How can we bring high drug doses to the lung?

Particle surface coating for dry powder inhaler formulations

INTRODUCTION

The development of dry powder inhalers (DPIs) is challenging due to the need for micronized particles to achieve lung delivery. The high specific surface area of micronized particles renders them cohesive and adhesive. Addition of certain excipients like magnesium stearate has been reported to coat the particles and improve the aerosolization in the carrier-based DPI. Therefore, application of particle coating in DPI developments has been investigated and expanded over the years, along with the growing need of high-dose carrier-free DPIs.

AREA COVERED

In addition to modifying inter-particulate forces, particle coating has also been demonstrated to effectively provide moisture resistance, modify particle morphology, improve the stability of biologics, alter dissolution behaviors for DPI developments. These different coating functions have been discussed in the current work. Moreover, various coating techniques including solvent-based coating, dry coating, and vapor coating, as well as coating characterization have been summarized in the present review.

EXPERT OPINION

The extent of particle coating is critical to DPI performance; however, there is a demand for advanced characterization techniques to quantify and understand the coating quality. Further advancements in coating materials, methods, characterization techniques are needed to better relate coating properties to performance, especially for complex drug modalities.

Posaconazole nanocrystals dry powder inhalers for the local treatment of invasive pulmonary aspergillosis

Invasive pulmonary aspergillosis poses a significant threat to immunocompromised patients, characterized by high mortality rates. Posaconazole (PSZ), a second-generation triazole antifungal, exhibits broad-spectrum activity but suffers from limited pulmonary concentrations and notable systemic side effects when administered orally or intravenously. This study focuses on optimizing PSZ nanocrystals-agglomerated particles for dry powder inhalers (DPIs) to enhance solubility, dissolution rates, and pulmonary deposition, ultimately improving therapeutic efficacy while minimizing systemic adverse effects. We employed wet medium milling and spray-drying techniques to formulate PSZ nanocrystals-agglomerated DPIs. Various stabilizers including HPMC, HPC, Soluplus, and PVPK30, were systematically evaluated to optimize physicochemical properties. Aerosolization performance was assessed using the Next Generation Impactor, while antifungal efficacy was evaluated through in vitro and in vivo studies. The optimized PSZ DPIs demonstrated significant enhancements in solubility and dissolution rates, with a fine particle fraction (FPF) of 78.58 ± 3.21%, ensuring optimal lung delivery. In vitro experiments revealed potent effects with minimal cytotoxicity to lung cells. In vivo studies indicated that the optimized formulation achieved a Cmax/AUC0→∞ ratio in lung tissues that was 27.32 and 6.76-fold higher than that of the oral suspension, highlighting increased local drug concentrations. This approach presents a scalable, cost-effective strategy for the pulmonary delivery of PSZ, ensuring high drug loading and promising clinical outcomes in treating pulmonary fungal infections.

A Novel Inhalable Dry Powder to Trigger Delivery of Voriconazole for Effective Management of Pulmonary Aspergillosis

Invasive pulmonary aspergillosis (IPA) is a fatal fungal infection with a high mortality rate. Voriconazole (VCZ) is considered a first-line therapy for IPA and shows efficacy in patients for whom other antifungal treatments have been unsuccessful. The objective of this study was to develop a high-potency VCZ-loaded liposomal system in the form of a dry-powder inhaler (DPI) using the spray-drying technique to convert liposomes into a nanocomposite microparticle (NCMP) DPI, formulated using a thin-film hydration technique. The physicochemical properties, including size, morphology, entrapment efficiency, and loading efficiency, of the formulated liposomes were evaluated. The NCMPs were then examined to determine their drug content, production yield, and aerodynamic size. The L3NCMP was formulated using a 1:1 lipid/L-leucine ratio and was selected for in vitro studies of cell viability, antifungal activity, and stability. These formulated inhalable particles offer a promising approach to the effective management of IPA.

Particulate bioaerogels for respiratory drug delivery

The bioaerogel microparticles have been recently developed for respiratory drug delivery and attract fast increasing interests. These highly porous microparticles have ultralow density and hence possess much reduced aerodynamic diameter, which favour them with greatly enhanced dispersibility and improved aerosolisation behaviour. The adjustable particle geometric dimensions by varying preparation methods and controlling operation parameters make it possible to fabricate bioaerogel microparticles with accurate sizes for efficient delivery to the targeted regions of respiratory tract (i.e. intranasal and pulmonary). Additionally, the technical process can provide bioaerogel microparticles with the opportunities of accommodating polar, weak polar and non-polar drugs at sufficient amount to satisfy clinical needs, and the adsorbed drugs are primarily in the amorphous form that potentially can facilitate drug dissolution and improve bioavailability. Finally, the nature of biopolymers can further offer additional advantageous characteristics of improved mucoadhesion, sustained drug release and subsequently elongated time for continuous treatment on-site. These fascinating features strongly support bioaerogel microparticles to become a novel platform for effective delivery of a wide range of drugs to the targeted respiratory regions, with increased drug residence time on-site, sustained drug release, constant treatment for local and systemic diseases and anticipated better-quality of therapeutic effects.

Designing inhaled small molecule drugs for severe respiratory diseases: an overview of the challenges and opportunities

INTRODUCTION

Inhaled drugs offer advantages for the treatment of respiratory diseases over oral drugs by delivering the drug directly to the lung, thus improving the therapeutic index. There is an unmet medical need for novel therapies for lung diseases, exacerbated by a multitude of challenges for the design of inhaled small molecule drugs.

AREAS COVERED

The authors review the challenges and opportunities for the design of inhaled drugs for respiratory diseases with a focus on new target discovery, medicinal chemistry, and pharmacokinetic, pharmacodynamic, and toxicological evaluation of drug candidates.

EXPERT OPINION

Inhaled drug discovery is facing multiple unique challenges. Novel biological targets are scarce, as is the guidance for medicinal chemistry teams to design compounds with inhalation-compatible features. It is exceedingly difficult to establish a PK/PD relationship given the complexity of pulmonary PK and the impact of physical properties of the drug substance on PK. PK, PD and toxicology studies are technically challenging and require large amounts of drug substance. Despite the current challenges, the authors foresee that the design of inhaled drugs will be facilitated in the future by our increasing understanding of pathobiology, emerging medicinal chemistry guidelines, advances in drug formulation, PBPK models, and in vitro toxicology assays.

Inhalable dry powder product (DPP) of mRNA lipid nanoparticles (LNPs) for pulmonary delivery

Pulmonary delivery of mRNA via inhalation is a very attractive approach for RNA-based therapy for treatment of lung diseases. In this work, we have demonstrated successful development of an mRNA-lipid nanoparticle (LNP) dry powder product (DPP), wherein the LNPs were spray dried using hydroalcoholic solvent along with mannitol and leucine as excipients. The desired critical attributes for the DPP were accomplished by varying the excipients, lipid composition, concentration of LNPs, and weight percentage of mRNA. Leucine alone or in combination with mannitol improved the formulation by increasing the mRNA yield as well as decreasing the particle size. Intratracheal administration of the DPP in mice resulted in luciferase expression in the trachea and lungs indicating successful delivery of functional mRNA. Our results show formulation optimization of mRNA LNPs administered in the form of DPP results in an efficacious functional delivery with great promise for future development of mRNA therapeutics for lung diseases.

Inhalation Dosage Forms: A Focus on Dry Powder Inhalers and Their Advancements

In this review, an extensive analysis of dry powder inhalers (DPIs) is offered, focusing on their characteristics, formulation, stability, and manufacturing. The advantages of pulmonary delivery were investigated, as well as the significance of the particle size in drug deposition. The preparation of DPI formulations was also comprehensively explored, including physico-chemical characterization of powders, powder processing techniques, and formulation considerations. In addition to manufacturing procedures, testing methods were also discussed, providing insights into the development and evaluation of DPI formulations. This review also explores the design basics and critical attributes specific to DPIs, highlighting the significance of their optimization to achieve an effective inhalation therapy. Additionally, the morphology and stability of 3 DPI capsules (Spiriva, Braltus, and Onbrez) were investigated, offering valuable insights into the properties of these formulations. Altogether, these findings contribute to a deeper understanding of DPIs and their development, performance, and optimization of inhalation dosage forms.

Discovery of the Potent and Selective Inhaled Janus Kinase 1 Inhibitor AZD4604 and Its Preclinical Characterization

JAK-STAT cytokines are critical in regulating immunity. Persistent activation of JAK-STAT signaling pathways by cytokines drives chronic inflammatory diseases such as asthma. Herein, we report on the discovery of a highly JAK1-selective, ATP-competitive series of inhibitors having a 1000-fold selectivity over other JAK family members and the approach used to identify compounds suitable for inhaled administration. Ultimately, compound 16 was selected as the clinical candidate, and upon dry powder inhalation, we could demonstrate a high local concentration in the lung as well as low plasma concentrations, suggesting no systemic JAK1 target engagement. Compound 16 has progressed into clinical trials. Using 16, we found JAK1 inhibition to be more efficacious than JAK3 inhibition in IL-4-driven Th2 asthma.

Targeting Inflammation in Non-Small Cell Lung Cancer through Drug Repurposing

Lung cancer is the most common cause of cancer-related deaths. Lung cancers can be classified as small-cell (SCLC) or non-small cell (NSCLC). About 84% of all lung cancers are NSCLC and about 16% are SCLC. For the past few years, there have been a lot of new advances in the management of NSCLC in terms of screening, diagnosis and treatment. Unfortunately, most of the NSCLCs are resistant to current treatments and eventually progress to advanced stages. In this perspective, we discuss some of the drugs that can be repurposed to specifically target the inflammatory pathway of NSCLC utilizing its well-defined inflammatory tumor microenvironment. Continuous inflammatory conditions are responsible to induce DNA damage and enhance cell division rate in lung tissues. There are existing anti-inflammatory drugs which were found suitable for repurposing in non-small cell lung carcinoma (NSCLC) treatment and drug modification for delivery via inhalation. Repurposing anti-inflammatory drugs and their delivery through the airway is a promising strategy to treat NSCLC. In this review, suitable drug candidates that can be repurposed to treat inflammation-mediated NSCLC will be comprehensively discussed together with their administration via inhalation from physico-chemical and nanocarrier perspectives.

An expert opinion on respiratory delivery of high dose powders for lung infections

INTRODUCTION

High dose powder inhalation is evolving as an important approach to to treat lung infections. It is important to its identify applications, consider the factors affecting high dose powder delivery, and assess the effect of high dose drugs in patients.

AREA COVERED

Both current and pipeline high dose inhalers and their applications have been summarized. Challenges and opportunities to high dose delivery have been highlighted after reviewing formulation techniques in the context of factors affecting aerosolization, devices, and patient factors.

EXPERT OPINION

High dose inhaled delivery of antimicrobials is an innovative way to increase treatment efficacy of respiratory infections, tackle drug resistance, and the scarcity of new antimicrobials. The high dose inhaled technology also has potential for systemic action; however, innovations in formulation strategies and devices are required to realize its full potential. Advances in formulation strategies include the use of excipients or the engineering of particles to decrease the cohesive property of microparticles and their packing density. Similarly, selection of a synergistic drug instead of an excipient can be considered to increase aerosolization and stability. Device development focused on improving dispersion and loading capacity is also important, and modification of existing devices for high dose delivery can also be considered.

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

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

High dose nanocrystalline solid dispersion powder of voriconazole for inhalation

In the current work, we aimed to deliver high dose of voriconazole (VRC) to lung through dry powder for inhalation (DPIs). Furthermore, the research tested the hypothesis that drug nanocrystals can escape the clearance mechanisms in lung by virtue of their size and rapid dissolution. High dose nanocrystalline solid dispersion (NCSD) based DPI of VRC was prepared using a novel spray drying process. Mannitol (MAN) and soya lecithin (LEC) were used as crystallization inducer and stabilizer, respectively. The powders were characterized for physicochemical and aerodynamic properties. Chemical interactions contributing to generation and stabilization of VRC nanocrystals in the matrix of MAN were established using computational studies. Performance of NCSD (VRC-N) was compared with microcrystalline solid dispersion (VRC-M) in terms of dissolution, uptake in A549 and RAW 264.7 cells. Plasma and lung distribution of VRC-N and VRC-M in Balb/c mice upon insufflation was compared with the intravenous product. In VRC-N, drug nanocrystals of size 645.86 ± 56.90 nm were successfully produced at VRC loading of 45%. MAN created physical barrier to crystal growth by interacting with N- of triazole and F- of pyrimidine ring of VRC. An increase in drug loading to 60% produced VRC crystals of size 4800 ± 200 nm (VRC-M). The optimized powders were crystalline and showed deposition at stage 2 and 3 in NGI. In comparison to VRC-M, more than 80% of VRC-N dissolved rapidly in around 5-10 mins, therefore, showed higher and lower drug uptake into A549 and RAW 264.7 cells, respectively. In contrast to intravenous product, insufflation of VRC-N and VRC-M led to higher drug concentrations in lung in comparison to plasma. VRC-N showed higher lung AUC_0-24 due to escape of macrophage clearance.

Effect of inner physical properties on powder adhesion in inhalation capsules in case of a high resistance device

The inhalation performance of a dry powder inhaler (DPI) depends on the inhalation patterns of patients, inhalation particle characteristics and inhalation devices. In capsule-based DPIs, the capsule plays an important role in the dispersion of inhalation particles. The present study investigated the effects of inner physical properties of capsules on drug release from capsules-based DPIs with high resistance device. Atomic force microscopy (AFM) was used to evaluate the capsule physical properties, such as the capsule inner structure and surface potential, of three capsules with different compositions (G-Cap, PEG/G-Cap, and HPMC-Cap). As a model dry powder for capsule-based DPIs, the dry powder in Spiriva^® Inhalation Capsules containing tiotropium bromide was used. Inhalation performance was evaluated using a twin-stage liquid impinge and Handihaler^® (flow rate 30 l/min). The results indicated that the capsule inner surface presented with numerous valleys and mountains, regardless of the capsule type. Furthermore, the valley and mountain areas on the capsule inner surface showed a significantly higher or lower surface potential. Following inhalation of capsule-based DPIs, the drug remained in the valleys on the capsule inner surface; however, no significant difference was observed in the drug release from capsule and lung drug delivery. Therefore, inhalation performance in capsule-based DPIs when a high resistance device, such as Handihaler^®, is used at an appropriately flow rate is not markedly affected by the physical properties of the capsule inner surface due to capsule composition.

Inhaled antibiotic-loaded polymeric nanoparticles for the management of lower respiratory tract infections

Lower respiratory tract infections (LRTIs) are one of the leading causes of deaths in the world. Currently available treatment for this disease is with high doses of antibiotics which need to be administered frequently. Instead, pulmonary delivery of drugs has been considered as one of the most efficient routes of drug delivery to the targeted areas as it provides rapid onset of action, direct deposition of drugs into the lungs, and better therapeutic effects at low doses and is self-administrable by the patients. Thus, there is a need for scientists to design more convenient pulmonary drug delivery systems towards the innovation of a novel treatment system for LRTIs. Drug-encapsulating polymer nanoparticles have been investigated for lung delivery which could significantly reduce the limitations of the currently available treatment system for LRTIs. However, the selection of an appropriate polymer carrier for the drugs is a critical issue for the successful formulations of inhalable nanoparticles. In this review, the current understanding of LRTIs, management systems for this disease and their limitations, pulmonary drug delivery systems and the challenges of drug delivery through the pulmonary route are discussed. Drug-encapsulating polymer nanoparticles for lung delivery, antibiotics used in pulmonary delivery and drug encapsulation techniques have also been reviewed. A strong emphasis is placed on the impact of drug delivery into the infected lungs.

A quantitative approach to predicting lung deposition profiles of pharmaceutical powder aerosols

Dry powder inhalers (DPI) are widely used systems for pulmonary delivery of therapeutics. The inhalation performance of DPIs is influenced by formulation features, inhaler device and inhalation pattern. The current review presents the affecting factors with great focus on powder characteristics which include particle size, shape, surface, density, hygroscopicity and crystallinity. The properties of a formulation are greatly influenced by a number of physicochemical factors of drug and added excipients. Since available particle engineering techniques result in particles with a set of modifications, it is difficult to distinguish the effect of an individual feature on powder deposition behavior. This necessitates developing a predictive model capable of describing all influential factors on dry powder inhaler delivery. Therefore, in the current study, a model was constructed to correlate the inhaler device properties, inhalation flow rate, particle characteristics and drug/excipient physicochemical properties with the resultant fine particle fraction. The r² value of established correlation was 0.74 indicating 86% variability in FPF values is explained by the model with the mean absolute errors of 0.22 for the predicted values. The authors believe that this model is capable of predicting the lung deposition pattern of a formulation with an acceptable precision when the type of inhaler device, inhalation flow rate, physicochemical behavior of active and inactive ingredients and the particle characteristics of DPI formulations are considered.

Development of High Dose Oseltamivir Phosphate Dry Powder for Inhalation Therapy in Viral Pneumonia

Oseltamivir phosphate (OP) is an antiviral drug available only as oral therapy for the treatment of influenza and as a potential treatment option when in combination with other medication in the fight against the corona virus disease (COVID-19) pneumonia. In this study, OP was formulated as a dry powder for inhalation, which allows drug targeting to the site of action and potentially reduces the dose, aiming a more efficient therapy. Binary formulations were based on micronized excipient particles acting like diluents, which were blended with the drug OP. Different excipient types, excipient ratios, and excipient size distributions were prepared and examined. To investigate the feasibility of delivering high doses of OP in a single dose, 1:1, 1:3, and 3:1 drug/diluent blending ratios have been prepared. Subsequently, the aerosolization performance was evaluated for all prepared formulations by cascade impaction using a novel medium-resistance capsule-based inhaler (UNI-Haler). Formulations with micronized trehalose showed relatively excellent aerosolization performance with highest fine-particle doses in comparison to examined lactose, mannitol, and glucose under similar conditions. Focusing on the trehalose-based dry-powder inhalers' (DPIs) formulations, a physicochemical characterization of extra micronized grade trehalose in relation to the achieved performance in dispersing OP was performed. Additionally, an early indication of inhaled OP safety on lung cells was noted by the viability MTT assay utilizing Calu-3 cells.

Pulmonary route of administration is instrumental in developing therapeutic interventions against respiratory diseases

Pulmonary route of drug delivery has drawn significant attention due to the limitations associated with conventional routes and available treatment options. Drugs administered through pulmonary route has been an important research area that focuses on to developing effective therapeutic interventions for asthma, chronic obstructive pulmonary disease, tuberculosis, lung cancer etc. The intravenous route has been a natural route of delivery of proteins and peptides but associated with several issues including high cost, needle-phobia, pain, sterility issues etc. These issues might be addressed by the pulmonary administration of macromolecules to achieving an effective delivery and efficacious therapeutic impact. Efforts have been made to develop novel drug delivery systems (NDDS) such as nanoparticles, microparticles, liposomes and their engineered versions, polymerosomes, micelles etc to achieving targeted and sustained delivery of drug(s) through pulmonary route. Further, novel approaches such as polymer-drug conjugates, mucoadhesive particles and mucus penetrating particles have attracted significant attention due to their unique features for an effective delivery of drugs. Also, use of semi flourinated alkanes is in use for improvising the pulmonary delivery of lipophilic drugs. Present review focuses on to unravel the mechanism of pulmonary absorption of drugs for major pulmonary diseases. It summarizes the development of interventional approaches using various particulate and vesicular drug delivery systems. In essence, the orchestrated attempt presents an inflammatory narrative on the advancements in the field of pulmonary drug delivery.

Co-Amorphization of Kanamycin with Amino Acids Improves Aerosolization

Different formulation techniques have been investigated to prepare highly aerosolizable dry powders to deliver a high dose of antibiotics to the lung for treating local infections. In this study, we investigated the influence of the co-amorphization of a model drug, kanamycin, with selected amino acids (valine, methionine, phenylalanine, and tryptophan) by co-spray drying on its aerosolization. The co-amorphicity was confirmed by thermal technique. The physical stability was monitored using low-frequency Raman spectroscopy coupled with principal component analysis. Except for the kanamycin-valine formulation, all the formulations offered improved fine particle fraction (FPF) with the highest FPF of 84% achieved for the kanamycin-methionine formulation. All the co-amorphous formulations were physically stable for 28 days at low relative humidity (25 °C/<15% RH) and exhibited stable aerosolization. At higher RH (53%), even though methionine transformed into its crystalline counterpart, the kanamycin-methionine formulation offered the best aerosolization stability without any decrease in FPF. While further studies are warranted to reveal the underlying mechanism, this study reports that the co-amorphization of kanamycin with amino acids, especially with methionine, has the potential to be developed as a high dose kanamycin dry powder formulation.

Generation of High Dose Inhalable Effervescent Dispersions against Pseudomonas aeruginosa Biofilms

PURPOSE

Novel particle engineering approach was used in this study to generate high dose inhalable effervescent particles with synergistic effects against Pseudomonas aeruginosa biofilms.

METHODS

Spray dried co-amorphous salt of ciprofloxacin (CFX) and tartaric acid (TA) was prepared and coated with external layer of sodium bicarbonate and silica coated silver nanobeads. Design of experiments (DOE) was used to optimize physicochemical properties of particles for enhanced lung deposition.

RESULTS

Generated particles were co-amorphous CFX/TA showing that CFX lost its zwitterionic form and exhibiting distinct properties to CFX/HCl as assessed by FTIR and thermal analysis. Particles exhibited mass mean aerodynamic diameter (MMAD) of 3.3 μm, emitted dose of 78% and fine particle dose of 85%. Particles were further evaluated via antimicrobial assessment of minimum inhibitory concentrations (MIC) and minimum biofilm eradication concentration (MBEC). MIC and MBEC results showed that the hybrid particles were around 3-5 times more effective when compared to CFX signifying that synergistic effect was achieved. Diffusing wave spectroscopy results showed that the silver containing particles had a disruptive effect on rheological properties as opposed to silver free particles.

CONCLUSIONS

Overall, these results showed the potential to use particle engineering to generate particles that are highly disruptive of bacterial biofilms.

Pulmonary delivery of a p38 α/β MAP kinase inhibitor: bioanalytical method validation and biodistribution in rat plasma and respiratory tissues

PF-03715455, an inhaled p38 α/β mitogen-activated protein (MAP) kinase inhibitor (MAPK), has being identified as an agent with potential therapeutic action on lung diseases such as COPD and severe asthma. However, little is known about this MAPKs local and systemic pharmacokinetics after pulmonary delivery. Consequently, the aim of the present work was to develop and validate a method of extraction and quantification of PF-03715455 in rat plasma and lung tissues and to determine the drug biodistribution in plasma and respiratory tissues after intratracheal administration of the drug solution in rats. The method was validated in rat plasma samples and resulted selective and linear in the concentration range of 0.08-100 ng/ml. Then a partial validation was carried out on samples obtained by the extraction and quantification of PF-03715455 from rat lung homogenate in order to ascertain method applicability on lung tissue samples. The intratracheal administration of drug in solution to rats evidenced a rapid elimination from the plasma, while on the contrary a prolonged residence time in lung tissue was evidenced. In conclusion, a linear, accurate, precise and reproducible method has been developed and validated according to FDA and EMA guidelines to quantify plasmatic and tissue-associated concentrations of PF-03715455 in order to investigate this compound in pharmacokinetics pre-clinical studies in rats. The administration of drug solution evidenced a prolonged permanence of the drug in the lungs that could be related to a slow absorption/poor permeability of the drug across airways epithelia.

In Silico Optimization of Fiber-Shaped Aerosols in Inhalation Therapy for Augmented Targeting and Deposition across the Respiratory Tract

Motivated by a desire to uncover new opportunities for designing the size and shape of fiber-shaped aerosols towards improved pulmonary drug delivery deposition outcomes, we explore the transport and deposition characteristics of fibers under physiologically inspired inhalation conditions in silico, mimicking a dry powder inhaler (DPI) maneuver in adult lung models. Here, using computational fluid dynamics (CFD) simulations, we resolve the transient translational and rotational motion of inhaled micron-sized ellipsoid particles under the influence of aerodynamic (i.e., drag, lift) and gravitational forces in a respiratory tract model spanning the first seven bifurcating generations (i.e., from the mouth to upper airways), coupled to a more distal airway model representing nine generations of the mid-bronchial tree. Aerosol deposition efficiencies are quantified as a function of the equivalent diameter (dp) and geometrical aspect ratio (AR), and these are compared to outcomes with traditional spherical particles of equivalent mass. Our results help elucidate how deposition patterns are intimately coupled to dp and AR, whereby high AR fibers in the narrow range of dp = 6-7 µm yield the highest deposition efficiency for targeting the upper- and mid-bronchi, whereas fibers in the range of dp= 4-6 µm are anticipated to cross through the conducting regions and reach the deeper lung regions. Our efforts underscore previously uncovered opportunities to design the shape and size of fiber-like aerosols towards targeted pulmonary drug delivery with increased deposition efficiencies, in particular by leveraging their large payloads for deep lung deposition.

Carrier-free combination dry powder inhaler formulation of ethionamide and moxifloxacin for treating drug-resistant tuberculosis

This study aimed to develop a combination dry powder formulation of ethionamide and moxifloxacin HCl as this combination is synergistic against drug-resistant Mycobacterium tuberculosis (Mtb). L-leucine (20% w/w) was added in the formulations to maximize the process yield. Moxifloxacin HCl and/or ethionamide powders with/without L-leucine were produced using a Buchi Mini Spray-dryer. A next generation impactor was used to determine the in vitro aerosolization efficiency. The powders were also characterized for other physicochemical properties and cytotoxicity. All the spray-dried powders were within the aerodynamic size range of <5.0 µm except ethionamide-only powder (6.0 µm). The combination powders with L-leucine aerosolized better (% fine particle fraction (FPF): 61.3 and 61.1 for ethionamide and moxifloxacin, respectively) than ethionamide-only (%FPF: 9.0) and moxifloxacin-only (%FPF: 30.8) powders. The combination powder particles were collapsed with wrinkled surfaces whereas moxifloxacin-only powders were spherical and smooth and ethionamide-only powders were angular-shaped flakes. The combination powders had low water content (<2.0%). All the powders were physically stable at 15% RH and 25 ± 2 °C during 1-month storage and tolerated by bronchial epithelial cell-lines up to 100 µg/ml. The improved aerosolization of the combination formulation may be helpful for the effective treatment of drug-resistant tuberculosis. Further studies are required to understand the mechanisms for improved aerosolization and test the synergistic activity of the combination powder.

Effects of the antibiotic component on in-vitro bacterial killing, physico-chemical properties, aerosolization and dissolution of a ternary-combinational inhalation powder formulation of antibiotics for pan-drug resistant Gram-negative lung infections

Combinational antibiotic formulations have emerged as an important strategy to combat antibiotic resistance. The main objective of this study was to examine effects of individual components on the antimicrobial activity, physico-chemical properties, aerosolization and dissolution of powder aerosol formulations when three synergistic drugs were co-spray dried. A ternary dry powder formulation consisting of meropenem (75.5 %w/w), colistin (15.1 %w/w) and rifampicin (9.4 %w/w) at the selected ratio was produced by spray drying. The ternary formulation was characterized for in-vitro antibacterial activity, physico-chemical properties, surface composition, aerosol performance and dissolution. All of the formulations demonstrated excellent aerosolization behavior achieving a fine particle fraction of >70%, which was substantially higher than those for the Meropenem-SD and Colistin-Meropenem formulations. The results indicated that rifampicin controlled the surface morphology of the ternary and binary combination formulations resulting in the formation of highly corrugated particles. Advanced characterization of surface composition by XPS supported the hypothesis that rifampicin was enriched on the surface of the combination powder formulations. All spray-dried formulations were amorphous and absorbed substantial amount of water at the elevated humidity. Storage at the elevated humidity caused a substantial decline in aerosolization performance for the Meropenem-SD and Colistin-Meropenem, which was attributed to increased inter-particulate capillary forces or particle fusion. In contrast, the ternary combination and binary Meropenem-Rifampicin formulations showed no change in aerosol performance at the elevated storage humidity conditions; attributable to the enriched hydrophobicity of rifampicin on the particle surface that acted as a barrier against moisture condensation and particle fusion. Interestingly, in the ternary formulation rifampicin enrichment on the surface did not interfere with the dissolution of other two components (i.e. meropenem and colistin). Our study provides an insight on the impact of each component on the performance of co-spray dried combinational formulations.

Assessing Aerosol Performance of a Dry Powder Carrier Formulation with Increasing Doses Using a Novel Inhaler

This study aims to investigate the implications of loaded formulation mass on aerosol performance using a reservoir novel dry powder inhaler containing a custom dosing cup to deliver carrier-based formulation to the lungs. A 3D printed dosing cup with volume size of 133.04 mm³ was manufactured to allow for the progressive loading of different carrier formulation masses of 1% beclomethasone dipropionate BDP (w/w) formulation (10 to 60 mg, with increments of 10 mg), in a novel customizable DPI device. Scanning electron micrographs were used to investigate BDP detachment from carrier particles post-aerosolisation and particle deposition on the USP induction port. The subsequent aerosol performance analysis was performed using the next generation impactor (NGI). Incrementally increasing the loading mass to 60 mg led to decreases in BDP detachment from carrier particles, resulting in significant decreases in aerosol performance. Increases in loading dose mass led to progressively decreased detachment of BDP from the carrier and the overall aerosol performance in comparison to the initial mass of 10 mg. These results are likely to be due to a decrease in void volume within the dosing cup with increased loading mass leading to altered airflow, decreased impaction forces and the possibility of a significant quantity of large carrier particles introducing a 'sweeping' effect on the inhaler inner surface. This study has shown that despite the decreased BDP detachment from the carrier and decreased aerosol performance, the dose delivered to the lung still increased due to the higher loaded dose.

Drugs/lamellae interface influences the inner structure of double-loaded liposomes for inhaled anti-TB therapy: An in-depth small-angle neutron scattering investigation

With the aim of developing new drug carriers for inhalation therapy, we report here an in depth investigation of the structure of multilamellar liposomes loaded with two well-established anti-tubercular (anti-TB) drugs, isoniazid (INH) and rifampicin (RIF), by means of small-angle neutron-scattering (SANS) analysis. Unloaded, single drug-loaded and co-loaded liposomes were prepared using different amounts of drugs and characterized regarding size, encapsulation efficiency and drug release. Detailed information on relevant properties of the investigated host-guest structures, namely the steric bilayer thickness, particle dispersion, number of lamellae and drug localization was studied by SANS. Results showed that RIF-liposomes were less ordered than unloaded liposomes. INH induced a change in the inter-bilayer periodical spacing, while RIF-INH co-loading stabilized the multilamellar liposome architecture, as confirmed by the increment of the drug loading capacity. These findings could be useful for the understanding of in vitro and in vivo behavior of these systems and for the design of new drug carriers, intended for inhaled therapy.

Novel Inhalable Ciprofloxacin Dry Powders for Bronchiectasis Therapy: Mannitol-Silk Fibroin Binary Microparticles with High-Payload and Improved Aerosolized Properties

Non-cystic fibrosis bronchiectasis (NCFB) is a chronic respiratory disease associated with the high morbidity and mortality. Long-term intermittent therapy by inhalable antibiotics has recently emerged as an effective approach for NCFB treatment. However, the effective delivery of antibiotics to the lung requires administering a high dose to the site of infection. Herein, we investigated the novel inhalable silk-based microparticles as a promising approach to deliver high-payload ciprofloxacin (CIP) for NCFB therapy. Silk fibroin (SF) was applied to improve drug-payload and deposit efficiency of the dry powder particles. Mannitol was added as a mucokinetic agent. The dry powder inhaler (DPI) formulations of CIP microparticles were evaluated in vitro in terms of the aerodynamic performance, particle size distribution, drug loading, morphology, and their solid state. The optimal formulation (highest drug loading, 80%) exhibited superior aerosolization performance in terms of fine particle fraction (45.04 ± 0.84%), emitted dose (98.10 ± 1.27%), mass median aerodynamic diameter (3.75 ± 0.03 μm), and geometric standard deviation (1.66 ± 0.10). The improved drug loading was due to the electrostatic interactions between the SF and CIP by adsorption, and the superior aerosolization efficiency would be largely attributed to the fluffy and porous cotton-like property and low-density structure of SF. The presented results indicated the novel inhalable silk-based DPI microparticles of CIP could provide a promising strategy for the treatment of NCFB.

Impact of capsule type on aerodynamic performance of inhalation products: A case study using a formoterol-lactose binary or ternary blend

The aerodynamic performance of a dry powder for inhalation depends on the formulation and the dry powder inhaler (DPI). In the case of capsule-based DPIs, the capsule also plays a role in the powder aerosolisation and the dispersion of the micronized drug during the inhalation. This study evaluated the impact of gelatine capsules (Quali-G™ and Hard Gelatine Capsules for DPIs), cold-gelled hypromellose (HPMC) capsules (Quali-V^®-I and Vcaps^®) and thermal-gelled HPMC capsules (Vcaps^®Plus) from Qualicaps^® and Capsugel^® respectively, on the delivered dose (DD), fine particle dose (FPD), and capsule retention for formoterol-lactose binary and ternary blends. This study used a low resistance Axahaler^® DPI based on the RS01 design (Plastiape, Italy). Similar trends were observed with the different capsule types that packaged both dry powder formulations. The highest DD and FPD and the lowest formoterol capsule retention were observed with cold-gelled HPMC capsules such as Quali-V-I^® and Vcaps^®, without significant differences between these capsules (p > 0.05, one-way ANOVA with Newman-Keuls post-hoc test) for both dry powders. Therefore, the capsule composition and manufacturing process have an influence on aerodynamic performance. In addition, the ternary blend showed higher DDs and FPDs but also higher capsule retention in comparison to the binary blend.

High dose dry powder inhalers to overcome the challenges of tuberculosis treatment

Tuberculosis (TB) is a major global health burden. The emergence of the human immunodeficiency virus (HIV) epidemic and drug resistance has complicated global TB control. Pulmonary delivery of drugs using dry powder inhalers (DPI) is an emerging approach to treat TB. In comparison with the conventional pulmonary delivery for asthma and chronic obstructive pulmonary disease (COPD), TB requires high dose delivery to the lung. However, high dose delivery depends on the successful design of the inhaler device and the formulation of highly aerosolizable powders. Particle engineering techniques play an important role in the development of high dose dry powder formulations. This review focuses on the development of high dose dry powder formulations for TB treatment with background information on the challenges of the current treatment of TB and the potential for pulmonary delivery. Particle engineering techniques with a particular focus on the spray drying and a summary of the developed dry powder formulations using different techniques are also discussed.

Formulation of High-Performance Dry Powder Aerosols for Pulmonary Protein Delivery

PURPOSE

Pulmonary delivery of biologics is of great interest, as it can be used for the local treatment of respiratory diseases or as a route to systemic drug delivery. To reach the full potential of inhaled biologics, a formulation platform capable of producing high performance aerosols without altering protein native structure is required.

METHODS

A formulation strategy using Particle Replication in Non-wetting Templates (PRINT) was developed to produce protein dry powders with precisely engineered particle morphology. Stability of the incorporated proteins was characterized and the aerosol properties of the protein dry powders was evaluated in vitro with an Andersen Cascade Impactor (ACI).

RESULTS

Model proteins bovine serum albumin (BSA) and lysozyme were micromolded into 1 μm cylinders composed of more than 80% protein, by mass. Extensive characterization of the incorporated proteins found no evidence of alteration of native structures. The BSA formulation produced a mass median aerodynamic diameter (MMAD) of 1.77 μm ± 0.06 and a geometric standard deviation (GSD) of 1.51 ± 0.06 while the lysozyme formulation had an MMAD of 1.83 μm ± 0.12 and a GSD of 1.44 ± 0.03.

CONCLUSION

Protein dry powders manufactured with PRINT could enable high-performance delivery of protein therapeutics to the lungs.

Inhalational supplementation of metformin butyrate: A strategy for prevention and cure of various pulmonary disorders

The management of chronic lung diseases such as cancer, asthma, COPD and pulmonary hypertension remains unsatisfactory till date, and several strategies are being tried to control the same. Metformin, a popular anti-diabetic drug has shown promising effects in pre-clinical studies and has been subject to several trials in patients with debilitating pulmonary diseases. However, the clinical evidence for the use of metformin in these conditions is disappointing. Recent observations suggest that metformin use in diabetic patients is associated with an increase in butyrate-producing bacteria in the gut microbiome. Butyrate, similar to metformin, shows beneficial effects in pathological conditions found in pulmonary diseases. Further, the pharmacokinetic data of metformin suggests that metformin is predominantly concentrated in the gut, even after absorption. Butyrate, on the other hand, has a short half-life and thus oral supplementation of butyrate and metformin is unlikely to result in high concentrations of these drugs in the lung. In this paper, we review the pre-clinical studies of metformin and butyrate pertaining to pathologies commonly encountered in chronic lung diseases and underscore the need to administer these drugs directly to the lung via the inhalational route.

Intratracheal Administration of siRNA Dry Powder Targeting Vascular Endothelial Growth Factor Inhibits Lung Tumor Growth in Mice

Inhalation therapy using small-interfering RNA (siRNA) is a potentially effective therapeutic strategy for lung cancer because of its high gene-silencing effects and sequence specificity. Previous studies reported that intratracheal administration of siRNA using pressurized metered dose inhalers or nebulizers could suppress tumor growth in murine lung metastatic models. Although dry powder inhalers are promising devices due to their low cost, good portability, and preservability, the anti-tumor effects of siRNA dry powder have not been elucidated. To evaluate the gene-silencing and anti-tumor effects of intratracheally delivered siRNA dry powder, vascular endothelial growth factor-specific siRNA (VEGF-siRNA) dry powder was administered intratracheally to mice with metastatic lung tumors consisting of B16F10 melanoma cells or Lewis lung carcinoma cells. A single intratracheal administration of VEGF-siRNA dry powder reduced VEGF levels in both bronchoalveolar lavage fluid and lung tumor tissue. Furthermore, repeated intratracheal administration of VEGF-siRNA dry powder suppressed the number of visible metastatic foci on the lung surface and tumor area in lung tissues. Taken together, intratracheal administration of siRNA dry powder could be a novel therapeutic strategy for lung cancer through the suppression of specific genes expressed in lung tumor tissue.

4-Amino-7,8-dihydro-1,6-naphthyridin-5(6 H)-ones as Inhaled Phosphodiesterase Type 4 (PDE4) Inhibitors: Structural Biology and Structure-Activity Relationships

Rational design of a novel template of naphthyridinones rapidly led to PDE4 inhibitors with subnanomolar enzymatic potencies. X-ray crystallography confirmed the binding mode of this novel template. We achieved compounds with double-digit picomolar enzymatic potencies through further structure-based design by targeting both the PDE4 enzyme metal-binding pocket and occupying the solvent-filled pocket. A strategy for lung retention and long duration of action based on low aqueous solubility was followed. In vivo efficacies were measured in a rat lung neutrophilia model by suspension microspray and dry powder administration. Suspension microspray of potent compounds showed in vivo efficacy with a clear dose-response. Despite sustained lung levels, dry powder administration performed much less well and without proper dose-response, highlighting clear differences between the two formulations. This indicates a deficiency in the low aqueous solubility strategy for long duration lung efficacy.

Development of fine solid-crystal suspension with enhanced solubility, stability, and aerosolization performance for dry powder inhalation

Dry powder for inhalation (DPI) is an attractive approach for the treatment of local lung diseases. However, the application of drugs with poor water solubility is often limited due to the dissolution obstacles in the fluid layer of the lung lining. In this study, fine solid-crystal suspension (FSCS) was proposed as a solvent-free method to improve the solubility of a drug with poor solubility (itraconazole) and achieve high deposition efficiency simultaneously. The FSCS, in which the crystalline drug particle was highly dispersed in the crystalline excipient, was initially prepared as drug-excipient extrudate by hot melt extrusion, followed by jet milling into fine particles. Unlike the amorphous solid dispersion in the high-energy state, which is liable to recrystallize and aggregate, the FSCS was expected not only to improve the solubility of itraconazole, but also to maintain excellent physical stability. As evidenced in the solubility and stability studies, the solubility of itraconazole in the FSCS was approximately 145-fold greater than that of the raw material, and the crystalline form of itraconazole in the FSCS was also unchanged after storage in the accelerated condition for 6 months (40°C and 75% relative humidity [RH]). The improved solubility might be ascribed to the reduced crystal size and increased wettability, as confirmed by the particle size and contact angle test. The FSCS also showed an encouragingly high fine-particle fraction of 50.59±0.67%, which might have benefited from the appropriate particle size. Therefore, the FSCS was suggested as a promising DPI for delivery of drugs with poor water solubility.

Selective Nonsteroidal Glucocorticoid Receptor Modulators for the Inhaled Treatment of Pulmonary Diseases

A class of potent, nonsteroidal, selective indazole ether-based glucocorticoid receptor modulators (SGRMs) was developed for the inhaled treatment of respiratory diseases. Starting from an orally available compound with demonstrated anti-inflammatory activity in rat, a soft-drug strategy was implemented to ensure rapid elimination of drug candidates to minimize systemic GR activation. The first clinical candidate 1b (AZD5423) displayed a potent inhibition of lung edema in a rat model of allergic airway inflammation following dry powder inhalation combined with a moderate systemic GR-effect, assessed as thymic involution. Further optimization of inhaled drug properties provided a second, equally potent, candidate, 15m (AZD7594), that demonstrated an improved therapeutic ratio over the benchmark inhaled corticosteroid 3 (fluticasone propionate) and prolonged the inhibition of lung edema, indicating potential for once-daily treatment.

A review of co-milling techniques for the production of high dose dry powder inhaler formulation

Drug delivery by inhalation offers several advantages compared to other dosage forms, including rapid clinical onset, high bioavailability, and minimal systemic side effects. Drug delivery to the lung can be achieved as liquid suspensions or solutions in nebulizers and pressurized metered-dose inhalers (pMDI), or as dry powders in dry powder inhalers (DPIs). Compared to other delivery systems, DPIs are, in many cases, considered the most convenient as they are breath actuated and do not require the use of propellants. Currently, the delivery of low drug doses for the treatment of lung conditions such as asthma and chronic obstructive pulmonary disease are well established, with numerous commercial products available on the market. The delivery of low doses can be achieved from either standard carrier- or aggregate-based formulations, which are unsuitable in the delivery of high doses due to particle segregation associated with carrier active site saturation and the cohesiveness of micronized aggregates which have poor flow and de-agglomeration properties. High-dose delivery is required for the treatment of lung infection (i.e. antibiotics) and in the emerging application of drug delivery for the management of systemic conditions (i.e. diabetes). Therefore, there is a demand for new methods for production of high-dose dry powder formulations. This paper presents a review of co-mill processing, for the production of high-efficiency inhalation therapies, including the jet mill, mechanofusion, or ball mill methodologies. We investigate the different techniques, additives, and drugs studied, and impact on performance in DPI systems.

Inhalable Antimicrobials for Treatment of Bacterial Biofilm-Associated Sinusitis in Cystic Fibrosis Patients: Challenges and Drug Delivery Approaches

Bacterial biofilm-associated chronic sinusitis in cystic fibrosis (CF) patients caused by Pseudomonas aeruginosa infections and the lack of available treatments for such infections constitute a critical aspect of CF disease management. Currently, inhalation therapies to combat P. aeruginosa infections in CF patients are focused mainly on the delivery of antimicrobials to the lower respiratory tract, disregarding the sinuses. However, the sinuses constitute a reservoir for P. aeruginosa growth, leading to re-infection of the lungs, even after clearing an initial lung infection. Eradication of P. aeruginosa from the respiratory tract after a first infection has been shown to delay chronic pulmonary infection with the bacteria for up to two years. The challenges with providing a suitable treatment for bacterial sinusitis include: (i) identifying a suitable antimicrobial compound; (ii) selecting a suitable device to deliver the drug to the sinuses and nasal cavities; and (iii) applying a formulation design, which will mediate delivery of a high dose of the antimicrobial directly to the site of infection. This review highlights currently available inhalable antimicrobial formulations for treatment and management of biofilm infections caused by P. aeruginosa and discusses critical issues related to novel antimicrobial drug formulation design approaches.

An investigation of surface properties, local elastic modulus and interaction with simulated pulmonary surfactant of surface modified inhalable voriconazole dry powders using atomic force microscopy

l-Leucine modified voriconazole spray dried micropartcles.