The role of particle physico-chemical properties in pulmonary drug delivery for tuberculosis therapy

The study of galactomannans with different molecular weights and their ability to form microparticles suitable for pulmonary delivery

The influence of locust bean gum (LBG) galactomannans (GMs) molecular weight (Mw) to assemble microparticulate systems was evaluated, and carriers for deep lung delivery were developed. A commercial batch of LBG with a mannose/galactose (M/G) ratio of 2.4 (batch 1) was used to study the influence of different microwave partial acid hydrolysis conditions on carbohydrate composition, glycosidic linkages, and aqueous solutions viscosity. The microwave treatment did not affect the composition, presenting 4-Man (36-42 %), 4,6-Man (27-35 %), and T-Gal (24-25 %) as the main glycosidic linkages. Depolymerization led to a viscosity reduction (≤0.005 Pa·s) with no major impact on polysaccharide debranching. The structural composition of the LBG galactomannans were further elucidated with sequence-specific proteins using carbohydrate microarray technologies. A second batch of LBG (M/G 3.3) was used to study the impact of GMs with different Mw on microparticle assembling, characteristics, and insulin release kinetics. The low-Mw GMs microparticles led to a faster release (20 min) than the higher-Mw (40 min) ones, impacting the release kinetics. All microparticles exhibited a safety profile to cells of the respiratory tract. However, only the higher-Mw GMs allowed the assembly of microparticles with sizes suitable for this type of administration.

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

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

The Pharmacokinetics of CPZEN-45, a Novel Anti-Tuberculosis Drug, in Guinea Pigs

CPZEN-45 is a novel compound with activity against drug-susceptible and drug-resistant tuberculosis (TB). The present study was undertaken to determine the best dose and dosing regimen of inhalable CPZEN-45 powders to use in efficacy studies with TB-infected guinea pigs. The disposition of CPZEN-45 after intravenous, subcutaneous (SC), and direct pulmonary administration (INS) was first determined to obtain their basal pharmacokinetic (PK) parameters. Then, the disposition of CPZEN-45 powders after passive inhalation using consecutive and sequential doses was evaluated. Plasma concentration versus time curves and PK parameters indicated that the absorption of CPZEN-45 after INS was faster than after SC administration (Ka = 12.94 ± 5.66 h-1 and 1.23 ± 0.55 h-1, respectively), had a longer half-life (2.06 ± 1.01 h versus 0.76 ± 0.22 h) and had higher bioavailability (67.78% and 47.73%, respectively). The plasma concentration versus time profiles and the lung tissue concentration at the end of the study period were not proportional to the dose size after one, two, and three consecutive passive inhalation doses. Three sequential passive inhalation doses maintained therapeutic concentration levels in plasma and lung tissue for a longer time than three consecutive doses (10 h vs. 3 h, respectively). Future studies to evaluate the efficacy of inhaled CPZEN-45 powders should employ sequential doses of the powder, with one nominal dose administered to animals three times per day.

Polysaccharide-Based Carriers for Pulmonary Insulin Delivery: The Potential of Coffee as an Unconventional Source

Non-invasive routes for insulin delivery are emerging as alternatives to currently painful subcutaneous injections. For pulmonary delivery, formulations may be in powdered particle form, using carriers such as polysaccharides to stabilise the active principle. Roasted coffee beans and spent coffee grounds (SCG) are rich in polysaccharides, namely galactomannans and arabinogalactans. In this work, the polysaccharides were obtained from roasted coffee and SCG for the preparation of insulin-loaded microparticles. The galactomannan and arabinogalactan-rich fractions of coffee beverages were purified by ultrafiltration and separated by graded ethanol precipitations at 50% and 75%, respectively. For SCG, galactomannan-rich and arabinogalactan-rich fractions were recovered by microwave-assisted extraction at 150 °C and at 180 °C, followed by ultrafiltration. Each extract was spray-dried with insulin 10% (w/w). All microparticles had a raisin-like morphology and average diameters of 1-5 µm, which are appropriate for pulmonary delivery. Galactomannan-based microparticles, independently of their source, released insulin in a gradual manner, while arabinogalactan-based ones presented a burst release. The microparticles were seen to be non-cytotoxic for cells representative of the lung, specifically lung epithelial cells (A549) and macrophages (Raw 264.7) up to 1 mg/mL. This work shows how coffee can be a sustainable source of polysaccharide carriers for insulin delivery via the pulmonary route.

Fluid Films as Models for Understanding the Impact of Inhaled Particles in Lung Surfactant Layers

Pollution is currently a public health problem associated with different cardiovascular and respiratory diseases. These are commonly originated as a result of the pollutant transport to the alveolar cavity after their inhalation. Once pollutants enter the alveolar cavity, they are deposited on the lung surfactant (LS) film, altering their mechanical performance which increases the respiratory work and can induce a premature alveolar collapse. Furthermore, the interactions of pollutants with LS can induce the formation of an LS corona decorating the pollutant surface, favoring their penetration into the bloodstream and distribution along different organs. Therefore, it is necessary to understand the most fundamental aspects of the interaction of particulate pollutants with LS to mitigate their effects, and design therapeutic strategies. However, the use of animal models is often invasive, and requires a careful examination of different bioethics aspects. This makes it necessary to design in vitro models mimicking some physico-chemical aspects with relevance for LS performance, which can be done by exploiting the tools provided by the science and technology of interfaces to shed light on the most fundamental physico-chemical bases governing the interaction between LS and particulate matter. This review provides an updated perspective of the use of fluid films of LS models for shedding light on the potential impact of particulate matter in the performance of LS film. It should be noted that even though the used model systems cannot account for some physiological aspects, it is expected that the information contained in this review can contribute on the understanding of the potential toxicological effects of air pollution.

Polysaccharide-based formulations as potential carriers for pulmonary delivery - A review of their properties and fates

Polysaccharides can be elite carriers for therapeutic molecules due to their versatility and low probability to trigger toxicity and immunogenic responses. Local and systemic therapies can be achieved through particle pulmonary delivery, a promising non-invasive alternative. Successful pulmonary delivery requires particles with appropriate flowability to reach alveoli and avoid premature clearance mechanisms. Polysaccharides can form micro-, nano-in-micro-, and large porous particles, aerogels, and hydrogels. Herein, the characteristics of polysaccharides used in drug formulations for pulmonary delivery are reviewed, providing insights into structure-function relationships. Charged polysaccharides can confer mucoadhesion, whereas the ability for specific sugar recognition may confer targeting capacity for alveolar macrophages. The method of particle preparation must be chosen considering the properties of the components and the delivery device to be utilized. The fate of polysaccharide-based carriers is dependent on enzyme-triggered hydrolytic and/or oxidative mechanisms, allowing their complete degradation and elimination through urine or reutilization of released monosaccharides.

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.

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.

Targeted therapy in chronic diseases using nanomaterial-based drug delivery vehicles

The application of nanomedicines is increasing rapidly with the promise of targeted and efficient drug delivery. Nanomedicines address the shortcomings of conventional therapy, as evidenced by several preclinical and clinical investigations indicating site-specific drug delivery, reduced side effects, and better treatment outcome. The development of suitable and biocompatible drug delivery vehicles is a prerequisite that has been successfully achieved by using simple and functionalized liposomes, nanoparticles, hydrogels, micelles, dendrimers, and mesoporous particles. A variety of drug delivery vehicles have been established for the targeted and controlled delivery of therapeutic agents in a wide range of chronic diseases, such as diabetes, cancer, atherosclerosis, myocardial ischemia, asthma, pulmonary tuberculosis, Parkinson's disease, and Alzheimer's disease. After successful outcomes in preclinical and clinical trials, many of these drugs have been marketed for human use, such as Abraxane®, Caelyx®, Mepact®, Myocet®, Emend®, and Rapamune®. Apart from drugs/compounds, novel therapeutic agents, such as peptides, nucleic acids (DNA and RNA), and genes have also shown potential to be used as nanomedicines for the treatment of several chronic ailments. However, a large number of extensive clinical trials are still needed to ensure the short-term and long-term effects of nanomedicines in humans. This review discusses the advantages of various drug delivery vehicles for better understanding of their utility in terms of current medical needs. Furthermore, the application of a wide range of nanomedicines is also described in the context of major chronic diseases.

Sodium Hyaluronate Nanocomposite Respirable Microparticles to Tackle Antibiotic Resistance with Potential Application in Treatment of Mycobacterial Pulmonary Infections

Tuberculosis resistant cases have been estimated to grow every year. Besides Mycobacterium tuberculosis, other mycobacterial species are responsible for an increasing number of difficult-to-treat infections. To increase efficacy of pulmonary treatment of mycobacterial infections an inhalable antibiotic powder targeting infected alveolar macrophages (AMs) and including an efflux pump inhibitor was developed. Low molecular weight sodium hyaluronate sub-micron particles were efficiently loaded with rifampicin, isoniazid and verapamil, and transformed in highly respirable microparticles (mean volume diameter: 1 μm) by spray drying. These particles were able to regenerate their original size upon contact with aqueous environment with mechanical stirring or sonication. The in vitro drugs release profile from the powder was characterized by a slow release rate, favorable to maintain a high drug level inside AMs. In vitro antimicrobial activity and ex vivo macrophage infection assays employing susceptible and drug resistant strains were carried out. No significant differences were observed when the powder, which did not compromise the AMs viability after a five-day exposure, was compared to the same formulation without verapamil. However, both preparations achieved more than 80% reduction in bacterial viability irrespective of the drug resistance profile. This approach can be considered appropriate to treat mycobacterial respiratory infections, regardless the level of drug resistance.

Glucosamine/L-lactide copolymers as potential carriers for the development of a sustained rifampicin release system using Mycobacterium smegmatis as a tuberculosis model

The present study aims at developing a new, ultrafine particle-based efficient antibiotic delivery system for the treatment of tuberculosis. The carrier material to make the rifampicin (RIF)-loaded particles is a low molecular weight star-shaped polymer produced from glucosamine (core building unit) and L-lactide (GluN-LLA). Particles were made via electrohydrodynamic atomization. Prolonged release (for up to 14 days) of RIF from these particles is reported. Drug release data fits the Korsmeyer-Peppas equation, which suggests the occurrence of a modified diffusion-controlled RIF release mechanism in vitro and is also supported by differential scanning calorimetry and drug leaching tests. Cytotoxicity tests on Mycobacterium smegmatis showed that antibiotic-free GluN-LLA and polylactides (PLA) particles (reference materials) did not show any significant anti-bacterial activity. The minimum inhibitory concentration and minimum bactericidal concentration values obtained for RIF-loaded particles showed 2- to 4-fold improvements in the anti-bacterial activity relative to the free drug. Cytotoxicity tests on macrophages indicated that cell death correlates with an increase of particle concentration but is not significantly affected by material type or particle size. Confocal microscopy was used to track internalization and localization of particles in the macrophages. The uptake of GluN-LLA particles is higher than those of their PLA counterparts. In addition, after phagocytosis, the GluN-LLA particles stayed in the cytoplasm and showed favorable long-term drug release behavior, which facilitated the killing of intracellular bacteria when compared to free RIF. The present studies suggest that these drug carrier materials are potentially very attractive candidates for the development of high-payload, sustained-release antibiotic/resorbable polymer particle systems for treating bacterial lung infections.

Effective nebulization of interferon-γ using a novel vibrating mesh

BACKGROUND

Interferon gamma (IFN-γ) is a clinically relevant immunomodulatory cytokine that has demonstrated significant potential in the treatment and management of respiratory diseases such as tuberculosis and pulmonary fibrosis. As with all large biomolecules, clinical translation is dependent on effective delivery to the disease site and delivery of IFN-γ as an aerosol offers a logical means of drug targeting. Effective localization is often hampered by instability and a lack of safe and efficient delivery systems. The present study sought to determine how effectively IFN-γ can be nebulized using two types of vibrating mesh nebulizer, each with differing mesh architectures, and to investigate the comparative efficiency of delivery of therapeutically active IFN-γ to the lungs.

METHODS

Nebulization of IFN-γ was carried out using two different Aerogen vibrating mesh technologies with differing mesh architectures. These technologies represent both a standard commercially available mesh type (Aerogen Solo®) and a new iteration mesh (Photo-defined aperture plate (PDAP®). Extensive aerosol studies (aerosol output and droplet analysis, non-invasive and invasive aerosol therapy) were conducted in line with regulatory requirements and characterization of the stability and bioactivity of the IFN-γ post-nebulization was confirmed using SDS-PAGE and stimulation of Human C-X-C motif chemokine 10 (CXCL 10) also known as IFN-γ-induced protein 10KDa (IP 10) expression from THP-1 derived macrophages (THP-1 cells).

RESULTS

Aerosol characterization studies indicated that a significant and reproducible dose of aerosolized IFN-γ can be delivered using both vibrating mesh technologies. Nebulization using both devices resulted in an emitted dose of at least 93% (100% dose minus residual volume) for IFN-γ. Characterization of aerosolized IFN-γ indicated that the PDAP was capable of generating droplets with a significantly lower mass median aerodynamic diameter (MMAD) with values of 2.79 ± 0.29 μm and 4.39 ± 0.25 μm for the PDAP and Solo respectively. The volume median diameters (VMD) of aerosolized IFN-γ corroborated this with VMDs of 2.33 ± 0.02 μm for the PDAP and 4.30 ± 0.02 μm for the Solo. SDS-PAGE gels indicated that IFN-γ remains stable after nebulization by both devices and this was confirmed by bioactivity studies using a THP-1 cell model in which an alveolar macrophage response to IFN-γ was determined. IFN-γ nebulized by the PDAP and Solo devices had no significant effect on the key inflammatory biomarker cytokine IP-10 release from this model in comparison to non-nebulized controls. Here we demonstrate that it is possible to combine IFN-γ with vibrating mesh nebulizer devices and facilitate effective aerosolisation with minimal impact on IFN-γ structure or bioactivity.

CONCLUSIONS

It is possible to nebulize IFN-γ effectively with vibrating mesh nebulizer devices without compromising its stability. The PDAP allows for generation of IFN-γ aerosols with improved aerodynamic properties thereby increasing its potential efficiency for lower respiratory tract deposition over current technology, whilst maintaining the integrity and bioactivity of IFN-γ. This delivery modality therefore offers a rational means of facilitating the clinical translation of inhaled IFN-γ.

Exploring inhalable polymeric dry powders for anti-tuberculosis drug delivery

The growing interest on polymeric delivery systems for pulmonary administration of drugs anticipates a more direct and efficient treatment of diseases such as tuberculosis (TB) that uses the pulmonary route as the natural route of infection. Polymeric microparticles or nano-in-microparticles offer target delivery of drugs to the lungs and the potential to control and sustain drug release within TB infected macrophages improving the efficiency of the anti-TB treatment and reducing side effects. In a dry powder form these inhalable delivery systems have increased stability and prolonged storage time without requiring refrigeration, besides being cost-effective and patient convenient. Thus, this review aims to compile the recent innovations of inhalable polymeric dry powder systems for the delivery of anti-TB drugs exploring the methods of production, aerodynamic characterization and the efficacy of targeted drug delivery systems using in vitro and in vivo models of the disease. Advanced knowledge and promising outcomes of these systems are anticipated to simplify and revolutionize the pulmonary drug delivery and to contribute towards more effective anti-TB treatments.

High dose dry powder inhalers to overcome the challenges of tuberculosis treatment

Tuberculosis (TB) is a major global health burden. The emergence of the human immunodeficiency virus (HIV) epidemic and drug resistance has complicated global TB control. Pulmonary delivery of drugs using dry powder inhalers (DPI) is an emerging approach to treat TB. In comparison with the conventional pulmonary delivery for asthma and chronic obstructive pulmonary disease (COPD), TB requires high dose delivery to the lung. However, high dose delivery depends on the successful design of the inhaler device and the formulation of highly aerosolizable powders. Particle engineering techniques play an important role in the development of high dose dry powder formulations. This review focuses on the development of high dose dry powder formulations for TB treatment with background information on the challenges of the current treatment of TB and the potential for pulmonary delivery. Particle engineering techniques with a particular focus on the spray drying and a summary of the developed dry powder formulations using different techniques are also discussed.

A review on recent technologies for the manufacture of pulmonary drugs

This review discusses recent developments in the manufacture of inhalable dry powder formulations. Pulmonary drugs have distinct advantages compared with other drug administration routes. However, requirements of drugs properties complicate the manufacture. Control over crystallization to make particles with the desired properties in a single step is often infeasible, which calls for micronization techniques. Although spray drying produces particles in the desired size range, a stable solid state may not be attainable. Supercritical fluids may be used as a solvent or antisolvent, which significantly reduces solvent waste. Future directions include application areas such as biopharmaceuticals for dry powder inhalers and new processing strategies to improve the control over particle formation such as continuous manufacturing with in-line process analytical technologies.

Piper regnellii extract biopolymer-based microparticles: production, characterization and antifungal activity

AIMS

This study aims to improve characteristics of Piper regnellii extract to make it applicable in formulations to treat dermatophytosis, also known as ringworm.

METHODS AND RESULTS

Microparticles (MPs) were produced by spray drying with gelatin, alginate and chitosan as encapsulating agents; characterized by scanning electron microscopy, encapsulation efficiency, thermal analyses and X-ray diffraction; and tested against Trichophyton rubrum by broth microdilution. Produced MPs had a mean diameter less than 2 μm, an increase in stability and release of the extract and good results for encapsulation efficiency, being 85·6% to gelatin MP, 71·3% to chitosan MP and 60·6% to alginate. MPs preserved the antifungal activity of P. regnellii extract T. rubrum.

CONCLUSION

Microencapsulation provided a significant improvement in the stability of the P. regnellii extract and better solubilization of chemical compounds, maintaining the antifungal effect against T. rubrum.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results are useful for developing a formulation to treat fungal infections caused by dermatophyte species.

Microencapsulated Solid Lipid Nanoparticles as a Hybrid Platform for Pulmonary Antibiotic Delivery

Solid lipid nanoparticles (SLN) containing rifabutin (RFB), with pulmonary administration purposes, were developed through a technique that avoids the use of organic solvents or sonication. To facilitate their pulmonary delivery, the RFB-loaded SLN were included in microspheres of appropriate size using suitable excipients (mannitol and trehalose) through a spray-drying technique. Confocal analysis microscopy showed that microspheres are spherical and that SLN are efficiently microencapsulated and homogeneously distributed throughout the microsphere matrices. The aerodynamic diameters observed an optimal distribution for reaching the alveolar region. The dry powder's performance during aerosolization and the in vitro drug deposition were tested using a twin-impinger approach, which confirmed that the microspheres can reach the deep lung. Isothermal titration calorimetry revealed that SLN have higher affinity for mannitol than for trehalose. Upon microsphere dissolution in aqueous media, SLN were readily recovered, maintaining their physicochemical properties. When these dry powders reach the deep lung, microspheres are expected to readily dissolve, delivering the SLN which, in turn, will release RFB. The in vivo biodistribution of microencapsulated RFB-SLN demonstrated that the antibiotic achieved the tested organs 15 and 30 min post pulmonary administration. Their antimycobacterial activity was also evaluated in a murine model of infection with a Mycobacterium tuberculosis strain H37Rv resulting in an enhancement of activity against M. tuberculosis infection compared to nontreated animals. These results suggest that RFB-SLN microencapsulation is a promising approach for the treatment of tuberculosis.

Composite CD-MOF nanocrystals-containing microspheres for sustained drug delivery

Metal-organic frameworks (MOFs), which are typically embedded in polymer matrices as composites, are emerging as a new class of carriers for sustained drug delivery. Most of the MOFs and the polymers used so far in these composites, however, are not pharmaceutically acceptable. In the investigation reported herein, composites of γ-cyclodextrin (γ-CD)-based MOFs (CD-MOFs) and polyacrylic acid (PAA) were prepared by a solid in oil-in-oil (s/o/o) emulsifying solvent evaporation method. A modified hydrothermal protocol has been established which produces efficiently at 50 °C in 6 h micron (5-10 μm) and nanometer (500-700 nm) diameter CD-MOF particles of uniform size with smooth surfaces and powder X-ray diffraction patterns that are identical with those reported in the literature. Ibuprofen (IBU) and Lansoprazole (LPZ), both insoluble in water and lacking in stability, were entrapped with high drug loading in nanometer-sized CD-MOFs by co-crystallisation (that is more effective than impregnation) without causing MOF crystal degradation during the loading process. On account of the good dispersion of drug-loaded CD-MOF nanocrystals inside polyacrylic acid (PAA) matrices and the homogeneous distribution of the drug molecules within these crystals, the composite microspheres exhibit not only spherical shapes and sustained drug release over a prolonged period of time, but they also demonstrate reduced cell toxicity. The cumulative release rate for IBU (and LPZ) follows the trend: IBU-γ-CD complex microspheres (ca. 80% in 2 h) > IBU microspheres > IBU-CD-MOF/PAA composite microspheres (ca. 50% in 24 h). Importantly, no burst release of IBU (and LPZ) was observed from the CD-MOF/PAA composite microspheres, suggesting an even distribution of the drug as well as strong drug carrier interactions inside the CD-MOF. In summary, these composite microspheres, composed of CD-MOF nanocrystals embedded in a biocompatible polymer (PAA) matrix, constitute an efficient and pharmaceutically acceptable MOF-based carrier for sustained drug release.

The formulation of nanomedicines for treating tuberculosis

Recent estimates indicate that tuberculosis (TB) is the leading cause of death worldwide, alongside the human immunodeficiency virus (HIV) infection. The current treatment is effective, but is associated with severe adverse-effects and noncompliance to prescribed regimens. An alternative route of drug delivery may improve the performance of existing drugs, which may have a key importance in TB control and eradication. Recent advances and emerging technologies in nanoscale systems, particularly nanoparticles (NPs), have the potential to transform such approach to human health and disease. Until now, several nanodelivery systems for the pulmonary administration of anti-TB drugs have been intensively studied and their utility as an alternative to the classical TB treatment has been suggested. In this context, this review provides a comprehensive analysis of recent progress in nanodelivery systems for pulmonary administration of anti-TB drugs. Additionally, more convenient and cost-effective alternatives for the lung delivery, different types of NPs for oral and topical are also being considered, and summarized in this review. Lastly, the future of this growing field and its potential impact will be discussed.

Protective effect of magnolol-loaded polyketal microparticles on lipopolysaccharide-induced acute lung injury in rats

Magnolol has shown inhibitory effects on NO production and TNF-alpha production in lipopolysaccharide (LPS)-activated macrophages and LPS-induced acute lung injury; however, the poor solubility of magnolol has hindered its clinical success. In this study, magnolol-loaded microparticles were prepared via single emulsion method from a polyketal polymer, termed PK3. The particle sizes of magnolol-loaded PK3 microparticle is 3.73 ± 0.41 μm, and was suitable for phagocytosis by macrophages and pulmonary drug delivery. PK3 microparticles exhibited excellent biocompatibility both in vitro and in vivo. More importantly, intratracheal delivery of these magnolol-loaded microparticles significantly reduced the lung inflammatory responses at low dosage of magnolol (0.5 mg/kg), and have great clinical potential in treating acute lung injury.

Inhaled drug treatment for tuberculosis: Past progress and future prospects

Since the 1990s the rising incidence of multiple drug resistant TB, particularly in the context of human immunodeficiency virus co-infected patients, has threatened global TB control. At that time funding agencies began to support formal investigation of aerosol therapy which until then had been the subject of case reports of individual investigators. Over the last decade, proponents of aerosol therapy have increased in number within the TB research community as the incidence of multiple and extremely drug resistant TB has increased dramatically around the world. Aerosol therapy offers the potential to deliver drug at target concentrations directly into the lungs, use the alveolar-capillary interface to achieve systemic levels, while reducing the risk of systemic toxicity seen with parentally administered doses. In addition, there are insufficient new drugs in the pipeline to anticipate the appearance of a new regimen in time to assure future control of drug resistance. Consequently, alternative strategies are critical to achieving global TB control, and inhaled therapies should be considered as one such strategy.

Effects of nanoparticles on the mechanical functioning of the lung

Nanotechnology is a rapidly expanding field that has very promising applications that will improve industry, medicine, and consumer products. However, despite the growing widespread use of engineered nanoparticles in these areas, very little has been done to assess the potential health risks they may pose to high-risk areas of the body, particularly the lungs. In this review we first briefly discuss the structure of the lungs and establish that the pulmonary surfactant (PS), given its vulnerability and huge contribution to healthy lung function, is a mechanism of great concern when evaluating potential nanoparticle interactions within the lung. To warrant that these interactions can occur, studies on the transport of nanoaerols are reviewed to highlight that a plethora of factors contribute to a nanoparticle's ability to travel to the deep regions of the lung where PS resides. The focus of this review is to determine the extent that physicochemical characteristics of nanoparticles such as size, hydrophobicity, and surface charge effect PS function. Numerous nanoparticle types are taken into consideration in order to effectively evaluate observed consistencies across numerous nanoparticle types and develop general trends that exist among the physicochemical characteristics of interest. Biological responses from other mechanisms/components of the lung are briefly discussed to provide further insights on how the toxicology of different nanoparticles is determined. We conclude by discussing general trends that summarize consistencies observed among the studies in regard to physicochemical properties and their effects on monolayer function, addressing current gaps in our understanding, and discussing the future outlook of this field of research.