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

Inhalable solid lipid nanoparticles of levofloxacin for potential tuberculosis treatment

Delivering novel antimycobacterial agents through the pulmonary route using nanoparticle-based systems shows promise for treating diseases like tuberculosis. However, creating dry powder inhaler (DPI) with suitable aerodynamic characteristics while preserving nanostructure integrity and maintaining bioactivity until the active ingredient travels deeply into the lungs is a difficult challenge. We developed DPI formulations containing levofloxacin-loaded solid lipid nanoparticles (SLNs) via spray-drying technique with tailored aerosolization characteristics for effective inhalation therapy. A range of biophysical techniques, including transmission electron microscopy, confocal microscopy, and scanning electron microscopy were used to measure the morphologies and sizes of the spray-dried microparticles that explored both the geometric and aerodynamic properties. Spray drying substantially reduced the particle sizes of the SLNs while preserving their nanostructural integrity and enhancing aerosol dispersion with efficient mucus penetration. Despite a slower uptake rate compared to plain SLNs, the polyethylene glycol modified formulations exhibited enhanced cellular uptake in both A549 and NR8383 cell lines. The percent viability of Mycobacterium bovis had dropped to nearly 0 % by day 5 for both types of SLNs. Interestingly, the levofloxacin-loaded SLNs demonstrated a lower minimum bactericidal concentration (0.25 µg/mL) compared with pure levofloxacin (1 µg/mL), which indicated the formulations have potential as effective treatments for tuberculosis.

Development of a dry powder insufflation device with application in in vitro cell-based assays in the context of respiratory delivery

Research on pharmaceutical dry powders has been increasing worldwide, along with increased therapeutic strategies for an application through the pulmonary or the nasal routes. In vitro methodologies and tests that mimic the respiratory environment and the process of inhalation itself are, thus, essential. The literature frequently reports cell-based in vitro assays that involve testing the dry powders in suspension. This experimental setting is not adequate, as both the lung and the nasal cavity are devoid of abundant liquid. However, devices that permit powder insufflation over cells in culture are either scarce or technically complex and expensive, which is not feasible in early stages of research. In this context, this work proposes the development of a device that allows the delivery of dry powders onto cell surfaces, thus simulating inhalation more appropriately. Subsequently, a quartz crystal microbalance (QCM) was used to establish a technique enabling the determination of dry powder deposition profiles. Additionally, the determination of the viability of respiratory cells (A549) after the insufflation of a dry powder using the developed device was performed. In all, a prototype for dry powder insufflation was designed and developed, using 3D printing methods for its production. It allowed the homogenous dispersion of the insufflated powders over a petri dish and a QCM crystal, and a more detailed study on how dry powders disperse over the supports. The device, already protected by a patent, still requires further improvement, especially regarding the method for powder weighing and the efficiency of the insufflation process, which is being addressed. The impact of insufflation of air and of locust bean gum (LBG)-based microparticles revealed absence of cytotoxic effect, as cell viability roughly above 70 % was always determined.

Chitosan/bovine serum albumin layer-by-layer assembled particles for non-invasive inhaled drug delivery to the lungs

Layer-by-Layer (LbL) assembly of polyelectrolytes on a solid core particle is a well-established technique used to deliver drugs, proteins, regenerative medicines, combinatorial therapy, etc. It is a multifunctional delivery system which can be engineered using various core template particles and coating polymers. This study reports the development and in-vitro evaluation of LbL assembled particles for non-invasive inhaled delivery to the lungs. The LbL assembled particles were prepared by successively coating polyelectrolyte macromolecules, glycol chitosan and bovine serum albumin on 0.5- and 4.5-μm polystyrene particles. The LbL assembly of polyelectrolytes was confirmed by reversible change in zeta potential and sequential increase in the particle size after accumulation of the layer. The prepared LbL particles were further assessed for aerodynamic properties using two distinct nebulizers, and toxicity assessment in normal lung cells. The in-vitro aerosolization study performed using next generation impactor coupled with Pari LC Plus and Aeroeclipse nebulizer showed that both the LbL assembled 0.5 and 4.5-μm particles had MMAD <5 μm confirming suitable aerodynamic properties for non-invasive lung delivery. The in-vitro cytotoxicity, and TEER integrity following treatment with the LbL assembled particles in normal lung epithelial and fibroblasts showed no significant cytotoxicity rendering the LbL assembled particles safe. This study extends the efficiency of LbL assembled particles for novel applications towards delivery of small and large molecules into the lungs.

Emerging Process Modeling Capabilities for Dry Powder Operations for Inhaled Formulations

Dry powder inhaler (DPI) products are commonly formulated as a mixture of micronized drug particles and large carrier particles, with or without additional fine particle excipients, followed by final powder filling into dose containment systems such as capsules, blisters, or reservoirs. DPI product manufacturing consists of a series of unit operations, including particle size reduction, blending, and filling. This review provides an overview of the relevant critical process parameters used for jet milling, high-shear blending, and dosator/drum capsule filling operations across commonly utilized instruments. Further, this review describes the recent achievements regarding the application of empirical and mechanistic models, especially discrete element method (DEM) simulation, in DPI process development. Although to date only limited modeling/simulation work has been accomplished, in the authors' perspective, process design and development are destined to be more modeling/simulation driven with the emphasis on evaluating the impact of material attributes/process parameters on process performance. The advancement of computational power is expected to enable modeling/simulation approaches to tackle more complex problems with better accuracy when dealing with real-world DPI process operations.

Predicting particle deposition using a simplified 8-path in silico human lung prototype

Understanding particle deposition in the human lung is crucial for the assessment of environmental pollutants and the design of new drug delivery systems. Traditionally, research has been carried out by experimental analysis, but this generally requires expensive equipment and exposure of volunteers to radiation, resulting in limited data. To overcome these drawbacks, there is an emphasis on the development of numerical models capable of accurate predictive analysis. The most advanced of these computer simulations are based on three-dimensional computational fluid dynamics. Solving the flow equations in a complete, fully resolved lung airway model is currently not feasible due to the computational resources required. In the present work, a simplified lung model is presented and validated for accurate prediction of particle deposition. Simulations are performed for an 8-path approximation to a full lung airway model. A novel boundary condition method is used to ensure accurate results in truncated flow branches. Simulations are performed at a steady inhalation flow rate of 18 l min-1, corresponding to a low activity breathing rate, while the effects of particle size and density are investigated. Comparison of the simulation results with available experimental data shows that reasonably accurate results can be obtained at a small fraction of the cost of a full airway model. The simulations clearly evaluate the effect of both particle size and particle density. Most importantly, the results show an improvement over a previously documented single-path model, both in terms of accuracy and the ability to obtain regional deposition rates. The present model represents an improvement over previously used simplified models, including single-path models. The multi-path reduced airway approach described can be used by researchers for general and patient-specific analyses of particle deposition and for the design of effective drug delivery systems.

Carrier-Free Inhalable Dry Microparticles of Celecoxib: Use of the Electrospraying Technique

Upregulation of cyclooxygenase (COX-2) plays an important role in lung cancer pathogenesis. Celecoxib (CLX), a selective COX-2 inhibitor, may have beneficial effects in COVID-19-induced inflammatory storms. The current study aimed to develop carrier-free inhalable CLX microparticles by electrospraying as a dry powder formulation for inhalation (DPI). CLX microparticles were prepared through an electrospraying method using a suitable solvent mixture at two different drug concentrations. The obtained powders were characterized in terms of their morphology, solid state, dissolution behavior, and aerosolization performance. Electrosprayed particles obtained from the ethanol-acetone solvent mixture with a drug concentration of 3 % w/v exhibited the best in vitro aerosolization properties. The value of the fine particle fraction obtained for the engineered drug particles was 12-fold higher than that of the untreated CLX. When the concentration of CLX was increased, a remarkable reduction in FPF was obtained. The smallest median mass aerodynamic diameter was obtained from the electrosprayed CLX at a 3% concentration (2.82 µm) compared to 5% (3.25 µm) and untreated CLX (4.18 µm). DSC and FTIR experiments showed no change in drug crystallinity or structure of the prepared powders during the electrospraying process. The findings of this study suggest that electrospraying has potential applications in the preparation of DPI formulations.

Investigation of potential substandard dry powder inhalers on EU and North African markets – evaluation of the delivered and fine particle doses

Purpose

Discovery of falsified Symbicort 320/9 Turbohaler identified in the UK in 2013 demonstrated that falsified dry powder inhalers were also present in the European market. This work aimed to investigate the current situation of formoterol-containing dry powder inhalers in Europe and North Africa by assessing their aerodynamic performance profile.

Methods

A total of eight registered formoterol-based dry powder inhalers over the European and North African markets were involved in this study, including the reference drug Foradil. Samples were prepared using a multistage liquid impinger (MsLI) and further analyzed by a validated HPLC-UV method to determine the delivered and the fine particle doses (FPDs). This study also examined the impact of freezing-thawing cycles on sample stability in terms of analytical purpose handling.

Results

No substandard dry powder inhalers were identified among the medicinal products involved in this work. The delivered dose (DD) of assessed drugs varied from 8.33 to 9.69 µg, while the FPD was between 1.86 and 3.35 µg. As expected, this work confirmed that the capsule composition and the barrier properties of the primary packaging can affect the FPD of dry powder for inhalation use.

Conclusions

The FPD of products C and B was, respectively, 17.4 and 14.2% superior to Foradil, products D and H had the closest values compared to the original drug, and product F was 34.5% inferior. Additionally, this work showed that a high FPD can be achieved using HPMC capsules and moisture-impermeable primary packaging.

The Study of Spray-Freeze-Drying Technique for Development of Novel Combination pMDIs, Part I: Study on the Preparation Method

Clinically available pressurized metered-dose inhalers (pMDIs) mainly directly use micronized drugs as inhalable microparticles. Although technology for preparing pMDIs has proven to obtain clinically appropriate aerosol performance, the fine particle fraction and delivered dose content uniformity (DDCU) of pMDIs still need to be improved. DDCU problem is usually exacerbated by patients' handling errors prior to taking a dose. In this study, novel phospholipid microparticle inhalation pMDIs were prepared by a spray-freeze-drying process using mometasone furoate and formoterol fumarate dihydrate as model drugs and distearoylphosphatidylcholine as an excipient. Combined with the material composition, the atomization and freeze-drying processes were also studied. Our data showed that both atomization parameters of gas–liquid ratio and freeze-drying curve settings met the requirements of drug design. According to aerodynamic performance in vitro and DDCU evaluation, the performance of the phospholipid microparticle inhalation pMDI was better than that of the micronized drug microparticle pMDI. In conclusion, preparing pMDIs with particle engineering has the potential to ensure accuracy of quantification and to improve the efficiency of drug deposition in lungs in clinical practice.

Rational Development of a Carrier-Free Dry Powder Inhalation Formulation for Respiratory Viral Infections via Quality by Design: A Drug-Drug Cocrystal of Favipiravir and Theophylline

Formulating pharmaceutical cocrystals as inhalable dosage forms represents a unique niche in effective management of respiratory infections. Favipiravir, a broad-spectrum antiviral drug with potential pharmacological activity against SARS-CoV-2, exhibits a low aqueous solubility. An ultra-high oral dose is essential, causing low patient compliance. This study reports a Quality-by-Design (QbD)-guided development of a carrier-free inhalable dry powder formulation containing a 1:1 favipiravir-theophylline (FAV-THP) cocrystal via spray drying, which may provide an alternative treatment strategy for individuals with concomitant influenza infections and chronic obstructive pulmonary disease/asthma. The cocrystal formation was confirmed by single crystal X-ray diffraction, powder X-ray diffraction, and the construction of a temperature-composition phase diagram. A three-factor, two-level, full factorial design was employed to produce the optimized formulation and study the impact of critical processing parameters on the resulting median mass aerodynamic diameter (MMAD), fine particle fraction (FPF), and crystallinity of the spray-dried FAV-THP cocrystal. In general, a lower solute concentration and feed pump rate resulted in a smaller MMAD with a higher FPF. The optimized formulation (F1) demonstrated an MMAD of 2.93 μm and an FPF of 79.3%, suitable for deep lung delivery with no in vitro cytotoxicity observed in A549 cells.