection against pneumonic plague in animal models remains a significant concern. In this study, we compared immunoprotection against pneumonic plague provided by rF1, rV10 (a truncation of LcrV), and rF1-V10, and vaccinations delivered via aerosolized intratracheal (i.t.) inoculation or subcutaneous (s.c.) injection. We further considered three vaccine formulations: conventional liquid, dry powder produced by spray freeze drying, or dry powder reconstituted in PBS. The main findings are: (i) rF1-V10 immunization with any formulation via i.t. or s.c. routes conferred 100% protection against Y. pestis i.t. infection; (ii) rF1 or rV10 immunization using i.t. delivery provided significantly stronger protection than rF1 or rV10 immunization via s.c. delivery; and (iii) powder formulations of subunit vaccines induced immune responses and provided protection equivalent to those elicited by unprocessed liquid formulations of vaccines. Our data indicate that immunization with a powder formulation of rF1-V10 vaccines via an i.t. route may be a promising vaccination strategy for providing protective immunity against pneumonic plague.

Combination and nanotechnology based pharmaceutical strategies for combating respiratory bacterial biofilm infections

Respiratory infections are one of the major global health problems. Among them, chronic respiratory infections caused by biofilm formation are difficult to treat because of both drug tolerance and poor drug penetration into the complex biofilm structure. A major part of the current research on combating respiratory biofilm infections have been focused on destroying the matrix of extracellular polymeric substance and eDNA of the biofilm or promoting the penetration of antibiotics through the extracellular polymeric substance via delivery technologies in order to kill the bacteria inside. There are also experimental data showing that certain inhaled antibiotics with simple formulations can effectively penetrate EPS to kill surficially located bacteria and centrally located dormant bacteria or persisters. This article aims to review recent advances in the pharmaceutical strategies for combating respiratory biofilm infections with a focus on nanotechnology-based drug delivery approaches. The formation and characteristics of bacterial biofilm infections in the airway mucus are presented, which is followed by a brief review on the current clinical approaches to treat respiratory biofilm infections by surgical removal and antimicrobial therapy, and also the emerging clinical treatment approaches. The current combination of antibiotics and non-antibiotic adjuvants to combat respiratory biofilm infections are also discussed.

Transformation of nanoparticles into compacts: A study on PLGA and celecoxib nanoparticles

Oral delivery of nanoparticles possesses many advantages for delivery of active pharmaceutical ingredients (APIs) to the gastrointestinal tract. However, the poor physical stability of nanoparticles in liquid state is often a challenge. Removing water from the nanosuspensions and transforming the nanoparticles into solid particulate matter in the form of, e.g., tablets could be a potential approach to increase the stability of nanoparticles. The aim of this study was to transform nanoparticles into compacts and to investigate the redispersion of nanoparticles from compacts as well as the dissolution behavior of these compacts. DL-lactide-co-glycolide copolymer (PLGA) nanoparticles and celecoxib (CLX) nanoparticles were used as two model nanoparticle systems and fabricated into nano-embedded microparticles (NEMs) and subsequently compressed into compacts. The compacts were evaluated with respect to the redispersibility of the nanoparticles, as well as the dissolution characteristics of CLX. The results showed that the NEMs could be readily compressed into compacts with sufficient mechanical strength. The size of the redispersed PLGA nanoparticles from the compacts using 2-hydroxypropyl-β-cyclodextrin (HPβCD) as stabilizer was comparable to the original nanoparticles. In contrast, the redispersibility of CLX nanoparticles from the compacts was not as effective as for the PLGA nanoparticles evidenced by a significant increase in the size and polydispersity index (PDI) of the redispersed nanoparticles. Nonetheless, an obvious enhancement in dissolution rate of CLX was observed from the compacts with CLX nanoparticles. It is concluded that transforming polymeric nanoparticles into compacts via NEMs provides stabilization and allows redispersion into original nanoparticles. Despite the reduced redispersibility, compacts loaded with nanoparticles exhibited improved dissolution rate compared with the crystalline drug. Loading of nanoparticles into compacts is a promising approach to overcome the poor stability of nanoparticle within oral drug delivery of nanoparticles.

Inhalable Microparticles Embedding Calcium Phosphate Nanoparticles for Heart Targeting: The Formulation Experimental Design

Inhalation of Calcium Phosphate nanoparticles (CaPs) has recently unmasked the potential of this nanomedicine for a respiratory lung-to-heart drug delivery targeting the myocardial cells. In this work, we investigated the development of a novel highly respirable dry powder embedding crystalline CaPs. Mannitol was selected as water soluble matrix excipient for constructing respirable dry microparticles by spray drying technique. A Quality by Design approach was applied for understanding the effect of the feed composition and spraying feed rate on typical quality attributes of inhalation powders. The in vitro aerodynamic behaviour of powders was evaluated using a medium resistance device. The inner structure and morphology of generated microparticles were also studied. The 1:4 ratio of CaPs/mannitol led to the generation of hollow microparticles, with the best aerodynamic performance. After microparticle dissolution, the released nanoparticles kept their original size.

Nano Spray-Dried Drugs for Oral Administration: A Review

Spray drying is an important technology that is fast, simple, reproducible, and scalable. It has a wide application range, that is, in food, chemicals, and encapsulation of pharmaceuticals. The technology can be divided into conventional spray drying and nano spray drying. The key advantage of nano spray drying is the production of drug-loaded nanosized particles for various drug delivery applications. The recent developments in nano spray dryer technology and the market launch of the Nano Spray Dryer B-90 by Büchi Labortechnik AG in 2009 enabled the production of submicron spray-dried particles. This review focuses on nanosized drug delivery systems intended for oral administration produced by nano spray drying. First, the nano spray drying concept, the basic technologies implemented in the equipment, and the effects of the various process parameters on the final dry submicron powder properties are presented. Then, the topics of new formulation strategies of oral drugs are highlighted with examples that have entered the research literature in recent years. Next, the subjects of direct conversion of poorly water-soluble drugs, encapsulation of drugs, and drying of preformed nanoparticles are considered. Finally, topics such as morphology, particle size, size distribution, surface analysis, bioavailability, drug release, release kinetics, and solid-state characterization (by differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, nuclear magnetic resonance) of oral drug delivery systems produced by nano spray drying are discussed. The review attempts to provide a comprehensive knowledge base with current literature and foresight to researchers working in the field of pharmaceutical technology and nanotechnology and especially in the field of nano spray drying.

Intratracheal inoculation of AHc vaccine induces protection against aerosolized botulinum neurotoxin A challenge in mice

Botulinum neurotoxin (BoNT), produced by Clostridium botulinum, is generally known to be the most poisonous of all biological toxins. In this study, we evaluate the protection conferred by intratracheal (i.t.) inoculation immunization with recombinant Hc subunit (AHc) vaccines against aerosolized BoNT/A intoxication. Three AHc vaccine formulations, i.e., conventional liquid, dry powder produced by spray freeze drying, and AHc dry powder reconstituted in water are prepared, and mice are immunized via i.t. inoculation or subcutaneous (s.c.) injection. Compared with s.c.-AHc-immunized mice, i.t.-AHc-immunized mice exhibit a slightly stronger protection against a challenge with 30,000× LD₅₀ aerosolized BoNT/A. Of note, only i.t.-AHc induces a significantly higher level of toxin-neutralizing mucosal secretory IgA (SIgA) production in the bronchoalveolar lavage of mice. In conclusion, our study demonstrates that the immune protection conferred by the three formulations of AHc is comparable, while i.t. immunization of AHc is superior to s.c. immunization against aerosolized BoNT/A intoxication.

Spray-dried multidrug particles for pulmonary co-delivery of antibiotics with N-acetylcysteine and curcumin-loaded PLGA-nanoparticles

Nowadays, the resistance of bacterial biofilms towards the available antibiotics is a severe problem. Therefore, many efforts were devoted to develop new formulations using nanotechnology. We have developed an inhalable microparticle formulation using spray-drying combining multiple drugs: an antibiotic (tobramycin, ciprofloxacin or azithromycin), N-acetylcysteine (NAC), and curcumin (Cur). The use of PLGA nanoparticles (NP) also allowed incorporating curcumin to facilitate spray drying and modify the release of some compounds. The aerosolizable microparticles formulations were characterized in terms of size, morphology, and aerodynamic properties. Biocompatibility when tested on macrophage-like cells was acceptable after 20 h exposure for concentrations up to at least 32 µg/mL. Antibacterial activity of free drugs versus drugs in the multiple drug formulations was evaluated on P. aeruginosa in the same range. When co-delivered the efficacy of tobramycin was enhanced compared to the free drug for the 1 µg/mL concentration. The combinations of azithromycin and ciprofloxacin with NAC and Cur did not show an improved antibacterial activity. Bacteria-triggered cytokine release was not inhibited by free antibiotics, except for TNF-α. In contrast, the application of NAC and the addition of curcumin-loaded PLGA NPs showed a higher potential to inhibit TNF-α, IL-8, and IL-1β release. Overall, the approach described here allows simultaneous delivery of antibacterial, mucolytic, and anti-inflammatory compounds in a single inhalable formulation and may therefore pave the way for a more efficient therapy of pulmonary infections.

Overcoming the Solubility Barrier of Ibuprofen by the Rational Process Design of a Nanocrystal Formulation

Wet media milling, coupled with spay drying, is a commonly proposed formulation strategy for the production and solidification of nanosuspensions in order to overcome the solubility barrier of BCS Class II substances. However, the application of mechanically and thermally intensive processes is not straightforward in the cases of ductile and/or low melting point substances that may additionally be susceptible to eutectic formation. Using ibuprofen (IBU) as a model drug with non-favorable mechanical and melting properties, we attempt to rationalize nanocrystal formulation and manufacturing in an integrated approach by implementing Quality by Design (QbD) methodology, particle informatics techniques and computationally assisted process design. Wet media milling was performed in the presence of different stabilizers and co-milling agents, and the nanosuspensions were solidified by spray-drying. The effects of key process parameters (bead diameter, milling time and rotational speed) and formulation variables (stabilizer type and drug/stabilizer ratio) on the critical quality attributes (CQAs), i.e., Z-average size, polydispersity index (PDI), ζ-potential and redispersibility of spray-dried nanosuspensions were evaluated, while possible correlations between IBU free surface energy and stabilizer effectiveness were studied. The fracture mechanism and surface stabilization of IBU were investigated by computer simulation of the molecular interactions at the crystal lattice level. As a further step, process design accounting for mass-energy balances and predictive thermodynamic models were constructed to scale-up and optimize the design space. Contemplating several limitations, our multilevel approach offers insights on the mechanistic pathway applicable to the substances featuring thermosensitivity and eutectic tendency.

Spray Drying for the Preparation of Nanoparticle-Based Drug Formulations as Dry Powders for Inhalation

Nanoparticle-based therapeutics have been used in pulmonary formulations to enhance delivery of poorly water-soluble drugs, protect drugs against degradation and achieve modified release and drug targeting. This review focuses on the use of spray drying as a solidification technique to produce microparticles containing nanoparticles (i.e., nanoparticle (NP) agglomerates) with suitable properties as dry powders for inhalation. The review covers the general aspects of pulmonary drug delivery with emphasis on nanoparticle-based dry powders for inhalation and the principles of spray drying as a method for the conversion of nanosuspensions to microparticles. The production and therapeutic applications of the following types of NP agglomerates are presented: nanoporous microparticles, nanocrystalline agglomerates, lipid-based and polymeric formulations. The use of alternative spray-drying techniques, namely nano spray drying, and supercritical CO2-assisted spray drying is also discussed as a way to produce inhalable NP agglomerates.

Nanoparticle-mediated macrophage targeting-a new inhalation therapy tackling tuberculosis

Despite the potent clinical efficacy of linezolid (LNZ) against drug-resistant tuberculosis, its safety and tolerability remain of major concern. Our objective is to develop antitubercular inhalable LNZ nano-embedded microparticles. In this context, LNZ incorporated in non-structured lipid carriers (NLCs) was characterized in terms of colloidal, morphological, thermal, and release profiles. The potential of LNZ-NLCs to cross mucosal barriers and invade alveolar macrophages (AM, MH-S cells) was appraised. In vivo proof of concept was accomplished via orotracheal administration to mice. Respirable microparticles prepared by spray drying NLCs with diluents were assessed for their size, shape, flowability, aerosolization performance, and lung deposition pattern. NLCs (809-827 nm in size, zeta potential - 37.4 to - 58.9 mV) ensued 19% LNZ loading and pH-independent sustained release. Penetration studies revealed 73% LNZ crossing mucus within 1 h. Meanwhile, viability assay on A549 cells ensured an IC50 of 1.2 and 0.32 mg/mL for plain and LNZ-NLCs, respectively. CLSM confirmed phagocytosis of NLCs by MH-S macrophages, while H&E staining demonstrated NLC accumulation in murine AM in vivo with no signs of histopathological/biochemical changes. Bronchoalveolar lavage showed significantly low levels of LDH and total proteins (TP) for LNZ-NLCs highlighting their superior safety. Respirable microparticles embedding LNZ-NLCs ensured excellent aerosolization (MMAD 2 μm, FPF 93%) denoting perfect alveolar deposition. The developed inhalation therapy provided sustained LNZ release, mucus penetrability, potential safety in therapeutic doses, in vitro and in vivo macrophage targetability, and preferential deposition in the deep lung. Overall positive outcomes rely on reduced dose, dosing frequency, and per se superior safety circumventing systemic-associated life-threatening side effects. Graphical abstract.

Enteric Release Essential Oil Prepared by Co-Spray Drying Methacrylate/Polysaccharides-Influence of Starch Type

Oregano essential oil (EO) enteric release powder was formulated by spray drying feed emulsions stabilized with polysaccharides (PSC) and Eudragit® L100 (PLM). Different modified starches were used in the PSC component. Spray-dried powders were evaluated for particle size and morphology, dynamic packing, flowability, chemical interactions, reconstitution, and gastric protection. Feed emulsions were stable, indicating the good emulsification ability of the PLM/PSC combination. The presence of polymer in the encapsulating wall neutralized electrostatic charges indicating physical attraction, and FTIR spectra showed peaks of both PLM and PSC without significant shifting. Furthermore, the presence of polymer influenced spray drying, resulting in the elimination of surface cavities and the improvement of powder packing and flowability, which was best when the surface-active, low-viscosity sodium octenyl succinate starch was used (angle of repose 42°). When a PLM/PSC ratio of 80/20 was used in the encapsulating wall, the spray-dried product showed negligible re-emulsification and less than 15% release in pH 1.2 medium for 2 h, confirming gastric protection, whereas at pH 6.8, it provided complete re-emulsification and release. In conclusion, (1) polymer-PSC physical interaction promoted the formation of a smoother particle surface and product with improved technological properties, which is important for further processing, and (2) the gastro protective function of Eudragit® L100 was not impaired due to the absence of significant chemical interactions.

Roles of maltodextrin and inulin as matrix formers on particle performance of inhalable drug nanocrystal-embedded microparticles

The objective of this study was to investigate the influence of inulin (IL) and maltodextrin (MD) as matrix formers on the physical properties of drug nanocrystal-embedded microparticles (NEM) during spray-drying and storage. The redispersibility, aerodynamic performance and phase behaviour of NEM/MD and NEM/IL stored at different water activity (a_w) values were evaluated. NEM with 2 g/g (relative to the weight of drug) of IL and MD exhibited the excellent performance after spray-drying. The water activity significantly influenced the redispersibility and aerodynamic performance of NEM/MD and NEM/IL. The NEM/MD presented a higher T_g at all a_w values than did NEM/IL. The moisture-induced collapse of the amorphous glassy matrix of IL and MD could be responsible for the poor redispersibility and aerodynamic performance of NEM/IL and NEM/MD, respectively. The NEM/MD exhibited better aerodynamic performance at high a_w (0.528) than did NEM/IL. Therefore, MD could be an excellent matrix former for inhalable NEM.

Influence of stabilizer type and concentration on the lung deposition and retention of resveratrol nanosuspension-in-microparticles

The purpose of this study was to explore the influence of stabilizer type and concentration on the properties of spray dried nanosuspension-in-microparticles (NS-in-MPs) for inhalation. Taking resveratrol (RES) as a Biopharmaceutical Classification System II (BCS II) model drug, the RES containing nanosuspensions were fabricated by high pressure homogenization method with different stabilizers including sodium dodecyl sulphate (SDS), sodium alginate (SA), chitosan (CS) and polyvinyl alcohol (PVA). Then, the nanosuspensions were spray dried with mannitol to obtain inhalable NS-in-MPs. The particle size, morphology, drug existing state, in vitro aerodynamic performance, in vitro release behavior, lung retention and pharmacokinetic behaviors were characterized. It was found that the morphology, lung deposition as well as in vitro drug release from the microparticles were significantly influenced by stabilizer type, with 1% PVA as stabilizer presenting the highest fine particle fraction (FPF). Meanwhile, taking PVA as an example, it was found stabilizer concentration could alter morphology and flowability of the microparticles, and the FPF value decreased with the increase of stabilizer concentration. Further drug retention and in vivo pharmacokinetic studies demonstrated that the positively charged stabilizer CS could facilitate drug retention and minimize drug expose to the systemic circulation. In conclusion, the deposition and lung retention behavior of NS-in-MPs could be well tuned by selecting different type or concentration of stabilizers, which could facilitate local lung diseases therapy.

Development of inhalable curcumin loaded Nano-in-Microparticles for bronchoscopic photodynamic therapy

Photodynamic therapy is amongst the most rapidly developing therapeutic strategies against cancer. However, most photosensitizers are administered intravenously with very few reports about pulmonary applications. To address this issue, an inhalable formulation consisting of nanoparticles loaded with photosensitizer (i.e. curcumin) was developed. The nanoparticles were prepared using nanoprecipitation method. Dynamic light scattering measurements of the curcumin loaded nanoparticles revealed a hydrodynamic diameter of 181.20 ± 11.52 nm. In vitro irradiation experiments with human lung epithelial carcinoma cells (A549) showed a selective cellular toxicity of the nanoparticles upon activation using LED irradiating device. Moreover, curcumin nanoparticles exhibited a dose-dependent photocytotoxicity and the IC₅₀ values of curcumin were directly dependent on the radiation fluence used. The nanoparticles were subsequently spray dried using mannitol as a stabilizer to produce Nano-in-Microparticles with appropriate aerodynamic properties for a sufficient deposition in the lungs. This was confirmed using the next generation impactor, which revealed a large fine particle fraction (64.94 ± 3.47%) and a mass median aerodynamic diameter of 3.02 ± 0.07 μm. Nano-in-Microparticles exhibited a good redispersibility and disintegrated into the original nanoparticles upon redispersion in aqueous medium. The Langmuir monolayer experiments revealed an excellent compatibility of the nanoparticles with the lung surfactant. Results from this study showed that the Nano-in-Microparticles are promising drug carriers for the photodynamic therapy of lung cancer.

The influence of spatial distribution on add-on therapy of designed Ca-Alg/CS MEMs system

To improve the efficacy and reduce the systemic toxicity of the diabetes mellitus, herewith, we developed a novel microparticles-embedded microcapsules (MEMs) system, synthesized from calcium alginate/chitosan (Ca-Alg/CS), by emulsion gelation using a high voltage electrostatic droplet generator. In our study, we selected two antidiabetic drugs insulin (INS) and metformin (MET) as model drugs to investigate different spatial distribution appropriate of MEMs system. Characterization based on particle size and morphology, encapsulation efficiency and drug loading, as well as drug delivery properties were carried out on the MEMs system. Typical multi-chamber structure was shown by SEM and the optical spectra. The average diameters of microparticles and Ca-Alg/CS MEMs were 2100 nm and 410 μm, respectively. Insulin and MET were embedded into MEMs via electrostatic reaction according to FT-IR spectra. Moreover, drug loading and encapsulation efficiency of INS were higher than that of MET in this system when drugs were loaded alone or together. More importantly, this system has potential for orderly drug release and well sustained release when MET in the inner and INS in the outer space could be applied as a combination therapy for diabetes. The obtained in vivo experimental data on diabetes rats has shown that the designed MEMs system resulted in a higher hypoglycemic effect within add-on therapy.

Ciprofloxacin-loaded lipid-core nanocapsules as mucus penetrating drug delivery system intended for the treatment of bacterial infections in cystic fibrosis

Treatment of bacterial airway infections is essential for cystic fibrosis therapy. However, effectiveness of antibacterial treatment is limited as bacteria inside the mucus are protected from antibiotics and immune response. To overcome this biological barrier, ciprofloxacin was loaded into lipid-core nanocapsules (LNC) for high mucus permeability, sustained release and antibacterial activity. Ciprofloxacin-loaded LNC with a mean size of 180nm showed a by 50% increased drug permeation through mucus. In bacterial growth assays, the drug in the LNC had similar minimum inhibitory concentrations as the free drug in P. aeruginosa and S. aureus. Interestingly, formation of biofilm-like aggregates, which were observed for S. aureus treated with free ciprofloxacin, was avoided by exposure to LNC. With the combined advantages over the non-encapsulated drug, ciprofloxacin-loaded LNC represent a promising drug delivery system with the prospect of an improved antibiotic therapy in cystic fibrosis.

Ciprofloxacin-loaded PLGA nanoparticles against cystic fibrosis P. aeruginosa lung infections

Current pulmonary treatments against Pseudomonas aeruginosa infections in cystic fibrosis (CF) lung suffer from deactivation of the drug and immobilization in thick and viscous biofilm/mucus blend, along with the general antibiotic resistance. Administration of nanoparticles (NPs) with high antibiotic load capable of penetrating the tight mesh of biofilm/mucus can be an advent to overcome the treatment bottlenecks. Biodegradable and biocompatible polymer nanoparticles efficiently loaded with ciprofloxacin complex offer a solution for emerging treatment strategies. NPs were prepared under controlled conditions by utilizing MicroJet Reactor (MJR) to yield a particle size of 190.4±28.6nm with 0.089 PDI. Encapsulation efficiency of the drug was 79% resulting in a loading of 14%. Release was determined to be controlled and medium-independent in PBS, PBS+0.2% Tween 80 and simulated lung fluid. Cytotoxicity assays with Calu-3 cells and CF bronchial epithelial cells (CFBE41o^-) indicated that complex-loaded PLGA NPs were non-toxic at concentrations ≫ MIC_cipro against lab strains of the bacteria. Antibacterial activity tests revealed enhanced activity when applied as nanoparticles. NPs' colloidal stability in mucus was proven. Notably, a decrease in mucus turbidity was observed upon incubation with NPs. Herewith, ciprofloxacin complex-loaded PLGA NPs are introduced as promising pulmonary nano drug delivery systems against P.aeruginosa infections in CF lung.