Will pulmonary drug delivery for systemic application ever fulfill its rich promise?

Unravelling the in vivo dynamics of liposomes: Insights into biodistribution and cellular membrane interactions

Liposomes, as a colloidal drug delivery system dating back to the 1960s, remain a focal point of extensive research and stand as a highly efficient drug delivery method. The amalgamation of technological and biological advancements has propelled their evolution, elevating them to their current status. The key attributes of biodegradability and biocompatibility have been instrumental in driving substantial progress in liposome development. Demonstrating a remarkable ability to surmount barriers in drug absorption, enhance stability, and achieve targeted distribution within the body, liposomes have become pivotal in pharmaceutical research. In this comprehensive review, we delve into the intricate details of liposomal drug delivery systems, focusing specifically on their pharmacokinetics and cell membrane interactions via fusion, lipid exchange, endocytosis etc. Emphasizing the nuanced impact of various liposomal characteristics, we explore factors such as lipid composition, particle size, surface modifications, charge, dosage, and administration routes. By dissecting the multifaceted interactions between liposomes and biological barriers, including the reticuloendothelial system (RES), opsonization, enhanced permeability and retention (EPR) effect, ATP-binding cassette (ABC) phenomenon, and Complement Activation-Related Pseudoallergy (CARPA) effect, we provide a deeper understanding of liposomal behaviour in vivo. Furthermore, this review addresses the intricate challenges associated with translating liposomal technology into practical applications, offering insights into overcoming these hurdles. Additionally, we provide a comprehensive analysis of the clinical adoption and patent landscape of liposomes across diverse biomedical domains, shedding light on their potential implications for future research and therapeutic developments.

Application of ensemble machine learning approach to assess the factors affecting size and polydispersity index of liposomal nanoparticles

Liposome nanoparticles have emerged as promising drug delivery systems due to their unique properties. Assessing particle size and polydispersity index (PDI) is critical for evaluating the quality of these liposomal nanoparticles. However, optimizing these parameters in a laboratory setting is both costly and time-consuming. This study aimed to apply a machine learning technique to assess the impact of specific factors, including sonication time, extrusion temperature, and compositions, on the size and PDI of liposomal nanoparticles. Liposomal solutions were prepared and subjected to sonication with varying values for these parameters. Two compositions: (A) HSPC:DPPG:Chol:DSPE-mPEG2000 at 55:5:35:5 molar ratio and (B) HSPC:Chol:DSPE-mPEG2000 at 55:40:5 molar ratio, were made using remote loading method. Ensemble learning (EL), a machine learning technique, was employed using the Least-squares boosting (LSBoost) algorithm to accurately model the data. The dataset was randomly split into training and testing sets, with 70% allocated for training. The LSBoost algorithm achieved mean absolute errors of 1.652 and 0.0105 for modeling the size and PDI, respectively. Under conditions where the temperature was set at approximately 60 °C, our EL model predicted a minimum particle size of 116.53 nm for composition (A) with a sonication time of approximately 30 min. Similarly, for composition (B), the model predicted a minimum particle size of 129.97 nm with sonication times of approximately 30 or 55 min. In most instances, a PDI of less than 0.2 was achieved. These results highlight the significant impact of optimizing independent factors on the characteristics of liposomal nanoparticles and demonstrate the potential of EL as a decision support system for identifying the best liposomal formulation. We recommend further studies to explore the effects of other independent factors, such as lipid composition and surfactants, on liposomal nanoparticle characteristics.

HSPB5 Inhibition by NCI-41356 Reduces Experimental Lung Fibrosis by Blocking TGF-β1 Signaling

Idiopathic pulmonary fibrosis is a chronic, progressive and lethal disease of unknown etiology that ranks among the most frequent interstitial lung diseases. Idiopathic pulmonary fibrosis is characterized by dysregulated healing mechanisms that lead to the accumulation of large amounts of collagen in the lung tissue that disrupts the alveolar architecture. The two currently available treatments, nintedanib and pirfenidone, are only able to slow down the disease without being curative. We demonstrated in the past that HSPB5, a low molecular weight heat shock protein, was involved in the development of fibrosis and therefore was a potential therapeutic target. Here, we have explored whether NCI-41356, a chemical inhibitor of HSPB5, can limit the development of pulmonary fibrosis. In vivo, we used a mouse model in which fibrosis was induced by intratracheal injection of bleomycin. Mice were treated with NaCl or NCI-41356 (six times intravenously or three times intratracheally). Fibrosis was evaluated by collagen quantification, immunofluorescence and TGF-β gene expression. In vitro, we studied the specific role of NCI-41356 on the chaperone function of HSPB5 and the inhibitory properties of NCI-41356 on HSPB5 interaction with its partner SMAD4 during fibrosis. TGF-β1 signaling was evaluated by immunofluorescence and Western Blot in epithelial cells treated with TGF-β1 with or without NCI-41356. In vivo, NCI-41356 reduced the accumulation of collagen, the expression of TGF-β1 and pro-fibrotic markers (PAI-1, α-SMA). In vitro, NCI-41356 decreased the interaction between HSPB5 and SMAD4 and thus modulated the SMAD4 canonical nuclear translocation involved in TGF-β1 signaling, which may explain NCI-41356 anti-fibrotic properties. In this study, we determined that inhibition of HSPB5 by NCI-41356 could limit pulmonary fibrosis in mice by limiting the synthesis of collagen and pro-fibrotic markers. At the molecular level, this outcome may be explained by the effect of NCI-41356 inhibiting HSPB5/SMAD4 interaction, thus modulating SMAD4 and TGF-β1 signaling. Further investigations are needed to determine whether these results can be transposed to humans.

Nanomaterials for Delivering Antibiotics in the Therapy of Pneumonia

Bacterial pneumonia is one of the leading causes of death worldwide and exerts a significant burden on health-care resources. Antibiotics have long been used as first-line drugs for the treatment of bacterial pneumonia. However, antibiotic therapy and traditional antibiotic delivery are associated with important challenges, including drug resistance, low bioavailability, and adverse side effects; the existence of physiological barriers further hampers treatment. Fortunately, these limitations may be overcome by the application of nanotechnology, which can facilitate drug delivery while improving drug stability and bioavailability. This review summarizes the challenges facing the treatment of bacterial pneumonia and also highlights the types of nanoparticles that can be used for antibiotic delivery. This review places a special focus on the state-of-the-art in nanomaterial-based approaches to the delivery of antibiotics for the treatment of pneumonia.

Micro-fluidic Spray Freeze Dried Ciprofloxacin Hydrochloride-Embedded Dry Powder for Inhalation

Active pharmaceutical ingredient (API)-embedded dry powder for inhalation (AeDPI) is highly desirable for pulmonary delivery of high-dose drug. Herein, a series of spray freeze-dried (SFD) ciprofloxacin hydrochloride (CH)-embedded dry powders were fabricated via a self-designed micro-fluidic spray freeze tower (MFSFT) capable of tuning freezing temperature of cooling air as the refrigerant medium. The effects of total solid content (TSC), mass ratio of CH to _L-leucine (Leu) as the aerosol dispersion enhancer, and the freezing temperature on particle morphology, size, density, moisture content, crystal properties, flowability, and aerodynamic performance were investigated. It was found that the Leu content and freezing temperature had considerable influence on the fine particle fraction (FPF) of the SFD microparticles. The optimal formulation (CH/Leu = 7:3, TSC = 2%w/w) prepared at - 40°C exhibited remarkable effective drug deposition (~ 33.38%), good aerodynamic performance (~ 47.69% FPF), and excellent storage stability with ultralow hygroscopicity (~ 1.93%). This work demonstrated the promising feasibility of using the MFSFT instead of conventional liquid nitrogen assisted method in the research and development of high-dose AeDPI.

Inhaled Medicines: Past, Present, and Future

The purpose of this review is to summarize essential pharmacological, pharmaceutical, and clinical aspects in the field of orally inhaled therapies that may help scientists seeking to develop new products. After general comments on the rationale for inhaled therapies for respiratory disease, the focus is on products approved approximately over the last half a century. The organization of these sections reflects the key pharmacological categories. Products for asthma and chronic obstructive pulmonary disease include β -2 receptor agonists, muscarinic acetylcholine receptor antagonists, glucocorticosteroids, and cromones as well as their combinations. The antiviral and antibacterial inhaled products to treat respiratory tract infections are then presented. Two "mucoactive" products-dornase α and mannitol, which are both approved for patients with cystic fibrosis-are reviewed. These are followed by sections on inhaled prostacyclins for pulmonary arterial hypertension and the challenging field of aerosol surfactant inhalation delivery, especially for prematurely born infants on ventilation support. The approved products for systemic delivery via the lungs for diseases of the central nervous system and insulin for diabetes are also discussed. New technologies for drug delivery by inhalation are analyzed, with the emphasis on those that would likely yield significant improvements over the technologies in current use or would expand the range of drugs and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of approved orally inhaled drug products for a variety of respiratory diseases and for systemic administration should be helpful in making judicious decisions about the development of new or improved inhaled drugs. These aspects include the choices of the active ingredients, formulations, delivery systems suitable for the target patient populations, and, to some extent, meaningful safety and efficacy endpoints in clinical trials.

Permeability Properties of an In Vitro Model of the Alveolar Epithelium

Cell culture models of epithelial barriers in the body are widely used to study the permeation of nutrients, drugs, infectious agents and pollutants into the body tissues and circulation. The NCI-H441 cell line cultured at the air-liquid interface mimics certain phenotypic and functional characteristics of the human alveolar epithelium. Here the permeability properties of the NCI-H441 model were characterised and compared against published data using experimental measurements and mathematical modelling. Cells were cultured under air-liquid interface conditions and trans-epithelial electrical resistance (TEER) and apparent permeability (P _app) to sodium fluorescein (MW 383 Da) and fluorescently labelled dextrans (MW 4000-150,000 Da) was measured. It was found that TEER was independent of cell seeding density while P _app decreased with higher seeding density and plateaued beyond a density of 500,000 cells/cm². Using the framework of functional pore analysis, a mathematical model was fitted to P _app values measured in this work as well as previously published datasets from human cell lines and primary human and rat cells. It was found that the air-liquid interface NCI-H441 model most closely matched the primary cell line results in contrast to published data using A549 and liquid-interface NCI-H441 cell cultures, supporting the use of this model to study the permeability of the alveolar epithelium to large molecules.

Facile preparation of liposome-encapsulated Zn–DTPA from soy lecithin for decorporation of radioactive actinides

Diethylenetriaminepentaacetic acid (DTPA) is an attractive decorporation agent that can enhance the excretion of radioactive actinides such as plutonium, americium, and curium after a radiological incident. However, DTPA is excreted in a short period of time after administration. Several formulations have been developed to improve DTPA pharmacokinetics properties. In this project, liposomes were prepared facilely from soy lecithin as a nanocarrier for pulmonary delivery of Zn–DTPA. Lipid hydration, reverse phase evaporation, and mechanical sonication were three methods evaluated for the preparation of liposome-encapsulated Zn-DTPA (lipo-Zn-DTPA). Mechanical sonication was the method of choice due to simple apparatus and facile preparation. Lipo-Zn–DTPA exhibited a hydrodynamic diameter of 178 ± 2 nm and a spherical shape. The loading capacity and encapsulation efficiency of Zn–DTPA were 41 ± 5 mg/g and 10% ± 1%, respectively. Lyophilization of lipo-Zn–DTPA for extended storage did not affect the amount of encapsulated drug or damage the structure of liposomes. An in vivo cytotoxicity test confirmed no serious adverse effect of Zn–DTPA encapsulated lecithin liposomes in rats.

Novel Approaches for the Treatment of Pulmonary Tuberculosis

Tuberculosis (TB) is a contagious airborne disease caused by Mycobacterium tuberculosis, which primarily affects human lungs. The progression of drug-susceptible TB to drug-resistant strains, MDR-TB and XDR-TB, has become worldwide challenge in eliminating TB. The limitations of conventional TB treatment including frequent dosing and prolonged treatment, which results in patient’s noncompliance to the treatment because of treatment-related adverse effects. The non-invasive pulmonary drug administration provides the advantages of targeted-site delivery and avoids first-pass metabolism, which reduced the dose requirement and systemic adverse effects of the therapeutics. With the modification of the drugs with advanced carriers, the formulations may possess sustained released property, which helps in reducing the dosing frequency and enhanced patients’ compliances. The dry powder inhaler formulation is easy to handle and storage as it is relatively stable compared to liquids and suspension. This review mainly highlights the aerosolization properties of dry powder inhalable formulations with different anti-TB agents to understand and estimate the deposition manner of the drug in the lungs. Moreover, the safety profile of the novel dry powder inhaler formulations has been discussed. The results of the studies demonstrated that dry powder inhaler formulation has the potential in enhancing treatment efficacy.

Developing inhaled protein therapeutics for lung diseases

Biologic therapeutics such as protein/polypeptide drugs are conventionally administered systemically via intravenous injection for the treatment of diseases including lung diseases, although this approach leads to low target site accumulation and the potential risk for systemic side effects. In comparison, topical delivery of protein drugs to the lung via inhalation is deemed to be a more effective approach for lung diseases, as proteins would directly reach the target in the lung while exhibiting poor diffusion into the systemic circulation, leading to higher lung drug retention and efficacy while minimising toxicity to other organs. This review examines the important considerations and challenges in designing an inhaled protein therapeutics for local lung delivery: the choice of inhalation device, structural changes affecting drug deposition in diseased lungs, clearance mechanisms affecting an inhaled protein drug’s lung accumulation, protein stability, and immunogenicity. Possible approaches to overcoming these issues will also be discussed.

Preclinical Development of Orally Inhaled Drugs (OIDs)-Are Animal Models Predictive or Shall We Move Towards In Vitro Non-Animal Models?

Respiratory diseases constitute a huge burden in our society, and the global respiratory drug market currently grows at an annual rate between 4% and 6%. Inhalation is the preferred administration method for treating respiratory diseases, as it: (i) delivers the drug directly at the site of action, resulting in a rapid onset; (ii) is painless, thus improving patients' compliance; and (iii) avoids first-pass metabolism reducing systemic side effects. Inhalation occurs through the mouth, with the drug generally exerting its therapeutic action in the lungs. In the most recent years, orally inhaled drugs (OIDs) have found application also in the treatment of systemic diseases. OIDs development, however, currently suffers of an overall attrition rate of around 70%, meaning that seven out of 10 new drug candidates fail to reach the clinic. Our commentary focuses on the reasons behind the poor OIDs translation into clinical products for the treatment of respiratory and systemic diseases, with particular emphasis on the parameters affecting the predictive value of animal preclinical tests. We then review the current advances in overcoming the limitation of animal animal-based studies through the development and adoption of in vitro, cell-based new approach methodologies (NAMs).

Physical stability of dry powder inhaler formulations

Introduction: Dry powder inhalers (DPIs) are popular for pulmonary drug delivery. Various techniques have been employed to produce inhalation drug particles and improve the delivery efficiency of DPI formulations. Physical stability of these DPI formulations is critical to ensure the delivery of a reproducible dose to the airways over the shelf-life.Areas covered: This review focuses on the impact of solid-state stability on aerosolization performance of DPI drug particles manufactured by powder production approaches and particle-engineering techniques. It also highlights the different analytical tools that can be used to characterize the physical instability originating from production and storage.Expert opinion: A majority of the DPI literature focuses on the effects of physico-chemical properties such as size, morphology, and density on aerosolization. While little has been reported on the physical stability, particularly the stability of engineered drug particles for use in DPIs. Literature data have shown that different particle-engineering methods and storage conditions may cause physical instability of dry powders for inhalation and can significantly change the aerosol performance. A systematic examination of physical instability mechanisms in DPI formulations is necessary during formulation development in order to select the optimum formulation with satisfactory stability. In addition, the use of appropriate characterization tools is critical to detect and understand physical instability during the development of DPI formulations.

Optimization of Ciprofloxacin Hydrochloride Spray-Dried Microparticles for Pulmonary Delivery Using Design of Experiments

Ciprofloxacin is a broad-spectrum antibiotic for treatment of pulmonary diseases such as chronic obstructive pulmonary disease and cystic fibrosis. The purpose of this work was to rationally study the spray drying of ciprofloxacin in order to identify the formulation and operating conditions that lead to a product with aerodynamic properties appropriate for dry powder inhalation. A 2^4 - 1 fractional factorial design was applied to investigate the effect of selected variables (i.e., ciprofloxacin hydrochloride (CIP) concentration, drying air inlet temperature, feed flow rate, and atomization air flow rate) on several product and process parameters (i.e., particle size, aerodynamic diameter, moisture content, densities, porosity, powder flowability, outlet temperature, and process yield) and to determine an optimal condition. The studied factors had a significant effect on the evaluated responses (higher p value 0.0017), except for the moisture content (p value > 0.05). The optimal formulation and operating conditions were as follows: CIP concentration 10 mg/mL, drying air inlet temperature 110°C, feed volumetric flow rate 3.0 mL/min, and atomization air volumetric flow rate 473 L/h. The product obtained under this set had a particle size that guarantees access to the lung, a moisture content acceptable for dry powder inhalation, fair flowability, and high process yield. The PDRX and SEM analysis of the optimal product showed a crystalline structure and round and dimpled particles. Moreover, the product was obtained by a simple and green spray drying method.

Regulatory pitfalls and opportunities when repurposing for inhalation therapy

This article reviews regulatory considerations for companies wishing to develop drugs for delivery via the respiratory tract (e.g., by oral inhalation or intranasally) using molecules previously approved for a different therapeutic indication and/or a different delivery route. Conceptually, such repurposing has many medical and business advantages, but turning promising ideas into real products requires overcoming a number of practical challenges. Obtaining regulatory approval to market a candidate product comes at the end of a product development, but being aware of the regulatory requirements is necessary before the development even starts. Understanding the scope and type of data that regulatory agencies would like to see may have a decisive influence on the design of the development program itself. For example, even for repurposed drugs, safety, efficacy, quality, and usability must be demonstrated, either from prior knowledge or through newly generated data. Furthermore, products for respiratory delivery have unique regulatory challenges due to the nature of these drug-device combinations.

Drug delivery to the lungs: challenges and opportunities

Pulmonary drug delivery is relatively complex because the respiratory tract has evolved defense mechanisms to keep inhaled drug particles out of the lungs and to remove or inactivate them once deposited. In addition to these mechanical, chemical and immunological barriers, pulmonary drug delivery is adversely affected by the behavioral barriers of poor adherence and poor inhaler technique. Strategies to mitigate the effects of these barriers include use of inhaler devices and formulations that deliver drug to the lungs efficiently, appropriate inhaler technique and improved education of patients. Owing to the advantages offered by the pulmonary route, the challenges that the route poses are worth addressing, and if successfully addressed, the pulmonary route offers huge opportunities, often fulfilling unmet clinical needs.