Inhaled Antibiotics for Mycobacterial Lung Disease

Liposomal drug delivery to the lungs: a post covid-19 scenario

High local delivery of anti-infectives to the lungs is required for activity against infections of the lungs. The present pandemic has highlighted the potential of pulmonary delivery of anti-infective agents as a viable option for infections like Covid-19, which specifically causes lung infections and mortality. To prevent infections of such type and scale in the future, target-specific delivery of drugs to the pulmonary region is a high-priority area in the field of drug delivery. The suboptimal effect of oral delivery of anti-infective drugs to the lungs due to the poor biopharmaceutical property of the drugs makes this delivery route very promising for respiratory infections. Liposomes have been used as an effective delivery system for drugs due to their biocompatible and biodegradable nature, which can be used effectively for target-specific drug delivery to the lungs. In the present review, we focus on the use of liposomal drug delivery of anti-infectives for the acute management of respiratory infections in the wake of Covid-19 infection.

Targeted and efficient delivery of rifampicin to macrophages involved in non-tuberculous mycobacterial infection via mannosylated solid lipid nanoparticles

Non-tuberculous mycobacterial infections are representative difficult-to-cure lung diseases with high incidence. Conventional treatments have several limitations such as negative side effects and increased drug resistance due to long-term administration. To overcome these limitations, there is a growing need for more stable drug delivery systems. Among the various drug delivery platforms developed thus far, solid lipid nanoparticles can be effectively loaded with hydrophobic substances and their physicochemical properties can be easily manipulated through surface modification, which makes them highly suitable drug delivery materials. Recent studies have reported the successful development of nanoparticles capable of selectively delivering drugs by targeting lectin-like receptors overexpressed on the surface of immune cells. Among these lectin-like receptors, the mannose receptor is a promising target because it is expressed on the surface of macrophages and is involved in immune activity. This study sought to synthesize rifampicin-loaded mannose surface-modified solid lipid nanoparticles (Man-RIF SLNs). The Man-RIF SLN synthesis process was first optimized, after which the characteristics of the synthesized particles were analyzed using dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), and transmission electron microscopy (TEM). The surface modification with mannose was confirmed through FT-IR analysis. More importantly, the synthesized Man-RIF SLNs exhibited antibacterial and anti-biofilm properties against Mycobacterium intracellulare, a causative agent of non-tuberculous lung disease. Therefore, this study demonstrated that mannose receptor-targeted rifampicin delivery through solid lipid nanoparticles can be effectively applied to the treatment of non-tuberculous lung disease. Moreover, Man-RIF SLNs could also be used for the targeted delivery of drugs to several types of carcinoma cells or immune cells, as well as to treat lung diseases.

Conjugation of Vancomycin with a Single Arginine Improves Efficacy against Mycobacteria by More Effective Peptidoglycan Targeting

Drug resistant bacterial infections have emerged as one of the greatest threats to public health. The discovery and development of new antimicrobials and anti-infective strategies are urgently needed to address this challenge. Vancomycin is one of the most important antibiotics for the treatment of Gram-positive infections. Here, we introduce the vancomycin-arginine conjugate (V-R) as a highly effective antimicrobial against actively growing mycobacteria and difficult-to-treat mycobacterial biofilm populations. Further improvement in efficacy through combination treatment of V-R to inhibit peptidoglycan synthesis and ethambutol to inhibit arabinogalactan synthesis underscores the ability to identify compound synergies to more effectively target the Achilles heel of the cell-wall assembly. Moreover, we introduce mechanistic activity data and a molecular model derived from a d-Ala-d-Ala-bound vancomycin structure that we hypothesize underlies the molecular basis for the antibacterial improvement attributed to the arginine modification that is specific to peptidoglycan chemistry employed by mycobacteria and distinct from Gram-positive pathogens.

Aerosol pulmonary immune engineering

Aerosolization of immunotherapies poses incredible potential for manipulating the local mucosal-specific microenvironment, engaging specialized pulmonary cellular defenders, and accessing mucosal associated lymphoid tissue to redirect systemic adaptive and memory responses. In this review, we breakdown key inhalable immunoengineering strategies for chronic, genetic, and infection-based inflammatory pulmonary disorders, encompassing the historic use of immunomodulatory agents, the transition to biological inspired or derived treatments, and novel approaches of complexing these materials into drug delivery vehicles for enhanced release outcomes. Alongside a brief description of key immune targets, fundamentals of aerosol drug delivery, and preclinical pulmonary models for immune response, we survey recent advances of inhaled immunotherapy platforms, ranging from small molecules and biologics to particulates and cell therapies, as well as prophylactic vaccines. In each section, we address the formulation design constraints for aerosol delivery as well as advantages for each platform in driving desirable immune modifications. Finally, prospects of clinical translation and outlook for inhaled immune engineering are discussed.

Clofazimine Inhalation Suspension Demonstrates Promising Toxicokinetics in Canines for Treating Pulmonary Nontuberculous Mycobacteria Infection

Pulmonary nontuberculous mycobacteria (NTM) infection is recognized as a major global health concern due to its rising prevalence worldwide. As an opportunistic pathogen with increasing antibiotics resistance, prolonged systemic dosing with multiple antibiotics remains the primary treatment paradigm. These prolonged treatments, administered predominantly by oral or parenteral routes, often lead to systemic toxicity. A novel inhaled formulation of clofazimine may finally resolve issues of toxicity, thereby providing for improved NTM therapy. Clofazimine inhalation suspension was evaluated in canines to determine toxicity over 28 days of once-a-day dosing. The good laboratory practice (GLP) repeat dosing study evaluated low, mid, and high dosing (2.72 mg/kg and 2.95 mg/kg; 5.45 mg/kg and 5.91 mg/kg; and 10.87 mg/kg and 10.07 mg/kg, average male versus female dosing) of nebulized clofazimine over 30, 60, and 120 min using a jet nebulizer. Toxicokinetic analyses were performed on study days 29, 56, and 84. All three dose levels showed significant residual drug in lung tissue, demonstrating impressive lung loading and long lung residence. Drug concentrations in the lung remained well above the average NTM MIC at all time points, with measurable clofazimine levels at 28 and 56 days postdosing. In contrast, plasma levels of clofazimine were consistently measurable only through 14 days postdosing, with measurements below the limit of quantitation at 56 days postdosing. Clofazimine inhalation suspension may provide an effective therapy for the treatment of NTM infections through direct delivery of antibiotic to the lungs, overcoming the systemic toxicity seen in oral clofazimine treatment for NTM.

Inhalable microparticles as drug delivery systems to the lungs in a dry powder formulations

Inhalation-administrated drugs remain an interesting possibility of addressing pulmonary diseases. Direct drug delivery to the lungs allows one to obtain high concentration in the site of action with limited systemic distribution, leading to a more effective therapy with reduced required doses and side effects. On the other hand, there are several difficulties in obtaining a formulation that would meet all the criteria related to physicochemical, aerodynamic and biological properties, which is the reason why only very few of the investigated systems can reach the clinical trial phase and proceed to everyday use as a result. Therefore, we focused on powders consisting of polysaccharides, lipids, proteins or natural and synthetic polymers in the form of microparticles that are delivered by inhalation to the lungs as drug carriers. We summarized the most common trends in research today to provide the best dry powders in the right fraction for inhalation that would be able to release the drug before being removed by natural mechanisms. This review article addresses the most common manufacturing methods with novel modifications, pros and cons of different materials, drug loading capacities with release profiles, and biological properties such as cytocompatibility, bactericidal or anticancer properties.

Multiresistant organisms: bacteria and beyond

PURPOSE OF REVIEW

Infections with multiresistant organisms are an emerging problem, cause early mortality post lung transplantation and are sometimes associated with graft dysfunction. Frequently they raise questions about the selection of lung transplant candidates and therapeutic management post lung transplantation. There are no guidelines and management must be individualized. This review summarizes the available therapeutic options in cases of multidrug-resistant (MDR) organisms and outcomes after lung transplant.

RECENT FINDINGS

Improvements in diagnosis, new and more effective drugs and the experience gained in the management of these infections in lung transplantation, lead to a more optimistic horizon than that found a decade ago.

SUMMARY

Update on the management of Burkholderia cepacia complex, Mycobacterium abscessus complex, Aspergillus spp., Scedosporium spp. and Lomentospora prolificans infections. This review clarifies current posttransplant outcomes and adds a little hope in these scenarios.

Anti-Glomerular Basement Membrane Nephritis Potentially Induced by Nebulized Tobramycin Inhalation

Objective: To describe a case of anti-glomerular basement membrane (GBM) nephritis that occurred shortly after initiation of nebulized tobramycin (TOB) therapy using intravenous solution, suggesting an association with the inhalation therapy and the disease onset. Background: With the emergence of antimicrobial resistance, clinical importance of aminoglycosides that usually remain susceptibility against gram-negative organisms is increasingly acknowledged. Despite the growing number of evidence supporting the effectiveness of aminoglycoside inhalation therapy for respiratory tract infections, its clinical application has yet to be widely approved by Japanese health insurance. Case Presentation: A 79-year-old Japanese woman had developed amyotrophic lateral sclerosis and experienced recurrent pneumonia mainly caused by Pseudomonas aeruginosa, which required monthly treatments with broad-spectrum antibiotics. Owing to the limited approval, we had no choice but to use intravenous TOB solution for inhalation therapy as an off-label use under an endorsement of the Institutional Review Board of the hospital. Although the repeated pneumonia subsided, the patient subsequently needed immunosuppressive therapy along with plasma exchanges for the treatment of anti-GBM nephritis. Conclusion: Although this off-label use of intravenous solutions is common in both clinical and research purposes, our case raised an issue that its safety needs to be re-evaluated.

Nanoparticulate β-Cyclodextrin with Gallium Tetraphenylporphyrin Demonstrates in Vitro and in Vivo Antimicrobial Efficacy against Mycobacteroides abscessus and Mycobacterium avium

The emergence of drug-resistant pathogens causes the greatest challenge for drug development research. Recently, gallium(III)-based compounds have received great attention as novel antimicrobial agents against drug-resistant pathogens. Here, we synthesized a new β-cyclodextrin Ga nanoparticle (CDGaTP) using Ga tetraphenylporphyrin (GaTP, a hemin analogue) and β-cyclodextrin. The newly synthesized nanoparticle was nontoxic and efficient at a single dose, showing sustained drug release for 15 days in vitro. CDGaTP's activity with transferrin or lactoferrin was tested, and synergism in activity was observed against nontuberculosis mycobacteria (NTM), Mycobacterium avium (M. avium), and Mycobacteroides abscessus. Human serum albumin (HSA) decreased the efficacy of both GaTP and CDGaTP in a concentration-dependent manner. The NTMs incubated with GaTP or CDGaTP significantly produced reactive oxygen species (ROS), indicating potential inhibition of antioxidant enzymes, such as catalase. The single-dose CDGaTP displayed a prolonged intracellular inhibitory activity in an in vitro macrophage infection model against both NTMs. In addition, CDGaTP, not GaTP, was effective in a murine lung M. avium infection model when delivered via intranasal administration. These results suggest that CDGaTP provides new opportunities for the development of gallium-porphyrin based antibiotics.

Inhaled Liposomal Antimicrobial Delivery in Lung Infections

The management of difficult-to-treat acute and chronic respiratory infections (infections in cystic fibrosis, non-cystic fibrosis bronchiectasis, immunocompromised and mechanically ventilated patients) and difficult-to-treat pathogens (including multidrug-resistant strains) has become a challenge in clinical practice. The arsenal of conventional antibiotic drugs can be limited by tissue penetration, toxicities, or increasing antibiotic resistance. Inhaled antimicrobials are an interesting therapeutic approach for optimizing the management of respiratory infections. Due to extensive developments in liposome technology, a number of inhaled liposome-based antibiotic and antifungal formulations are available for human use and many products are undergoing clinical trials. Liposomes are biocompatible, biodegradable, and nontoxic vesicles able to encapsulate and carry antimicrobials, enhancing the therapeutic index of various agents and retention at the desired target within the lung. Liposomes reduce drug toxicity and improve tolerability, leading to better compliance and to decreased respiratory side effects. The aim of this article was to provide an up-to-date overview of nebulized liposomal antimicrobials for lung infections (with a special focus on liposomal amikacin, tobramycin, ciprofloxacin, and amphotericin B for inhalation), discussing the feasibility and therapeutic potential of these new strategies of preventing and treating bacteria, mycobacterial and fungal infections.

Stability and In Vitro Aerodynamic Studies of Inhalation Powders Containing Ciprofloxacin Hydrochloride Applying Different DPI Capsule Types

In the case of capsule-based dry powder inhalation systems (DPIs), the selection of the appropriate capsule is important. The use of gelatin, gelatin-PEG, and HPMC capsules has become widespread in marketed capsule-based DPIs. We aimed to perform a stability test according to the ICH guideline in the above-mentioned three capsule types. The results of the novel combined formulated microcomposite were more favorable than those of the carrier-free formulation for all capsule types. The use of HPMC capsules results in the greatest stability and thus the best in vitro aerodynamic results for both DPI powders after six months. This can be explained by the fact that the residual solvent content (RSC) of the capsules differs. Under the applied conditions the RSC of the HPMC capsule decreased the least and remained within the optimal range, thus becoming less fragmented, which was reflected in the RSC, structure and morphology of the particles, as well as in the in vitro aerodynamic results (there was a difference of approximately 10% in the lung deposition results). During pharmaceutical dosage form developments, emphasis should be placed in the case of DPIs on determining which capsule type will be used for specific formulations.

Amikacin Liposome Inhalation Suspension in Refractory Mycobacterium avium Complex Lung Disease: A Profile of Its Use

Amikacin liposome inhalation suspension (ALIS) [Arikayce^® Liposomal (EU); Arikayce^® (USA)], a liposomal suspension of the aminoglycoside amikacin (590 mg) for nebulization via the Lamira^® Nebulizer System, is available as add-on therapy for treatment-refractory Mycobacterium avium complex (MAC) lung disease in adults who have little or no alternative treatment options. Its addition to guideline-based therapy (GBT) significantly improved the likelihood of achieving sputum culture conversion (defined as three consecutive monthly MAC-negative sputum cultures) by month 6 relative to GBT alone in adults with treatment-refractory MAC lung disease, with the conversion response maintained over up to 12 months' therapy and at 3 months' post treatment in significantly higher proportions of ALIS plus GBT than GBT alone recipients. ALIS as an add-on therapy to GBT was associated with an increased risk of respiratory adverse reactions compared with GBT alone, but treatment-emergent adverse events associated with systemic amikacin exposure were uncommon.

Advances in Pulmonary Drug Delivery

Pulmonary drug delivery represents an attractive, non-invasive administration option. In addition to locally acting drugs, molecules that are intended to produce systemic effects can be delivered via the pulmonary route. Several factors need to be considered in the context of delivering drugs to or via the lungs—in addition to the drug itself, its formulation into an appropriate inhalable dosage form of sufficient stability is critical. It is also essential that this formulation is paired with a suitable inhaler device, which generates an aerosol of a particle/droplet size that ensures deposition in the desired region of the respiratory tract. Lastly, the patient’s (patho-) physiology and inhalation manoeuvre are of importance. This Special Issue brings together recent advances in the areas of inhalation device testing, aerosol formulation development, use of in vitro and in silico models in pulmonary drug deposition and drug disposition studies, and pulmonary delivery of complex drugs, such as vaccines, antibiotics and peptides, to or via the lungs.

Short-Chain Fatty Acids Promote Mycobacterium avium subsp. hominissuis Growth in Nutrient-Limited Environments and Influence Susceptibility to Antibiotics

Mycobacterium avium subsp. hominissuis (MAH) is a common intracellular pathogen that infects immunocompromised individuals and patients with pre-existing chronic lung diseases, such as cystic fibrosis, who develop chronic and persistent pulmonary infections. The metabolic remodeling of MAH in response to host environmental stresses or within biofilms formed in bronchial airways plays an important role in development of the persistence phenotype contributing to the pathogen’s tolerance to antibiotic treatment. Recent studies suggest a direct relationship between bacterial metabolic state and antimicrobial susceptibility, and improved antibiotic efficacy has been associated with the enhanced metabolism in bacteria. In the current study, we tested approximately 200 exogenous carbon source-dependent metabolites and identified short-chain fatty acid (SCFA) substrates (propionic, butyric and caproic acids) that MAH can utilize in different physiological states. Selected SCFA enhanced MAH metabolic activity in planktonic and sessile states as well as in the static and established biofilms during nutrient-limited condition. The increased bacterial growth was observed in all conditions except in established biofilms. We also evaluated the influence of SCFA on MAH susceptibility to clinically used antibiotics in established biofilms and during infection of macrophages and found significant reduction in viable bacterial counts in vitro and in cultured macrophages, suggesting improved antibiotic effectiveness against persistent forms of MAH.

The Use of Amikacin Liposome Inhalation Suspension (Arikayce) in the Treatment of Refractory Nontuberculous Mycobacterial Lung Disease in Adults

Nontuberculous mycobacteria (NTM) can cause and perpetuate chronic inflammation and lung infection. Despite having the diagnostic criteria, as defined by the American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA), clinicians find it challenging to diagnose and treat NTM-induced lung disease. Inhaled antibiotics are suitable for patients with lung infection caused by Pseudomonas aeruginosa and other organisms, but until recently, their utility in NTM-induced infection was not established. The most common NTM pathogens identified are the slow-growing Mycobacterium avium complex (MAC) and the rapid-growing M. abscessus complex (MABSC), both of which include several subspecies. Other less commonly isolated species include M. kansasii, M. simiae, and M. fortuitum. NTM strains are frequently more resistant than what is found in bacterial sputum cultures. Until recently, there was no approved inhaled antibiotic therapy for patients who were culture positive for pulmonary NTM infection. Of late, inhaled amikacin has been under investigation for the treatment of NTM-induced pulmonary infection. The FDA approved Arikayce (amikacin liposome inhalation suspension or ALIS) based on results from the ongoing Phase 3 CONVERT trial. In this study, the use of Arikayce met its primary endpoint of sputum culture conversion by the sixth month of treatment. The addition of Arikayce to guideline-based therapy led to negative sputum cultures for NTM by month 6 in 29% of patients compared to 8.9% of patients treated with guideline-based therapy alone. The effectiveness of Arikayce holds promise. However, due to limited data on Arikayce's safety, it is currently useful only for a specific population, particularly patients with refractory NTM-induced lung disease. Future trials must verify the target group and endorse the clinical benefits of Arikayce.

Novel Administration of Clofazimine for the Treatment of Mycobacterium avium Infection

Clofazimine has demonstrated in vitro activity against many nontuberculous mycobacteria. We present the case of a woman with cystic fibrosis who developed disseminated macrolide-resistant Mycobacterium avium infection following lung transplantation treated in part with clofazimine. We describe the novel administration of clofazimine via gastrostomy tube.

State-of-the-art treatment strategies for nontuberculous mycobacteria infections

INTRODUCTION

Non-tuberculous Mycobacteria (NTM) are a group of organisms whose importance in medicine seems to be increasing in recent times. The increasing number of patients susceptible to these diseases make it necessary to expand our knowledge of therapeutic options and to explore future possibilities for the development of a therapeutic arsenal.

AREAS COVERED

In this review, the authors provide a brief introduction about the present importance of NTM and describe the present recommendations of the available guidelines for their treatment. They include a description of the future options for the management of these patients, especially focusing on new antibiotics. The authors also look at possibilities for future therapeutic options, such as antibiofilm strategies.

EXPERT OPINION

No actual changes have been made to the current recommendations for the management of most NTM infections (except perhaps the availability of nebulized amikacin). However, it is also true that we have increased the number of available antibiotic treatment options with good in vitro activity against NTM. The use of these drugs in selected cases could increase the therapeutic possibilities. However, some problems are still present, such as the knowledge of the actual meaning of a NTM isolate, and will probably be a key part of future research.

Emerging trends in inhaled drug delivery

Ideally, inhaled therapy is driven by the needs of specific disease management. Lung biology interfaces with inhaler performance to allow optimal delivery of therapeutic agent for disease treatment. Inhalation aerosol products consist of the therapeutic agent, formulation, and device. The manufacturing specifications on each of the components, and their combination, allow accurate and reproducible control of measures of quality and in-vitro performance. These product variables in combination with patient variables, including co-ordination skill during inhaler use, intrinsic lung biology, disease and consequent pulmonary function, contribute to drug safety and efficacy outcomes. Due to the complexity of pulmonary drug delivery, predicting biological outcomes from first principles has been challenging. Ongoing research appears to offer new insights that may allow accurate prediction of drug behavior in the lungs. Disruptive innovations were characteristic of research and development in inhaled drug delivery at the end of the last century. Although there were relatively few new inhaled products launched in the first decade of the new millennium it was evident that the earlier years of exploration resulted in maturation of commercially successful technologies. A significant increase in new and generic products has occurred in the last decade and technical, regulatory and disease management trends are emerging. Some of these developments can trace their origins to earlier periods of creativity in the field while others are a reflection of advances in other areas of basic and computer, sciences and engineering. Select biological and technical advances are highlighted with reflections on the potential to impact future clinical and regulatory considerations.