Recent Advances in Inhaled Nanoformulations of Vaccines and Therapeutics Targeting Respiratory Viral Infections.

With the rapid outbreak of respiratory viral infections, various biological (e.g. vaccines, peptides, recombinant proteins, antibodies and genes) and antiviral agents (e.g. ribavirin, palivizumab and valaciclovir) have been successfully developed for the treatment of respiratory virus infections such as influenza, respiratory syncytial virus and SARS-CoV-2 infections. These therapeutics are conventionally delivered via oral, intramuscular or injection route and are associated with several adverse events due to systemic toxicity. The inherent in vivo instability of biological therapeutics may hinder them from being administered without proper formulations. Therefore, we have witnessed a boom in nanotechnology coupled with a needle-free administration approach such as the inhalation route for the delivery of complex therapeutics to treat respiratory infections. This review discussed the recent advances in the inhalation strategies of nanoformulations that target virus respiratory infections.

Toxicity of curcumin nanoparticles towards alveolar macrophage: Effects of surface charges.

Curcumin has been used for chronic lung diseases management due to its diversified molecular actions. However, the potential cytotoxicity which occurs in cells following the exposure to high concentrations of curcumin has been overlooked. This study evaluated the toxic events of curcumin nanoparticles (Cur-NPs) with alterable surface polarity in alveolar macrophages (NR8383). We aimed to establish the correlation between the toxicity of Cur-NPs with different surface charges and the internalization mechanisms of the NPs. Toxicity data showed that positively charged Cur-NPs (IC50: 9.77 ± 0.5 µg/mL) was the most potent against NR8383, followed by negatively charged Cur-NPs (IC50:13.33 ± 0.9 µg/mL) and neutral Cur-NPs (IC50:18.68 ± 1.2 µg/mL). Results from mitochondrial membrane potential, ATP content and intracellular ROS in NR8383 showed similar ranking to the toxicity assay. The predominant uptake pathway for positively and negatively charged Cur-NPs was via clathrin-mediated endocytosis, while neutral Cur-NPs was internalized via phagocytosis, micropinocytosis and clathrin-mediated endocytosis. Positively charged Cur-NPs mediates the cytotoxicity of NR8383 via lysosomal and mitochondrial-associated destabilization upon entry. In conclusion, the cytotoxicity of Cur-NPs on NR8383 is surface-charge dependent, which in turn is associated to the uptake pathway and localization of Cur-NPs in cells.

Nanotechnology-based therapeutics for targeting inflammatory lung diseases.

The physiochemical properties of drugs used in treating inflammation-associated lung diseases (i.e., asthma, chronic obstructive pulmonary disease, pulmonary fibrosis) play an important role in determining the effectiveness of formulations. Most commonly used drugs are associated with low solubility, low stability and rapid clearance, thus resulting in low bioavailability and therapeutic index. This review focuses on current trends and development of drugs (i.e., corticosteroids, long-acting ß-agonists and biomacromolecules such as DNA, siRNA and mRNA) employed to treat inflammatory lung diseases. In addition, this review includes the current challenges of and future perspective with regard to nanotechnology in the treatment of inflammatory lung diseases.

Various lung diseases, including asthma, chronic obstructive pulmonary disease and pulmonary fibrosis, are associated with persistent inflammation, aberrant lung structure and consequent loss of lung function. Common treatments for inflammatory-related lung diseases rely on the use of anti-inflammatory agents to relieve symptoms and alleviate lung injury. In some severe cases, patients do not respond to anti-inflammatory agents even though larger doses have been administered. Therefore, researchers have employed a nanotechnology approach to deliver drugs in an attempt to achieve effective therapeutic outcomes. These nanoparticles, which are usually designed with a particle size <1000 nm, are formulated to deliver various drugs (i.e., corticosteroids, long-acting ß-agonists and biomacromolecules such as DNA, siRNA and mRNA) to treat inflammation-associated lung diseases. Nanoparticles can be delivered by inhalation, ingestion or injection. To date, several different nanoparticle carriers have been studied, including liposomes, solid lipid nanoparticles, polymer-based nanoparticles and dendrimers.

Advances in Polyhydroxyalkanoate Nanocarriers for Effective Drug Delivery: An Overview and Challenges.

Polyhydroxyalkanoates (PHAs) are natural polymers produced under specific conditions by certain organisms, primarily bacteria, as a source of energy. These up-and-coming bioplastics are an undeniable asset in enhancing the effectiveness of drug delivery systems, which demand characteristics like non-immunogenicity, a sustained and controlled drug release, targeted delivery, as well as a high drug loading capacity. Given their biocompatibility, biodegradability, modifiability, and compatibility with hydrophobic drugs, PHAs often provide a superior alternative to free drug therapy or treatments using other polymeric nanocarriers. The many formulation methods of existing PHA nanocarriers, such as emulsion solvent evaporation, nanoprecipitation, dialysis, and in situ polymerization, are explained in this review. Due to their flexibility that allows for a vessel tailormade to its intended application, PHA nanocarriers have found their place in diverse therapy options like anticancer and anti-infective treatments, which are among the applications of PHA nanocarriers discussed in this article. Despite their many positive attributes, the advancement of PHA nanocarriers to clinical trials of drug delivery applications has been stunted due to the polymers' natural hydrophobicity, controversial production materials, and high production costs, among others. These challenges are explored in this review, alongside their existing solutions and alternatives.

In situ functionalizing calcium phosphate biomaterials with curcumin for the prevention of bacterial biofilm infections.

This study developed a novel bioactive bone substitute (hydroxyapatite, HA) with improved anti-biofilm activity by functionalizing with curcumin (anti-biofilm compound) which provide sufficient flux of curcumin concentration for 14 days. The released curcumin acts to inhibit biofilm formation and control the number of viable planktonic cells simultaneously. To prepare curcumin-functionalized HA, different concentrations of curcumin (up to 3% w/v) were added simultaneously during the precipitation process of HA. The highest loading (50 mg/g HA) of curcumin onto HA was achieved with 2% w/v of curcumin. Physicochemical characterizations of curcumin-functionalized HA composites revealed that curcumin was successfully incorporated onto HA. Curcumin was sustainably released over 14 days, while higher curcumin release was observed in acidic condition (pH 4.4) compared to physiological (pH 7.4). The cytotoxicity assays revealed that no significant difference on bone cells growth on curcumin-functionalized HA and non-functionalized HA. Curcumin-functionalized HA was effective to inhibit bacterial cell attachment and subsequent biofilm maturation stages. The anti-biofilm effect was stronger against Staphylococcus aureus compared to Pseudomonas aeruginosa. The curcumin-functionalized HA composite significantly delayed the maturation of S. aureus compared to non-functionalized HA in which microcolonies of cells only begin to appear at 96 h. Up to 3.0 log reduction in colony forming unit (CFU)/mL of planktonic cells was noted at 24 h of incubation for both microorganisms. Thus, in this study we have suggested that curcumin loaded HA could be an alternative antimicrobial agent to control the risk of infections in post-surgical implants.

Development and Evaluation of Paclitaxel and Curcumin Dry Powder for Inhalation Lung Cancer Treatment.

Despite the effort to develop efficient targeted drug delivery for lung cancer treatment, the outcome remains unsatisfactory with a survival rate of 15% after 5 years of diagnosis. Inhalation formulation is an ideal alternative that could ensure the direct deposition of chemotherapeutics to the lungs. However, the design of an inhalable formulation that could simultaneously achieve a high local chemotherapeutic dose to the solid tumor and exert low pulmonary toxicities is a challenge, as the presence of 10-30% of chemotherapeutics in the lung is sufficient to induce toxicity. Therefore, this study aimed to develop a simple dry powder inhalation (DPI) formulation containing a model chemotherapeutic agent (paclitaxel, PTX) and a natural antioxidant (curcumin, CUR) that acts to protect healthy lung cells from injury during direct lung delivery. The co-jet-milling of CUR and PTX resulted in formulations with suitable aerosol performance, as indicated in the high fine particle fractions (FPF) (>60%) and adequate mass median aerodynamic diameter (MMAD). The CUR/PTX combination showed a more potent cytotoxic effect against lung cancer cells. This is evident from the induction of apoptosis/necrotic cell death and G2/M cell cycle arrests in both A549 and Calu-3 cells. The increased intracellular ROS, mitochondrial depolarization and reduced ATP content in A549 and Calu-3 cells indicated that the actions of CUR and PTX were associated with mitochondrial oxidative stress. Interestingly, the presence of CUR is crucial to neutralize the cytotoxic effects of PTX against healthy cells (Beas-2B), and this is dose-dependent. This study presents a simple approach to formulating an effective DPI formulation with preferential cytotoxicity towards lung cancer.

Functionalizing the surface of hydroxyapatite drug carrier with carboxylic acid groups to modulate the loading and release of curcumin nanoparticles.

This study has evaluated the effect of functionalizing surface charges of hydroxyapatite on the modulation of loading and release of curcumin nanoparticles. The increase in loading and release of curcumin nanoparticles indirectly translates to enhanced anti-cancer effect. Owing to the hydrophobic characteristics of curcumin which have resulted in low bioavailability in cancer cells, the engineering curcumin into nanoparticles is therefore a viable solution to overcomes its limitation. In order to maintain a sustained release profile of curcumin nanoparticles, curcumin nanoparticles were loaded (Cur-NPs) onto hydroxyapatite (HA) via physical adsorption. To regulate the adsorption capacity of Cur-NPs onto HA, we functionalized HA with different carboxylic acids (lactic acid, tartaric acid and citric acid). The presence of carboxylic groups on HA significantly affected the binding and the release profile of Cur-NPs. The effects of Cur-NPs loaded HA were evaluated on breast cancer cell line (MCF-7), which included cell proliferation, cellular uptake of Cur-NPs, apoptosis and cell cycle analysis. The results showed that carboxylic acid-functionalized HA demonstrated higher anti-proliferating activity and time dependent cytoplasmic uptake of Cur-NPs in MCF-7 cells compared to unmodified HA. In addition, Cur-NPs loaded on functionalized HA induced higher apoptosis and cell cycle arrest in MCF-7 cells compared to unmodified HA. The present study indicates that the delivery of Cur-NPs to breast cancer using carboxylic acid-functionalized HA carrier could improve their anti-cancer activities.

The potential to treat lung cancer via inhalation of repurposed drugs.

Lung cancer is a highly invasive and prevalent disease with ineffective first-line treatment and remains the leading cause of cancer death in men and women. Despite the improvements in diagnosis and therapy, the prognosis and outcome of lung cancer patients is still poor. This could be associated with the lack of effective first-line oncology drugs, formation of resistant tumors and non-optimal administration route. Therefore, the repurposing of existing drugs currently used for different indications and the introduction of a different method of drug administration could be investigated as an alternative to improve lung cancer therapy. This review describes the rationale and development of repositioning of drugs for lung cancer treatment with emphasis on inhalation. The review includes the current progress of repurposing non-cancer drugs, as well as current chemotherapeutics for lung malignancies via inhalation. Several potential non-cancer drugs such as statins, itraconazole and clarithromycin, that have demonstrated preclinical anti-cancer activity, are also presented. Furthermore, the potential challenges and limitations that might hamper the clinical translation of repurposed oncology drugs are described.

Sweetening Inhaled Antibiotic Treatment for Eradication of Chronic Respiratory Biofilm Infection.

PURPOSE: The failure of chronic therapy with antibiotics to clear persistent respiratory infection is the key morbidity and mortality factor for patients with chronic lung diseases, primarily due to the presence of biofilm in the lungs. It is hypothesised that carbon sources, such as mannitol, could stimulate the metabolic activity of persister cells within biofilms and restore their susceptibility to antibiotics. The aims of the current study are to: (1) establish a representative in vitro model of Pseudomonas aeruginosa biofilm lung infection, and (2) investigate the effects of nebulised mannitol on antibiotic efficacy, focusing on ciprofloxacin, in the eradication of biofilm. METHOD: Air interface biofilm was cultured onto Snapwell inserts incorporated into a modified pharmacopeia deposition apparatus, the Anderson Cascade Impactor (ACI). Three different formulations including mannitol only, ciprofloxacin only and combined ciprofloxacin and mannitol were nebulised onto the P. aeruginosa biofilm using the modified ACI. Antibacterial effectiveness was evaluated using colony-forming units counts, biofilm penetration and scanning electron microscopy. RESULTS: Nebulised mannitol promotes the dispersion of bacteria from the biofilm and demonstrated a synergistic enhancement of the antibacterial efficacy of ciprofloxacin compared to delivery of antibiotic alone. CONCLUSIONS: The combination of ciprofloxacin and mannitol may provide an important new strategy to improve antibiotic therapy for the treatment of chronic lung infections. Furthermore, the development of a representative lung model of bacterial biofilm could potentially be used as a platform for future new antimicrobial pre-clinical screening.

The achievement of ligand-functionalized organic/polymeric nanoparticles for treating multidrug resistant cancer.

INTRODUCTION: The effectiveness of conventional cancer chemotherapy is hampered by the occurrence of multidrug resistance (MDR) in tumor cells. Although many studies have reported the development of novel MDR chemotherapeutic agents, clinical success is lacking owing to the high associated toxicity. Nanoparticle-based delivery of chemotherapeutic drugs has emerged as alternative approach to treat MDR cancers via exploitation of leaky vasculature in the tumor microenvironment. Accordingly, functionalization of nanoparticles with target specific ligands can be employed to achieve significant improvements in the treatment of MDR cancer. Areas covered: This review focuses on the recent advances in the functionalization of nanocarriers with specific ligands, including antibodies, transferrin, folate, and peptides to overcome MDR cancer. The limitations of effective ligand-functionalized nanoparticles as well as therapeutic successes in ligand targeting are covered in the review. Expert opinion: Targeting MDR tumors with ligand-functionalized nanoparticles is a promising approach to improve the treatment of cancer. With this approach, higher drug concentrations at targeted sites would be achieved with lower dosage frequencies and reduced side effects in comparison to existing formulations of chemotherapeutic drugs. However, potential toxicities and immunological responses to ligands should be carefully reviewed for viable options in for future MDR cancer treatment.

Resveratrol solid lipid microparticles as dry powder formulation for nasal delivery, characterization and in vitro deposition study.

This study focuses on development and in vitro characterisation of a nasal delivery system based on uncoated or chitosan-coated solid lipid microparticles (SLMs) containing resveratrol, a natural anti-inflammatory molecule, as an effective alternative to the conventional steroidal drugs. The physico-chemical characteristics of the SLMs loaded with resveratrol were evaluated in terms of morphology, size, thermal behaviour and moisture sorption. The SLMs appeared as aggregates larger than 20 µm. In vitro nasal deposition was evaluated using a USP specification Apparatus E 7-stage cascade impactor equipped with a standard or a modified nasal deposition apparatus. More than 95% of resveratrol was recovered onto the nasal deposition chamber and stage 1 of impactor, suggesting that the SLMs mostly deposited in the nasal cavity. Additionally, the SLMs were not toxic on RPMI 2650 nasal cell line up to a concentration of approximately 40 µM of resveratrol.

Synthesis and Characterization of Inhalable Flavonoid Nanoparticle for Lung Cancer Cell Targeting.

Current cancer treatments are not adequate to cure cancer disease, as most chemotherapeutic drugs do not differentiate between cancerous and non-cancerous cells; which lead to systemic toxicity and adverse effects. We have developed a promising approach to deliver a potential anti-cancer compound (curcumin) for lung cancer treatment through pulmonary delivery. Three different sizes of curcumin micellar nanoparticles (Cur-NPs) were fabricated and their cytotoxicity effects (proliferation, apoptosis, cell cycle progression) were evaluated against non-small-cell lung cancer, human lung carcinoma (A549) and human lung adenocarcinoma (Calu-3). The in vitro cytotoxicity assay showed that Cur-NPs were more effective to kill lung cancer cells compared to DMSO-solubilised raw curcumin. The potency of the anti-cancer killing activities was size-dependent. Both raw curcumin and Cur-NPs were not toxic to healthy lung cells (BEAS-2B). Smaller Cur-NPs accumulated within nucleus, membrane and cytoplasm. Cur-NPs also induced apoptosis and caused G2/M arrest in both A549 and Calu-3 cell lines. Compared to raw curcumin, Cur-NPs were more effective in suppressing the expression of the inflammatory marker, Interleukin-8 (IL8). The aerosol performance of Cur-NPs was characterized using the next generation impactor (NGI). All Cur-NPs showed promising aerosolization property with mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) ranging between 4.8-5.2 and 2.0-2.1, respectively. This study suggests that inhaled curcumin nanoparticles could potentially be used for lung cancer treatment with minimal side effects.

Co-spray dried resveratrol and budesonide inhalation formulation for reducing inflammation and oxidative stress in rat alveolar macrophages.

Oxidative stress is instrumental in the pathogenesis and progression of chronic obstructive pulmonary disease (COPD). Novel therapeutic strategies that target macrophages, based on the use of antioxidant compounds, could be explored to improve corticosteroid responses in COPD patients. In this study, inhalable microparticles containing budesonide (BD) and resveratrol (RES) were prepared and characterized. This approach was undertaken to develop a multi-drug inhalable formulation with anti-oxidant and anti-inflammatory activities for treatment of chronic lung diseases. The inhalable microparticles containing different ratios of BD and RES were prepared by spray drying. The physico-chemical properties of the formulations were characterized in terms of surface morphology, particle size, physical and thermal stability. Additionally, in vitro aerosol performances of these formulations were evaluated with the multi-stage liquid impinger (MSLI) at 60 and 90 l/min, respectively. The cytotoxicity effect of the formulations was evaluated using rat alveolar macrophages. The biological responses of alveolar macrophages in terms of cytokine expressions, nitric oxide (NO) production and free radical scavenging activities were also tested. The co-spray dried (Co-SD) microparticles of all formulations exhibited morphologies appropriate for inhalation administration. Analysis of the deposition profiles showed an increase in aerosol performance proportional to BD concentration. Cell viability assay demonstrated that alveolar macrophages could tolerate a wide range of RES and BD concentrations. In addition, RES and BD were able to decrease the levels of tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in lipopolysaccharide (LPS) induced alveolar macrophages. This study has successfully established the manufacture of Co-SD formulations of RES and BD with morphology and aerosol properties suitable for inhalation drug delivery, negligible in vitro toxicity and enhanced efficacy to control inflammation and oxidative stress in LPS-induced alveolar macrophages.

Curcumin Nanoparticles Attenuate Production of Pro-inflammatory Markers in Lipopolysaccharide-Induced Macrophages.

PURPOSE: The surface charge of nanoparticles is an important factor that controls efficiency and cellular uptake. The aim of this study was to investigate the efficacy of curcumin nanoparticles (Cur-NPs) with different surface charges, in terms of toxicity, internalization, anti-inflammatory and anti-oxidant activities towards alveolar macrophages cells. METHODS: The surface charge of curcumin nanoparticles (positive, negative and neutral), with an average diameter of 30 nm, were synthesized and characterized. Polyvinyl-alcohol, polyvinylpyrrolidone and dextran were used as coatings to confer negative, positive and neutral charges. The synthesized Cur-NPs were evaluated for particle size, encapsulation efficiency, surface charge, qualitative and quantitative cellular uptakes, anti-oxidant and anti-inflammatory activities. RESULTS: Positively charged nanoparticles showed higher cytotoxicity effects compared to negative and neutral particles. The same trend was observed in antioxidant activity, which included radical scavenging and nitric oxide production. In addition, the anti-inflammatory activity (interleukin-1ß, IL-6 and TNF-α) depleted in the order: positive>negative>neutral. The void neutral-, positively- and negatively-charged nanoparticles did not show any cytotoxic effects. CONCLUSION: The difference in activity for different surface charges of Cur-NPs may be due to the internalization rate of the particles by alveolar macrophages. Intracellular uptake measurements demonstrated that Cur-NPs with positive surface charges possessed the strongest interaction with alveolar macrophages.

Combination of Silver Nanoparticles and Curcumin Nanoparticles for Enhanced Anti-biofilm Activities.

Biofilm tolerance has become a serious clinical concern in the treatment of nosocomial pneumonia owing to the resistance to various antibiotics. There is an urgent need to develop alternative antimicrobial agents or combination drug therapies that are effective via different mechanisms. Silver nanoparticles (AgNPs) have been developed as an anti-biofilm agent for the treatment of infections associated with the use of mechanical ventilations, such as endotracheal intubation. Meanwhile curcumin, a phenolic plant extract, has displayed natural anti-biofilm properties through the inhibition of bacterial quorum sensing systems. The aim of this study was to investigate the possible synergistic/additive interactions of AgNPs and curcumin nanoparticles (Cur-NPs) against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) microorganisms. The combination of AgNPs and Cur-NPs (termed Cur-SNPs) at 100 µg/mL disrupted 50% of established bacterial biofilms (formed on microtiter plates). However, further increase in the concentration of Cur-SNPs failed to effectively eliminate the biofilms. To achieve the same effect, at least 500 µg/mL Cur-NP alone was needed. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) revealed that combination therapy (Cur-SNPs) was the most potent to eradicate preformed biofilm compared to monodrug therapy. These agents are also nontoxic to healthy human bronchial epithelial cells (BEAS2B).

Fabrication of Curcumin Micellar Nanoparticles with Enhanced Anti-Cancer Activity.

Although curcumin is effective in killing cancer cells, its low water solubility and inadequate bioavailability remain major limitations to its therapeutic application. Formulating curcumin micellar nanoparticles (Cur-NPs) encapsulated with a biodegradable polymer can significantly improve curcumin's solubility, stability, and bioavailability in vitro. In this study, differently sized Cur-NPs coated with polyvinyl alcohol (PVA) were engineered. The particle size, encapsulation efficiency, in vitro release, stability, cytotoxicity, and cellular uptake of these Cur-NPs were characterized in several cancer cell lines. The results showed that, relative to solubilized curcumin, Cur-NPs demonstrated higher cytotoxicity against cancer cells. To our knowledge, this study is the first to demonstrate that the extent of the anti-cancer potency and cellular uptake of Cur-NPs is directly correlated to particle size, where Cur-NPs with the smallest size (28 nm) were the most potent. Confocal microscopy revealed the subcellular localization of the smaller Cur-NPs (28 nm) to be in both the nucleus and cytoplasm, while the larger particles (200 nm) were only localized in the cytoplasm.

In vitro biological activity of resveratrol using a novel inhalable resveratrol spray-dried formulation.

The aim of the study was to prepare inhalable resveratrol by spray drying for the treatment of chronic obstructive pulmonary disease (COPD). Resveratrol, with a spherical morphology and particle diameter less than 5 µm, was successfully manufactured. Fine particle fraction (FPF) and mass median aerodynamic diameter (MMAD) of spray-dried resveratrol was 39.9 ± 1.1% and 3.7 ± 0.1 µm, respectively, when assessed with an Andersen cascade impactor (ACI) at 60 l/min. The cytotoxicity results of resveratrol on Calu-3 revealed that the cells could tolerate high concentration of resveratrol (up to 160 µM). In addition, in transport experiments using Snapwells, it was observed that more than 80% of the deposited dry powder was transported across the Calu-3 cells to the basal chamber within four hours. The expression of interleukin-8 (IL-8) from Calu-3 induced with tumor necrosis factor alpha (TNF-α), transforming growth factor beta (TGF-ß1) and lipopolysaccharide (LPS) were significantly reduced after treatment with spray-dried resveratrol. The antioxidant assay (radical scavenging activity and nitric oxide production) showed spray-dried resveratrol to possess an equivalent antioxidant property as compared to vitamin C. Results presented in this investigation suggested that resveratrol could potentially be developed as a dry powder for inhalation for the treatment of inflammatory lung diseases like COPD.

Is the cellular uptake of respiratory aerosols delivered from different devices equivalent?

The study focuses on the application of a cell integrated modified Andersen Cascade Impactor (ACI) as an in vitro lung model for the evaluation of aerosols' behaviour of different formulation devices, containing the same active drug, specifically nebuliser, pressurised metered dose inhaler (pMDI) and dry powder inhaler (DPI). Deposition and transport profiles of the three different inhaled salbutamol sulphate (SS) formulations with clinically relevant doses were evaluated using a modified ACI coupled with the air interface Calu-3 bronchial cell model. Reproducible amounts of SS were deposited on Snapwells for the different formulations, with no significant difference in SS deposition found between the standard ACI plate and modified plate. The transport of SS aerosols produced from pMDI formulation had similar transport kinetics to nebulised SS but significantly higher compared to the DPI, which could have led to the differences in clinical outcomes. Furthermore, drug absorption of different inhaled formulation devices of the same aerodynamic fraction was found not to be equivalent due to their physical chemical properties upon aerosolisation. This study has established an in vitro platform for the evaluation of the different inhaled formulations in physiologically relevant pulmonary conditions.

Nano- and micro-based inhaled drug delivery systems for targeting alveolar macrophages.

INTRODUCTION: Macrophages are the most versatile cells in the hematopoietic system and are strategically distributed in tissues to fight pathogens or other foreign particles. In the lung, however, for intracellular infections such as tuberculosis, pneumonia and aspergillosis, bacteria and fungi utilize the alveolar macrophage as a breeding ground. This has become a challenge for the treatment of these infections, as most drugs do not effectively reach the macrophages at therapeutic levels. Alveolar macrophages also play an important role to initiative adaptive immunity toward combating inflammation and cancer in the lung. AREAS COVERED: This review focuses on the development of micro- and nanotechnology-based drug delivery systems to target alveolar macrophages in association with intracellular infections, cancer and lung inflammation. Aspects of nanoparticle and micron-sized particle engineering through exploitation of particles' physicochemical characteristics such as particle size, surface charge and geometry of particles are discussed. In addition, the application of nanocarriers such as liposomes, polymeric nanoparticles and dendrimers are covered with respect to macrophage targeting. EXPERT OPINION: Drug delivery targeted to alveolar macrophages in the lung is becoming a reality thanks to micro- and nanotechnology breakthrough. The literature review shows that regulation of physicochemical parameters of particles could be a recipe to enhance macrophage targeting and uptake. However, there is still a need to identify more target-specific receptors in order to facilitate drug targeting. Besides that, the toxicity of nanocarriers arising from prolonged residence in the lung should be taken into consideration during formulation.

Development of an inhaled controlled release voriconazole dry powder formulation for the treatment of respiratory fungal infection.

The present research aimed to develop and characterize a sustained release dry powder inhalable formulation of voriconazole (VRZ) for invasive pulmonary aspergillosis. The developed formulations were studied for their in vitro release profile, aerosol, and physicochemical properties as well as interactions with lung epithelia in terms of toxicity and transport/uptake. VRZ and VRZ loaded poly lactide microparticles (VLM) were prepared by aqueous/organic cosolvent and organic spray drying, respectively. Powders were characterized using laser diffraction, differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), dynamic vapor sorption (DVS), and electron microscopy. Aerosol performance was evaluated using an RS01 dry powder inhaler and in vitro cascade impaction. Uptake across Calu-3 lung epithelia was studied, using aerosol deposition of the powder onto cells cultured in an air interface configuration, and compared to dissolution using a conventional dialysis membrane. Additionally, toxicity of VRZ and VLM and the potential impact of transmembrane proteins on uptake were investigated. The particle size and the aerosol performance of spray-dried VRZ and VLM were suitable for inhalation purposes. VRZ exhibited a median volume diameter of 4.52 ± 0.07 µm while VLM exhibited 2.40 ± 0.05 µm. Spray-dried VRZ was crystalline and VLM amorphous as evaluated by DSC and XRPD, and both powders exhibited low moisture sorption between 0 and 90% RH (<1.2% w/w) by DVS. The fine particle fraction (FPF) (% aerosol <5 µm) for the VRZ was 20.86 ± 1.98% while the VLM showed significantly improved performance (p < 0.01) with an FPF of 43.56 ± 0.13%. Both VRZ and VLM were not cytotoxic over a VRZ concentration range of 1.2 nM to 30 µM, and the VLM particles exhibited a sustained release over 48 h after being deposited on the Calu-3 cell line or via conventional dialysis-based dissolution measurements. Lastly, VRZ exhibited polarized transport across epithelia with basal to apical transport being slower than apical to basal. Influx and efflux transports may also play a role as transport was altered in the presence of a number of inhibitors. This study has established an inhalable and sustained release powder of VRZ for targeting invasive pulmonary aspergillosis.