Pulmonary delivery nanomedicines towards circumventing physiological barriers: Strategies and characterization approaches

Inhalable lipid-based nanocarriers covered by polydopamine for effective mucus penetration and pulmonary retention

To overcome the critical challenge in drug inhalation for pulmonary diseases, we innovatively proposed that polydopamine (PDA) as a surface modification material had great potential to improve the mucus permeation and pulmonary retention of inhalable lipid-based nanocarriers. We prepared PDA coated lipid nanoemulsions/solid lipid nanoparticles/liposomes and systematically evaluated their interactions with mucin and pulmonary retention after inhalation. PDA-coated lipid-based nanocarriers exhibited weaker interactions with mucins, higher mucus permeability and cellular uptake by the respiratory epithelium cells compared to PEGylated lipid-based nanocarriers. However, the pulmonary retention advantage of PDA coating was shown in lipid nanoemulsions (< 50 nm) and solid lipid nanoparticles (< 100 nm). Liposomes (∼ 150 nm) with PEGylation possessed higher pulmonary retention than that coated by PDA. It was suggested that PEGylated liposomes were liable to be phagocytosed by alveolar macrophages due to binding with specific antibodies. Overall, this work suggests that PDA as a surface modification material of inhalable lipid-based nanocarriers holds promise for effective mucus penetration and pulmonary retention.

Harnessing Surface Hydrophilicity of Inhalable Nanoparticles for Precision Delivery of Glucagon-like Peptide-1 Receptor Agonists or Anti-Asthmatic Therapeutics

Rational adjustment of surface physicochemical properties of inhalable nanocarriers significantly influences their in vivo fate during pulmonary delivery. Among these, surface hydrophilicity/hydrophobicity has been recognized as a critical factor in the transmucosal process. However, the impacts of surface hydrophilicity/hydrophobicity on the transcellular performance and ultimate therapeutic effects of pulmonary-delivered nanosystems still remain unelucidated. In this study, we developed a series of liposomes with varying surface hydrophilicity to investigate the effect of surface properties on both local and systemic drug delivery. Interestingly, low-hydrophilic liposomes exhibited enhanced systemic absorption, whereas high-hydrophilic liposomes demonstrated prolonged pulmonary residence after inhalation. To validate this principle, we applied two disease models. In a type II diabetes mellitus model, low hydrophilic liposomes loaded with GLP-1 receptor agonists (Liraglutide or Semaglutide) showed excellent systemic drug delivery and hypoglycemic effects. In an OVA-induced allergic asthma model, budesonide-loaded high hydrophilic liposomes significantly alleviated symptoms while reducing dosing frequency. Mechanistic studies further revealed that liposomes with lower surface hydrophilicity could enhance the transcellular transport efficiency of the drug through alveolar epithelial cells, while those with higher surface hydrophilicity prolonged the pulmonary residence of the drug by decreasing alveolar epithelium transportation and the avoidance of macrophage clearance. Lastly, we evaluated the biocompatibility of these liposomes following inhalation. Overall, tuning the surface hydrophilicity/hydrophobicity of inhalable nanocarriers to suit local or systemic delivery goals offers valuable insights for the rational design of advanced pulmonary delivery systems.

Elucidating structure of endogenous phospholipids on in vivo absorption of octreotide following lung administration

Phospholipids as endogenous pulmonary components have received extensive attention on promoting the transmembrane absorption of peptides and proteins. However, considering their diversified structure, influence of phospholipid structural characteristics on drug absorption across lung epithelial cells, together with the underlying absorption-promoting mechanisms, remain unclear. Therefore, in this study, taking octreotide as a model drug, phospholipids with different "tail" and "head" structures were adopted in the form of blank liposomes to investigate their structural characteristics on drug absorption utilizing both 3D Transwell cell models and Sprague Dawley rats. It was demonstrated that indeed the absorption-enhancing capacity of phospholipids was their structure-dependent. Among the tail (non-polar) structures, a moderately increased alkyl chain length could facilitate drug absorption across the pulmonary epithelium, with the highest enhancement ratio observed for Dipalmitoyl Phosphatidylcholine (DPPC) containing a palmitoyl group of 16 carbons, and its apparent permeability coefficient (Papp) increased 2.4 times compared to octreotide solution. Among the head (polar) structures, charged functional groups could contribute to better drug permeation, and Dipalmitoyl Phosphatidylserine (DPPS) containing a protonated amino (NH3+) and a deprotonated carboxyl (COO-) exhibited a 4.6-fold increase in Papp compared to octreotide solution. Mechanism studies disclosed a paracellular pathway-mediated drug transport across lung epithelial cells. In summary, phospholipids can serve as biosafe absorption enhancers for pulmonary drug delivery, with the extent depending on their structure, which could provide a theoretical basis for pulmonary delivery of macromolecules for systemic absorption.

Nanoparticle-Based Dry Powder Inhaler Containing Ciprofloxacin for Enhanced Targeted Antibacterial Therapy

Background: Ciprofloxacin (CIP) is a poorly water-soluble fluoroquinolone-type antibiotic that can be useful in the treatment of lung infections. When the drugs are delivered directly to the lungs, a smaller dosage is needed to achieve the desired effect compared to the oral administration. Moreover, the application of nanoparticles potentially enhances the effectiveness of the treatments while lowering the possible side effects. Therefore, we aimed to develop a "nano-in-micro" structured dry powder inhaler formulation containing CIP. Methods: A two-step preparation method was used. Firstly, a nanosuspension was first prepared using a high-performance planetary mill by wet milling. After the addition of different additives (leucine and mannitol), the solid formulations were created by spray drying. The prepared DPI samples were analyzed by using laser diffraction, nanoparticle tracking analysis, scanning electron microscopy, X-ray powder diffraction, and differential scanning calorimetry. The solubility and in vitro dissolution tests in artificial lung fluid and in vitro aerodynamic investigations (Spraytec® device, Andersen Cascade Impactor) were carried out. Results: The nanosuspension (D50: 140.0 ± 12.8 nm) was successfully prepared by the particle size reduction method. The DPIs were suitable for inhalation based on the particle diameter and their spherical shape. Improved surface area and amorphization after the preparation processes led to faster drug release. The excipient-containing systems were characterized by large lung deposition (fine particle fraction around 40%) and suitable aerodynamic diameter (between 3 and 4 µm). Conclusions: We have successfully formulated a nanosized antibiotic-containing formulation for pulmonary delivery, which could provide a potential treatment for patients with different respiratory infections.

Pulmonary delivery of dual-targeted nanoparticles improves tumor accumulation and cancer cell targeting by restricting macrophage interception in orthotopic lung tumors

Despite the recognized potential of inhaled nanomedicines to enhance and sustain local drug concentrations for lung cancer treatment, the influence of macrophage uptake on targeted nanoparticle delivery to and within tumors remains unclear. Here, we developed three ligand-coated nanoparticles for pulmonary delivery in lung cancer therapy: phenylboronic acid-modified nanoparticles (PBA-NPs), PBA combined with folic acid (FA-PBA-NPs), and PBA with mannose (MAN-PBA-NPs). In vitro, MAN-PBA-NPs were preferentially internalized by macrophages, whereas FA-PBA-NPs exhibited superior uptake by cancer cells compared to macrophages. Following intratracheal instillation into mice with orthotopic Lewis lung carcinoma tumors, all three nanoparticles showed similar lung retention. However, MAN-PBA-NPs were more prone to interception by lung macrophages, which limited their accumulation in tumor tissues. In contrast, both PBA-NPs and FA-PBA-NPs achieved comparable high tumor accumulation (∼11.3% of the dose). Furthermore, FA-PBA-NPs were internalized by ∼30% of cancer cells, significantly more than the 10-18% seen with PBA-NPs or MAN-PBA-NPs. Additionally, FA-PBA-NPs loaded with icaritin effectively inhibited the Wnt/β-catenin pathway, resulting in superior anti-tumor efficacy through targeted cancer cell delivery. Overall, FA-PBA-NPs demonstrated advantageous competitive uptake kinetics by cancer cells compared to macrophages, enhancing tumor targeting and therapeutic outcomes.

Nanomedicine Innovations for Lung Cancer Diagnosis and Therapy

Lung cancer remains a challenge within the realm of oncology. Characterized by late-stage diagnosis and resistance to conventional treatments, the currently available therapeutic strategies encompass surgery, radiotherapy, chemotherapy, immunotherapy, and biological therapy; however, overall patient survival remains suboptimal. Nanotechnology has ushered in a new era by offering innovative nanomaterials with the potential to precisely target cancer cells while sparing healthy tissues. It holds the potential to reshape the landscape of cancer management, offering hope for patients and clinicians. The assessment of these nanotechnologies follows a rigorous evaluation process similar to that applied to chemical drugs, which includes considerations of their pharmacokinetics, pharmacodynamics, toxicology, and clinical effectiveness. However, because of the characteristics of nanoparticles, standard toxicological tests require modifications to accommodate their unique characteristics. Effective therapeutic strategies demand a profound understanding of the disease and consideration of clinical outcomes, physicochemical attributes of nanomaterials, nanobiointeractions, nanotoxicity, and regulatory compliance to ensure patient safety. This review explores the promise of nanomedicine in lung cancer treatment by capitalizing on its unique physicochemical properties. We address the multifaceted challenges of lung cancer and its tumor microenvironment and provide an overview of recent developments in nanoplatforms for early diagnosis and treatment that can enhance patient outcomes and overall quality of life.

Advanced drug delivery systems for the management of local conditions

Localized disorders, even though originally confined to a specific body part, can progress into potentially life-threatening systemic disorders if treated inappropriately. Local treatment is often highly challenging due to poor penetration of therapeutic agents from their vehicles into the affected body site. Systemic treatment on the other hand often comes with unspecific side effects. The skin is the largest organ of the body, and conditions such as wounds and bacterial or fungal infections disrupt its natural barrier properties, important for the homeostasis of the human body. Advanced drug delivery systems for treating these conditions could greatly improve the treatment outcome and patient compliance. Other parts of the body that are of interest regarding localized treatment are, for example, the eyes along with mucosal tissues which are present in the vagina and lungs. Rather than focusing on specific diseases or parts of the body, this review provides an overview of the different drug delivery platforms that have been employed for enhanced local treatment. The following systems will be discussed: nanoparticle-based systems, such as nanocrystals, polymeric, lipidic, and inorganic nanoparticles, and nanogels; cyclodextrin inclusion complexes; and several devices like microarray patches, wound dressings, and films.

Nanotechnology-Based Therapeutics for Airway Inflammatory Diseases

Under the concept of "one airway, one disease", upper and lower airway inflammatory diseases share similar pathogenic mechanisms and are collectively referred to as airway inflammatory diseases. With industrial development and environmental changes, the incidence of these diseases has gradually increased. Traditional treatments, including glucocorticoids, antihistamines, and bronchodilators, have alleviated much of the discomfort experienced by patients. However, conventional drug delivery routes have inherent flaws, such as significant side effects, irritation of the respiratory mucosa, and issues related to drug deactivation. In recent years, nanomaterials have emerged as excellent carriers for drug delivery and are being increasingly utilized in the treatment of airway inflammatory diseases. These materials not only optimize the delivery of traditional medications but also facilitate the administration of various new drugs that target novel pathways, thereby enhancing the treatment outcomes of inflammatory diseases. This study reviews the latest research on nano-drug delivery systems used in the treatment of airway inflammatory diseases, covering traditional drugs, immunotherapy drugs, antimicrobial drugs, plant-derived drugs, and RNA drugs. The challenges involved in developing nano-delivery systems for these diseases are discussed, along with a future outlook. This review offers new insights that researchers can utilize to advance further research into the clinical application of nano-drug delivery systems for treating airway inflammatory diseases.

Inhalable Metal-Organic Frameworks: A Promising Delivery Platform for Pulmonary Diseases Treatment

Inhalation delivery, offering a direct pathway for administering drugs to the lungs in the form of dry powders or aerosols, stands out as an optimal approach for the localized treatment of pulmonary diseases. However, the intricate anatomical architecture of the lung often poses challenges in maintaining effective drug concentrations within the lungs over extended periods. This highlights the pressing need to develop rational inhalable drug delivery systems that can improve treatment outcomes for respiratory diseases. Metal-organic frameworks (MOFs) assembled from inorganic metal ions and organic ligands, characterized by customizable porous architecture and chemical composition, modifiable porosity, vast surface area, straightforward surface modification, and adjustable biocompatibility, have garnered extensive attention in the biomedical sphere. The introduction of MOFs into inhalation therapy represents a promising avenue to navigate past the hurdles associated with traditional inhalation methods. Therefore, this review summarizes the characteristics of inhalation delivery together with the latest advances, challenges, and opportunities in utilizing inhalable MOFs for treating lung diseases and discusses prospects in this field alongside the potential pathways for translating this strategy into clinic.

Aggregation-Caused Quenching Dyes as Potent Tools to Track the Integrity of Antitumor Nanocarriers: A Mini-Review

Cancer has become one of the major causes of death worldwide. Chemotherapy remains a cornerstone of cancer treatment. To enhance the tumor-targeting efficiency of chemotherapy agents, pharmaceutical scientists have developed nanocarriers. However, the in vivo structural integrity and dynamic changes in nanocarriers after administration are not well understood, which may significantly impact their tumor-targeting abilities. In this paper, we propose the use of environmentally responsive fluorescent probes to track the integrity of antitumor nanocarriers. We compare three main types of dyes: fluorescence resonance energy transfer (FRET) dyes, aggregation-induced emission (AIE) dyes, and aggregation-caused quenching (ACQ) dyes. Among them, ACQ dyes, possessing sensitive water-quenching properties and easily detected "on-off" switching behavior, are regarded as the most promising choice. We believe that ACQ dyes are suitable for investigating the in vivo fate of antitumor nanocarriers and can aid in designing improved nanoformulations for chemotherapy agents.

Nanomedicines for Pulmonary Drug Delivery: Overcoming Barriers in the Treatment of Respiratory Infections and Lung Cancer

The pulmonary route for drug administration has garnered a great deal of attention in therapeutics for treating respiratory disorders. It allows for the delivery of drugs directly to the lungs and, consequently, the maintenance of high concentrations at the action site and a reduction in systemic adverse effects compared to other routes, such as oral or intravenous. Nevertheless, the pulmonary administration of drugs is challenging, as the respiratory system tries to eliminate inhaled particles, being the main responsible mucociliary escalator. Nanomedicines represent a primary strategy to overcome the limitations of this route as they can be engineered to prolong pulmonary retention and avoid their clearance while reducing drug systemic distribution and, consequently, systemic adverse effects. This review analyses the use of pulmonary-administered nanomedicines to treat infectious diseases affecting the respiratory system and lung carcinoma, two pathologies that represent major health threats.

An inhalable nanoparticle enabling virulence factor elimination and antibiotics delivery for pneumococcal pneumonia therapy

Streptococcus pneumoniae (S. pneumoniae) is a major cause of community-acquired pneumonia. Current standard clinical therapies mainly focus on combating S. pneumoniae through antibiotics. However, the limited delivery of antibiotics and the undetoxified hydrogen peroxide (H2O2) virulence factor secreted by S. pneumoniae impede the therapeutic outcomes. Here we report an inhalable catalase (CAT)-tannic acid (TA) nanoassembly for local antibiotic (levofloxacin) delivery and simultaneously neutralizing the secreted H2O2 virulence factors to treat pneumococcal pneumonia. After aerosol inhalation, the inhalable formulation (denoted as CT@LVX) effectively accumulates in lung tissues through TA-mediated mucoadhesion. CAT can reduce alveolar epithelial cells apoptosis by catalyzing the decomposition of accumulated H2O2 in the infected lung tissues. In synergy with antibiotic LVX-mediated S. pneumoniae elimination, CT@LVX significantly decreases lung injury companied with reduced inflammatory, resulting in 100 % survival of mice with pneumonia. In a clinically isolated S. pneumoniae strain-induced pneumonia mouse model, CT@LVX also shows superior outcomes compared to the traditional antibiotic treatment, highlighting its potential clinical application prospects.

Phospholipids of inhaled liposomes determine the in vivo fate and therapeutic effects of salvianolic acid B on idiopathic pulmonary fibrosis

Since phospholipids have an important effect on the size, surface potential and hardness of liposomes that decide their in vivo fate after inhalation, this research has systematically evaluated the effect of phospholipids on pulmonary drug delivery by liposomes. In this study, liposomes composed of neutral saturated/unsaturated phospholipids, anionic and cationic phospholipids were constructed to investigate how surface potential and the degree of saturation of fatty acid chains determined their mucus and epithelium permeability both in vitro and in vivo. Our results clearly indicated that liposomes composed of saturated neutral and anionic phospholipids possessed high stability and permeability, compared to that of liposomes composed of unsaturated phospholipids and cationic phospholipids. Furthermore, both in vivo imaging of fluorescence-labeled liposomes and biodistribution of salvianolic acid B (SAB) that encapsulated in liposomes were performed to estimate the effect of phospholipids on the lung exposure and retention of inhaled liposomes. Finally, inhaled SAB-loaded liposomes exhibited enhanced therapeutic effects in a bleomycin-induced idiopathic pulmonary fibrosis mice model via inhibition of inflammation and regulation on coagulation-fibrinolytic system. Such findings will be beneficial to the development of inhalable lipid-based nanodrug delivery systems for the treatment of respiratory diseases where inhalation is the preferred route of administration.

Nanostructure-Mediated Transport of Therapeutics through Epithelial Barriers

The ability to precisely treat human disease is facilitated by the sophisticated design of pharmacologic agents. Nanotechnology has emerged as a valuable approach to creating vehicles that can specifically target organ systems, effectively traverse epithelial barriers, and protect agents from premature degradation. In this review, we discuss the molecular basis for epithelial barrier function, focusing on tight junctions, and describe different pathways that drugs can use to cross barrier-forming tissue, including the paracellular route and transcytosis. Unique features of drug delivery applied to different organ systems are addressed: transdermal, ocular, pulmonary, and oral delivery. We also discuss how design elements of different nanoscale systems, such as composition and nanostructured architecture, can be used to specifically enhance transepithelial delivery. The ability to tailor nanoscale drug delivery vehicles to leverage epithelial barrier biology is an emerging theme in the pursuit of facilitating the efficacious delivery of pharmacologic agents.

Realveolarization with inhalable mucus-penetrating lipid nanoparticles for the treatment of pulmonary fibrosis in mice

The stemness loss-associated dysregeneration of impaired alveolar type 2 epithelial (AT2) cells abolishes the reversible therapy of idiopathic pulmonary fibrosis (IPF). We here report an inhalable mucus-penetrating lipid nanoparticle (LNP) for codelivering dual mRNAs, promoting realveolarization via restoring AT2 stemness for IPF treatment. Inhalable LNPs were first formulated with dipalmitoylphosphatidylcholine and our in-house-made ionizable lipids for high-efficiency pulmonary mucus penetration and codelivery of dual messenger RNAs (mRNAs), encoding cytochrome b5 reductase 3 and bone morphogenetic protein 4, respectively. After being inhaled in a bleomycin model, LNPs reverses the mitochondrial dysfunction through ameliorating nicotinamide adenine dinucleotide biosynthesis, which inhibits the accelerated senescence of AT2 cells. Concurrently, pathological epithelial remodeling and fibroblast activation induced by impaired AT2 cells are terminated, ultimately prompting alveolar regeneration. Our data demonstrated that the mRNA-LNP system exhibited high protein expression in lung epithelial cells, which markedly extricated the alveolar collapse and prolonged the survival of fibrosis mice, providing a clinically viable strategy against IPF.

Impact of physicochemical properties on biological effects of lipid nanoparticles: Are they completely safe

Lipid nanoparticles (LNPs) are promising materials and human-use approved excipients, with manifold applications in biomedicine. Researchers have tended to focus on improving the pharmacological efficiency and organ targeting of LNPs, while paid relatively less attention to the negative aspects created by their specific physicochemical properties. Here, we discuss the impacts of LNPs' physicochemical properties (size, surface hydrophobicity, surface charge, surface modification and lipid composition) on the adsorption-transportation-distribution-clearance processes and bio-nano interactions. In addition, since there is a lack of review emphasizing on toxicological profiles of LNPs, this review outlined immunogenicity, inflammation, hemolytic toxicity, cytotoxicity and genotoxicity induced by LNPs and the underlying mechanisms, with the aim to understand the properties that underlie the biological effects of these materials. This provides a basic strategy that increased efficacy of medical application with minimized side-effects can be achieved by modulating the physicochemical properties of LNPs. Therefore, addressing the effects of physicochemical properties on toxicity induced by LNPs is critical for understanding their environmental and health risks and will help clear the way for LNPs-based drugs to eventually fulfill their promise as a highly effective therapeutic agents for diverse diseases in clinic.

Pulmonary drug delivery devices and nanosystems as potential treatment strategies for acute respiratory distress syndrome (ARDS)

Despite advances in drug delivery technologies, treating acute respiratory distress syndrome (ARDS) is challenging due to pathophysiological barriers such as lung injury, oedema fluid build-up, and lung inflammation. Active pharmaceutical ingredients (API) can be delivered directly to the lung site of action with the use of aerosol-based drug delivery devices, and this circumvents the hepatic first-pass effect and improves the bioavailability of drugs. This review discusses the various challenges and barriers for pulmonary drug delivery, current interventions for delivery, considerations for effective drug delivery, and the use of nanoparticle drug delivery carriers as potential strategies for delivering therapeutics in ARDS. Nanosystems have the added benefit of entrapping drugs, increase pulmonary drug bioavailability, and using biocompatible and biodegradable excipients that can facilitate targeted and/or controlled delivery. These systems provide an alternative to existing conventional systems. An effective way to deliver drugs for the treatment of ARDS can be by using colloidal systems that are aerosolized or inhaled. Drug distribution to the deeper pulmonary tissues is necessary due to the significant endothelial cell destruction that is prevalent in ARDS. The particle size of nanoparticles (<0.5 μm) makes them ideal candidates for treating ARDS as they can reach the alveoli. A look into the various potential benefits and limitations of nanosystems used for other lung disorders is also considered to indicate how they may be useful for the potential treatment of ARDS.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Efferocytosis-Inspired Biomimetic Nanoplatform for Targeted Acute Lung Injury Therapy

Acute lung injury (ALI) is a serious inflammatory disease that causes impairment of pulmonary function. Phenotypic modulation of macrophage in the lung using fibroblast growth factor 21 (FGF21) may be a potential strategy to alleviate lung inflammation. Consequently, achieving specific delivery of FGF21 to the inflamed lung and subsequent efficient FGF21 internalization by macrophages within the lung becomes critical for effective ALI treatment. Here, an apoptotic cell membrane-coated zirconium-based metal-organic framework UiO-66 is reported for precise pulmonary delivery of FGF21 (ACM@U-FGF21) whose design is inspired by the process of efferocytosis. ACM@U-FGF21 with apoptotic signals is recognized and internalized by phagocytes in the blood and macrophages in the lung, and then the intracellular ACM@U-FGF21 can inhibit the excessive secretion of pro-inflammatory cytokines by these cells to relieve the inflammation. Utilizing the homologous targeting properties inherited from the source cells and the spontaneous recruitment of immune cells to inflammatory sites, ACM@U-FGF21 can accumulate preferentially in the lung after injection. The results prove that ACM@U-FGF21 effectively reduces inflammatory damage to the lung by modulating lung macrophage polarization and suppressing the excessive secretion of pro-inflammatory cytokines by activated immune cells. This study demonstrates the usefulness of efferocytosis-inspired ACM@U-FGF21 in the treatment of ALI.

Exploring the influence of microstructure and phospholipid type of liposomes on their interaction with lung

Liposome is a promising carrier for pulmonary drug delivery and the nano-sized liposomes have been widely investigated in the treatment of lung diseases. However, there still lack the knowledge of micron-sized liposomes for lung delivery, which have more advantages in terms of drug loading and sustained drug release capacity. The micron-sized liposomes can be classified into multilamellar liposome (MLL) and multivesicular liposome (MVL) according to their microstructure, thus, this study focused on exploring how the micron-sized liposomes with different microstructure and phospholipid composition influence their interaction with the lung. The MLL and MVL were prepared from different types of phospholipids (including soya phosphatidylcholine (SPC), egg yolk phosphatidylcholine (EPC), and dipalmitoyl phosphatidylcholine (DPPC)) with geometric diameter around 5 μm, and their in vitro pulmonary cell uptake, in vivo lung retention and organ distribution were investigated. The results showed that the microstructure of liposomes didn't affect pulmonary cellular uptake, in vivo lung retention and organ distribution. MLL and MVL prepared with the same phospholipid had similar cellular uptake in both NR8383 cells and A549 cells, and both of them possessed prolonged lung retention and limited distribution in other organs during 72 h. Notably, the phospholipid type presented remarkable influence on liposomes' interaction with the lung. SPC-based liposomes exhibited higher cellular uptake than the DPPC-based ones in both NR8383 cells and A549 cells, also possessed a better lung retention behavior. In conclusion, this study might provide theoretical knowledge for designing micron-sized liposomes intended for lung delivery.

Preclinical evaluation of novel synthesised nanoparticles based on tyrosine poly(ester amide) for improved targeted pulmonary delivery

Fixed dose combinations (FDCs) incorporating two or three medicines in a single inhaler have been created to enhance patient compliance and hence clinical outcomes. However, the development of dry powder inhalers (DPIs), particularly for FDCs, faces challenges pertinent to formulation uniformity and reproducibility. Therefore, this project aimed to employ nanotechnology to develop a FDC of DPIs for market-leading medicines-fluticasone propionate (FP) and salmeterol xinafoate (SAL)-for asthma management. Nanoaggregates were prepared using a novel biocompatible and biodegradable poly(ester amide) based on the amino acid tyrosine, utilising a one-step interfacial polymerisation process. The produced tyrosine poly (ester amide) drug-loaded nanoparticles were evaluated for content uniformity, PSA, FTIR, TEM, DSC, XRD and aerodynamic performance (in vitro and in vivo). The optimised formulation demonstrated high entrapment efficiency- > 90%. The aerodynamic performance in terms of the emitted dose, fine particle fraction and respirable dose was superior to the carrier-based marketed product. In-vivo studies showed that FP (above the marketed formulation) and SAL reached the lungs of mice in a reproducible manner. These results highlight the superiority of novel FDC FP/SAL nanoparticles prepared via a one-step process, which can be used as a cost-effective and efficient method to alleviate the burden of asthma.

Polysaccharides screening for pulmonary mucus penetration by molecular dynamics simulation and in vitro verification

Mucus penetration is one of the physiologic barriers of inhalation and nanocarriers can effectively facilitate the permeation of drugs. The interactions between the nanocarriers and mucin are crucial for penetration across the mucus layer on the respiratory tract. In this study, we proposed a molecular dynamics (MD) simulation method for the screening of polysaccharides that acted as the surface modification materials for inhalable nano-preparations to facilitate mucus penetration. MD revealed all-atom interactions between the monomers of polysaccharides, including dextran (DEX)/hyaluronic acid (HA)/carboxymethyl chitosan (CMCS) and the human mucin protein MUC5AC (hMUC5AC). The obtained data showed that DEX formed stronger non-covalent bonds with hMUC5AC compared to HA and CMCS, which suggested that HA and CMCS had better mucus permeability than DEX. For the in vitro verification, HA/CMCS-coated liposomes and DEX/PEG-inserted liposomes were prepared. The results of mucin interactions and mucus penetration studies confirmed that HA and CMCS possessed the weakest interactions with mucin and facilitated the mucus penetration, which was in consistent with the data from MD simulation. This work may shed light on the MD simulation-based screening of surface modification materials for inhalable nano-preparations to facilitate mucus penetration.

Opportunities and Challenges for Inhalable Nanomedicine Formulations in Respiratory Diseases: A Review

Lungs experience frequent interactions with the external environment and have an abundant supply of blood; therefore, they are susceptible to invasion by pathogenic microorganisms and tumor cells. However, the limited pharmacokinetics of conventional drugs in the lungs poses a clinical challenge. The emergence of different nano-formulations has been facilitated by advancements in nanotechnology. Inhaled nanomedicines exhibit better targeting and prolonged therapeutic effects. Although nano-formulations have great potential, they still present several unknown risks. Herein, we review the (1) physiological anatomy of the lungs and their biological barriers, (2) pharmacokinetics and toxicology of nanomaterial formulations in the lungs; (3) current nanomaterials that can be applied to the respiratory system and related design strategies, and (4) current applications of inhaled nanomaterials in treating respiratory disorders, vaccine design, and imaging detection based on the characteristics of different nanomaterials. Finally, (5) we analyze and summarize the challenges and prospects of nanomaterials for respiratory disease applications. We believe that nanomaterials, particularly inhaled nano-formulations, have excellent prospects for application in respiratory diseases. However, we emphasize that the simultaneous toxic side effects of biological nanomaterials must be considered during the application of these emerging medicines. This study aims to offer comprehensive guidelines and valuable insights for conducting research on nanomaterials in the domain of the respiratory system.

Nanomedicines for targeted pulmonary delivery: receptor-mediated strategy and alternatives

Pulmonary drug delivery of nanomedicines is promising for the treatment of lung diseases; however, their lack of specificity required for targeted delivery limit their applications. Recently, a variety of pulmonary delivery targeting nanomedicines (PDTNs) has been developed for enhancing drug accumulation in lung lesions and reducing systemic side effects. Furthermore, with the increasing profound understanding of the specific microenvironment of different local lung diseases, multiple targeting strategies have been employed to promote drug delivery efficiency, which can be divided into the receptor-mediated strategy and alternatives. In this review, the current publication trend on PDTNs is analyzed and discussed, revealing that the research in this area has been attracting much attention. According to the different unique microenvironments of lung lesions, the reported PDTNs based on the receptor-mediated strategy for lung cancer, lung infection, lung inflammation and pulmonary fibrosis are listed and summarized. In addition, several other well-established strategies for the design of these PDTNs, such as charge regulation, mucus delivery enhancement, stimulus-responsive drug delivery and magnetic force-driven targeting, are introduced and discussed. Besides, bottlenecks in the development of PDTNs are discussed. Finally, we highlight the challenges and opportunities in the development of PDTNs. We hope that this review will provide an overview of the available PDTNs for guiding the treatment of lung diseases.

Nanoparticle-based platforms for targeted drug delivery to the pulmonary system as therapeutics to curb cystic fibrosis: A review

Cystic fibrosis (CF) is a genetic disorder of the respiratory system caused by mutation of the Cystic Fibrosis Trans-Membrane Conductance Regulator (CFTR) gene that affects a huge number of people worldwide. It results in difficulty breathing due to a large accumulation of mucus in the respiratory tract, resulting in serious bacterial infections, and subsequent death. Traditional drug-based treatments face hindered penetration at the site of action due to the thick mucus layer. Nanotechnology offers possibilities for developing advanced and effective treatment platforms by focusing on drugs that can penetrate the dense mucus layer, fighting against the underlying bacterial infections, and targeting the genetic cause of the disease. In this review, current nanoparticle-mediated drug delivery platforms for CF, challenges in therapeutics, and future prospects have been highlighted. The effectiveness of the different types of nano-based systems conjugated with various drugs to combat the symptoms and the challenges of treating CF are brought into focus. The toxic effects of these nano-medicines and the various factors that are responsible for their effectiveness are also highlighted.

Rapamycin-based inhaled therapy for potential treatment of COPD-related inflammation: production and characterization of aerosolizable nano into micro (NiM) particles

Our paper describes the production and characterization of inhalable microparticles loaded with nanoparticles for the lung administration of rapamycin (Rapa). In detail, core-shell lipid/polymer hybrid nanoparticles loaded with Rapa (Rapa@Man-LPHNPs) were produced with mean size of about 128 nm and slightly negative ζ potential (-13.8 mV). A fluorescent graft polyaspartamide-poly(lactic-co-glycolic acid) copolymer (PHEA-g-RhB-g-PLGA) for use as the polymeric core was obtained by nanoprecipitation, while an appropriate mixture of DPPC and mannosylated phospholipid (DSPE-PEG2000-Man) was used to provide the macrophage-targeting lipid shell. The successful formation of Rapa@Man-LPHNPs was confirmed by TEM and DSC analyses. The loaded drug (4.3 wt% of the total weight) was slowly released from the polymeric core and protected from hydrolysis, with the amount of intact drug after 24 h of incubation in the medium being equal to 74 wt% (compared to 40% when the drug is freely incubated at the same concentration). To obtain a formulation administrable by inhalation, Rapa@Man-LPHNPs were entrapped inside PVA : LEU microparticles by using the nano into micro (NiM) strategy, specifically by spray drying (SD) in the presence of a pore-forming agent. In this way, NiM particles with geometric and theoretical aerodynamic diameters equal to 4.52 μm and 3.26 μm, respectively, were obtained. Furthermore, these particles showed optimal nebulization performance, having an FPF and an MMAD equal to 27.5% and 4.3 μm, respectively.

Targeted Molecular Therapeutics for Pulmonary Diseases: Addressing the Need for Precise Drug Delivery

Respiratory diseases are a major concern in public health, impacting a large population worldwide. Despite the availability of therapies that alleviate symptoms, selectively addressing the critical points of pathopathways remains a major challenge. Innovative formulations designed for reaching these targets within the airways, enhanced selectivity, and prolonged therapeutic effects offer promising solutions. To provide insights into the specific medical requirements of chronic respiratory diseases, the initial focus of this chapter is directed on lung physiology, emphasizing the significance of lung barriers. Current treatments involving small molecules and the potential of gene therapy are also discussed. Additionally, we will explore targeting approaches, with a particular emphasis on nanoparticles, comparing targeted and non-targeted formulations for pulmonary administration. Finally, the potential of inhaled sphingolipids in the context of respiratory diseases is briefly discussed, highlighting their promising prospects in the field.

Unraveling the Multifaceted Roles of Extracellular Vesicles: Insights into Biology, Pharmacology, and Pharmaceutical Applications for Drug Delivery

Extracellular vesicles (EVs) are nanoparticles released from various cell types that have emerged as powerful new therapeutic option for a variety of diseases. EVs are involved in the transmission of biological signals between cells and in the regulation of a variety of biological processes, highlighting them as potential novel targets/platforms for therapeutics intervention and/or delivery. Therefore, it is necessary to investigate new aspects of EVs' biogenesis, biodistribution, metabolism, and excretion as well as safety/compatibility of both unmodified and engineered EVs upon administration in different pharmaceutical dosage forms and delivery systems. In this review, we summarize the current knowledge of essential physiological and pathological roles of EVs in different organs and organ systems. We provide an overview regarding application of EVs as therapeutic targets, therapeutics, and drug delivery platforms. We also explore various approaches implemented over the years to improve the dosage of specific EV products for different administration routes.

Nano vs Resistant Tuberculosis: Taking the Lung Route

Tuberculosis (TB) is among the top 10 infectious diseases worldwide. It is categorized among the leading killer diseases that are the reason for the death of millions of people globally. Although a standardized treatment regimen is available, non-adherence to treatment has increased multi-drug resistance (MDR) and extensive drug-resistant (XDR) TB development. Another challenge is targeting the death of TB reservoirs in the alveoli via conventional treatment. TB Drug resistance may emerge as a futuristic restraint of TB with the scarcity of effective Anti-tubercular drugs. The paradigm change towards nano-targeted drug delivery systems is mostly due to the absence of effective therapy and increased TB infection recurrent episodes with MDR. The emerging field of nanotechnology gave an admirable opportunity to combat MDR and XDR via accurate diagnosis with effective treatment. The new strategies targeting the lung via the pulmonary route may overcome the new incidence of MDR and enhance patient compliance. Therefore, this review highlights the importance and recent research on pulmonary drug delivery with nanotechnology along with prevalence, the need for the development of nanotechnology, beneficial aspects of nanomedicine, safety concerns of nanocarriers, and clinical studies.

Harnessing inhaled nanoparticles to overcome the pulmonary barrier for respiratory disease therapy

The lack of effective treatments for pulmonary diseases presents a significant global health burden, primarily due to the challenges posed by the pulmonary barrier that hinders drug delivery to the lungs. Inhaled nanomedicines, with their capacity for localized and precise drug delivery to specific pulmonary pathologies through the respiratory route, hold tremendous promise as a solution to these challenges. Nevertheless, the realization of efficient and safe pulmonary drug delivery remains fraught with multifaceted challenges. This review summarizes the delivery barriers associated with major pulmonary diseases, the physicochemical properties and drug formulations affecting these barriers, and emphasizes the design advantages and functional integration of nanomedicine in overcoming pulmonary barriers for efficient and safe local drug delivery. The review also deliberates on established nanocarriers and explores drug formulation strategies rooted in these nanocarriers, thereby furnishing essential guidance for the rational design and implementation of pulmonary nanotherapeutics. Finally, this review cast a forward-looking perspective, contemplating the clinical prospects and challenges inherent in the application of inhaled nanomedicines for respiratory diseases.

Engineered lipid liquid crystalline nanoparticles as an inhaled nanoplatform for mucus penetration enhancement

Nanocarrier-assisted pulmonary drug delivery system has been widely employed for lung local disease treatment due to its enhanced drug lesion accumulation and reduced systematical side effects. However, the mucus barriers covered on the epithelia of trachea and bronchial tree construct a dense barrier for inhaled nanocarrier transport, which compromises the therapeutical effects. In this study, a lipid liquid crystalline nanoparticle NLP@Z with surface zwitterion material hexadecyl betaine (HB) modification and N-acetylcysteine (NAC) encapsulation was presented to exert the combination strategy of mucus-inert surface and mucus degradation. The HB modification endowed NLP@Z mucus-inert surface to inhibit the interaction between NLP@Z and mucins, and the encapsulated NAC could effectively degrade the mucins and further decrease the mucus viscosity. This combination strategy was proved to significantly promote the mucus penetration performance and enhance epithelial cell uptake. In addition, the proposed NLP@Z was equipped with desired nebulization property, which could be served as a potential pulmonary delivery nanoplatform. In summary, the proposed NLP@Z highlights the employment of the combination strategy for mucus penetration enhancement in pulmonary delivery, which may become a versatile platform for lung disease therapy.

Nanocarriers in Tuberculosis Treatment: Challenges and Delivery Strategies

The World Health Organization identifies tuberculosis (TB), caused by Mycobacterium tuberculosis, as a leading infectious killer. Although conventional treatments for TB exist, they come with challenges such as a heavy pill regimen, prolonged treatment duration, and a strict schedule, leading to multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. The rise of MDR strains endangers future TB control. Despite these concerns, the hunt for an efficient treatment continues. One breakthrough has been the use of nanotechnology in medicines, presenting a novel approach for TB treatment. Nanocarriers, such as lipid nanoparticles, nanosuspensions, liposomes, and polymeric micelles, facilitate targeted delivery of anti-TB drugs. The benefits of nanocarriers include reduced drug doses, fewer side effects, improved drug solubility, better bioavailability, and improved patient compliance, speeding up recovery. Additionally, nanocarriers can be made even more targeted by linking them with ligands such as mannose or hyaluronic acid. This review explores these innovative TB treatments, including studies on nanocarriers containing anti-TB drugs and related patents.

The role of protein corona on nanodrugs for organ-targeting and its prospects of application

Nowadays, nanodrugs become a hotspot in the high-end medical field. They have the ability to deliver drugs to reach their destination more effectively due to their unique properties and flexible functionalization. However, the fate of nanodrugs in vivo is not the same as those presented in vitro, which indeed influenced their therapeutic efficacy in vivo. When entering the biological organism, nanodrugs will first come into contact with biological fluids and then be covered by some biomacromolecules, especially proteins. The proteins adsorbed on the surface of nanodrugs are known as protein corona (PC), which causes the loss of prospective organ-targeting abilities. Fortunately, the reasonable utilization of PC may determine the organ-targeting efficiency of systemically administered nanodrugs based on the diverse expression of receptors on cells in different organs. In addition, the nanodrugs for local administration targeting diverse lesion sites will also form unique PC, which plays an important role in the therapeutic effect of nanodrugs. This article introduced the formation of PC on the surface of nanodrugs and summarized the recent studies about the roles of diversified proteins adsorbed on nanodrugs and relevant protein for organ-targeting receptor through different administration pathways, which may deepen our understanding of the role that PC played on organ-targeting and improve the therapeutic efficacy of nanodrugs to promote their clinical translation.

Investigation of Physico-Chemical Stability and Aerodynamic Properties of Novel "Nano-in-Micro" Structured Dry Powder Inhaler System

Pulmonary drug transport has numerous benefits. Large surface areas for absorption and limited drug degradation of the gastrointestinal system are provided through the respiratory tract. The administration is painless and easy for the patient. Due to their better stability when compared to liquid formulations, powders have gained popularity among pulmonary formulations. In the pharmaceutical sector, quality assurance and product stability have drawn a lot of attention. Due to this, it was decided to perform a long-term stability study on a previously developed, nanosized dry powder inhaler (DPI) formulation that contained meloxicam. Wet milling was implemented to reduce the particle size, and nano spray-drying was used to produce the extra-fine inhalable particles. The particle diameter was determined using dynamic light scattering and laser diffraction. Scanning electron microscopy was utilized to describe the morphology. X-ray powder diffraction and differential scanning calorimetry were applied to determine the crystallinity. In an artificial lung medium, the in vitro dissolution was studied. The Andersen Cascade Impactor was used to investigate the in vitro aerodynamic characteristics. The stability test results demonstrated that the DPI formulation maintained its essential qualities after 6 and 12 months of storage. Consequently, the product might be promising for further studies and development.

Recent Advances in Boosting EGFR Tyrosine Kinase Inhibitors-Based Cancer Therapy

Epidermal growth factor receptor (EGFR) plays a key role in signal transduction pathways associated with cell proliferation, growth, and survival. Its overexpression and aberrant activation in malignancy correlate with poor prognosis and short survival. Targeting inhibition of EGFR by small-molecular tyrosine kinase inhibitors (TKIs) is emerging as an important treatment model besides of chemotherapy, greatly reshaping the landscape of cancer therapy. However, they are still challenged by the off-targeted toxicity, relatively limited cancer types, and drug resistance after long-term therapy. In this review, we summarize the recent progress of oral, pulmonary, and injectable drug delivery systems for enhanced and targeting TKI delivery to tumors and reduced side effects. Importantly, EGFR-TKI-based combination therapies not only greatly broaden the applicable cancer types of EGFR-TKI but also significantly improve the anticancer effect. The mechanisms of TKI resistance are summarized, and current strategies to overcome TKI resistance as well as the application of TKI in reversing chemotherapy resistance are discussed. Finally, we provide a perspective on the future research of EGFR-TKI-based cancer therapy.

Application of PLGA as a Biodegradable and Biocompatible Polymer for Pulmonary Delivery of Drugs

Pulmonary administration of biodegradable polymeric formulation is beneficial in the treatment of various respiratory diseases. For respiratory delivery, the polymer must be non-toxic, biodegradable, biocompatible, and stable. Poly D, L-lactic-co-glycolic acid (PLGA) is a widely used polymer for inhalable formulations because of its attractive mechanical and processing characteristics which give great opportunities to pharmaceutical industries to formulate novel inhalable products. PLGA has many pharmaceutical applications and its biocompatible nature produces non-toxic degradation products. The degradation of PLGA takes place through the non-enzymatic hydrolytic breakdown of ester bonds to produce free lactic acid and glycolic acid. The biodegradation products of PLGA are eliminated in the form of carbon dioxide (CO₂) and water (H₂O) by the Krebs cycle. The biocompatible properties of PLGA are investigated in various in vivo and in vitro studies. The high structural integrity of PLGA particles provides better stability, excellent drug loading, and sustained drug release. This review provides detailed information about PLGA as an inhalable grade polymer, its synthesis, advantages, physicochemical properties, biodegradability, and biocompatible characteristics. The important formulation aspects that must be considered during the manufacturing of inhalable PLGA formulations and the toxicity of PLGA in the lungs are also discussed in this paper. Additionally, a thorough overview is given on the application of PLGA as a particulate carrier in the treatment of major respiratory diseases, such as cystic fibrosis, lung cancer, tuberculosis, asthma, and pulmonary hypertension.

Development of Inhalable Chitosan-Coated Oxymatrine Liposomes to Alleviate RSV-Infected Mice

Human respiratory syncytial virus (RSV) infection is the most important cause of acute lower respiratory tract infection in infants, neonates, and young children, even leading to hyperinflation and atelectasis. Oxymatrine (OMT), originating from natural herbs, possessed potential antivirus activity against influenza A virus, Coxsackie B3 virus, and RSV, whereas the absence of an in vivo study indicated the difficulties in overcoming the physiological obstacles. Since RSV basically replicated in lung tissue, in this study, we fabricated and characterized a chitosan (CS)-coated liposome with OMT loaded for the treatment of lethal RSV infection via inhalation. The results uncovered that OMT, as a hydrophilic drug, was liable to diffuse in the mucus layer and penetrate through the gas-blood barrier to enter systemic circulation quickly, which might restrict its inhibitory effect on RSV replication. The CS-coated liposome enhanced the distribution and retention of OMT in lung tissue without restriction from mucus, which contributed to the improved alleviative effect of OMT on lethal RSV-infected mice. Overall, this study provides a novel inhalation therapy for RSV infection, and the CS-coated liposome might be a potential inhalable nanocarrier for hydrophilic drugs to prevent pulmonary infections.

Could the Lung Be a Gateway for Amphotericin B to Attack the Army of Fungi?

Fungal diseases are a significant cause of morbidity and mortality worldwide, primarily affecting immunocompromised patients. Aspergillus, Pneumocystis, and Cryptococcus are opportunistic fungi and may cause severe lung disease. They can develop mechanisms to evade the host immune system and colonize or cause lung disease. Current fungal infection treatments constitute a few classes of antifungal drugs with significant fungi resistance development. Amphotericin B (AmB) has a broad-spectrum antifungal effect with a low incidence of resistance. However, AmB is a highly lipophilic antifungal with low solubility and permeability and is unstable in light, heat, and oxygen. Due to the difficulty of achieving adequate concentrations of AmB in the lung by intravenous administration and seeking to minimize adverse effects, nebulized AmB has been used. The pulmonary pathway has advantages such as its rapid onset of action, low metabolic activity at the site of action, ability to avoid first-pass hepatic metabolism, lower risk of adverse effects, and thin thickness of the alveolar epithelium. This paper presented different strategies for pulmonary AmB delivery, detailing the potential of nanoformulation and hoping to foster research in the field. Our finds indicate that despite an optimistic scenario for the pulmonary formulation of AmB based on the encouraging results discussed here, there is still no product registration on the FDA nor any clinical trial undergoing ClinicalTrial.gov.

Magnetic Nanoparticles: Current Advances in Nanomedicine, Drug Delivery and MRI

Magnetic nanoparticles (MNPs) have evolved tremendously during recent years, in part due to the rapid expansion of nanotechnology and to their active magnetic core with a high surface-to-volume ratio, while their surface functionalization opened the door to a plethora of drug, gene and bioactive molecule immobilization. Taming the high reactivity of the magnetic core was achieved by various functionalization techniques, producing MNPs tailored for the diagnosis and treatment of cardiovascular or neurological disease, tumors and cancer. Superparamagnetic iron oxide nanoparticles (SPIONs) are established at the core of drug-delivery systems and could act as efficient agents for MFH (magnetic fluid hyperthermia). Depending on the functionalization molecule and intrinsic morphological features, MNPs now cover a broad scope which the current review aims to overview. Considering the exponential expansion of the field, the current review will be limited to roughly the past three years.

Preparation and Evaluation of Mucus-Penetrating Inhalable Microparticles of Tiotropium Bromide Containing Sodium Glycocholate

This study aimed to prepare mucus-penetrating inhalable microparticles for dry powder inhalers and to evaluate their applicability in an asthma-induced rat model. Microparticles were prepared from water solutions containing tiotropium bromide, L-leucine, and sodium glycocholate (NaGc) as permeation enhancers using the spray drying method. Four formulations (SDL1, SDL2, SDL3, and SDL4) were used, depending on the various NaGc concentrations. Tiotropium microparticles were characterized by standard methods. Additionally, an asthma-induced rat model was used to confirm the effects of the formulations on lung function. Tiotropium microparticles with NaGc resulted in formulations with a more corrugated morphology and smaller particle size distribution than those without NaGc. SDL 1 had a rough surface with irregular morphology, and SDL 2, 3, and 4 had a corrugated morphology. All SDL formulations had an aerodynamic size of <3 µm. The microparticles with a corrugated morphology aerosolized better than SDL1 microparticles. The apparent permeability coefficient (Papp) values of SDL3 and SDL4 were significantly higher than those for raw tiotropium. In an in vivo study using an asthma-induced rat model, the specific airway resistance (Sraw), airway wall thickness, and mean alveolus size recovered to those of the negative control group in the SDL4 formulation.

Dry powder inhalers of antitubercular drugs

Despite advancements in the medical and pharmaceutical fields, tuberculosis remains a major health problem globally. Patients do not widely accept the conventional approach to treating tuberculosis (TB) due to prolonged treatment periods with multiple high doses of drugs and associated side effects. A pulmonary route is a non-invasive approach to delivering drugs, hormones, nucleic acid, steroids, proteins, and peptides directly to the lungs, improving the efficacy of the treatment and consequently decreasing the adverse effect of the treatment. This route has been successfully developed for the treatment of various respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), tuberculosis (TB), lung cancer, and other pulmonary infections. The major approaches of inhalation delivery systems include nebulizers, metered-dose inhalers (MDIs), and dry powder inhalers (DPIs). However, dry powder inhalers (DPIs) are more advantageous due to their stability and ability to deliver a high dose of the drug to the lungs. The present review analyzes the modern therapeutic approach of inhaled dry powders, with a special focus on novel drug delivery system (NDDS) based DPIs for the treatment of TB. The article also discussed the challenges of preparing inhalable dry powder formulations for the treatment of TB. The clinical development of inhalable anti-TB drugs is also reviewed.