Triple combination dry powder formulation of pretomanid, moxifloxacin, and pyrazinamide for treatment of multidrug-resistant tuberculosis.

Both latent and multidrug-resistant tuberculosis (TB) have been causing significant concern worldwide. A novel drug, pretomanid (PA-824), has shown a potent bactericidal effect against both active and latent forms of Mycobacterium tuberculosis (MTb) and a synergistic effect when combined with pyrazinamide and moxifloxacin. This study aimed to develop triple combination spray dried inhalable formulations composed of antitubercular drugs, pretomanid, moxifloxacin, and pyrazinamide (1:2:8 w/w/w), alone (PaMP) and in combination with an aerosolization enhancer, L-leucine (20 % w/w, PaMPL). The formulation PaMPL consisted of hollow, spherical, dimpled particles (<5 µm) and showed good aerosolization behaviour with a fine particle fraction of 70 %. Solid-state characterization of formulations with and without L-leucine confirmed the amorphous nature of moxifloxacin and pretomanid and the crystalline nature of pyrazinamide with polymorphic transformation after the spray drying process. Further, the X-ray photoelectron spectroscopic analysis revealed the predominant surface composition of L-leucine on PaMPL dry powder particles. The dose-response cytotoxicity results showed pyrazinamide and moxifloxacin were non-toxic in both A549 and Calu-3 cell lines up to 150 µg/mL. However, the cell viability gradually decreased to 50 % when the pretomanid concentration increased to 150 µg/mL. The in vitro efficacy studies demonstrated that the triple combination formulation had more prominent antibacterial activity with a minimum inhibitory concentration (MIC) of 1 µg/mL against the MTb H37Rv strain as compared to individual drugs. In conclusion, the triple combination of pretomanid, moxifloxacin, and pyrazinamide as an inhalable dry powder formulation will potentially improve treatment efficacy with fewer systemic side effects in patients suffering from latent and multidrug-resistant TB.

Co-spray dried inhalable composite powders of ciprofloxacin and alginate oligosaccharide as anti-biofilm therapy.

The treatment of chronic respiratory infections caused by biofilm formation are extremely challenging owing to poor drug penetration into the complex biofilm structure and high drug resistance. Local delivery of an antibiotic together with a non-antibiotic adjuvant to the lungs could often enhance the therapeutic responses by targeting different bacterial growth pathways and minimizing drug resistance. In this study, we designed new inhalable dry powders containing ciprofloxacin (CIP) and OligoG (Oli, a low-molecular-weight alginate oligosaccharide impairing the mucoid biofilms by interacting with their cationic ions) to combat respiratory bacterial biofilm infections. The resulting powders were characterized with respect to their morphology, solid-state property, surface chemistry, moisture sorption behavior, and dissolution rate. The aerosol performance and storage stability of the dry powders were also evaluated. The results showed that inhalable dry powders composed of CIP and Oli could be readily accomplished via the wet milling and spray drying process. Upon the storage under 20 ± 2 °C/20 ± 2 % relative humidity (RH) for one month, there was no significant change in the in vitro aerosol performances of the dry powders. In contrast, the dry powders became non-inhalable following the storage at 20 ± 2 °C/53 ± 2 % RH for one month due to the hygroscopic nature of Oli, which could be largely prevented by incorporation of leucine. Collectively, this study suggests that the newly developed co-spray-dried powders composed of CIP and Oli might represent a promising and alternative treatment strategy against respiratory bacterial biofilm infections.

Development and characterization of a spray-dried inhalable ternary combination for the treatment of Pseudomonas aeruginosa biofilm infection in cystic fibrosis.

Cystic fibrosis (CF) is an inherited lung disease characterised by the accumulation of thick layers of dried mucus in the lungs which serve as a nidus for chronic infection. Pseudomonas aeruginosa is the predominant cause of chronic lung infection in cystic fibrosis. The dense mucus coupled with biofilm formation hinder antibiotic penetration and prevent them from reaching their target. Mucoactive agents are recommended in the treatment of CF in combination with antibiotics. In spite of the extensive research in developing novel drug combinations for the treatment of lung infection in CF, to our knowledge, there is no study that combines antibiotic, antibiofilm and mucoactive agent in a single inhaled dry powder formulation. In the present study, we investigate the possibility of adding a mucoactive agent to our previously developed ciprofloxacinquercetin (antibiotic-antibiofilm) dry powder for inhalation. Three mucoactive agents, namely mannitol (MAN), N-acetyl-L-cysteine (NAC) and ambroxol hydrochloride (AMB), were investigated for this purpose. The ternary combinations were prepared via spray drying without the addition of excipients. All ternary combinations conserved or improved the antibacterial and biofilm inhibition activities of ciprofloxacin against P. aeruginosa (ATCC 10145). The addition of AMB resulted in an amorphous ternary combination (SD-CQA) with superior physical stability as indicated by DSC and nonambient XRPD. Furthermore, SD-CQA displayed better in vitro aerosolization performance (ED ∼ 71 %; FPF ∼ 49 %) compared to formulations containing MAN and NAC (ED ∼ 64 % and 44 %; FPF ∼ 44 % and 29 %, respectively). In conclusion, a ternary drug combination powder with suitable aerosolization, physical stability and antibacterial/antibiofilm properties was prepared by a single spray drying step.

Acceptance Testing of Used Cascade Impactor Stages Based on Pressure Drop Measurements in a Flow System Managed with a Critical Flow Venturi: Part I-Laboratory Proof-of-Principle.

Background: Cascade impactors are essential for measuring the aerodynamic particle size distribution delivered by metered dose, dry powder, and similar inhalable drug products. For quality control of used impactors, periodic optical inspection of the nozzles of each impactor stage (stage mensuration) is currently the only method sufficiently precise to test whether used impactors are suitable for continued use, in accord with pharmacopeial standards. Here, we demonstrate a new method for quality control of used impactors. The method combines stage-wise pressure-drop measurement with a critical flow venturi (CFV) for air flow management. This technique avoids the unacceptably large uncertainty in conventional air flow rate measurements and instead relies on pressure and temperature measurement upstream of the CFV. These measurements can be made precisely with affordable equipment. Methods: We placed a toroidally shaped CFV downstream of a Next Generation Impactor™** (NGI) and precisely measured the stagnation pressure (±0.02%) and temperature (±0.03%) upstream of this CFV at impactor inlet flow rates close to 60 L/min. Pressure-drop measurements (±0.25%) at stages 3-7 and the micro-orifice collector were made with capacitive diaphragm transducers and with a special lid to the NGI that allowed pneumatic connection to the interstage passageways before and after each impactor stage. Results: The measured pressure drop values matched, to fractional percentage precision, those predicted by the incompressible flow theory through the nozzles and the compressible flow theory through the CFV. Conclusions: Practical equipment has been assembled that measures, to fractional percentage precision, the pressure drop through impactor nozzles at precisely managed flow conditions. The experimental results support the relevant flow principles. The results, thereby, support the use of this method for quantifying whether used impactor stages are suitable for continued use in the testing of registered inhalable drug products, in accord with pharmacopeial standards.

Understanding the impact of mannitol on physical stability and aerosolization of spray-dried protein powders for inhalation.

Pulmonary delivery of protein-based therapeutics, including antibodies, is a promising option for treating respiratory diseases. Spray drying is a widely used method for producing dry powder formulations with mannitol being a commonly used excipient for these inhalation formulations. There is limited research available concerning the utilization of mannitol as an excipient in the spray drying of proteins and its impact on aerosol performance. This study highlights the importance to understand mannitol's potential role and impact in this context. To investigate the impact of mannitol on physical stability and aerosolization of spray-dried protein formulations, bovine serum albumin (BSA) was employed as a model protein and formulated with different concentrations of mannitol via spray drying. The spray-dried solids were characterized for their particle size using Malvern mastersizer and aerodynamic particle size using next generation impactor (NGI). Additionally, the solids were characterized with solid-state Fourier-transform infrared spectroscopy (ssFTIR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and solid-state nuclear magnetic resonance spectroscopy (ssNMR) to analyze the change in their secondary structure, crystallinity, particle morphology, and protein-excipient interaction, respectively. Size exclusion chromatography (SEC) was used to investigate changes in monomer content resulting from storage under stressed condition of 40 °C. Protein formulations containing more than 33 % mannitol by weight showed crystallization tendencies, causing an increase in monomer loss over time. ssNMR data also showed mixing heterogeneity of BSA and mannitol in the formulations with high mannitol contents. Futhermore, fine particle fraction (FPF) was found to decrease over time for the formulations containing BSA: Mannitol in the ratios of 2:1, 1:2, and 1:5, due to particle agglomeration induced by crystallization of mannitol. This study underscores the significant influence of excipients such as mannitol on the aerosol performance and storage stability of spray-dried protein formulations.

A counter-swirl design concept for dry powder inhalers.

A swirling airflow is incorporated in several dry powder inhalers (DPIs) for effective powder de-agglomeration. This commonly requires the use of a flow-straightening grid in the DPI to reduce drug deposition loss caused by large lateral spreading of the emerging aerosol. Here, we propose a novel grid-free DPI design concept that improves the aerosol flow characteristics and reduces the aforementioned drug loss. The basis of this design is the implementation of a secondary airflow that swirls in the opposite direction (counter-swirl) to that of a primary swirling airflow. In-vitro deposition, computational fluid dynamics simulations and particle image velocimetry measurements are used to evaluate the counter-swirl DPI aerosol performance and flow characteristics. In comparison with a baseline-DPI that has only a primary swirling airflow, the counter-swirl DPI has 20% less deposition of the emitted drug dose in the induction port and pre-separator of a next generation impactor (NGI). This occurs as a result of the lower flow-swirl generated from the counter-swirl DPI which eliminates the axial reverse flow outside of the mouthpiece and substantially reduces lateral spreading in the exiting aerosol. Modifications to the counter-swirl DPI design were made to prevent drug loss from the secondary airflow tangential inlets, which involved the addition of wall perforations in the tangential inlets and the separation of the primary and secondary swirling airflows by an annular channel. These modified DPI devices were successful in that aspect but had higher flow-swirl than that in the counter-swirl DPI and thus had higher drug mass retained in the device and deposited in the induction port and pre-separator of the NGI. The fine particle fraction in the aerosols generated from all the counter-swirl-based DPIs and the baseline-DPI are found to be statistically similar to each other.

Repurposing ebselen as an inhalable dry powder to treat respiratory tract infections.

Respiratory tract infections (RTIs) are one of the leading causes of death globally, lately exacerbated by the increasing prevalence of antimicrobial resistance. While antimicrobial resistance could be overcome by developing new antimicrobial agents, the use of a safe repurposed agent having potent antimicrobial activity against various RTIs can be an efficient and cost-effective alternative to overcome the long and complex process of developing and testing new drugs. Ebselen, a synthetic organoselenium drug originally developed to treat noise-inducing hearing problems, has shown promising antimicrobial activity in vitro against several respiratory pathogens including viruses (e.g., SARS-CoV-2, influenza A virus) and bacteria (e.g., Mycobacterium tuberculosis, Streptococcus pneumoniae, and Staphylococcus aureus). Inhaled drug delivery is considered a promising approach for treating RTIs, as it can ensure effective drug concentrations at a lower dose, thereby minimizing the side effects that are often encountered by using oral or injectable drugs. In this study, we developed inhalable ebselen dry powder formulations using a spray-drying technique. The amino acids leucine, methionine, and tryptophan were incorporated with ebselen to enhance the yield and aerosolization of the dry powders. The amino acid-containing ebselen dry powders showed a better yield (37-56.4 %) than the amino acid-free formulation (30.9 %). All dry powders were crystalline in nature. The mass median aerodynamic diameter (MMAD) was less than 5 µm for amino acids containing dry powders (3-4 µm) and slightly higher (5.4 µm) for amino acid free dry powder indicating their suitability for inhalation. The aerosol performance was higher when amino acids were used, and the leucine-containing ebselen dry powder showed the highest emitted dose (84 %) and fine particle fraction (68 %). All amino acid formulations had similar cytotoxicity as raw ebselen, tested in respiratory cell line (A549 cells), with half-maximal inhibitory concentrations (IC50) between 100 and 250 µg/mL. Raw ebselen and amino acid-containing dry powders showed similar potent antibacterial activity against the Gram-positive bacteria S. aureus and S. pneumoniae with minimum inhibitory concentrations of 0.31 µg/mL and 0.16 µg/mL, respectively. On the other hand, raw ebselen and the formulations showed limited antimicrobial activity against the Gram-negative pathogens Pseudomonas aeruginosa and Klebsiella pneumoniae. In summary, in this study we were able to develop amino-acid-containing inhalable dry powders of ebselen that could be used against different respiratory pathogens, especially Gram-positive bacteria, which could ensure more drug deposition in the respiratory tract, including the lungs. DPIs are generally used to treat lung (lower respiratory tract) diseases. However, DPIs can also be used to treat both upper and lower RTIs. The deposition of the dry powder in the respiratory tract is dependent on its physicochemical properties and this properties can be modulated to target the intended site of infection (upper and/or lower respiratory tract). Further studies will allow the development of similar formulations of individual and/or combination of antimicrobials that could be used to inhibit a number of respiratory pathogens.

Supercritical antisolvent-fluidized bed for the preparation of dry powder inhaler for pulmonary delivery of nanomedicine.

The supercritical antisolvent-fluidized bed coating process (SAS-FB) shows great potential as a technique to manufacture dry powder inhaler (DPI) that incorporate nanodrugs onto micronized matrix particles, capitalizing on the merits of both nanoparticle and pulmonary delivery. In this study, naringin (NAR), a pharmacologically active flavonoid with low solubility and in vivo degradation issues, was utilized as a model active pharmaceutical ingredient to construct nanomedicine-based DPI through SAS-FB. It is showed that processed NAR exhibited a near-spherical shape and an amorphous structure with an average size of around 130 nm. Notably, SAS-FB products prepared with different fluidized matrices resulted in varying deposition patterns, particularly when mixed with a coarse lactose to enhance the fine particle fraction (FPF) of the formulations. The FPF was positively associated with specific surface area of the SAS-FB products, while the specific surface area was directly related to surface roughness and particle size. In vitro dissolution studies using simulated lung fluid revealed that the NAR nanoparticles coated on the products were released immediately upon contact with solution, with a cumulative dissolution exceeding 90% within the first minute. Importantly, compared to oral raw NAR, the optimized DPI formulation demonstrated superior in vivo plasmatic and pulmonary AUC0→∞ by 51.33-fold and 104.07-fold respectively in a Sprague-Dawley rat model. Overall, SAS- FB technology provides a practical approach to produce nanomedicine DPI product that combine the benefits of nanoparticles with the aerodynamics properties of inhaled microparticles.

Impact of high shear blending on distribution of magnesium stearate on lactose for dry powder inhaled formulations.

The use of magnesium stearate along with lactose in Dry Powder Inhaler (DPI) formulations is increasing. The impact of different conditions of high shear blending on the distribution of magnesium stearate on lactose particles was investigated in this study. The formulated blends were manufactured using high shear blending of pre-blended coarse and fine lactose particles with 1.0% (w/w) magnesium stearate under different blending conditions, specifically blending speed and time. The effects of blending conditions on the distribution of magnesium stearate on lactose particles were clearly identifiable by characterizing the formulated blends by means of rheological evaluations, scanning electron microscopy, and chemical surface analysis using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Rheological properties were significantly affected in blends with magnesium stearate compared to blends without magnesium stearate. Blending speed exhibited a strong influence on the distribution of magnesium stearate on lactose surface, while blending time had relatively minor effect.

Microstructural insight into inhalation powder blends through correlative multi-scale X-ray computed tomography.

Dry powder inhalers (DPI) are important for topical drug delivery to the lungs, but characterising the pre-aerosolised powder microstructure is a key initial step in understanding the post-aerosolised blend performance. In this work, we characterise the pre-aerosolised 3D microstructure of an inhalation blend using correlative multi-scale X-ray Computed Tomography (XCT), identifying lactose and drug-rich phases at multiple length scales on the same sample. The drug-rich phase distribution across the sample is shown to be homogeneous on a bulk scale but heterogeneous on a particulate scale, with individual clusters containing different amounts of drug-rich phase, and different parts of a carrier particle coated with different amounts of drug-rich phase. Simple scalings of the drug-rich phase thickness with carrier particle size are used to derive the drug-proportion to carrier particle size relationship. This work opens new doors to micro-structural assessment of inhalation powders that could be invaluable for bioequivalence assessment of dry powder inhalers.

Spray dried progesterone formulations for carrier free dry powder inhalation.

Low oral absorption and extensive first pass metabolism of progesterone is reported for many oral formulations which warrants investigation into other routes of administration. It is the aim of this study to investigate the generation of inhaled formulations of progesterone though a spray drying approach with a focus on how spray drying impacts the physicochemical properties of progesterone. Formulations of progesterone with L-leucine and hydroxypropyl methylcellulose acetate succinate (HPMCAS) are reported to this aim. X-ray diffraction, spectroscopy and thermal analysis were used to characterise these formulations and confirmed that progesterone crystallises as the Form II polymorph during spray drying regardless of the solvent used. The resultant formulations showed higher aqueous solubility than progesterone Form I starting material and the addition of HPMCAS was shown to temporarily enable a supersaturated state. Thermal analysis was used to show that the Form II polymorph was sensitive to transformation to Form I during heating. The addition of L-leucine to the formulations reduced the temperature for the polymorphic transformation by âˆ¼ 10 °C. However, when HPMCAS was added to the formulation, the Form II polymorph was prevented from transforming to the Form I polymorph. Cascade impaction was used to determine the aerosol performance of the spray dried powders and showed promising lung deposition profiles (mass median aerodynamic diameter 5 µm) with significant variation depending on the organic solvent used and the ratio of organic to aqueous phase in the feedstock. However, further optimisation of formulations was required to direct more progesterone into the alveolar regions. The addition of HPMCAS was seen to increase the alveolar deposition and therefore formed a formulation with a lower fine particle fraction and mass median aerodynamic diameter. The most suitable formulation for inhalation was formed from a 50:50 acetone:water mixture and showed an ED, FPF and FPD of 81.7%, 44.5% and 7.3 mg respectively. Therefore, HPMCAS is suggested as a suitable excipient to increase solubility, prevent polymorphic transformation and improve inhalation properties of spray dried progesterone formulations. This study highlights the use of spray drying to form inhalable progesterone powders with higher solubility which may broaden the application of this medicine.

Enhanced powder dispersion of dual-excipient spray-dried powder formulations of a monoclonal antibody and its fragment for local treatment of severe asthma.

The advent of biologics has brought renewed hope for patients with severe asthma, a condition notorious for being hampered by poor response to conventional therapies and adverse drug reactions owing to corticosteroid dependence. However, biologics are administered as injections, thereby precluding the benefits inhalation therapy could offer such as increased bioavailability at the site of action, minimal systemic side effects, non-invasiveness, and self-administration. Here, 2-hydroxypropyl-beta-cyclodextrin and ʟ-leucine were co-spray-dried, as protein stabiliser and dispersion enhancer, respectively, at various weight ratios to produce a series of formulation platforms. Powder aerosolisation characteristics and particle morphology were assessed for suitability for pulmonary delivery. The selected platform with the best aerosol performance, a 1:1 ratio of the excipients, was then incorporated with a monoclonal antibody directed against IL-4 receptor alpha or its antigen-binding fragment. The dual-excipient antibody formulations exhibited emitted fraction of at least 80% and fine particle fraction exceeding 60% in cascade impactor study, while the residual moisture content was within a desirable range between 1% and 3%. The in vitro antigen-binding ability and inhibitory potency of the spray-dried antibody were satisfactorily preserved. The results from this study corroborate the viability of inhaled solid-state biomacromolecules as a promising treatment approach for asthma.

Exploring the influence of magnesium stearate content and mixing modality on the rheological properties and in vitro aerosolization of dry powder inhaler.

Since carrier-based dry powder inhalers (DPIs) suffer from inadequate drug deposition in the lung, an increasing number of marketed products have added magnesium stearate (MgSt) to improve the aerosolization, dispersion, and stability against moisture of DPI. However, for carrier-based DPI, there is a lack of examination of the optimal MgSt content as well as the mixing modality, and there is also a need to verify the applicability of rheological properties to predict the in vitro aerosolization of DPI formulations containing MgSt. Therefore, in this work, DPI formulations were prepared using fluticasone propionate as a model drug and commercial crystalline lactose Respitose® SV003 as a carrier within 1% MgSt content, the effect of MgSt content on the rheological and aerodynamic properties were investigated. After the optimal MgSt content was determined, the effects of mixing modality, mixing order, and carrier size on formulation properties were further investigated. Meanwhile, correlations were established between rheological parameters and in vitro drug deposition parameters, and the contribution of rheological parameters were determined using principal component analysis (PCA). The results showed that the optimal content of MgSt in DPI formulations is 0.25%-0.5% under both high-shear and low-shear, using medium-sized carriers (D50 around 70 µm) and low-shear mixing are beneficial for improving in vitro aerosolization. Good linear relationships between powder rheological parameters such as basic flow energy (BFE), specific energy (SE), Permeability and fine particle fraction (FPF) were established, PCA showed that both flowability and adhesion are key properties affecting FPF. In conclusion, both MgSt content and mixing modality can influence rheological properties of the DPI, which can be used as a screeing tool for DPI formuluation and preparation process optimization.

Effects of different mesh nebulizer sources on the dispersion of powder formulations produced with a new small-particle spray dryer.

The objective of this study was to explore the aerosolization performance of powders produced with different mesh nebulizer sources in the initial design of a new small-particle spray dryer system. An aqueous excipient enhanced growth (EEG) model formulation was spray dried using different mesh sources and the resulting powders were characterized based on (i) laser diffraction, (ii) aerosolization with a new infant air-jet dry powder inhaler, and (iii) aerosol transport through an infant nose-throat (NT) model ending with a tracheal filter. While few differences were observed among the powders, the medical-grade Aerogen Solo (with custom holder) and Aerogen Pro mesh sources were selected as lead candidates that produced mean fine particle fractions <5 µm and <1 µm in ranges of 80.6-77.4% and 13.1-16.0%, respectively. Improved aerosolization performance was achieved at a lower spray drying temperature. Lung delivery efficiencies through the NT model were in the range of 42.5-45.8% for powders from the Aerogen mesh sources, which were very similar to previous results with a commercial spray dryer. Ultimately, a custom spray dryer that can accept meshes with different characteristics (e.g., pore sizes and liquid flow rates) will provide particle engineers greater flexibility in producing highly dispersible powders with unique characteristics.

Novel therapeutic approach for the treatment of cystic fibrosis based on freeze-dried tridrug microparticles to treat cystic fibrosis.

BACKGROUND: Cystic fibrosis is a severe, autosomal recessive disease that shortens life expectancy. According to studies, approximately 27% of patients with CF aged 2-5 years and 60 to 70% of adult patients are infected with P. aeruginosa. The patients experience bronchospasm leading to a persistent contracted state of the airways. OBJECTIVES: The current work explores the possibility of combining ivacaftor and ciprofloxacin to combat the bacteria. A third drug L-salbutamol would be coated onto the surface of the drug-entrappped microparticles to instantaneously provide relief from bronchoconstriction. METHODS: The microparticles were prepared using bovine serum albumin and L-leucine using the freeze-drying approach. The process and formulation parameters were optimized. The prepared microparticles were surface coated by L-salbutamol using the dry-blending method. The microparticles were subjected to rigorous in-vitro characterization for entrapment, inhalability, antimicrobial activity, cytotoxicity study and safety. The performance of the microparticles to be loaded into a inhaler was checked by the Anderson cascade impactor. RESULTS: The freeze-dried microparticles had a particle size of 817.5 ± 5.6 nm with a polydispersity ratio of 0.33. They had a zeta potential of -23.3 ± 1.1 mV. The mass median aerodynamic diameter of the microparticles was 3.75 ± 0.07 µm, and the geometric standard diameter was 1.66 ± 0.033 µm. The microparticles showed good loading efficiency for all three drugs. DSC, SEM, XRD, and FTIR studies confirmed the entrapment of ivacaftor and ciprofloxacin. SEM and TEM scans observed the shape and the smooth surface. Antimicrobial synergism was proven by the agar broth, and dilution technique and the formulation was deemed safe by the results of the MTT assay. CONCLUSION: Freeze-dried microparticles of ivacaftor, ciprofloxacin, and L-salbutamol could pave way to a hitherto unexplored combination of drugs as a novel approach to treat P. aeruginosa infcetions and bronchoconstriction commonly associated with cystic fibrosis.

[Development of an Inhalation Dry Powder Preparation Method without Heat-drying Process].

Biopharmaceuticals, including therapeutic genes and proteins, are characterized by highly-targeted, specific action and flexible pharmacological design and have a rapidly growing market share; however, because of high molecular weight and low stability, injection is the most common delivery route of biopharmaceuticals. Thus, pharmaceutical innovations are required to provide alternative delivery routes for biopharmaceuticals. Pulmonary drug delivery via inhalation is a promising approach, particularly for targeting local diseases of the lung, because it can exert therapeutic effects in small doses and can noninvasively and directly deliver drugs to airway surfaces. However, biopharmaceutical inhalers must ensure that the biopharmaceuticals maintain their integrity as they are subjected to several types of physicochemical stress, such as hydrolysis, ultrasound, and heating, at various stages during the process from manufacturing to administration. In this symposium, I present a novel dry powder inhaler (DPI) preparation method without heat-drying, with the goal of developing biopharmaceutical DPIs. Spray-freeze-drying is a nonthermal drying technique that produces a powder with porous shapes; this powder has suitable inhalation characteristics for DPI. A model drug, plasmid DNA (pDNA), was stably prepared as a DPI using the spray-freeze-drying process. Under dry conditions, the powders maintained high inhalation characteristics and maintained pDNA integrity for 12 months. The powder induced pDNA expression in mouse lungs that exceeded at higher levels than the solution did. This novel preparation method is suitable for DPI preparation for various drugs and may help expand the clinical application of DPIs.

Co-Delivery of D-LAK Antimicrobial Peptide and Capreomycin as Inhaled Powder Formulation to Combat Drug-Resistant Tuberculosis.

INTRODUCTION: The emergence of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) posed a severe challenge to tuberculosis (TB) management. The treatment of MDR-TB involves second-line anti-TB agents, most of which are injectable and highly toxic. Previous metabolomics study of the Mtb membrane revealed that two antimicrobial peptides, D-LAK120-A and D-LAK120-HP13, can potentiate the efficacy of capreomycin against mycobacteria. AIMS: As both capreomycin and peptides are not orally available, this study aimed to formulate combined formulations of capreomycin and D-LAK peptides as inhalable dry powder by spray drying. METHODS AND RESULTS: A total of 16 formulations were prepared with different levels of drug content and capreomycin to peptide ratios. A good production yield of over 60% (w/w) was achieved in most formulations. The co-spray dried particles exhibited spherical shape with a smooth surface and contained low residual moisture of below 2%. Both capreomycin and D-LAK peptides were enriched at the surface of the particles. The aerosol performance of the formulations was evaluated with Next Generation Impactor (NGI) coupled with Breezhaler®. While no significant difference was observed in terms of emitted fraction (EF) and fine particle fraction (FPF) among the different formulations, lowering the flow rate from 90 L/min to 60 L/min could reduce the impaction at the throat and improve the FPF to over 50%. CONCLUSIONS: Overall, this study showed the feasibility of producing co-spray dried formulation of capreomycin and antimicrobial peptides for pulmonary delivery. Future study on their antibacterial effect is warranted.

Role of dispersion enhancer selection in the development of novel tratinterol hydrochloride dry powder inhalation formulations.

Tratinterol hydrochloride (TH) is a new long-acting bronchodilator with strong ß2 adrenoceptor stimulation activity. The aim of this study was to design a new carrier-based dry powder inhalation (DPI) formulation for TH and to investigate the effect of dispersion enhancers on the aerosol performance of TH in vitro. To this end, coarse lactose was used as a carrier. TH was micronized by using a jet mill and blended with the carrier to obtain a reference DPI formulation. Commercial magnesium stearate (MgSt) as received, micronized MgSt (MgSt-M), and fine lactose (FL) were used as the dispersion enhancers and formulated with the micronized TH (TH-M) and the carrier as DPI formulations. The obtained DPI formulations were characterized using dynamic light scattering (DLS), X-ray powder diffraction (XRPD), thermal analysis, powder rheometer, and Raman microscopy. A next generation pharmaceutical impactor (NGI) was used to evaluate the aerodynamic performance of the dry powders. The results showed that TH-M was in an inhalable particle size range, and based on the XRPD and thermal analysis, the solid form of TH-M did not change compared to the starting materials. The NGI results showed that the fine particle fraction (FPF) of TH could be increased with the addition of MgSt and FL as dispersion enhancers in the reference formulation. In addition, the FPF of TH could be increased with a decrease in the particle size of MgSt or an increase in the amount of FL. A combination of MgSt-M and FL could further improve the aerosol performance of TH. Raman spectroscopic imaging confirmed the spatial location of MgSt and TH at the surface of the carrier. This study demonstrates that TH could be formulated into carrier-based dry powder formulation for inhalation using coarse lactose as the carrier. The dual strategy based on using both MgSt and FL as dispersion enhancers improved the aerosol performance of a novel TH dry powder formulation.

Surface Modification of lactose carrier particles using a fluid bed coater to improve fine particle fraction for dry powder inhalers.

Surface roughness of carrier particles can impact dry powder inhaler (DPI) performance. There are opposing views on the effect of roughness on DPI performance. Hence, a systematic approach is needed to modify carrier surfaces and evaluate the impact on drug delivery. Carrier particle surfaces were modified by fluid bed coating with saturated lactose containing micronized lactose of different sizes (2, 5 and 8 µm) and coated to different levels (20, 40, 60 and 80%). Their drug delivery performance was assessed by the fine particle fraction (FPF). Roughness parameters, mean arithmetic roughness (Ra) and arithmetic mean height (Sa), of the carrier particles, were also evaluated using optical profilometry and scanning laser microscopy. Generally, particles of higher Ra had higher FPF. Higher Sa resulted in higher FPF only for particles with 60 and 80% coat levels. Reduced contact surface area between the drug particle and rougher carrier particle resulted in easier drug detachment during aerosolization. The 5 µm micronized lactose produced optimal carrier particles with respect to FPF and surface roughness. The study highlighted that with the ideal particles for surface roughening and coating level, surface roughening could be efficiently achieved by fluid bed coating for superior DPI performance.

Aerosolizable Plasmid DNA Dry Powders Engineered by Thin-film Freezing.

PURPOSE: This study was designed to test the feasibility of using thin-film freezing (TFF) to prepare aerosolizable dry powders of plasmid DNA (pDNA) for pulmonary delivery. METHODS: Dry powders of pDNA formulated with mannitol/leucine (70/30, w/w) with various drug loadings, solid contents, and solvents were prepared using TFF, their aerosol properties (i.e., mass median aerodynamic diameter (MMAD) and fine particle fraction (FPF)) were determined, and selected powders were used for further characterization. RESULTS: Of the nine dry powders prepared, their MMAD values were about 1-2 µm, with FPF values (delivered) of 40-80%. The aerosol properties of the powders were inversely correlated with the pDNA loading and the solid content in the pDNA solution before TFF. Powders prepared with Tris-EDTA buffer or cosolvents (i.e., 1,4-dioxane or tert-butanol in water), instead of water, showed slightly reduced aerosol properties. Ultimately, powders prepared with pDNA loading at 5% (w/w), 0.25% of solid content, with or without Tris-EDTA were selected for further characterization due to their overall good aerosol performance. The pDNA powders exhibited a porous matrix structure, with a moisture content of < 2% (w/w). Agarose gel electrophoresis confirmed the chemical integrity of the pDNA after it was subjected to TFF and after the TFF powder was actuated. A cell transfection study confirmed that the activity of the pDNA did not change after it was subjected to TFF. CONCLUSION: It is feasible to use TFF to produce aerosolizable pDNA dry powder for pulmonary delivery, while preserving the integrity and activity of the pDNA.