Inhaled drug therapy for treatment of tuberculosis

Microfluidics produced ATRA-loaded PLGA NPs reduced tuberculosis burden in alveolar epithelial cells and enabled high delivered dose under simulated human breathing pattern in 3D printed head models

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), is second only to COVID-19 as the top infectious disease killer worldwide. Multi-drug resistant TB (MDR-TB) may arise because of poor patient adherence to medications due to lengthy treatment duration and side effects. Delivering novel host directed therapies (HDT), like all trans retinoic acid (ATRA) may help to improve drug regimens and reduce the incidence of MDR-TB. Local delivery of ATRA to the site of infection leads to higher bioavailability and reduced systemic side effects. ATRA is poorly soluble in water and has a short half-life in plasma. Therefore, it requires a formulation step before it can be administered in vivo. ATRA loaded PLGA nanoparticles suitable for nebulization were manufactured and optimized using a scalable nanomanufacturing microfluidics (MF) mixing approach (MF-ATRA-PLGA NPs). MF-ATRA-PLGA NPs demonstrated a dose dependent inhibition of Mtb growth in TB-infected A549 alveolar epithelial cell model while preserving cell viability. The MF-ATRA-PLGA NPs were nebulized with the Aerogen Solo vibrating mesh nebulizer, with aerosol droplet size characterized using laser diffraction and the estimated delivered dose was determined. The volume median diameter (VMD) of the MF-ATRA-PLGA NPs was 3.00 ± 0.18 μm. The inhaled dose delivered in adult and paediatric 3D printed head models under a simulated normal adult and paediatric breathing pattern was found to be 47.05 ± 3 % and 20.15 ± 3.46 % respectively. These aerosol characteristics of MF-ATRA-PLGA NPs supports its suitability for delivery to the lungs via inhalation. The data generated on the efficacy of an inhalable, scalable and regulatory friendly ATRA-PLGA NPs formulation provides a foundation on which further pre-clinical testing can be built. Overall, the results of this project are promising for future research into ATRA loaded NPs formulations as inhaled host directed therapies for TB.

Advanced drug delivery and therapeutic strategies for tuberculosis treatment

Tuberculosis (TB) remains a significant global health challenge, necessitating innovative approaches for effective treatment. Conventional TB therapy encounters several limitations, including extended treatment duration, drug resistance, patient noncompliance, poor bioavailability, and suboptimal targeting. Advanced drug delivery strategies have emerged as a promising approach to address these challenges. They have the potential to enhance therapeutic outcomes and improve TB patient compliance by providing benefits such as multiple drug encapsulation, sustained release, targeted delivery, reduced dosing frequency, and minimal side effects. This review examines the current landscape of drug delivery strategies for effective TB management, specifically highlighting lipid nanoparticles, polymer nanoparticles, inorganic nanoparticles, emulsion-based systems, carbon nanotubes, graphene, and hydrogels as promising approaches. Furthermore, emerging therapeutic strategies like targeted therapy, long-acting therapeutics, extrapulmonary therapy, phototherapy, and immunotherapy are emphasized. The review also discusses the future trajectory and challenges of developing drug delivery systems for TB. In conclusion, nanomedicine has made substantial progress in addressing the challenges posed by conventional TB drugs. Moreover, by harnessing the unique targeting abilities, extended duration of action, and specificity of advanced therapeutics, innovative solutions are offered that have the potential to revolutionize TB therapy, thereby enhancing treatment outcomes and patient compliance.

Pharmacokinetic Considerations for Optimizing Inhaled Spray-Dried Pyrazinoic Acid Formulations

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a leading cause of death with 1.6 million deaths worldwide reported in 2021. Oral pyrazinamide (PZA) is an integral part of anti-TB regimens, but its prolonged use has the potential to drive the development of PZA-resistant Mtb. PZA is converted to the active moiety pyrazinoic acid (POA) by the Mtb pyrazinamidase encoded by pncA, and mutations in pncA are associated with the majority of PZA resistance. Conventional oral and parenteral therapies may result in subtherapeutic exposure in the lung; hence, direct pulmonary administration of POA may provide an approach to rescue PZA efficacy for treating pncA-mutant PZA-resistant Mtb. The objectives of the current study were to (i) develop novel dry powder POA formulations, (ii) assess their feasibility for pulmonary delivery using physicochemical characterization, (iii) evaluate their pharmacokinetics (PK) in the guinea pig model, and (iv) develop a mechanism-based pharmacokinetic model (MBM) using in vivo PK data to select a formulation providing adequate exposure in epithelial lining fluid (ELF) and lung tissue. We developed three POA formulations for pulmonary delivery and characterized their PK in plasma, ELF, and lung tissue following passive inhalation in guinea pigs. Additionally, the PK of POA following oral, intravenous, and intratracheal administration was characterized in guinea pigs. The MBM was used to simultaneously model PK data following administration of POA and its formulations via the different routes. The MBM described POA PK well in plasma, ELF, and lung tissue. Physicochemical analyses and MBM predictions suggested that POA maltodextrin was the best among the three formulations and an excellent candidate for further development as it has: (i) the highest ELF-to-plasma exposure ratio (203) and lung tissue-to-plasma exposure ratio (30.4) compared with POA maltodextrin and leucine (75.7/16.2) and POA leucine salt (64.2/19.3) and (ii) the highest concentration in ELF (CmaxELF: 171 nM) within 15.5 min, correlating with a fast transfer into ELF after pulmonary administration (KPM: 22.6 1/h). The data from the guinea pig allowed scaling, using the MBM to a human dose of POA maltodextrin powder demonstrating the potential feasibility of an inhaled product.

Drug combinations for inhalation: Current products and future development addressing disease control and patient compliance

Pulmonary delivery is an alternative route of administration with numerous advantages over conventional routes of administration. It provides low enzymatic exposure, fewer systemic side effects, no first-pass metabolism, and concentrated drug amounts at the site of the disease, making it an ideal route for the treatment of pulmonary diseases. Owing to the thin alveolar-capillary barrier, and large surface area that facilitates rapid absorption to the bloodstream in the lung, systemic delivery can be achieved as well. Administration of multiple drugs at one time became urgent to control chronic pulmonary diseases such as asthma and COPD, thus, development of drug combinations was proposed. Administration of medications with variable dosages from different inhalers leads to overburdening the patient and may cause low therapeutic intervention. Therefore, products that contain combined drugs to be delivered via a single inhaler have been developed to improve patient compliance, reduce different dose regimens, achieve higher disease control, and boost therapeutic effectiveness in some cases. This comprehensive review aimed to highlight the growth of drug combinations by inhalation over time, obstacles and challenges, and the possible progress to broaden the current options or to cover new indications in the future. Moreover, various pharmaceutical technologies in terms of formulation and device in correlation with inhaled combinations were discussed in this review. Hence, inhaled combination therapy is driven by the need to maintain and improve the quality of life for patients with chronic respiratory diseases; promoting drug combinations by inhalation to a higher level is a necessity.

Pharmacokinetic considerations for optimizing inhaled spray-dried pyrazinoic acid formulations

Tuberculosis (TB), caused by Mycobacterium tuberculosis ( Mtb ), remains a leading cause of death with 1.6 million deaths worldwide reported in 2021. Oral pyrazinamide (PZA) is an integral part of anti-TB regimens, but its prolonged use has the potential to drive development of PZA resistant Mtb . PZA is converted to the active moiety pyrazinoic acid (POA) by the Mtb pyrazinamidase encoded by pncA , and mutations in pncA are associated with the majority of PZA resistance. Conventional oral and parenteral therapies may result in subtherapeutic exposure in the lung, hence direct pulmonary administration of POA may provide an approach to rescue PZA efficacy for treating pncA- mutant PZA-resistant Mtb . The objectives of the current study were to i) develop novel dry powder POA formulations ii) assess their feasibility for pulmonary delivery using physicochemical characterization, iii) evaluate their pharmacokinetics (PK) in the guinea pig model and iv) develop a mechanism based pharmacokinetic model (MBM) using in vivo PK data to select a formulation providing adequate exposure in epithelial lining fluid (ELF) and lung tissue. We developed three POA formulations for pulmonary delivery and characterized their PK in plasma, ELF, and lung tissue following passive inhalation in guinea pigs. Additionally, the PK of POA following oral, intravenous and intratracheal administration was characterized in guinea pigs. The MBM was used to simultaneously model PK data following administration of POA and its formulations via the different routes. The MBM described POA PK well in plasma, ELF and lung tissue. Physicochemical analyses and MBM predictions suggested that POA maltodextrin was the best among the three formulations and an excellent candidate for further development as it has: (i) the highest ELF-to-plasma exposure ratio (203) and lung tissue-to-plasma exposure ratio (30.4) compared with POA maltodextrin and leucine (75.7/16.2) and POA leucine salt (64.2/19.3); (ii) the highest concentration in ELF ( Cmac ELF : 171 nM) within 15.5 minutes, correlating with a fast transfer into ELF after pulmonary administration ( k PM : 22.6 1/h). The data from the guinea pig allowed scaling, using the MBM to a human dose of POA maltodextrin powder demonstrating the potential feasibility of an inhaled product.

Table of Contents TOC/Abstract Graphic

A Current Perspective on the Potential of Nanomedicine for Anti-Tuberculosis Therapy

Tuberculosis (TB) is one of the ten infectious diseases that cause the highest amount of human mortality and morbidity. This infection, which is caused by a single pathogen, Mycobacterium tuberculosis, kills over a million people every year. There is an emerging problem of antimicrobial resistance in TB that needs urgent treatment and management. Tuberculosis treatment is complicated by its complex drug regimen, its lengthy duration and the serious side-effects caused by the drugs required. There are a number of critical issues around drug delivery and subsequent intracellular bacterial clearance. Drugs have a short lifespan in systemic circulation, which limits their activity. Nanomedicine in TB is an emerging research area which offers the potential of effective drug delivery using nanoparticles and a reduction in drug doses and side-effects to improve patient compliance with the treatment and enhance their recovery. Here, we provide a minireview of anti-TB treatment, research progress on nanomedicine and the prospects for future applications in developing innovative therapies.

Studies of the Specific Activity of Aerosolized Isoniazid against Tuberculosis in a Mouse Model

The aerosol inhalation delivery of isoniazid in mice was investigated, and the specific activity of the aerosol form of isoniazid was studied with the mouse model of tuberculosis infection, the M. tuberculosis H37Rv strain. Aerosol delivery was performed using a laminar-flow horizontal nucleation chamber. The inhalation dose was measured in real-time mode using a diffusion aerosol spectrometer. The mean particle diameter was 0.6 ± 0.03 μm, and the inhalation dose was 5–9 mg/kg. Pharmacokinetic measurements were carried out in nose-only and whole-body chambers. Isoniazid concentration in blood serum and its mass in the lungs were measured as a function of time using high-performance liquid chromatography. Studies of the specific activity of aerosolized isoniazid reveal that treatment with the aerosol lead to the complete recovery of the experimental tuberculosis infection as early as after 28 days after the start of inhalation treatment, while in the animals from the group receiving isoniazid per-orally, sole revivable tuberculosis mycobacteria were detected. Histologic examinations show that only a few macrophagal (nonspecific) granulomas without mycobacteria were detected in the spleen after per-oral and aerosol treatment, the number of granulomas on the 28th day being three times smaller in the latter case. The results show that the developed technique of isoniazid aerosol inhalation may have clinical potential.

A review of formulations and preclinical studies of inhaled rifampicin for its clinical translation

Inhaled drug delivery is a promising approach to achieving high lung drug concentrations to facilitate efficient treatment of tuberculosis (TB) and to reduce the overall duration of treatment. Rifampicin is a good candidate for delivery via the pulmonary route. There have been no clinical studies yet at relevant inhaled doses despite the numerous studies investigating its formulation and preclinical properties for pulmonary delivery. This review discusses the clinical implications of pulmonary drug delivery in TB treatment, the drug delivery systems reported for pulmonary delivery of rifampicin, animal models, and the animal studies on inhaled rifampicin formulations, and the research gaps hindering the transition from preclinical development to clinical investigation. A review of reports in the literature suggested there have been minimal attempts to test inhaled formulations of rifampicin in laboratory animals at relevant high doses and there is a lack of appropriate studies in animal models. Published studies have reported testing only low doses (≤ 20 mg/kg) of rifampicin, and none of the studies has investigated the safety of inhaled rifampicin after repeated administration. Preclinical evaluations of inhaled anti-TB drugs, such as rifampicin, should include high-dose formulations in preclinical models, determined based on allometric conversions, for relevant high-dose anti-TB therapy in humans.

Pulmonary Delivery of Emerging Antibacterials for Bacterial Lung Infections Treatment

Bacterial infections in the respiratory tract are considered as one of the major challenges to the public health worldwide. Pulmonary delivery is an attractive approach in the management of bacterial respiratory infections with a few inhaled antibiotics approved. However, with the rapid emergence of antibiotic-resistant bacteria, it is necessary to develop new/alternative inhaled antibacterial agents in the post-antibiotic era. A pipeline of novel biological antibacterial agents, including antimicrobial peptides, RNAi therapeutics, and bacteriophages, has emerged to combat bacterial infections with excellent performance. In this review, the causal effects of bacterial infections on the related pulmonary infectious diseases will be firstly introduced. This is followed by an overview on the development of emerging antibacterial therapeutics for managing lung bacterial infections through nebulization/inhalation of dried powders. The obstacles and underlying proposals regarding their clinical transformation are also discussed to seek insights for further development. Research on inhaled therapy of these emerging antibacterials are still in the infancy, but the promising progress warrants further attention.

Indian Guidelines on Nebulization Therapy

Inhalational therapy, today, happens to be the mainstay of treatment in obstructive airway diseases (OADs), such as asthma, chronic obstructive pulmonary disease (COPD), and is also in the present, used in a variety of other pulmonary and even non-pulmonary disorders. Hand-held inhalation devices may often be difficult to use, particularly for children, elderly, debilitated or distressed patients. Nebulization therapy emerges as a good option in these cases besides being useful in the home care, emergency room and critical care settings. With so many advancements taking place in nebulizer technology; availability of a plethora of drug formulations for its use, and the widening scope of this therapy; medical practitioners, respiratory therapists, and other health care personnel face the challenge of choosing appropriate inhalation devices and drug formulations, besides their rational application and use in different clinical situations. Adequate maintenance of nebulizer equipment including their disinfection and storage are the other relevant issues requiring guidance. Injudicious and improper use of nebulizers and their poor maintenance can sometimes lead to serious health hazards, nosocomial infections, transmission of infection, and other adverse outcomes. Thus, it is imperative to have a proper national guideline on nebulization practices to bridge the knowledge gaps amongst various health care personnel involved in this practice. It will also serve as an educational and scientific resource for healthcare professionals, as well as promote future research by identifying neglected and ignored areas in this field. Such comprehensive guidelines on this subject have not been available in the country and the only available proper international guidelines were released in 1997 which have not been updated for a noticeably long period of over two decades, though many changes and advancements have taken place in this technology in the recent past. Much of nebulization practices in the present may not be evidence-based and even some of these, the way they are currently used, may be ineffective or even harmful. Recognizing the knowledge deficit and paucity of guidelines on the usage of nebulizers in various settings such as inpatient, out-patient, emergency room, critical care, and domiciliary use in India in a wide variety of indications to standardize nebulization practices and to address many other related issues; National College of Chest Physicians (India), commissioned a National task force consisting of eminent experts in the field of Pulmonary Medicine from different backgrounds and different parts of the country to review the available evidence from the medical literature on the scientific principles and clinical practices of nebulization therapy and to formulate evidence-based guidelines on it. The guideline is based on all possible literature that could be explored with the best available evidence and incorporating expert opinions. To support the guideline with high-quality evidence, a systematic search of the electronic databases was performed to identify the relevant studies, position papers, consensus reports, and recommendations published. Rating of the level of the quality of evidence and the strength of recommendation was done using the GRADE system. Six topics were identified, each given to one group of experts comprising of advisors, chairpersons, convenor and members, and such six groups (A-F) were formed and the consensus recommendations of each group was included as a section in the guidelines (Sections I to VI). The topics included were: A. Introduction, basic principles and technical aspects of nebulization, types of equipment, their choice, use, and maintenance B. Nebulization therapy in obstructive airway diseases C. Nebulization therapy in the intensive care unit D. Use of various drugs (other than bronchodilators and inhaled corticosteroids) by nebulized route and miscellaneous uses of nebulization therapy E. Domiciliary/Home/Maintenance nebulization therapy; public & health care workers education, and F. Nebulization therapy in COVID-19 pandemic and in patients of other contagious viral respiratory infections (included later considering the crisis created due to COVID-19 pandemic). Various issues in different sections have been discussed in the form of questions, followed by point-wise evidence statements based on the existing knowledge, and recommendations have been formulated.

Polymeric Microparticles: Synthesis, Characterization and In Vitro Evaluation for Pulmonary Delivery of Rifampicin

Rifampicin, a potent broad-spectrum antibiotic, remains the backbone of anti-tubercular therapy. However, it can cause severe hepatotoxicity when given orally. To overcome the limitations of the current oral therapy, this study designed inhalable spray-dried, rifampicin-loaded microparticles using aloe vera powder as an immune modulator, with varying concentrations of alginate and L-leucine. The microparticles were assessed for their physicochemical properties, in vitro drug release and aerodynamic behavior. The spray-dried powders were 2 to 4 µm in size with a percentage yield of 45 to 65%. The particles were nearly spherical with the tendency of agglomeration as depicted from Carr’s index (37 to 65) and Hausner’s ratios (>1.50). The drug content ranged from 0.24 to 0.39 mg/mg, with an association efficiency of 39.28 to 96.15%. The dissolution data depicts that the in vitro release of rifampicin from microparticles was significantly retarded with a higher L-leucine concentration in comparison to those formulations containing a higher sodium alginate concentration due to its hydrophobic nature. The aerodynamic data depicts that 60 to 70% of the aerosol mass was emitted from an inhaler with MMAD values of 1.44 to 1.60 µm and FPF of 43.22 to 55.70%. The higher FPF values with retarded in vitro release could allow sufficient time for the phagocytosis of synthesized microparticles by alveolar macrophages, thereby leading to the eradication of M. tuberculosis from these cells.

Recent Developments in Drug Delivery for Treatment of Tuberculosis by Targeting Macrophages

Tuberculosis (TB) is among the greatest public health and safety concerns in the 21st century, Mycobacterium tuberculosis, which causes TB, infects alveolar macrophages and uses these cells as one of its primary sites of replication. The current TB treatment regimen, which consist of chemotherapy involving a combination of 3-4 antimicrobials for a duration of 6-12 months, is marked with significant side effects, toxicity, and poor compliance. Targeted drug delivery offers a strategy that could overcome many of the problems of current TB treatment by specifically targeting infected macrophages. Recent advances in nanotechnology and material science have opened an avenue to explore drug carriers that actively and passively target macrophages. This approach can increase the drug penetration into macrophages by using ligands on the nanocarrier that interact with specific receptors for macrophages. This review encompasses the recent development of drug carriers specifically targeting macrophages actively and passively. Future directions and challenges associated with development of effective TB treatment is also discussed.

Inhalable Mannosylated Rifampicin–Curcumin Co-Loaded Nanomicelles with Enhanced In Vitro Antimicrobial Efficacy for an Optimized Pulmonary Tuberculosis Therapy

Among respiratory infections, tuberculosis was the second deadliest infectious disease in 2020 behind COVID-19. Inhalable nanocarriers offer the possibility of actively targeting anti-tuberculosis drugs to the lungs, especially to alveolar macrophages (cellular reservoirs of the Mycobacterium tuberculosis). Our strategy was based on the development of a mannose-decorated micellar nanoformulation based in Soluplus^® to co-encapsulate rifampicin and curcumin. The former is one of the most effective anti-tuberculosis first-line drugs, while curcumin has demonstrated potential anti-mycobacterial properties. Mannose-coated rifampicin (10 mg/mL)–curcumin (5 mg/mL)-loaded polymeric micelles (10% w/v) demonstrated excellent colloidal properties with micellar size ~108 ± 1 nm after freeze-drying, and they remain stable under dilution in simulated interstitial lung fluid. Drug-loaded polymeric micelles were suitable for drug delivery to the deep lung with lung accumulation, according to the in vitro nebulization studies and the in vivo biodistribution assays of radiolabeled (99mTc) polymeric micelles, respectively. Hence, the nanoformulation did not exhibit hemolytic potential. Interestingly, the addition of mannose significantly improved (5.2-fold) the microbicidal efficacy against Mycobacterium tuberculosis H37Rv of the drug-co-loaded systems in comparison with their counterpart mannose-free polymeric micelles. Thus, this novel inhaled nanoformulation has demonstrated its potential for active drug delivery in pulmonary tuberculosis therapy.

Cationic inhalable particles for enhanced drug delivery to M. tuberculosis infected macrophages

Inhalable microparticle-based drug delivery platforms are being investigated extensively for Tuberculosis (TB) treatment as they offer efficient deposition in lungs and improved pharmacokinetics of the encapsulated cargo. However, the effect of physical parameters of microcarriers on interaction with Mycobacterium tuberculosis (Mtb) infected mammalian cells is underexplored. In this study, we report that Mtb-infected macrophages are highly phagocytic and microparticle surface charge plays a major role in particle internalization by infected cells. Microparticles of different sizes (0.5-2 μm) were internalized in large numbers by Mtb-infected THP-1 macrophages and murine primary Bone Marrow Derived Macrophages in vitro. Drastic improvement in particle uptake was observed with cationic particles in vitro and in mice lungs. Rapid uptake of rifampicin-loaded cationic microparticles allowed high intracellular accumulation of the drug and led to enhanced anti-bacterial function when compared to non-modified rifampicin-loaded microparticles. Cytocompatibility assay and histological analysis in vivo confirmed that the formulations were safe and did not elicit any adverse reaction. Additionally, pulmonary delivery of cationic particles in mice resulted in two-fold higher uptake in resident alveolar macrophages compared to non-modified particles. This study provides a framework for future design of drug carriers to improve delivery of anti-TB drugs inside Mtb-infected cells.

All trans retinoic acid as a host-directed immunotherapy for tuberculosis

Tuberculosis (TB) is the top bacterial infectious disease killer and one of the top ten causes of death worldwide. The emergence of strains of multiple drug-resistant tuberculosis (MDR-TB) has pushed our available stock of anti-TB agents to the limit of effectiveness. This has increased the urgent need to develop novel treatment strategies using currently available resources. An adjunctive, host-directed therapy (HDT) designed to act on the host, instead of the bacteria, by boosting the host immune response through activation of intracellular pathways could be the answer. The integration of multidisciplinary approaches of repurposing currently FDA-approved drugs, with a targeted drug-delivery platform is a very promising option to reduce the long timeline associated with the approval of new drugs - time that cannot be afforded given the current levels of morbidity and mortality associated with TB infection. The deficiency of vitamin A has been reported to be highly associated with the increased susceptibility of TB. All trans retinoic acid (ATRA), the active metabolite of vitamin A, has proven to be very efficacious against TB both in vitro and in vivo. In this review, we discuss and summarise the importance of vitamin A metabolites in the fight against TB and what is known regarding the molecular mechanisms of ATRA as a host-directed therapy for TB including its effect on macrophages cytokine profile and cellular pathways. Furthermore, we focus on the issues behind why previous clinical trials with vitamin A supplementation have failed, and how these issues might be overcome.

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Tuberculosis deaths and resistance are increasing – novel therapies are needed.

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Vitamin A deficiency is a strong risk factor for active tuberculosis in contacts.

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All Trans Retinoic Acid is a promising host-directed therapy for tuberculosis.

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It has pleiotropic effects on macrophages & other immune cells in vitro and in vivo.

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Inhaled rather than systemic All Trans Retinoic Acid therapy may be most effective.

Appraisal of fluoroquinolone-loaded carubinose-linked hybrid nanoparticles for glycotargeting to alveolar macrophages

There is a curious case in Alveolar macrophages (AM), the frontline defence recruits that contain the spread of all intruding bacteria. In response to Mycobacterium tuberculosis (M.tb), AM either contain the spread or are modulated by M.tb to create a region for their replication. The M.tb containing granulomas so formed are organised structures with confined boundaries. The limited availability of drugs inside AM aid drug tolerance and poor therapeutic outcomes in diseases like tuberculosis. The present work proves the glycotargeting efficiency of levofloxacin (LVF) to AM. The optimised formulation developed displayed good safety with 2% hemolysis and a viability of 61.14% on J774A.1 cells. The physicochemical characterisations such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) proved that carubinose linkage was accomplished and LVF is entrapped inside carubinose-linked hybrid formulation (CHF) and hybrid formulation (HF) in amorphous form. The transmission electron microscopy (TEM) images revealed a core-shell structure of HF. The particle size of 471.5 nm estimated through dynamic light scattering (DLS) is enough to achieve active and passive targeting to AM. The nanoparticle tracking analysis (NTA) data revealed that the diluted samples were free from aggregates. Fluorescence-activated cell sorting (FACS) data exhibited excellent uptake via CHF (15 times) and HF(3 times) with reference to plain fluorescein isothiocyanate (FITC). The pharmacokinetic studies revealed that CHF and HF release the entrapped moiety LVF in a controlled manner over 72 h. The stability studies indicated that the modified formulation remains stable over 6 months at 5 ± 3℃. Hence, hybrid systems can be efficiently modified via carubinose to target AM via the parenteral route.

Efficacy and safety of combined isoniazid-rifampicin-pyrazinamide-levofloxacin dry powder inhaler in treatment of pulmonary tuberculosis: A randomized controlled trial

OBJECTIVE

To determine the efficacy and safety of add-on dry powder for inhalation (DPI) of combined anti-TB agents prepared as a particulate system (study group) compared with placebo DPI (control group) in patients diagnosed with pulmonary TB.

METHODS

This study was a randomized, placebo-controlled, double-blinded parallel design. Subjects were pulmonary TB patients, new or re-treatment, aged 18 years or older. The eligible patients were randomly allocated (1:1) to either the study group or the control group using stratified blocked randomization. The add-on DPI of combined anti-TB therapy (each capsule contained isoniazid 5 mg, rifampicin 2 mg, pyrazinamide 16 mg, and levofloxacin 2 mg) was used throughout the course of the standard oral anti-TB treatment. The primary outcome was Mycobacterium tuberculosis (MTB) sputum culture conversion measured after receiving treatment for eight weeks. Secondary outcomes were clinical signs and symptoms of pulmonary TB and adverse drug reactions (ADRs) related to anti-TB agents. The percentages of patients who achieved the primary outcome were compared (95% confidence interval). All analyses were performed using the modified intention-to-treat principle.

RESULTS

91 patients were randomly allocated: 44 to the study group and 47 to the control group. Important baseline data (%peak expiratory flow rate, chest X-ray findings, resistance to anti-TB agents, renal and liver function tests) were similar between the two groups. Although the percentages of patients who achieved the primary outcome were similar in both groups (34/44 [77.3%] in the study group and (34/47 [72.3%] in the control group; relative risk [RR] 1.07, 95% CI 0.84-1.36; p = 0.589), the study group patients seemed to achieve the primary outcome earlier than the control group (22/44 [50.0%] vs 15/47 [31.9%]; RR 1.57, 95% CI 0.94-2.61; p = 0.079) at the end of week 4. Cough was significantly lower in the study group than in the control group (23/44 [52.3%] vs 43/47 [91.5%]; RR 0.57, 95% CI 0.43-0.77; p < 0.001) at week 4 of treatment. Hemoptysis was found in approximately half of each group at baseline. The percentage of patients having hemoptysis was substantially reduced at week 2 of treatment (5 [11.4%] in the study group and 11 [23.0%] in the control group, p = 0.132). Regarding safety outcomes, no dyspnea or severe ADRs were reported. Adverse events (AEs) related to oral anti-TB agents, (e.g. liver function tests) were in normal ranges in most patients in both groups during the treatment. The incidences of common AEs reported (e.g. anorexia, dizziness, numbness, arthralgia, rash, and itching) were similar between the two groups, while the incidences of nausea and vomiting were significantly lower in the study group than the control group (38.6% vs 74.5%, p = 0.001, and 43.2% vs 66.0%, p = 0.029, respectively).

CONCLUSIONS

Add-on combined anti-TB DPI therapy to the standard oral anti-TB treatment did not increase MTB sputum culture conversion at two months of treatment. However, the percentage of patients having cough in the study group was significantly lower than in the control group at two months after treatment. A reduction in cough might represent adequate response to treatment, and result in a decreased risk of spread of infection. Combined anti-TB DPI therapy was safe. Further study investigated in a larger sample using higher strengths of DPI therapy is required.

Resistant Tuberculosis: the Latest Advancements of Second-line Antibiotic Inhalation Products

Drug-resistant tuberculosis (TB) can be considered the man-made result of interrupted, erratic or inadequate TB therapy. As reported in WHO data, resistant Mycobacterium tuberculosis (Mtb) strains continue to constitute a public health crisis. Mtb is naturally able to survive host defence mechanisms and to resist most antibiotics currently available. Prolonged treatment regimens using the available first-line drugs give rise to poor patient compliance and a rapid evolution of strains resistant to rifampicin only or to both rifampicin and isoniazid (multi drug-resistant, MDR-TB). The accumulation of mutations may give rise to extensively drug-resistant strains (XDR-TB), i.e. strains with resistance also to fluoroquinolones and to the injectable aminoglycoside, which represent the second-line drugs. Direct lung delivery of anti-tubercular drugs, as an adjunct to conventional routes, provides high concentrations within the lungs, which are the intended target site of drug delivery, representing an interesting strategy to prevent or reduce the development of drug-resistant strains. The purpose of this paper is to describe and critically analyse the most recent and advanced results in the formulation development of WHO second-line drug inhalation products, with particular focus on dry powder formulation. Although some of these formulations have been developed for other lung infectious diseases (Pseudomonas aeruginosa, nontuberculous mycobacteria), they could be valuable to treat MDR-TB and XDR-TB.

A triple combination 'nano' dry powder inhaler for tuberculosis: in vitro and in vivo pulmonary characterization

Inhalation route of drug delivery is the most favorable for pulmonary infections wherein direct drug delivery is desired to the lungs. Tuberculosis is one such infection suffering from poor therapeutic efficacy because of low patient compliance due to high drug dosing and lengthy treatment protocols. The current research work was undertaken to develop a dry powder inhaler (DPI) for administration of three first-line antitubercular antibiotics directly to the lungs to improve the treatment rates. Nanoformulations of isoniazid, pyrazinamide, and rifampicin were prepared, spray-dried to obtain a dry powder system, and blended with inhalation grade lactose to develop the DPI. The DPI was evaluated for its flow properties, pulmonary deposition, dissolution profile, and stability. The DPI possessed excellent flow properties with a fine particle fraction of 45% and a mass median aerodynamic diameter of approximately 5 µm indicating satisfactory lung deposition. In vitro drug release exhibited a sustained release of the formulations. In vivo studies showed a prolonged deposition in the lung at elevated concentrations compared to oral therapy. Stability studies proved that the formulation remained stable at accelerated and long-term stability conditions. The DPI could complement the existing oral therapy in enhancing the therapeutic efficacy in patients.

In-air particle generation by on-chip electrohydrodynamics

Electrohydrodynamic atomization has been emerging as a powerful approach for respiratory treatment, including the generation and delivery of micro/nanoparticles as carriers for drugs and antigens. In this work, we present a new conceptual design in which two nozzles facilitate dual electrospray coexisting with ionic wind at chamfered tips by a direct current power source. Experimental results by a prototype have demonstrated the capability of simultaneously generating-and-delivering a stream of charged reduced particles. The concept can be beneficial to pulmonary nano-medicine delivery since the mist of nanoparticles is migrated without any restriction of either the collector or the assistance of external flow, but is pretty simple in designing and manufacturing devices.

Preference of inhalants over pills/injections among pulmonary tuberculosis patients in Western India: A cross-sectional study

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India shares the highest burden of TB & MDR-TB cases in the world.

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Currently, pills/injections are two modes of treatment available for TB patients.

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Inhalants could be preferred and acceptable drug delivery method among TB patients.

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Exploration of diverse drug delivery options for TB patients is recommended.

Background

Presently, pills and injections are the two modes of therapeutic treatment available for tuberculosis (TB) patients. Many researchers have hypothesized inhalation drug delivery for reducing treatment times and possibly limiting the insurgence of drug resistance. This study was aimed at identifying and assessing the preferences of inhalation therapy over injections/pills among pulmonary TB patients.

Method

Cross-sectional study design was used and a sample of 477 participants were recruited at selected three Directly Observed Treatment Short-Course (DOTS) centers in Bhiwandi city. Data was collected through self-reported questionnaire. Descriptive statistics were reported, and binomial regression models were applied for data analysis.

Results

The preference of inhalants over pills/injections among pulmonary TB patients was significantly associated with clinical characteristics. The patients who underwent treatment for more than 1 year were 1.7 times more likely to prefer inhalants over pills/injections when compared with treatment duration of less than 1 year. Similarly, patients taking five or more pills/day were 1.7 times more likely to prefer inhalants over pills/injections when compared with patients taking 1–4 pills per day.

Conclusion

The study results signify that inhalants could be an acceptable method of drug delivery in this population of TB patients. Diverse drug delivery options for TB patients may greatly contribute towards TB treatment adherence.

Inhalable particles containing isoniazid and rifabutin as adjunct therapy for safe, efficacious and relapse-free cure of experimental animal tuberculosis in one month

We investigated the preclinical efficacy and safety/tolerability of biodegradable polymeric particles containing isoniazid (INH) and rifabutin (RFB) dry powder for inhalation (DPI) as an adjunct to oral first-line therapy. Mice and guinea pigs infected with Mycobacterium tuberculosis H37Rv (Mtb) were treated with ∼80 and ∼300 μg of the DPI, respectively, for 3-4 weeks starting 3, 10, and 30 days post-infection. Adjunct combination therapy eliminated culturable Mtb from the lungs and spleens of all but one of 52 animals that received the DPI. Relapse-free cure was not achieved in one mouse that received DPI + oral, human-equivalent doses (HED) of four drugs used in the Directly Observed Treatment, Short Course (DOTS), starting 30 days post-infection. Oral doses (20 mg/Kg/day, each) of INH + RFB reduced Mtb burden from ∼10⁶ to ∼10³ colony-forming units. Combining half the oral dose with DPI prevented relapse of infection four weeks after stopping the treatment. The DPI was safe in rodents, guinea pigs, and monkeys at 1, 10, and 100 μg/day doses over 90 days. In conclusion, we show the efficacy and safety/tolerability of the DPI as an adjunct to oral chemotherapy in three different animal models of TB.

Studies on the safety and the tissue distribution of inhaled high-dose amorphous and crystalline rifampicin in a rat model

Inhaled delivery of rifampicin has the potential to achieve high drug concentrations in the lung and the blood for efficient treatment of tuberculosis (TB). Due to its existence as polymorphs, in vivo evaluation of the respiratory tract safety of inhalable amorphous and crystalline rifampicin particles, at clinically relevant high-dose, is necessary. This study investigates the lung and liver safety and the tissue distribution of rifampicin after intra-tracheal administration of high (≥25 mg/kg) doses of amorphous and crystalline powder formulations to Sprague Dawley rats. Powder formulations were administered by intra-tracheal insufflation to rats. Lung and liver safety were evaluated by histopathology. Serum alanine transaminase (ALT) and aspartate aminotransferase (AST) assays were performed to study the hepatic effects. Rifampicin was quantified in the tissues using LC-MS/MS. Intra-tracheal administration of rifampicin decreased the drug burden on the liver compared to oral administration based on its lower serum ALT activity. Repeated-dose intra-tracheal rifampicin was well tolerated by rats, confirmed by the absence of drug or delivery induced complexities. The histopathological evaluation of rat lungs, after both single and repeated drug administration for seven days, suggested the absence of drug-induced toxicity. Following single intra-tracheal delivery of 50 mg/kg doses, comparable rifampicin concentrations to that from same oral dose were observed in lung, liver, heart and brain. Inhaled delivery of high-dose rifampicin was safe to rat lungs and liver suggesting its potential for localized as well as systemic drug delivery without toxicity concerns.

Pharmacokinetics of rifampicin after repeated intra-tracheal administration of amorphous and crystalline powder formulations to Sprague Dawley rats

Rifampicin is one of the key drugs used to treat tuberculosis and is currently used orally. The use of higher oral doses of rifampicin is desired for better therapeutic efficacy, but this is accompanied by increased risk of systemic toxicity thus limiting its recommended oral dose to 10 mg/kg per day. Inhaled delivery of rifampicin is a potential alternative mode of delivery, to achieve high drug concentrations in both the lung and potentially the systemic circulation. In addition, rifampicin exists either as amorphous or crystalline particles, which may show different pharmacokinetic behaviour. However, disposition behaviour of amorphous and crystalline rifampicin formulations after inhaled high-dose delivery is unknown. In this study, rifampicin pharmacokinetics after intra-tracheal administration of carrier-free, amorphous and crystalline powder formulations to Sprague Dawley rats were evaluated. The formulations were administered once daily for seven days by oral, intra-tracheal and oral plus intra-tracheal delivery, and the pharmacokinetics were studied on day 0 and day 6. Intra-tracheal administration of the amorphous formulation resulted in a higher area under the plasma concentration curve (AUC) compared to the crystalline formulation. For both formulations, the intra-tracheal delivery led to significantly higher AUC compared to the oral delivery at the same dose suggesting higher rifampicin bioavailability from the inhaled route. Increasing the intra-tracheal dose resulted in a more than dose proportional AUC suggesting non-linear pharmacokinetics of rifampicin from the inhaled route. Upon repeated administration for seven days, no significant decrease in the AUCs were observed suggesting the absence of rifampicin induced enzyme auto-induction in this study. The present study suggests an advantage of inhaled delivery of rifampicin in achieving higher drug bioavailability compared to the oral route.

Potential for bacteriophage therapy for Staphylococcus aureus pneumonia with influenza A coinfection

The ability of influenza A virus to evolve, coupled with increasing antimicrobial resistance, could trigger an influenza pandemic with great morbidity and mortality. Much of the 1918 influenza pandemic mortality was likely due to bacterial coinfection, including Staphylococcus aureus pneumonia. S. aureus resists many antibiotics. The lack of new antibiotics suggests alternative antimicrobials, such as bacteriophages, are needed. Potential delivery routes for bacteriophage therapy (BT) include inhalation and intravenous injection. BT has recently been used successfully in compassionate access pulmonary infection cases. Phage lysins, enzymes that hydrolyze bacterial cell walls and which are bactericidal, are efficacious in animal pneumonia models. Clinical trials will be needed to determine whether BT can ameliorate disease in influenza and S. aureus coinfection.

Designing inhalable metal organic frameworks for pulmonary tuberculosis treatment and theragnostics via spray drying

Inhalable metal organic framework (MOF) aerosols have been developed via spray drying as a therapy for multi-drug resistant (MDR) tuberculosis (TB). The CuPOA₂ (pyrazinoate acid) MOFs can be tailored to exhibit a respirable mass median aerodynamic diameter (MMAD) of 2.6 μm. This method is repeated to manufacture Gd_0.1Cu_0.9(POA)₂ MOFs for inhalable theragnostics.

Inhalable solid lipid nanoparticles for intracellular tuberculosis infection therapy: macrophage-targeting and pH-sensitive properties

Mycobacterium tuberculosis (MTB) is one of the most threatening pathogens for its latent infection in macrophages. The intracellular MTB isolated itself from drugs and could spread via macrophages. Therefore, a mannose-modified macrophage-targeting solid lipid nanoparticle, MAN-IC-SLN, loading the pH-sensitive prodrug of isoniazid (INH), was designed to treat the latent tuberculosis infection. The surface of SLNs was modified by a synthesized 6-octadecylimino-hexane-1,2,3,4,5-pentanol (MAN-SA) to target macrophages, and the modified SLNs showed a higher cell uptake in macrophages (97.2%) than unmodified SLNs (42.4%). The prodrug, isonicotinic acid octylidene-hydrazide (INH-CHO), was synthesized to achieve the pH-sensitive release of INH in macrophages. The INH-CHO-loaded SLNs exhibited a pH-sensitive release profile and accomplished a higher accumulated release in pH 5.5 media (82.63 ± 2.12%) compared with the release in pH 7.4 media (58.83 ± 3.84%). Mycobacterium smegmatis was used as a substitute for MTB, and the MAN-IC-SLNs showed a fourfold increase of intracellular antibiotic efficacy and enhanced macrophage uptake because of the pH-sensitive degradation of INH-CHO and MAN-SA in SLNs, respectively. For the in vivo antibiotic efficacy test, the SLNs group displayed an 83% decrease of the colony-forming unit while the free INH group only showed a 60% decrease. The study demonstrates that macrophage targeting and pH-sensitive SLNs can be used as a promising platform for the latent tuberculosis infection. Graphical Abstract Table of contents: Macrophage-targeting and pH-sensitive solid lipid nanoparticles (SLN) were administrated to the lung via nebulization. Macrophage targeting was achieved by appropriate particle size and surface mannose modification with synthesized MAN-SA. After being swallowed by macrophages, the prodrug, Isonicotinic acid octylidene-hydrazide (INH-CHO), quickly released isoniazid, which was triggered by the intracellular acid environment. The SLNs exhibited higher intracellular antibiotic efficacy due to their macrophage-targeting and pH-sensitive properties.

Respiratory Tract: Structure and Attractions for Drug Delivery Using Dry Powder Inhalers

Respiratory tract is one of the oldest routes for drug delivery. It can be used for local and systemic drug deliveries. Inhalation therapy has several advantages over oral. It delivers the drug efficiently to the lung with minimal systemic exposure, thus avoiding systemic side effects common with oral route. In this review, different types of inhaler devices are illustrated like metered dose inhalers (MDIs), dry powder inhalers (DPIs), nebulizers, and the new soft mist inhalers (SMIs). Since dry powder is more stable than when in liquid form, we will discuss in detail DPIs highlighting different techniques utilized in preparation of dry powders with or without carrier to improve flowability and drug delivery to deep lungs. Types of DPIs are briefly discussed with examples from the market. Several mechanisms for particle deposition are mentioned with factors governing the process. Pharmacokinetic profile of the inhaled particles is detailed starting from the dissolution, followed by the rapid absorption and ending with systemic clearance. New technologies like 3D printing in pulmonary field are also highlighted.

An Inhalable Theranostic System for Local Tuberculosis Treatment Containing an Isoniazid Loaded Metal Organic Framework Fe-MIL-101-NH2-From Raw MOF to Drug Delivery System

The theranostic approach to local tuberculosis treatment allows drug delivery and imaging of the lungs for a better control and personalization of antibiotic therapy. Metal-organic framework (MOF) Fe-MIL-101-NH2 nanoparticles were loaded with isoniazid. To optimize their functionality a 2³ factorial design of spray-drying with poly(lactide-co-glycolide) and leucine was employed. Powder aerodynamic properties were assessed using a twin stage impinger based on the dose emitted and the fine particle fraction. Magnetic resonance imaging (MRI) contrast capabilities were tested on porous lung tissue phantom and ex vivo rat lungs. Cell viability and uptake studies were conducted on murine macrophages RAW 246.9. The final product showed good aerodynamic properties, modified drug release, easier uptake by macrophages in relation to raw isoniazid-MOF, and MRI contrast capabilities. Starting from raw MOF, a fully functional inhalable theranostic system with a potential application in personalized tuberculosis pulmonary therapy was developed.

Development and Characterization of a Dry Powder Formulation for Anti-Tuberculosis Drug Spectinamide 1599

PURPOSE

Human tuberculosis (TB) is a global health problem that causes nearly 2 million deaths per year. Anti-TB therapy exists, but it needs to be administered as a cocktail of antibiotics for six months. This lengthy therapy results in low patient compliance and is the main reason attributable to the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis.

METHODS

One alternative approach is to combine anti-TB multidrug therapy with inhalational TB therapy. The aim of this work was to develop and characterize dry powder formulations of spectinamide 1599 and ensure in vitro and in vivo delivered dose reproducibility using custom dosators.

RESULTS

Amorphous dry powders of spectinamide 1599 were successfully spray dried with mass median aerodynamic diameter (MMAD) = 2.32 ± 0.05 μm. The addition of L-leucine resulted in minor changes to the MMAD (1.69 ± 0.35 μm) but significantly improved the inhalable portion of spectinamide 1599 while maintaining amorphous qualities. Additionally, we were able to demonstrate reproducibility of dry powder administration in vitro and in vivo in mice.

CONCLUSIONS

The corresponding systemic drug exposure data indicates dose-dependent exposure in vivo in mice after dry powder intrapulmonary aerosol delivery in the dose range 15.4 - 32.8 mg/kg.

Crystalline adduct of moxifloxacin with trans-cinnamic acid to reduce the aqueous solubility and dissolution rate for improved residence time in the lungs

A crystalline adduct of the anti-tubercular drug, moxifloxacin and trans-cinnamic acid (1:1 molar ratio (MCA_1:1)) was prepared to prolong the residence time of the drug in the lungs by reducing its solubility and dissolution rate. Whether the adduct is a salt or cocrystal has not been unequivocally determined. Equilibrium solubility and intrinsic dissolution rate measurements for the adduct (MCA_1:1) in phosphate buffered saline (PBS, pH 7.4) revealed a significant decrease in the solubility of moxifloxacin (from 17.68 ± 0.85 mg mL^-1 to 6.10 ± 0.05 mg mL^-1) and intrinsic dissolution rate (from 0.47 ± 0.04 mg cm^-2 min^-1 to 0.14 ± 0.03 mg cm^-2 min^-1) compared to the supplied moxifloxacin. The aerosolization behaviour of the adduct from an inhaler device, Aerolizer^®, using a Next Generation Impactor showed a fine particle fraction of 30.4 ± 1.2%. The dissolution behaviour of the fine particle dose of respirable particles collected was assessed in a small volume of stationary mucus fluid using a custom-made dissolution apparatus. The respirable adduct particles showed a lower dissolution (microscopic observation) and permeation compared to the supplied moxifloxacin. The crystalline adduct MCA_1:1 has a lower solubility and dissolution rate than moxifloxacin and could improve the local residence time and therapeutic action of moxifloxacin in the lungs.

A Spray-Dried Combination of Capreomycin and CPZEN-45 for Inhaled Tuberculosis Therapy

Tuberculosis (TB) remains the single most serious infectious disease attributable to a single-causative organism. A variety of drugs have been evaluated for pulmonary delivery as dry powders: capreomycin sulfate has shown efficacy and was safely delivered by inhalation at high doses to human volunteers, whereas CPZEN-45 is a new drug that has also been shown to kill resistant TB. The studies here combine these drugs-acting by different mechanisms-as components of single particles by spray-drying, yielding a new combination drug therapy. The spray-dried combination powder was prepared in an aerodynamic particle size range suitable for pulmonary delivery. Physicochemical storage stability was demonstrated for a period of 6 months. The spray-dried combination powders of capreomycin and CPZEN-45 have only moderate affinity for mucin, indicating that delivered drug will not be bound by these mucins in the lung and available for microbicidal effects. The pharmacokinetics of disposition in guinea pigs demonstrated high local concentrations of drug following direct administration to the lungs and subsequent systemic bioavailability. Further studies are required to demonstrate the in vivo efficacy of the combination to confirm the therapeutic potential of this novel combination.

Preclinical Development of Inhalable d-Cycloserine and Ethionamide To Overcome Pharmacokinetic Interaction and Enhance Efficacy against Mycobacterium tuberculosis

We compared the pharmacokinetics and efficacy of a combination of d-cycloserine (DCS) and ethionamide (ETO) via oral and inhalation routes in mice. The plasma half-life (t _1/2) of oral ETO at a human-equivalent dose decreased from 4.63 ± 0.61 h to 1.64 ± 0.40 h when DCS was coadministered. The area under the concentration-time curve from 0 h to time t (AUC_{0- t} ) was reduced to one-third. Inhalation overcame the interaction. Inhalation, but not oral doses, reduced the lung CFU/g of Mycobacterium tuberculosis H37Rv from 6 to 3 log₁₀ in 4 weeks, indicating bactericidal activity.

Intrinsic Antibacterial Activity of Nanoparticles Made of β-Cyclodextrins Potentiates Their Effect as Drug Nanocarriers against Tuberculosis

Multi-drug-resistant tuberculosis (TB) is a major public health problem, concerning about half a million cases each year. Patients hardly adhere to the current strict treatment consisting of more than 10 000 tablets over a 2-year period. There is a clear need for efficient and better formulated medications. We have previously shown that nanoparticles made of cross-linked poly-β-cyclodextrins (pβCD) are efficient vehicles for pulmonary delivery of powerful combinations of anti-TB drugs. Here, we report that in addition to being efficient drug carriers, pβCD nanoparticles are endowed with intrinsic antibacterial properties. Empty pβCD nanoparticles are able to impair Mycobacterium tuberculosis (Mtb) establishment after pulmonary administration in mice. pβCD hamper colonization of macrophages by Mtb by interfering with lipid rafts, without inducing toxicity. Moreover, pβCD provoke macrophage apoptosis, leading to depletion of infected cells, thus creating a lung microenvironment detrimental to Mtb persistence. Taken together, our results suggest that pβCD nanoparticles loaded or not with antibiotics have an antibacterial action on their own and could be used as a carrier in drug regimen formulations effective against TB.

Excipient-free isoniazid aerosol administration in mice: Evaporation-nucleation particle generation, pulmonary delivery and body distribution

Excipient-free isoniazid aerosol formation and pulmonary delivery in mice are studied. An evaporation-nucleation route is used for the generation of isoniazid aerosol. Particle diameters and number concentrations are measured with an aerosol spectrometer consisting of a diffusion battery, condensation chamber, and photoelectric counter. The pulmonary delivery of isoniazid particles is studied in both nose-only (NO) and whole-body (WB) inhalation chambers for the particle mean diameter and number concentration to be 600 nm and 6 × 10⁶ cm^-3, respectively. It is found that the rate of drug systemic absorption in the WB chamber is 27% higher than that for the NO one because of an additional consumption of drug orally from the fur in the WB chamber. The particle deposition efficiency ε in the mouse respiratory tract is measured as a function of mean diameter. The quantity ε is equal to 0.7 for the particle diameter d = 10 nm and decreases to 0.2 with the diameter increasing to 300 nm, and then, at d > 300 nm the deposition efficiency increases with diameter to 0.5 at d = 2000 nm. The bioavailability of the aerosol form of isoniazid (72 ± 10%) is very close to that for the per-oral form (61 ± 10%).

Ethambutol-Loaded Solid Lipid Nanoparticles as Dry Powder Inhalable Formulation for Tuberculosis Therapy

Ethambutol hydrocloride (EMB) is an anti-tuberculosis drug, which is commonly used as a protection agent against of unrecognized resistance to other drugs employed to treat this disease. Since oral form of EMB has some side effects and cellular toxicity, direct administration of EMB into lungs seems to be an attractive and reasonable option in order to overcome these side effects. Our main goal in this study was assessment of pulmonary administration through dry powder inhaler (DPI) using EMB-loaded solid lipid nanoparticles (SLNs). We prepared EMB-loaded SLNs using two techniques (hot homogenization and ultrasonication). DPI formulations were made by spray drying of EMB-loaded SLNs with and without mannitol. For investigation of flowbility of the prepared powders, Carr's index and Hausner ratio, and for in vitro deposition of the powders, Next Generation Impactor (NGI) analysis were used. The encapsulation efficiency and particle size of obtained particles were higher than 98% and sub-100 nm, respectively. Toxicity investigation of EMB-loaded SLNs via MTT assay showed biocompatibility and non-toxicity of the SLNs. Results of flowability and aerodynamic traits assessment of EMB-loaded SLN DPI powder confirmed the suitability of prepared powders. Overall, the attained results showed that EMB-loaded SLN DPI has high potential for direct treatment of tuberculosis.

Development of Inhalable Superparamagnetic Iron Oxide Nanoparticles (SPIONs) in Microparticulate System for Antituberculosis Drug Delivery

Tuberculosis (TB) is an infectious disease which affects millions of people worldwide. Inhalable polymeric dry powders are promising alternatives as anti-TB drug carriers to the alveoli milieu and infected macrophages, with potential to significantly improve the therapeutics efficiency. Here, the development of a magnetically responsive microparticulate system for pulmonary delivery of an anti-TB drug candidate (P3) is reported. Microparticles (MPs) are developed based on a cast method using calcium carbonate sacrificial templates and incorporate superparamagnetic iron oxide nanoparticles to concentrate MPs in alveoli and enable drug on demand release upon actuation of an external alternate magnetic field (AMF). The MPs are shown to be suitable for P3 delivery to the lower airways and for alveolar macrophage phagocytosis. The developed MPs reveal unique and promising features to be used as an inhalable dry powder allowing the AMF control over dosage and frequency of drug delivery anticipating improved TB treatments.

Considerations in preparing for clinical studies of inhaled rifampicin to enhance tuberculosis treatment

Drug delivery via the inhaled route has advantages for treating local and systemic diseases. Pulmonary drug delivery may have potential in treating tuberculosis (TB), which is mainly localised in the lung (pulmonary tuberculosis ∼75%) while also affecting other organs (extra-pulmonary tuberculosis). Currently, rifampicin, a first-line anti-tubercular drug, is given orally and the maximum daily oral dose is the lesser of 10 mg/kg or 600 mg. Since only a small fraction of this dose is available in the lung, concentrations may frequently fail to reach bactericidal levels, and therefore, contribute to the development of multi-drug resistant pulmonary TB. Pulmonary delivery of rifampicin, either alone or in addition to the standard oral dose, has the potential to achieve a high concentration of rifampicin in the lung at a relatively low administered dose that is sufficient to kill bacteria and reduce the development of drug resistance. As yet, no clinical study in humans has reported the pharmacokinetics or the efficacy of pulmonary delivery of rifampicin for TB. This review discusses the opportunities and challenges of rifampicin delivery via the inhaled route and important considerations for future clinical studies on high dose inhaled rifampicin are illustrated.

Poly(ethylene carbonate)-containing polylactic acid microparticles with rifampicin improve drug delivery to macrophages

Objective

Pulmonary delivery of antibiotics will decrease the required dose for efficient treatment of lung infections and reduce systemic side effects of the drug. The objective was to evaluate the applicability of poly(ethylene carbonate) (PEC) for the preparation of inhalable, antibiotic-containing particles.

Methods

Rifampicin (RF)-loaded microparticles were prepared by electrospraying a carrier matrix of polylactic acid (PLA) with 0%, 5% and 10% PEC.

Key findings

Prepared particles had an aerodynamic diameter between 4 and 5 μm. Within 60 min, PEC-containing particles released 35–45% of RF, whereas PLA particles released only 15% of RF. Irrespective of particle composition, uptake of RF by macrophages was improved to 40–60% when formulated in microparticles compared to 0.4% for RF in solution, and intracellular localisation of particles was confirmed using confocal microscopy. Effect on macrophage and alveolar cell viability was similar for all particles whereas the minimal inhibitory concentrations against Pseudomonas aeruginosa and Escherichia coli for RF-containing PEC particles were twofold lower than for PLA particles, explained by the faster release of RF from PEC-containing particles.

Conclusions

The inclusion of PEC in PLA microparticles increased the release of RF and the inhibitory effect against two bacteria species while displaying physical particle properties similar to PLA particles.

The Expanding Diversity of Mycobacterium tuberculosis Drug Targets

After decades of relative inactivity, a large increase in efforts to discover antitubercular therapeutics has brought insights into the biology of Mycobacterium tuberculosis (Mtb) and promising new drugs such as bedaquiline, which inhibits ATP synthase, and the nitroimidazoles delamanid and pretomanid, which inhibit both mycolic acid synthesis and energy production. Despite these advances, the drug discovery pipeline remains underpopulated. The field desperately needs compounds with novel mechanisms of action capable of inhibiting multi- and extensively drug -resistant Mtb (M/XDR-TB) and, potentially, nonreplicating Mtb with the hope of shortening the duration of required therapy. New knowledge about Mtb, along with new methods and technologies, has driven exploration into novel target areas, such as energy production and central metabolism, that diverge from the classical targets in macromolecular synthesis. Here, we review new small molecule drug candidates that act on these novel targets to highlight the methods and perspectives advancing the field. These new targets bring with them the aspiration of shortening treatment duration as well as a pipeline of effective regimens against XDR-TB, positioning Mtb drug discovery to become a model for anti-infective discovery.

Proniosomes derived niosomes: recent advancements in drug delivery and targeting

Vesicular drug delivery systems have gained wide attention in the field of nanotechnology. Among them proniosomes become the superior over other vesicular carriers. Proniosomes are dry formulations of water soluble nonionic surfactant coated carrier system which immediately forms niosomes upon hydration. They have the capability to overcome the instability problems associated with niosomes and liposomes and have the potential to improve solubility, bioavailability, and absorption of various drugs. Furthermore, they offer versatile drug delivery concept for enormous number of hydrophilic and hydrophobic drugs. They have the potential to deliver drugs effectively through different routes at specific site of action to achieve controlled release action and reduce toxic effects associated with drugs. This review discusses the general preparation techniques of proniosomes and mainly focus on the applications of proniosomes in drug delivery and targeting. Moreover, this review demonstrates critical appraisal of the literature for proniosomes. Additionally, this review extensively explains the potential of proniosomes in delivering drugs via different routes, such as oral, parenteral, dermal and transdermal, ocular, oral mucosal, vaginal, pulmonary, and intranasal. Finally, the comparison of proniosomes with niosomes manifests the clear distinction between them. Moreover, proniosomes need to be explored for proteins and peptide delivery and in the field of nutraceuticals and develop pilot plant scale up studies to investigate them in industrial set up.