The topical study of inhaled drug (salbutamol) delivery in idiopathic pulmonary fibrosis

Impact of the diseased lung microenvironment on the in vivo fate of inhaled particles

Inhalation drug delivery is superior for local lung disease therapy. However, there are several unique absorption barriers for inhaled drugs to overcome, including limited drug deposition at the target site, mucociliary clearance, pulmonary macrophage phagocytosis, and systemic exposure. Moreover, the respiratory disease state can affect or even destroy the physiology of the lung, thus influencing the in vivo fate of inhaled particles compared with that in healthy lungs. Nevertheless, limited information is available on this effect. Thus, in this review, we present pathological changes of the lung microenvironment under varied respiratory diseases and their influence on the in vivo fate of inhaled particles; such insights could provide a basis for rational inhalation particle design based on specific disease states.

A Review of Non-Invasive Drug Delivery through Respiratory Routes

With rapid and non-invasive characteristics, the respiratory route of administration has drawn significant attention compared with the limitations of conventional routes. Respiratory delivery can bypass the physiological barrier to achieve local and systemic disease treatment. A scientometric analysis and review were used to analyze how respiratory delivery can contribute to local and systemic therapy. The literature data obtained from the Web of Science Core Collection database showed an increasing worldwide tendency toward respiratory delivery from 1998 to 2020. Keywords analysis suggested that nasal and pulmonary drug delivery are the leading research topics in respiratory delivery. Based on the results of scientometric analysis, the research hotspots mainly included therapy for central nervous systems (CNS) disorders (Parkinson’s disease, Alzheimer’s disease, depression, glioblastoma, and epilepsy), tracheal and bronchial or lung diseases (chronic obstructive pulmonary disease, asthma, acute lung injury or respiratory distress syndrome, lung cancer, and idiopathic pulmonary fibrosis), and systemic diseases (diabetes and COVID-19). The study of advanced preparations contained nano drug delivery systems of the respiratory route, drug delivery barriers investigation (blood-brain barrier, BBB), and chitosan-based biomaterials for respiratory delivery. These results provided researchers with future research directions related to respiratory delivery.

Mass spectrometry detection of inhaled drug in distal fibrotic lung

Background

Currently the only available therapies for fibrotic Interstitial Lung Disease are administered systemically, often causing significant side effects. Inhaled therapy could avoid these but to date there is no evidence that drug can be effectively delivered to distal, fibrosed lung. We set out to combine mass spectrometry and histopathology with rapid sample acquisition using transbronchial cryobiopsy to determine whether an inhaled drug can be delivered to fibrotic, distal lung parenchyma in participants with Interstitial Lung Disease.

Methods

Patients with radiologically and multidisciplinary team confirmed fibrotic Interstitial Lung Disease were eligible for this study. Transbronchial cryobiopsies and endobronchial biopsies were taken from five participants, with Interstitial Lung Disease, within 70 min of administration of a single dose of nebulised ipratropium bromide. Thin tissue cryosections were analysed by Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry imaging and correlated with histopathology. The remainder of the cryobiopsies were homogenised and analysed by Liquid Chromatography—tandem Mass Spectrometry.

Results

Drug was detected in proximal and distal lung samples from all participants. Fibrotic regions were identified in research samples of four of the five participants. Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry imaging showed co-location of ipratropium with fibrotic regions in samples from three participants.

Conclusions

In this proof of concept study, using mass spectrometry, we demonstrate for the first-time that an inhaled drug can deposit in distal fibrotic lung parenchyma in patients with Interstitial Lung Disease. This suggests that drugs to treat pulmonary fibrosis could potentially be administered by the inhaled route.

Trial registration A prospective clinical study approved by London Camden and Kings Cross Research Ethics Committee and registered on clinicaltrials.gov (NCT03136120)

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02026-5.

Molecular pathways and role of epigenetics in the idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with unknown etiological factors that can progress to other dangerous diseases like lung cancer. Environmental and genetic predisposition are the two major etiological or risk factors involved in the pathology of the IPF. Among the environmental risk factors, smoking is one of the major causes for the development of IPF. Epigenetic pathways like nucleosomes remodeling, DNA methylation, histone modifications and miRNA mediated genes play a crucial role in development of IPF. Mutations in the genes make the epigenetic factors as important drug targets in IPF. Transcriptional changes due to environmental factors are also involved in the progression of IPF. The mutations in human telomerase reverse transcriptase (hTERT) have shown decreased life expectancy in IPF patients. The TERT-gene is highly expressed in chronic smokers and makes the role of epigenetics evident. Drug like nintedanib acts through vascular endothelial growth factor receptors (VEGFR), while drug pirfenidone acts through transforming growth factor (TGF), which is useful in IPF. Gefitinib, a tyrosine kinase inhibitor of EGFR, is useful as an anti-fibrosis agent in preclinical models. Newer drugs such as Celgene-CC90001 and FibroGen-FG-3019 are currently under investigations acts through the modulating epigenetic mechanisms. Thus, the study on epigenetics opens a wide window for the discovery of newer drugs. This study provides an elementary analysis of multiple regulators of epigenetics and their roles associated with the pathology of IPF. Further, this review also includes epigenetic drugs under development in preclinical and clinical stages.

Idiopathic Interstitial Pneumonias: A Review of the Past and Emerging Therapies

PURPOSE

This article is an in-depth review of the complex classification, diagnosis, and treatment of idiopathic interstitial pneumonias (IIP), as well as emergence of new treatment options.

SUMMARY

Idiopathic interstitial pneumonias consist of various subgroup classifications that require expert analysis of imaging and histology to accurately diagnose this broad group of patients. Timely and accurate assessment of these patients is key in developing an appropriate pharmacological plan. The pathophysiology of IIP is not well understood but has been linked to an immune response resulting in inflammation, fibrosis, or proliferation of lung tissue which reduces lung function. Lung transplantation is currently the only curative option for treatment, but many new antiproliferative and immunosuppressive agents are being used to effectively slow the progression of lung dysfunction.

CONCLUSION

An often mixed radiological and histological pattern along with the invasive nature of biopsy for gold standard diagnosis create a challenge for the accurate identification of IIP. Further understanding of these idiopathic interstitial pneumonias will pave the way forward to the emergence of new treatment options and updates to standards of care.

Emerging drug delivery strategies for idiopathic pulmonary fibrosis treatment

Idiopathic pulmonary fibrosis (IPF) is a debilitating and fatal condition that causes severe scarring of the lungs. While the pathogenesis of IPF continues to be extensively studied and several factors have been considered, an exact cause has yet to be established. With inadequate treatment options and no cure available, overall disease prognosis is still poor. Existing oral therapies, pirfenidone and nintedanib, may attempt to improve the patients' quality of life by mitigating symptoms and slowing disease progression, however chronic doses and systemic deliveries of these drugs can lead to severe side effects. The lack of effective treatment options calls for further investigation of restorative as well as additional palliative therapies for IPF. Nanoparticle-based sustained drug delivery strategies can be utilized to ensure targeted delivery for site-specific treatment as well as long-acting therapy, improving overall patient compliance. This review provides an update on promising strategies for the delivery of anti-fibrotic agents, along with an overview of key therapeutic targets as well as relevant emerging therapies currently being evaluated for IPF treatment.

Idiopathic pulmonary fibrosis: Disease mechanisms and drug development

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease of unknown cause characterized by relentless scarring of the lung parenchyma leading to reduced quality of life and earlier mortality. IPF is an age-related disorder, and with the population aging worldwide, the economic burden of IPF is expected to steadily increase in the future. The mechanisms of fibrosis in IPF remain elusive, with favored concepts of disease pathogenesis involving recurrent microinjuries to a genetically predisposed alveolar epithelium, followed by an aberrant reparative response characterized by excessive collagen deposition. Pirfenidone and nintedanib are approved for treatment of IPF based on their ability to slow functional decline and disease progression; however, they do not offer a cure and are associated with tolerability issues. In this review, we critically discuss how cutting-edge research in disease pathogenesis may translate into identification of new therapeutic targets, thus facilitate drug discovery. There is a growing portfolio of treatment options for IPF. However, targeting the multitude of profibrotic cytokines and growth factors involved in disease pathogenesis may require a combination of therapeutic strategies with different mechanisms of action.

Translational pharmacology of an inhaled small molecule αvβ6 integrin inhibitor for idiopathic pulmonary fibrosis

The αvβ6 integrin plays a key role in the activation of transforming growth factor-β (TGFβ), a pro-fibrotic mediator that is pivotal to the development of idiopathic pulmonary fibrosis (IPF). We identified a selective small molecule αvβ6 RGD-mimetic, GSK3008348, and profiled it in a range of disease relevant pre-clinical systems. To understand the relationship between target engagement and inhibition of fibrosis, we measured pharmacodynamic and disease-related end points. Here, we report, GSK3008348 binds to αvβ6 with high affinity in human IPF lung and reduces downstream pro-fibrotic TGFβ signaling to normal levels. In human lung epithelial cells, GSK3008348 induces rapid internalization and lysosomal degradation of the αvβ6 integrin. In the murine bleomycin-induced lung fibrosis model, GSK3008348 engages αvβ6, induces prolonged inhibition of TGFβ signaling and reduces lung collagen deposition and serum C3M, a marker of IPF disease progression. These studies highlight the potential of inhaled GSK3008348 as an anti-fibrotic therapy.

The αvβ6 integrin is key in activating the pro-fibrotic cytokine TGFβ in idiopathic pulmonary fibrosis. Here, the authors show an inhaled small molecule αvβ6 inhibitor GSK3008348 induces prolonged inhibition of TGFβ signaling pathways in human and murine models of lung fibrosis via αvβ6 degradation.

Feasibility of Aerosolized Alpha-1 Antitrypsin as a Therapeutic Option

Inhalation therapy is integral in the management of patients with chronic obstructive pulmonary disease (COPD). Specifically, intravenous augmentation therapy is available to patients with alpha-1 antitrypsin deficiency (AATD), although there is insufficient alpha-1 antitrypsin (AAT) delivery to the lungs to modify airways inflammation. In contrast, the inhaled route allows replacement therapy to reach the target site of action and with higher AAT levels. Patients certainly support the inhalation route as an alternative to intravenous injections, obviating repetitive needle insertion and allowing treatment empowerment rather than dependency on traveling to specialized units. The difficulty with inhalation has been the ability to target the formulation to the pathophysiological site of disease: the emphysematous lung parenchyma of the small alveolated airways. Recent advances have suggested nebulizers as being able to deliver an adequate dose, consistently and reproducibly, and, coupled with developments in formulation science, allowed replacement therapy to reach the epithelial lining fluid of the small airways. The bench science has been translated to the first randomized, placebo-controlled clinical trial to study the effects of nebulized AAT, which, although not meeting the primary endpoint of prolonging time to first exacerbation, showed this treatment modality was safe and achievable in a large patient cohort. Indeed, learning from this trial suggests the importance of choosing the right clinical endpoints, and recent key advances in lung physiology indices allow better assessment of the "silent zone" of small airways disease. Knowledge from other respiratory diseases will complement treating patients with AATD, where there is considerable innovation in aerosol science and inhalation medicine directed at utilizing the inhaled route. Indeed, it could be postulated that the inhaled route may not only achieve local pulmonary therapeutic benefit, but through systemic absorption and controlled pharmacokinetic profiling, the formulation may reach and treat liver disease.

Inhaled Biologicals for the Treatment of Cystic Fibrosis

Background:

Cystic Fibrosis (CF), one of the most frequent genetic diseases, is characterized by the production of viscous mucus in several organs. In the lungs, mucus clogs the airways and traps bacteria, leading to recurrent/resistant infections and lung damage. For cystic fibrosis patients, respiratory failure is still lethal in early adulthood since available treatments display incomplete efficacy.

Objective:

The objective of this review is to extend the current knowledge in the field of available treat-ments for cystic fibrosis. A special focus has been given to inhaled peptide-based drugs.

Methods:

The current review is based on recent and/or relevant literature and patents already available in various scientific databases, which include PubMed, PubMed Central, Patentscope and Science Direct. The information obtained through these diverse databases is compiled, critically interpreted and presented in the current study. An in-depth but not systematic approach to the specific research question has been adopted.

Results:

Recently, peptides have been proposed as possible pharmacologic agents for the treatment of respiratory diseases. Of note, peptides are suitable to be administered by inhalation to maximize efficacy and reduce systemic side effects. Moreover, innovative delivery carriers have been developed for drug administration through inhalation, allowing not only protection against proteolysis, but also a prolonged and controlled release.

Conclusion:

Here, we summarize newly patented peptides that have been developed in the last few years and advanced technologies for inhaled drug delivery to treat cystic fibrosis.

In Vivo Effects of Salbutamol Residues on Blood Lipid, Lung Structure, Gene Expression, and Gut Microorganism Composition

Salbutamol (SAL), one of the prohibited veterinary drugs, has been proven to be harmful to animals, but very few studies reported the underlying mechanism of actions and the effects after SAL intake. In this study, Ba-Ma minipigs were used as the animal model to demonstrate the impacts of SAL residues on blood lipid and the lung bronchial structures and the regulation of gene expression and gut microorganism population. The results showed that (1) SAL decreased the indexes of serum lipid and organ, (2) SAL widely retained in various tissues and organs, (3) the lung bronchial expanded under the influence of SAL, (4) the gene expression of growth-related ghrelin has increased, and (5) the residues of SAL affected the composition of gut microorganism population, which could be associated with the mechanism of action of SAL on pig. The findings suggest that SAL could be harmful to minipigs by altering the blood lipid, bronchial morphology, gastric mucosal gene expression, and the gut microorganism population.

Comparison of Salbutamol Delivery Efficiency for Jet versus Mesh Nebulizer Using Mice

Recent reports using a breathing simulator system have suggested that mesh nebulizers provide more effective medication delivery than jet nebulizers. In this study, the performances of jet and mesh nebulizers were evaluated by comparing their aerosol drug delivery efficiencies in mice. We compared four home nebulizers: two jet nebulizers (PARI BOY SX with red and blue nozzles), a static mesh nebulizer (NE-U22), and a vibrating mesh nebulizer (NE-SM1). After mice were exposed to salbutamol aerosol, the levels of salbutamol in serum and lung were estimated by ELISA. The residual volume of salbutamol was the largest at 34.6% in PARI BOY SX, while the values for NE-U22 and NE-SM1 mesh nebulizers were each less than 1%. The salbutamol delivery efficiencies of NE-U22 and NE-SM1 were higher than that of PARI BOY SX, as the total delivered amounts of lung and serum were 39.9% and 141.7% as compared to PARI BOY SX, respectively. The delivery efficiency of the mesh nebulizer was better than that of the jet nebulizer. Although the jet nebulizer can generate smaller aerosol particles than the mesh nebulizer used in this study, the output rate of the jet nebulizer is low, resulting in lower salbutamol delivery efficiency. Therefore, clinical validation of the drug delivery efficiency according to nebulizer type is necessary to avoid overdose and reduced drug wastage.

Studies of Radioaerosol Deposition in the Respiratory Tract

Deposition of aerosols in the respiratory tract can be quantitatively and qualitatively studied by scintigraphy. The most commonly used radionuclide for this purpose is technetium-99m. The effects of various factors on particle deposition have been investigated by using radiolabeled aerosols in the past decade. Most of these studies were in vivo but some were in vitro or ex vivo. The factors examined include particle size, formulation, inhaler design, inhalation flowrate, body posture, and gravity. They have been shown to influence pulmonary deposition, nasal high flow nebulization, and intranasal delivery. A thorough understanding of the various factors is required for the advancement of respiratory-drug delivery. Scintigraphy is a powerful technique that can assist in this regard.

Is there room for further innovation in inhaled therapy for airways disease?

Inhaled medication is the cornerstone in the treatment of patients across a spectrum of respiratory diseases including asthma and chronic obstructive pulmonary disease. The benefits of inhaled therapy have long been recognised but the most important innovations have occurred over the past 60 years, beginning with the invention of the pressurised metered dose inhaler. However, despite over 230 different device and drug combinations currently being available, disease control is far from perfect. Here we look at how innovation in inhaler design may improve treatments for respiratory diseases and how new formulations may lead to treatments for diseases beyond the lungs. We look at the three main areas where innovation in inhaled therapy is most likely to occur: 1) device engineering and design; 2) chemistry and formulations; and 3) digital technology associated with inhalers. Inhaler design has improved significantly but considerable challenges still remain in order to continually innovate and improve targeted drug delivery to the lungs. Healthcare professionals want see innovations that motivate their patients to achieve their goal of improving their health, through better adherence to treatment. Patients want devices that are easy to use and to see that their efforts are rewarded by improvements in their condition.

KEY POINTS

The dictionary definition of innovation is the introduction of new things, ideas or ways of doing something. We show how this definition can be applied to inhaled therapy.We take a look at the past to see what drove innovation in inhaler design and how this has led to the current devices.We look at the current drivers of innovation in engineering, chemistry and digital technology and predict how this may translate to new devices.Can innovation help the healthcare professional manage their patients better?What does the patient expect from innovation in their device?

EDUCATIONAL AIMS

To understand the importance of inhaled medication in the treatment of lung diseases.To understand how innovation has helped advance some of the devices patients use today from basic and inefficient designs.To understand the obstacles that prevent patients from receiving optimal treatment from their inhalers.To understand how innovation in inhaler design can lead to improved treatment for patients and widen the range of diseases that can be treated via the inhaled route.

Inhaled Therapy in Respiratory Disease: The Complex Interplay of Pulmonary Kinetic Processes

The inhalation route is frequently used to administer drugs for the management of respiratory diseases such as asthma or chronic obstructive pulmonary disease. Compared with other routes of administration, inhalation offers a number of advantages in the treatment of these diseases. For example, via inhalation, a drug is directly delivered to the target organ, conferring high pulmonary drug concentrations and low systemic drug concentrations. Therefore, drug inhalation is typically associated with high pulmonary efficacy and minimal systemic side effects. The lung, as a target, represents an organ with a complex structure and multiple pulmonary-specific pharmacokinetic processes, including (1) drug particle/droplet deposition; (2) pulmonary drug dissolution; (3) mucociliary and macrophage clearance; (4) absorption to lung tissue; (5) pulmonary tissue retention and tissue metabolism; and (6) absorptive drug clearance to the systemic perfusion. In this review, we describe these pharmacokinetic processes and explain how they may be influenced by drug-, formulation- and device-, and patient-related factors. Furthermore, we highlight the complex interplay between these processes and describe, using the examples of inhaled albuterol, fluticasone propionate, budesonide, and olodaterol, how various sequential or parallel pulmonary processes should be considered in order to comprehend the pulmonary fate of inhaled drugs.