Inhaled Heparin: Therapeutic Efficacy and Recent Formulations

Improving hemocompatibility in tissue-engineered products employing heparin-loaded nanoplatforms

The enhancement of hemocompatibility through the use of nanoplatforms loaded with heparin represents a highly desirable characteristic in the context of emerging tissue engineering applications. The significance of employing heparin in biological processes is unquestionable, owing to its ability to interact with a diverse range of proteins. It plays a crucial role in numerous biological processes by engaging in interactions with diverse proteins and hydrogels. This review provides a summary of recent endeavors focused on augmenting the hemocompatibility of tissue engineering methods through the utilization of nanoplatforms loaded with heparin. This study also provides a comprehensive review of the various applications of heparin-loaded nanofibers and nanoparticles, as well as the techniques employed for encapsulating heparin within these nanoplatforms. The biological and physical effects resulting from the encapsulation of heparin in nanoplatforms are examined. The potential applications of heparin-based materials in tissue engineering are also discussed, along with future perspectives in this field.

Inhaled heparin: Past, present, and future

While heparin has traditionally served as a key anticoagulant in clinical practice for nearly a century, recent years have witnessed a growing interest in its role as a potent antiinflammatory and antiviral agent, as well as an anticancer agent. To address challenges with injection-based delivery, exploring patient-friendly routes such as oral and pulmonary delivery is crucial. This review specifically highlights the multiple therapeutic benefits of inhaled heparin. In summary, this review serves as a valuable source of information, providing deep insights into the diverse therapeutic advantages of inhaled heparin and its potential applications within clinical contexts.

Efficacy and safety of inhaled heparin in asthmatic and chronic obstructive pulmonary disease patients: a systematic review and a meta-analysis

Asthma and chronic obstructive pulmonary disease (COPD) are prevalent chronic respiratory disorders that cause significant morbidity and mortality. Some studies evaluated the use of inhaled unfractionated heparin (UFH) in the treatment of asthma and COPD. We aimed to synthesize the available evidence for the efficacy and safety of inhaled heparin in improving lung functions among asthmatic and COPD patients. A comprehensive search was performed using Pubmed, Embase, EBSCO, Scopus, Web of Science, Cochrane CENTRAL, WHO Clinical trials, clinicaltrials.gov, Iranian Clinical trials, Google Scholar, Research Gate, ProQuest Thesis, OVID, and medRxiv databases. Two independent reviewers included all pertinent articles according to PRISMA guidelines, and extract data independently. The two reviewers checked the quality of studies using the ROB2 tool. To determine the pooled effect estimate of the efficacy and safety of inhaled heparin, a meta-analysis was carried out using the R programming language. Publication bias was evaluated using Egger's regression test. The heterogeneity was explained using a meta-regression, and the quality of evidence was assessed by the GRADE approach. Twenty-six studies with a total of 581 patients were included in the qualitative analysis and 16 in the meta-analysis. The primary outcome was treatment success (improvement of lung function) that was measured by standardized mean differences (SMD) of the forced expiratory volume per second (FEV1) either per ml or percentage. Heparin has a large effect on both FEV1% and FEV1 ml when compared to the control group (SMD 2.7, 95% CI 1.00; 4.39; GRADE high, SMD 2.12, 95% CI - 1.49; 5.72: GRADE moderate, respectively). Secondary outcomes are other lung functions improving parameters such as PC20 (SMD 0.91, 95% CI - 0.15; 1.96). Meta-regression and subgroup analysis show that heparin type, dose, year of publication, study design, and quality of studies had a substantial effect. Regarding safety, inhaled heparin showed a good coagulation profile and mild tolerable side effects. Inhaled heparin showed improvement in lung functions either alone or when added to standard care. More large parallel RCTs are needed including COPD patients, children, and other types, and stages of asthmatic patients.

Role of Nebulized Heparin in Clinical Outcome of COVID-19 Patients with Respiratory Symptoms: A Systematic Review

Coronavirus disease-2019 (COVID-19) is an extremely contagious illness caused by the SARS-CoV-2 virus and has been declared a pandemic by the World Health Organization (WHO). There are currently no particular treatments, however, nebulized heparin has been offered as a viable therapy. The purpose of this systematic review is to assess the efficacy of nebulized heparin in COVID-19 patients with respiratory symptoms.

Methods

Relevant studies were identified through a systematic search of the PubMed, Medline, Embase, Cochrane Library and Web of Science, and Scopus databases. The search terms included "nebulized heparin," "COVID-19," and "SARS-CoV-2." Studies that evaluated the use of nebulized heparin in COVID-19 patients with respiratory symptoms were included. The rest of the studies along with those that were not published in English were excluded. The systematic review was registered under PROSPERO-CRD42023413927.

Observations

Five studies have been included in this systematic review. Case reports, case series, observational studies, and randomized controlled trial (RCT) comprised the studies. The patient sample sizes ranged from 2 to 98. The studies assessed the efficacy of nebulized heparin in COVID-19 patients with variable disease severity. The evaluated outcomes included mortality, hospital stay duration, oxygen requirements, and laboratory parameters.

Conclusion

Based on the clinical studies included in this systematic review, nebulized heparin may be useful in the management of COVID-19. Oxygen saturation was greater, inflammatory indicators were lower, and hospital stays were shorter in these patients. However, the studies had limitations, including inconsistent sample sizes, varying dosages of nebulized heparin, and no control groups. Nebulized heparin in patients with COVID-19 needs to be studied further to determine its safety and effectiveness.

How to cite this article

Gupta B, Ahluwalia P, Gupta N, Gupta A. Role of Nebulized Heparin in Clinical Outcome of COVID-19 Patients with Respiratory Symptoms: A Systematic Review. Indian J Crit Care Med 2023;27(8):572-579.

Heparin, Low Molecular Weight Heparin, and Non-Anticoagulant Derivatives for the Treatment of Inflammatory Lung Disease

Unfractionated heparin has multiple pharmacological activities beyond anticoagulation. These anti-inflammatory, anti-microbial, and mucoactive activities are shared in part by low molecular weight and non-anticoagulant heparin derivatives. Anti-inflammatory activities include inhibition of chemokine activity and cytokine synthesis, inhibitory effects on the mechanisms of adhesion and diapedesis involved in neutrophil recruitment, inhibition of heparanase activity, inhibition of the proteases of the coagulation and complement cascades, inhibition of neutrophil elastase activity, neutralisation of toxic basic histones, and inhibition of HMGB1 activity. This review considers the potential for heparin and its derivatives to treat inflammatory lung disease, including COVID-19, ALI, ARDS, cystic fibrosis, asthma, and COPD via the inhaled route.

Pharmacology of Heparin and Related Drugs: An Update

Heparin has been used extensively as an antithrombotic and anticoagulant for close to 100 years. This anticoagulant activity is attributed mainly to the pentasaccharide sequence, which potentiates the inhibitory action of antithrombin, a major inhibitor of the coagulation cascade. More recently it has been elucidated that heparin exhibits anti-inflammatory effect via interference of the formation of neutrophil extracellular traps and this may also contribute to heparin's antithrombotic activity. This illustrates that heparin interacts with a broad range of biomolecules, exerting both anticoagulant and nonanticoagulant actions. Since our previous review, there has been an increased interest in these nonanticoagulant effects of heparin, with the beneficial role in patients infected with SARS2-coronavirus a highly topical example. This article provides an update on our previous review with more recent developments and observations made for these novel uses of heparin and an overview of the development status of heparin-based drugs. SIGNIFICANCE STATEMENT: This state-of-the-art review covers recent developments in the use of heparin and heparin-like materials as anticoagulant, now including immunothrombosis observations, and as nonanticoagulant including a role in the treatment of SARS-coronavirus and inflammatory conditions.

Recent advances predict a bright future for nebulizers

PURPOSE OF REVIEW

With the improvement in device technology and delivery methods of inhaled medications, along with development of novel compounds and recognition of the importance of personalized approach in the management of chronic airway diseases, nebulizers have not only maintained their place in the treatment hierarchy of airway disease but have also proven a vital platform for the development of new classes of drugs.

RECENT FINDINGS

This short review explores recent advances in nebulized drug delivery in chronic obstructive pulmonary disease and other chronic airway diseases, emphasizing the progress in nebulizer technology, physiologic advantages of nebulized drug delivery and the high versatility of currently available and developing nebulizer-delivered pharmacotherapies.

SUMMARY

Versatility and efficiency of nebulizers allows for a broad spectrum of existing and novel therapies to be clinically studied, facilitating the progress in phenotype-targeted pharmacotherapies in the management of chronic airway diseases.

Novel Pulmonary Delivery of Drugs for the Management of Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia, affecting approximately 335 million patients worldwide. Comprehensive pharmacological treatment of AF includes medications for rate or rhythm control and anticoagulants to reduce the risk of thromboembolism; yet, these agents have significant limitations. Oral anti-arrhythmic agents have a slow onset of action, and rapid onset formulations require hospitalization for intravenous therapy. Orally administered drugs also require high doses to attain therapeutic levels, and thus dose-related severe adverse effects are often unavoidable. Given the therapeutic benefits of inhaled drug delivery, including rapid onset of action and very low doses to achieve therapeutic efficacy, this review will discuss the benefits of novel pulmonary delivery of drugs for the management of AF.

Cyclic and dimeric fibroblast growth factor 2 variants with high biomedical potential

Fibroblast growth factor 2 (FGF2) is a pleiotropic protein engaged in the regulation of key cellular processes in a wide spectrum of cells. FGF2 is an important object of basic research as well as a molecule used in regenerative medicine, in vitro cell culture maintenance, and as an anticancer drug carrier. However, the unsatisfactory stability and pleiotropic activities of the wild-type FGF2 largely limit its use as a medical product. To overcome these limitations, we have designed a set of FGF2-based macromolecules via sortase A-mediated cyclization and oligomerization. We obtained heparin-switchable FGF2 variants with enhanced stability and improved ability to stimulate cell proliferation and migration. We have shown that stimulation of glucose uptake by adipocytes is modulated by the architecture of FGF2 oligomers. Moreover, we used hyper-stable FGF2 variants for the construction of highly effective drug carriers for selective killing of FGFR1-overproducing cancer cells. The strategy for FGF2 engineering presented in this work provides novel insights into the design of growth factor variants for regenerative and anti-cancer precise medicine.

Inhaled heparin polysaccharide nanodecoy against SARS-CoV-2 and variants

The heparin polysaccharide nanoparticles block the interaction between heparan sulfate/S protein and inhibit the infection of both wild-type SARS-CoV-2 pseudovirus and the mutated strains through pulmonary delivery.Image 1.

Non-Specific Targets for Correction of Pneumonia Caused by Aerosols Containing Damaging Factors of Various Nature

This review article provides data on the current state of the pathogenesis peculiarities of body and lung inflammation (pneumonia) under the influence of damaging factors of various nature: infectious agents, chemical toxicants, as well as incorporated radionuclides, etc. The peculiarities of inflammation itself, as a typical pathological process, are considered. Information on mediators that induce the so-called pro-resolving phase of inflammation manifestations is given. Approaches to the neuroimmune correction of non-specific inflammation are substantiated. Data on the following alternative approaches to the correction of nonspecific inflammation are summarized: factors of the coagulation system, modulators of the integrated stress response, and modulators of sigma-1 receptors. Based on the data presented, general directions for the treatment of nonspecific pneumonia are formulated, including reflexogenic and anti-inflammatory therapy in combination with multimodal drugs, as well as pro-resolving therapy in combination with drugs that prevent fibrosis.

Early Effects of Low Molecular Weight Heparin Therapy with Soft-Mist Inhaler for COVID-19-Induced Hypoxemia: A Phase IIb Trial

In COVID-19-induced acute respiratory distress syndrome, the lungs are incapable of filling with sufficient air, leading to hypoxemia that results in high mortality among hospitalized patients. In clinical trials, low-molecular-weight heparin was administered via a specially designed soft-mist inhaler device in an investigator initiated, single-center, open-label, phase-IIb clinical trial. Patients with evidently worse clinical presentations were classed as the “Device Group”; 40 patients were given low-molecular-weight heparin via a soft mist inhaler at a dose of 4000 IU per administration, twice a day. The Control Group, also made up of 40 patients, received the standard therapy. The predetermined severity of hypoxemia and the peripheral oxygen saturation of patients were measured on the 1st and 10th days of treatment. The improvement was particularly striking in cases of severe hypoxemia. In the 10-day treatment, low-molecular-weight heparin was shown to significantly improve breathing capability when delivered via a soft-mist inhaler.

Pharmacological and clinical application of heparin progress: An essential drug for modern medicine

Heparin is the earliest and most widely used anticoagulant and antithrombotic drug that is still used in a variety of clinical indications. Since it was discovered in 1916, after more than a century of repeated exploration, heparin has not been replaced by other drugs, but a great progress has been made in its basic research and clinical application. Besides anticoagulant and antithrombotic effects, heparin also has antitumor, anti-inflammatory, antiviral, and other pharmacological activities. It is widely used clinically in cardiovascular and cerebrovascular diseases, lung diseases, kidney diseases, cancer, etc., as the first anticoagulant medicine in COVID-19 exerts anticoagulant, anti-inflammatory and antiviral effects. At the same time, however, it also leads to a lot of adverse reactions, such as bleeding, thrombocytopenia, elevated transaminase, allergic reactions, and others. This article comprehensively reviews the modern research progress of heparin compounds; discusses the structure, preparation, and adverse reactions of heparin; emphasizes the pharmacological activity and clinical application of heparin; reveals the possible mechanism of the therapeutic effect of heparin in related clinical applications; provides evidence support for the clinical application of heparin; and hints on the significance of exploring the wider application fields of heparin.

Elucidating the Interactions Between Heparin/Heparan Sulfate and SARS-CoV-2-Related Proteins-An Important Strategy for Developing Novel Therapeutics for the COVID-19 Pandemic

Owing to the high mortality and the spread rate, the infectious disease caused by SARS-CoV-2 has become a major threat to public health and social economy, leading to over 70 million infections and 1. 6 million deaths to date. Since there are currently no effective therapeutic or widely available vaccines, it is of urgent need to look for new strategies for the treatment of SARS-CoV-2 infection diseases. Binding of a viral protein onto cell surface heparan sulfate (HS) is generally the first step in a cascade of interaction that is required for viral entry and the initiation of infection. Meanwhile, interactions of selectins and cytokines (e.g., IL-6 and TNF-α) with HS expressed on endothelial cells are crucial in controlling the recruitment of immune cells during inflammation. Thus, structurally defined heparin/HS and their mimetics might serve as potential drugs by competing with cell surface HS for the prevention of viral adhesion and modulation of inflammatory reaction. In this review, we will elaborate coronavirus invasion mechanisms and summarize the latest advances in HS-protein interactions, especially proteins relevant to the process of coronavirus infection and subsequent inflammation. Experimental and computational techniques involved will be emphasized.

Emerging concepts and directed therapeutics for the management of asthma: regulating the regulators

Asthma is a common, heterogeneous and serious disease, its prevalence has steadily risen in most parts of the world, and the condition is often inadequately controlled in many patients. Hence, there is a major need for new therapeutic approaches. Mild-to-moderate asthma is considered a T-helper cell type-2-mediated inflammatory disorder that develops due to abnormal immune responses to otherwise innocuous allergens. Prolonged exposure to allergens and persistent inflammation results in myofibroblast infiltration and airway remodelling with mucus hypersecretion, airway smooth muscle hypertrophy, and excess collagen deposition. The airways become hyper-responsive to provocation resulting in the characteristic wheezing and obstructed airflow experienced by patients. Extensive research has progressed the understanding of the underlying mechanisms and the development of new treatments for the management of asthma. Here, we review the basis of the disease, covering new areas such as the role of vascularisation and microRNAs, as well as associated potential therapeutic interventions utilising reports from animal and human studies. We also cover novel drug delivery strategies that are being developed to enhance therapeutic efficacy and patient compliance. Potential avenues to explore to improve the future of asthma management are highlighted.

Glycosaminoglycans as Multifunctional Anti-Elastase and Anti-Inflammatory Drugs in Cystic Fibrosis Lung Disease

Neutrophil elastase (NE) is a major protease in the airways of patients with cystic fibrosis (CF) that activates airway inflammation by several mechanisms. NE stimulates epithelial toll like receptors (TLR) resulting in cytokine upregulation and release, upregulates MUC5AC, a major airway mucin, degrades both phagocytic receptors and opsonins resulting in both neutrophil and macrophage phagocytic failure, generates oxidative stress via extracellular generation and uptake of heme free iron, and activates other proteases. Altogether, these mechanisms create a significant inflammatory challenge that impairs innate immune function and results in airway remodeling. Currently, a major gap in our therapeutic approach to CF lung disease is the lack of an effective therapeutic strategy targeting active NE and its downstream pro-inflammatory sequelae. Polysulfated glycosaminoglycans (GAGs) are potent anti-elastase drugs that have additional anti-inflammatory properties. Heparin is a prototype of a glycosaminoglycan with both anti-elastase and anti-inflammatory properties. Heparin inhibits NE in an allosteric manner with high potency. Heparin also inhibits cathepsin G, blocks P-selectin and L-selectin, hinders ligand binding to the receptor for advanced glycation endproducts, and impedes histone acetyltransferase activity which dampens cytokine transcription and High Mobility Group Box 1 release. Furthermore, nebulized heparin treatment improves outcomes for patients with chronic obstructive pulmonary disease (COPD), asthma, acute lung injury and smoke inhalation. However, the anticoagulant activity of heparin is a potential contraindication for this therapy to be developed for CF lung disease. Therefore, modified heparins and other GAGs are being developed that retain the anti-elastase and anti-inflammatory qualities of heparin with minimal to no anticoagulant activity. The modified heparin, 2-O, 3-O desulfated heparin (ODSH), maintains anti-elastase and anti-inflammatory activities in vitro and in vivo, and has little residual anticoagulant activity. Heparan sulfate with O-sulfate residues but not N-sulfate residues blocks allergic asthmatic inflammation in a murine model. Polysulfated hyaluronic acid abrogates allergen- triggered rhinosinusitis in a murine model. Finally, nonsaccharide glycosaminoglycan mimetics with specific sulfate modifications can be designed to inhibit NE activity. Altogether, these novel GAGs or GAG mimetics hold significant promise to address the unmet need for inhaled anti-elastase and anti-inflammatory therapy for patients with CF.

Nebulized heparin for inhalation injury in burn patients: a systematic review and meta-analysis

Background

Smoke inhalation injury increases overall burn mortality. Locally applied heparin attenuates lung injury in burn animal models of smoke inhalation. It is uncertain whether local treatment of heparin is benefit for burn patients with inhalation trauma. We systematically reviewed published clinical trial data to evaluate the effectiveness of nebulized heparin in treating burn patients with inhalation injury.

Methods

A systematic search was undertaken in PubMed, the Cochrane Library, Embase, Web of Science, the Chinese Journals Full-text Database, the China Biomedical Literature Database and the Wanfang Database to obtain clinical controlled trails evaluating nebulized heparin in the treatment of burn patients with inhalation injury. Patient and clinical characteristics, interventions and physiological and clinical outcomes were recorded. Cochrane Risk of Bias Evaluation Tool and the Newcastle–Ottawa Scale were used to evaluate data quality. Potential publication bias was assessed by Egger’s test. A sensitivity analysis was conducted to assess the stability of the results. The meta-analysis was conducted in R 3.5.1 software.

Results

Nine trials were eligible for the systematic review and meta-analysis. Nebulized heparin can reduce lung injury and improve lung function in burn patients with inhalation injury without abnormal coagulation or bleeding, but the findings are still controversial. Mortality in the heparin-treated group was lower than that of the traditional treatment group (relative risk (RR) 0.75). The duration of mechanical ventilation (DOMV) was shorter in the heparin-treated group compared to the traditional treatment group (standardized mean difference (SMD) −0.78). Length of hospital stay was significantly shorter than that in the traditional treatment group (SMD −0.42), but incidence rates of pneumonia and unplanned reintubation were not significantly different in the study groups (RRs 0.97 and 0.88, respectively). No statistically significant publication biases were detected for the above clinical endpoints (p > 0.05).

Conclusions

Based on conventional aerosol therapy, heparin nebulization can further reduce lung injury, improve lung function, shorten DOMV and length of hospital stay, and reduce mortality, although it does not reduce the incidence of pneumonia and/or the unplanned reintubation rate.

Nebulized heparin and salbutamol versus salbutamol alone in acute exacerbations of chronic obstructive pulmonary disease requiring mechanical ventilation: a double-blind randomized controlled trial

Background

Nebulized heparin has been effectively used in the management of many pulmonary diseases. However, its effect on mechanically ventilated patients with acute exacerbation chronic obstructive pulmonary disease (AECOPD) has never been studied. This study aimed to assess the efficacy of nebulized heparin and salbutamol to increase ventilator-free days (VFD) in mechanically ventilated AECOPD patients and the effect of nebulized heparin on respiratory and coagulation functions.

Methods

In this double-blind controlled study, 60 mechanically ventilated adult patients with AECOPD were randomly allocated into two groups; heparin and salbutamol (HS) group and salbutamol only (S) group. In the HS group, patients received nebulized heparin (25,000 IU) and salbutamol (5 mg) every 6 hours. Patients in the S group received nebulized salbutamol only (5 mg). The treatment was continued while patients remained ventilated for a maximum of 14 days. The primary outcome was VFDs at day 14. PaCO2, PaO2/FiO2 ratio, number of nebulizations withheld, C-reactive protein (CRP) titer and activated partial thromboplastin time (APTT) were secondary outcomes.

Results

Patients in the Group HS had significantly more VFDs 4.7 ± 3.3 compared with those in the Group S 2.4 ± 2.6, P = 0.007. PaCO2 levels, PaO2/FiO2, the decrease in the CRP level and the increase in the APTT from the baseline showed no evidence of difference in both groups.

Conclusions

The co-administration of nebulized heparin and salbutamol, compared with salbutamol alone, significantly increased (VFDs) among mechanically ventilated AECOPD patients without increasing bleeding risks.

The non-anticoagulant promise of heparin and its mimetics

Heparin, the widely used anticoagulant and antithrombotic polysaccharide, has other potential therapeutic uses that arise from its similarity to heparan sulfate. This review provides a brief overview of the most recent developments in this field, paying particular respect to pulmonary and respiratory pharmacology. It has often been said that heparin, with its mimetics and derivatives, shows great promise in the treatment of inflammatory, infectious, and malignant conditions. Difficulties are encountered, however, in translating this promise into worthwhile treatment strategies for patients in some conditions. Several clinical trials of low molecular weight heparins as adjuvant therapy to standard treatment of lung cancers have recently provided no evidence to support the supposed beneficial effects of low molecular weight heparin.

A synthetic glycosaminoglycan reduces sinonasal inflammation in a murine model of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is characterized by sustained mucosal inflammation, impaired mucociliary clearance, loss of cilia and epithelial barrier breakdown, and tissue remodeling. Certain glycosaminoglycans inhibit various inflammatory mediators, suppress bacterial growth, and provide important functions in mucosal tissue repair and mucociliary clearance. Herein, we evaluated the effects of a synthetic glycosaminoglycan, GM-1111, on the clinical signs and inflammatory tissue changes associated with CRS in mice. CRS was generated by repeated intranasal applications of Aspergillus fumigatus (A. fumigatus) extracts over 4 weeks. Mice were then intranasally administered GM-1111 (600 μg per dose, 5 times a week) or vehicle (phosphate buffered saline, PBS) for an additional 4 weeks while still being given A. fumigatus extracts to maintain a chronic inflammatory environment with acute exacerbations. Clinical signs indicative of sinonasal inflammation were recorded throughout the study. After 9 weeks, whole blood and sinonasal tissues were harvested for hematological, histological, and biochemical examination. The clinical signs, white blood cell counts, tissue markers of sinonasal inflammation, and histological changes caused by A. fumigatus extract administration were compared to the healthy (PBS vehicle) and GM-1111-treated groups (n = 12 per treatment group). Compared to vehicle-treated animals, animals treated with GM-1111 demonstrated significant reductions in clinical signs (p<0.05), degenerative tissue changes, goblet cell hyperplasia, inflammatory cell infiltration (p<0.01), innate immunity- (tlr2, tlr4, myd88, il1b, tnfa, il6, and il12) and adaptive immunity-associated (ccl11, ccl24, ccl5, il4, il5, and il13) cytokine gene expression (p<0.05 to p<0.0001) in sinonasal tissues, and serum IgE levels (p<0.01). Our data suggest that GM-1111 significantly reduces local and systemic effects of CRS-associated sinonasal inflammation.

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.

Delivering drugs to the lungs: The history of repurposing in the treatment of respiratory diseases

The repurposing of drug delivery by the pulmonary route has been applied to treatment and prophylaxis of an increasingly wide range of respiratory diseases. Repurposing has been most successful for the delivery of inhaled bronchodilators and corticosteroids in patients with asthma and chronic obstructive pulmonary disease (COPD). Repurposing utilizes the advantages that the pulmonary route offers in terms of more targeted delivery to the site of action, the use of smaller doses, and a lower incidence of side-effects. Success has been more variable for other drugs and treatment indications. Pulmonary delivery is now well established for delivery of inhaled antibiotics in cystic fibrosis (CF), and in the treatment of pulmonary arterial hypertension (PAH). Other inhaled treatments such as those for idiopathic pulmonary fibrosis (IPF), lung transplant rejection or tuberculosis may also become routine. Repurposing has progressed in parallel with the development of new drugs, inhaler devices and formulations.