Development of Respirable Nanomicelle Carriers for Delivery of Amphotericin B by Jet Nebulization

Preparation, Optimization and In Vitro Characterization of Fluticasoneloaded Mixed Micelles Based on Stearic Acid-g-chitosan as a Pulmonary Delivery System

PURPOSE

The primary objective of this study was to optimize formulation variables and investigate the in vitro characteristics of fluticasone propionate (FP)-loaded mixed polymeric micelles, which were composed of depolymerized chitosan-stearic acid copolymer (DC-SA) in combination with either tocopheryl polyethylene glycol succinate or dipalmitoylphosphatidylcholine for pulmonary drug delivery.

METHODS

A D-optimal design was employed for the optimization procedure, considering lipid/ polymer ratio, polymer concentration, drug/ polymer ratio, and lipid type as independent variables. Dependent variables included particle size, polydispersion index, zeta potential, drug encapsulation efficiency, and loading efficiency of the polymeric micelles. Additionally, the nebulization efficacy and cell viability of the optimal FP-loaded DC-SA micellar formulations were evaluated.

RESULTS

The mixed polymeric micelles were successfully prepared with properties falling within the desired ranges, resulting in four optimized formulations. The release of FP from the optimal systems exhibited a sustained release profile over 72 hours, with 70% of the drug still retained within the core of the micelles. The nebulization efficiency of these optimal formulations reached up to 63%, and the fine particle fraction (FPF) ranged from 41% to 48%. Cellular viability assays demonstrated that FP-loaded DC-SA polymeric micelles exhibited lower cytotoxicity than the free drug but were slightly more cytotoxic than empty mixed micelles.

CONCLUSION

In conclusion, this study suggests that DC-SA/ lipid mixed micelles have the potential to serve as effective carriers for nebulizing poorly soluble FP.

Harnessing inhaled nanoparticles to overcome the pulmonary barrier for respiratory disease therapy

The lack of effective treatments for pulmonary diseases presents a significant global health burden, primarily due to the challenges posed by the pulmonary barrier that hinders drug delivery to the lungs. Inhaled nanomedicines, with their capacity for localized and precise drug delivery to specific pulmonary pathologies through the respiratory route, hold tremendous promise as a solution to these challenges. Nevertheless, the realization of efficient and safe pulmonary drug delivery remains fraught with multifaceted challenges. This review summarizes the delivery barriers associated with major pulmonary diseases, the physicochemical properties and drug formulations affecting these barriers, and emphasizes the design advantages and functional integration of nanomedicine in overcoming pulmonary barriers for efficient and safe local drug delivery. The review also deliberates on established nanocarriers and explores drug formulation strategies rooted in these nanocarriers, thereby furnishing essential guidance for the rational design and implementation of pulmonary nanotherapeutics. Finally, this review cast a forward-looking perspective, contemplating the clinical prospects and challenges inherent in the application of inhaled nanomedicines for respiratory diseases.

Could the Lung Be a Gateway for Amphotericin B to Attack the Army of Fungi?

Fungal diseases are a significant cause of morbidity and mortality worldwide, primarily affecting immunocompromised patients. Aspergillus, Pneumocystis, and Cryptococcus are opportunistic fungi and may cause severe lung disease. They can develop mechanisms to evade the host immune system and colonize or cause lung disease. Current fungal infection treatments constitute a few classes of antifungal drugs with significant fungi resistance development. Amphotericin B (AmB) has a broad-spectrum antifungal effect with a low incidence of resistance. However, AmB is a highly lipophilic antifungal with low solubility and permeability and is unstable in light, heat, and oxygen. Due to the difficulty of achieving adequate concentrations of AmB in the lung by intravenous administration and seeking to minimize adverse effects, nebulized AmB has been used. The pulmonary pathway has advantages such as its rapid onset of action, low metabolic activity at the site of action, ability to avoid first-pass hepatic metabolism, lower risk of adverse effects, and thin thickness of the alveolar epithelium. This paper presented different strategies for pulmonary AmB delivery, detailing the potential of nanoformulation and hoping to foster research in the field. Our finds indicate that despite an optimistic scenario for the pulmonary formulation of AmB based on the encouraging results discussed here, there is still no product registration on the FDA nor any clinical trial undergoing ClinicalTrial.gov.

Effect of Acyl Chain Length on Hydrophobized Cashew Gum Self-Assembling Nanoparticles: Colloidal Properties and Amphotericin B Delivery

Given its many potential applications, cashew gum hydrophobic derivatives have gained increasing attraction in recent years. We report here the effect of acyl chain length on hydrophobized cashew gum derivatives, using acetic, propionic, and butyric anhydrides on self-assembly nanoparticle properties and amphotericin B delivery. Nanoparticles with unimodal particle size distribution, highly negative zeta potential, and low PDI were produced. Butyrate cashew gum nanoparticles presented smaller size (<~100 nm) than acetylated and propionate cashew gum nanoparticles and no cytotoxicity in murine fibroblast cells was observed up to 100 µg/mL for loaded and unloaded nanoparticles. As a proof of concept of the potential use of the developed nanoparticle as a drug carrier formulation, amphotericin B (AmB) was encapsulated and fully characterized in their physicochemical, AmB association and release, stability, and biological aspects. They exhibited average hydrodynamic diameter lower than ~200 nm, high AmB efficiency encapsulations (up to 94.9%), and controlled release. A decrease in AmB release with the increasing of the anhydride chain length was observed, which explains the differences in antifungal activity against Candida albicans strains. An excellent storage colloidal stability was observed for unloaded and loaded AmB without use of surfactant. Considering the AmB delivery, the acyl derivative with low chain length is shown to be the best one, as it has high drug loading and AmB release, as well as low minimum inhibitory concentration against Candida albicans strains.

Potential of Nanotechnology-based Formulations in Combating Pulmonary Infectious Diseases: A Current Scenario

BACKGROUND

Pulmonary microbial infection is mainly caused by microbes like atypical bacteria, viruses, and fungi, on both the upper and lower respiratory tracts. One of the demands of the present is the use of nanotechnology-based treatments to fight various lung infections.

AIM

The main aim of the study is to explore all pulmonary infectious diseases and to compare the advanced and novel treatment approaches with the conventional methods which are available to treat infections.

METHODS

This work sheds light on pulmonary infectious diseases with their conventional and present treatment approaches along with a focus on the advantageous roles of nano-based formulations. In the literature, it has been reported that the respiratory system is the key target of various infectious diseases which gives rise to various challenges in the treatment of pulmonary infections.

RESULTS

The present review article describes the global situation of pulmonary infections and the different strategies which are available for their management, along with their limitations. The article also highlights the advantages and different examples of nanoformulations currently combating the limitations of conventional therapies.

CONCLUSION

The content of the present article further reflects on the summary of recently published research and review works on pulmonary infections, conventional methods of treatment with their limitations, and the role of nano-based approaches to combat the existing infectious diseases which will jointly help the researchers to produce effective drug formulations with desired pharmacological activities.

Amphiphilic hyperbranched polyglycerol nanoarchitectures for Amphotericin B delivery in Candida infections

Although Amphotericin B (AMB) is considered the most effective anti-mycotic agent for treating Candida infections, its clinical use is limited due to its high toxicity. To address this issue, we developed cholesterol-based dendritic micelles of hyperbranched polyglycerol (HPG), including cholesterol-cored HPG (Chol-HPG) and cholesterol end-capped HPG (HPG@Chol), for AMB delivery. The findings suggested that the presence of cholesterol moieties could control AMB loading and release properties. Dendritic micelles inhibited AMB hemolysis and cytotoxicity in HEK 293 and RAW 264.7 cell lines while increasing antifungal activity against C. albicans biofilm formation. Furthermore, significantly lower levels of renal and liver toxicity biomarkers compared to Fungizone® ensured AMB-incorporated dendritic micelle biosafety, which was confirmed by histopathological evaluations. Overall, the Chol-HPG and HPG@Chol dendritic micelles may be a viable alternative to commercially available AMB formulations as well as an effective delivery system for other poorly soluble antifungal agents.

Expanding the arsenal against pulmonary diseases using surface-functionalized polymeric micelles: breakthroughs and bottlenecks

Pulmonary diseases such as lung cancer, asthma and tuberculosis have remained one of the common challenges globally. Polymeric micelles (PMs) have emerged as an effective technique for achieving targeted drug delivery for a local as well as a systemic effect. These PMs encapsulate and protect hydrophobic drugs, increase pulmonary targeting, decrease side effects and enhance drug efficacy through the inhalation route. In the current review, emphasis has been placed on the different barriers encountered by the drugs given via the pulmonary route and the mechanism of PMs in achieving drug targeting. The applications of PMs in different pulmonary diseases have also been discussed in detail.

Self-assembled nanostructures of L-ascorbic acid alkyl esters support monomeric amphotericin B

Hypothesis

Amphotericin B (AmB) is a highly effective antimicrobial, with broad antimycotic and antiparasitic effect. However, AmB poor water-solubilisation and aggregation tendency limits its use for topical applications. We studied the capacity of nanostructures formed by alkyl esters of L-ascorbic acid (ASCn) to solubilise AmB and tested the relationship between the prevalence of the monomeric form of AmB and its effectiveness as antimicrobial agent.

Experiments

We developed self-assembled nanostructures formed by the commercial compound, palmitoyl ascorbic acid, as well as the shorter chained myristoyl and lauroyl ascorbic acid. AmB loaded ASCn nanostructures were studied by a combination of spectroscopic techniques, together with particle analysis, differential scanning calorimetry, microbiological tests, and Langmuir monolayer visualisation.

Findings

We found no direct relation between the antimicrobial capacity and the prevalence of the monomeric form of the drug. However, the later was related to chemical stability and colloidal robustness. Nanostructures formed by ASC16 in its anionic state provide an appropriate environment for AmB in its monomeric form, maintaining its antimicrobial capacity. Langmuir film visualisation supports spectrophotometric evidence, indicating that ASC16 allows the in-plane solubilisation of AmB. Coagels formed by ASC16 appear as promising for carrying AmB for dermal delivery.

A Critical Review on Emerging Trends in Dry Powder Inhaler Formulation for the Treatment of Pulmonary Aspergillosis

Pulmonary aspergillosis (PA), a pulmonary fungal infection caused by Aspergillus spp., is a concern for immunocompromised populations. Despite substantial research efforts, conventional treatments of PA using antifungal agents are associated with limitations such as excessive systemic exposure, serious side effects and limited availability of the therapeutics in the lungs for an adequate duration. To overcome the limitations associated with the conventional regimens, pulmonary delivery of antifungal agents has become a focal point of research because of the superiority of local and targeted drug delivery. Dry powder inhalers and nebulized formulations of antifungal agents have been developed and evaluated for their capability to effectively deliver antifungal agents to the lungs. Moreover, progress in nanotechnology and the utilization of nanocarriers in the development of pulmonary delivery formulations has allowed further augmentation of treatment capability and efficiency. Thus, the following review provides an insight into the advantages and therapeutic potential of the utilization of nanocarriers in pulmonary delivery of antifungal agents for the treatment of PA. In addition, discussions on formulation aspects and safety concerns together with the clinical and regulatory aspects of the formulations are presented, which suggest the possibility and desirability of utilization of nanocarriers in the treatment of PA.

Self-assembling cashew gum-graft-polylactide copolymer nanoparticles as a potential amphotericin B delivery matrix

Amphotericin B is an antibiotic used in the treatment of fungal disease and leishmania; however, it exhibits side effects to patients, hindering its wider application. Therefore, nanocarriers have been investigated as delivery systems for amphotericin B (AMB) in order to decrease its toxicity, besides increase bioavailability and solubility. Amphiphilic copolymers are interesting materials to encapsulate hydrophobic drugs such as AMB, hence copolymers of cashew gum (CG) and l-lactide (LA) were synthesized using two different CG:LA molar ratios (1:1 and 1:10). Data obtained revealed that copolymer nanoparticles present similar figures for particle sizes and zeta potentials; however, particle size of encapsulated AMB increases if compared to unloaded nanoparticles. The 1:10 nanoparticle sample has better stability although higher polydispersity index (PDI) if compared to 1:1 sample. High amphotericin (AMB) encapsulation efficiencies and low hemolysis were obtained. AMB loaded copolymers show lower aggregation pattern than commercial AMB solution. AMB loaded nanoparticles show antifungal activities against four C. albicans strains. It can be inferred that cashew gum/polylactide copolymers have potential as nanocarrier systems for AMB.

Development of amphotericin B-loaded propionate Sterculia striata polysaccharide nanocarrier

This work was aimed at the production and characterization of a new nanocarrier based on a Sterculia striata polysaccharide (SSP) modified via acylation reaction with propionic anhydride. Nanocapsules of propionated SSP (PSSP) were produced via spontaneous nanoemulsification process and tested as a potential amphotericin B (AMB) nanocarrier. Stable nanoparticles with a very low polydispersity index (0.08-0.29) and high zeta potential (ζ -42.7 to -53.8 mV) were obtained. Particle size was dependent on the degree of substitution and ranged from 205 to 286 nm. A nanocapsule with a degree of substitution (DS) of 2.53 (NC_P 2.53) was selected for encapsulation, biocompatibility, and antifungal evaluation against Candida albicans strains. A maximum of 98.3% AMB encapsulation was achieved. Encapsulated AMB was in its monomeric form and showed good biocompatibility and antifungal activity against four C. albicans strains. Data indicate that PSSP has potential as a nanocarrier system for AMB.

α-Linolenic acid-modified pluronic 127-CS copolymeric micelles for the skin targeted delivery of amphotericin B

In this study, an α-linolenic acid modified pluronic F127-block-chitosan (F127-(CS-LNA)₂) copolymer was synthesized to prepare topical amphotericin B (AMB)-loaded micelles (AMB-M) via a dialysis technique.

Reducing the toxicity of amphotericin B by encapsulation using methoxy poly(ethylene glycol)-b-poly(l-glutamic acid-co-l-phenylalanine)

Amphotericin B (AmB) is an antifungal drug used for serious fungal infections and leishmaniosis. However, its clinical application is limited because of its high toxicity. To resolve this problem, herein we loaded AmB into methoxy poly(ethylene glycol)-b-poly(l-glutamic acid-co-l-phenylalanine) (mPEG-b-P(Glu-co-Phe)) nanoparticles (l-AmB) via electrostatic, hydrophobic and π-π interactions. The l-AmB has excellent stability both in PBS and in plasma and shows a remarkably reduced hemolysis (17.1 ± 1.5%, 6 h) compared to the free AmB (94.2 ± 5.3%, 6 h). The nephrotoxicity of l-AmB is significantly lower than that of free AmB. The maximum tolerance dose (MTD) of l-AmB is 3.0 mg kg-1, which is 3.75 fold that of free AmB (MTD = 0.8 mg kg-1). The antimicrobial activity of the conjugate was retained in vivo, with l-AmB proving to be a more protective treatment for Aspergillus fumigatus infections in mice than AmB alone. These indicate that l-AmB is a formulation of AmB with low side effects.

Amphotericin B-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carrier (NLCs): effect of drug loading and biopharmaceutical characterizations

The aim of this study was to further investigate the effect of drug loading, drug entrapment efficiency, the drug release profiles and biopharmaceutical point of views of amphotericin B (AmB) lipid formulations, that is, degree of aggregation by UV-spectroscopy, in vitro hemolytic and antifungal activities. The optimum drug loading was 2.5% by weight corresponded to lipid fraction in formulation. Increasing of the drug entrapment was achieved by blending small amount of phospholipid in solid lipid nanoparticle (SLN) dispersions. All AmB lipid dispersions were less aggregated species and hemolytic response than Fungizone^® indicating that lipid nanoparticles could reduce its toxicity. The sustained release profiles of AmB formulations depended on its aggregated form and entrapment efficiency. Too high AmB loaded (5% w/w) showed a biphasic drug release profile probably due to some amounts of drug deposited on the nanosphere surface including in continuous phase which promptly released. For in vitro antifungal testing, all AmB lipid formulations were equal and more effective than both AmB itself and Fungizone^®. These observations suggested that AmB loaded SLNs, nanostructured lipid carriers and modified SLNs by blending lecithin could enhance AmB solubility, prolong release characteristics, reduce toxicity and improve antifungal activity.

Preparation of an optimized ciprofloxacin-loaded chitosan nanomicelle with enhanced antibacterial activity

OBJECTIVE

The objective of this study was to evaluate the effect of lipid structure on physicochemical properties of chitosan-fatty acid nanomicelles and prepare an optimum ciprofloxacin-loaded formulation from these conjugates which could enhance the antibacterial effects of drug against some important pathogens like P. aeruginosa.

SIGNIFICANCE

Nowadays, resistance in infectious diseases is a growing worldwide concern. Nanocarriers can increase the therapeutic index and consequently reduce the antibiotic resistance. By site-specific delivery of drug, the adverse effects of broad-spectrum antibiotics such as ciprofloxacin would be reduced.

METHODS

Fatty acid grafted chitosan conjugates were synthetized in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The effects of fatty acid type (stearic acid, palmitic acid, and linoleic acid) on physicochemical properties of conjugates were investigated. Ciprofloxacin was encapsulated in nanomicelles by thin film hydration method. Also, the preparation process was optimized with a central composite design. The antibacterial effect of optimum formulation against P. aeruginosa, K. pneumoniae, and S. pneumoniae species was determined.

RESULTS

All conjugates were synthetized with high yield values and the substitution degrees ranged between 2.13 and 35.46%. Ciprofloxacin was successfully encapsulated in nanomicelles. The optimum formulation showed high drug loading (≈ 19%), with particle size of about 260 nm and a sustained release profile of ciprofloxacin. The minimum inhibitory concentrations of ciprofloxacin in optimum formulation against P. aeruginosa and K. pneumoniae species were 4 and 2 times lower in comparison with the free drug, respectively.

CONCLUSIONS

The antibacterial effect of ciprofloxacin was improved by encapsulation of drug in chitosan nanomicelles.

Nanomaterials in the Prevention, Diagnosis, and Treatment of Mycobacterium Tuberculosis Infections

Despite the tremendous advancements that have been made in biomedical research, Mycobacterium tuberculosis (TB) still remains one of the top 10 causes of death worldwide, outpacing the Human Immunodeficiency Virus as a leading cause of death from an infectious disease. In the light of such significant disease burden, tremendous efforts have been made worldwide to stem this burgeoning spread of disease. The use of nanomaterials in TB management has increased in the past decade, particularly in the areas of early TB detection, prevention, and treatment. Nanomaterials have been proven to be efficacious in the rapid and accurate detection of TB pathogens. Novel nanocarriers have also shown tremendous promise in improving drug delivery, potentially enhancing drug concentrations in target organs while at the same time, reducing treatment frequency. In addition, the engineering of antigen nanocarriers represents an exciting front in TB research, potentially paving the way for the successful development of a new class of effective TB vaccines. This article discusses epidemiology and pathogenesis of TB infections, current TB therapeutics, advanced nanomaterials for anti-TB drug delivery, and TB vaccines. In addition, challenges and future perspectives in developing safe and effective nanomaterials in TB diagnosis and therapy are also presented.

Polymeric mixed micelles as nanomedicines: Achievements and perspectives

During the past few decades, polymeric micelles have raised special attention as novel nano-sized drug delivery systems for optimizing the treatment and diagnosis of numerous diseases. These nanocarriers exhibit several in vitro and in vivo advantages as well as increased stability and solubility to hydrophobic drugs. An interesting approach for optimizing these properties and overcoming some of their disadvantages is the combination of two or more polymers in order to assemble polymeric mixed micelles. This review article gives an overview on the current state of the art of several mixed micellar formulations as nanocarriers for drugs and imaging probes, evaluating their ongoing status (preclinical or clinical stage), with special emphasis on type of copolymers, physicochemical properties, in vivo progress achieved so far and toxicity profiles. Besides, the present article presents relevant research outcomes about polymeric mixed micelles as better drug delivery systems, when compared to polymeric pristine micelles. The reported data clearly illustrates the promise of these nanovehicles reaching clinical stages in the near future.

Biodegradable functional polycarbonate micelles for controlled release of amphotericin B

Amphotericin B (AmB), a poorly soluble and toxic antifungal drug, was encapsulated into polymeric micelles self-assembled from phenylboronic acid-functionalized polycarbonate/PEG (PEG-PBC) and urea-functionalized polycarbonate/PEG (PEG-PUC) diblock copolymers via hydrogen-bonding, boronate ester bond, and/or ionic interactions between the boronic acid group in the micellar core and amine group in AmB. Three micellar formulations were prepared: AmB/B micelles using PEG-PBC, AmB/U micelles using PEG-PUC and AmB/B+U mixed micelles using 1:1molar ratio of PEG-PBC and PEG-PUC. The average particle sizes of the micelles were in the range of 54.4-84.8nm with narrow size distribution and zeta potentials close to neutral. UV-Vis absorption analysis indicated that AmB/B micelles significantly reduced AmB aggregation status due to the interactions between AmB and the micellar core, while Fungizone® and AmB/U micelles had no effect. AmB/B+U mixed micelles exerted an intermediate effect. Both AmB/B micelles and AmB/B+U mixed micelles showed sustained drug release, with 48.6±2.1% and 59.2±1.8% AmB released respectively after 24hunder sink conditions, while AmB/U micelles displayed a burst release profile. All AmB-loaded micelles showed comparable antifungal activity to free AmB or Fungizone®, while AmB/B micelles and AmB/B+U mixed micelles were much less hemolytic than other formulations. Histological examination showed that AmB/B and AmB/B+U micelles led to a significantly lower number of apoptotic cells in the kidneys compared to Fungizone®, suggesting reduced nephrotoxicity of the micellar formulations in vivo. These phenylboronic acid-functionalized polymeric micelle systems are promising drug carriers for AmB to reduce non-specific toxicities without compromise in antifungal activity.

STATEMENT OF SIGNIFICANCE

There is a pressing need for a novel and cost-effective delivery system to reduce the toxicity induced by the antifungal agent, amphotericin B (AmB). In this study, phenylboronic acid-functionalized polycarbonate/PEG diblock copolymers were used to fabricate micelles for improved AmB-micelle interaction via the manipulation of hydrogen-bonding, boronate ester bond, ionic and hydrophobic interactions. Compared to free AmB and Fungizone®, the resultant micellar systems displayed improved stability while reducing non-specific toxicities without a compromise in antifungal activity. These findings demonstrate the potential of biodegradable functional polycarbonate micellar systems as promising carriers of AmB for the treatment of systemic fungal infections.

The function and performance of aqueous aerosol devices for inhalation therapy

OBJECTIVES

In this review paper, we explore the interaction between the functioning mechanism of different nebulizers and the physicochemical properties of the formulations for several types of devices, namely jet, ultrasonic and vibrating-mesh nebulizers; colliding and extruded jets; electrohydrodynamic mechanism; surface acoustic wave microfluidic atomization; and capillary aerosol generation.

KEY FINDINGS

Nebulization is the transformation of bulk liquids into droplets. For inhalation therapy, nebulizers are widely used to aerosolize aqueous systems, such as solutions and suspensions. The interaction between the functioning mechanism of different nebulizers and the physicochemical properties of the formulations plays a significant role in the performance of aerosol generation appropriate for pulmonary delivery. Certain types of nebulizers have consistently presented temperature increase during the nebulization event. Therefore, careful consideration should be given when evaluating thermo-labile drugs, such as protein therapeutics. We also present the general approaches for characterization of nebulizer formulations.

SUMMARY

In conclusion, the interplay between the dosage form (i.e. aqueous systems) and the specific type of device for aerosol generation determines the effectiveness of drug delivery in nebulization therapies, thus requiring extensive understanding and characterization.

Inhaled formulations and pulmonary drug delivery systems for respiratory infections

Respiratory infections represent a major global health problem. They are often treated by parenteral administrations of antimicrobials. Unfortunately, systemic therapies of high-dose antimicrobials can lead to severe adverse effects and this calls for a need to develop inhaled formulations that enable targeted drug delivery to the airways with minimal systemic drug exposure. Recent technological advances facilitate the development of inhaled anti-microbial therapies. The newer mesh nebulisers have achieved minimal drug residue, higher aerosolisation efficiencies and rapid administration compared to traditional jet nebulisers. Novel particle engineering and intelligent device design also make dry powder inhalers appealing for the delivery of high-dose antibiotics. In view of the fact that no new antibiotic entities against multi-drug resistant bacteria have come close to commercialisation, advanced formulation strategies are in high demand for combating respiratory 'super bugs'.

Nanotechnology and pulmonary delivery to overcome resistance in infectious diseases

Used since ancient times especially for the local treatment of pulmonary diseases, lungs and airways are a versatile target route for the administration of both local and systemic drugs. Despite the existence of different platforms and devices for the pulmonary administration of drugs, only a few formulations are marketed, partly due to physiological and technological limitations.

Respiratory infections represent a significant burden to health systems worldwide mainly due to intrahospital infections that more easily affect immune-compromised patients. Moreover, tuberculosis (TB) is an endemic infectious disease in many developing nations and it has resurged in the developed world associated with the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic.

Currently, medicine faces the specter of antibiotic resistance. Besides the development of new anti-infectious drugs, the development of innovative and more efficient delivery systems for drugs that went off patent appears as a promising strategy pursued by the pharmaceutical industry to improve the therapeutic outcomes and to prolong the utilities of their intellectual property portfolio. In this context, nanotechnology-based drug delivery systems (nano-DDS) emerged as a promising approach to circumvent the limitations of conventional formulations and to treat drug resistance, opening the hypothesis for new developments in this area.

Clinical experimentation with aerosol antibiotics: current and future methods of administration

Currently almost all antibiotics are administered by the intravenous route. Since several systems and situations require more efficient methods of administration, investigation and experimentation in drug design has produced local treatment modalities. Administration of antibiotics in aerosol form is one of the treatment methods of increasing interest. As the field of drug nanotechnology grows, new molecules have been produced and combined with aerosol production systems. In the current review, we discuss the efficiency of aerosol antibiotic studies along with aerosol production systems. The different parts of the aerosol antibiotic methodology are presented. Additionally, information regarding the drug molecules used is presented and future applications of this method are discussed.

New insights in the production of aerosol antibiotics. Evaluation of the optimal aerosol production system for ampicillin-sulbactam, meropenem, ceftazidime, cefepime and piperacillin-tazobactam

BACKGROUND

Several aerosol antibiotics are on the market and several others are currently being evaluated. Aim of the study was to evaluate the aerosol droplet size of five different antibiotics for future evaluation as an aerosol administration.

MATERIALS AND METHODS

The nebulizers Sunmist(®), Maxineb(®) and Invacare(®) were used in combination with four different "small <6 ml" residual cups and two "large <10 ml" with different loadings 2-4-6-8 ml (8 ml only for large residual cups) with five different antibiotic drugs (ampicilln-sulbactam, meropenem, ceftazidime, cefepime and piperacillin-tazobactam). The Mastersizer 2000 (Malvern) was used to evaluate the produced droplet size from each combination

RESULTS

Significant effect on the droplet size produced the different antibiotic (F=96.657, p<0.001) and the residual cup design (F=68.535, p<0.001) but not the different loading amount (p=0.127) and the nebulizer (p=0.715). Interactions effects were found significant only between antibiotic and residual cup (F=16.736, p<0.001). No second order interactions were found statistically significant.

CONCLUSION

Our results firstly indicate us indirectly that the chemical formulation of the drug is the main factor affecting the produced droplet size and secondly but closely the residual cup design.

Strategies for the design of orally bioavailable antileishmanial treatments

Leishmaniasis is one of the six major tropical diseases targeted by the World Health Organization. The most serious, life-threatening form is visceral leishmaniasis (VL). No vaccine is yet available for human use and chemotherapy is the main mean of dealing with this disease. This review focuses on the development of drug delivery systems (DDS) for treatment of leishmaniasis. After an overview of the significance of leishmaniasis in 2013, current chemotherapy and its limitations are considered, leading to possible strategies to improve the treatment of VL: new drugs, combinations of existing drugs and DDS, particularly for oral administration. Nanostructured biomaterials such as lipid-based or polymeric nanoparticles have unique physicochemical properties, ultra-small and controllable size, large surface area to mass ratio and the possibility of surface modification which can be used to advantage for the oral administration of antileishmanial drugs. They can improve the rate of dissolution of poorly water-soluble drugs, increase intestinal residence time by bioadhesion and, especially when lipid additives are used, influence the route and efficiency of absorption. These recent advances in this very active field should lead to better management of this serious disease.

Preparation and evaluation of inhalable itraconazole chitosan based polymeric micelles

Background

This study evaluated the potential of chitosan based polymeric micelles as a nanocarrier system for pulmonary delivery of itraconazole (ITRA).

Methods

Hydrophobically modified chitosan were synthesized by conjugation of stearic acid to the hydrophilic depolymerized chitosan. FTIR and ¹HNMR were used to prove the chemical structure and physical properties of the depolymerized and the stearic acid grafted chitosan. ITRA was entrapped into the micelles and physicochemical properties of the micelles were investigated. Fluorescence spectroscopy, dynamic laser light scattering and transmission electron microscopy were used to characterize the physicochemical properties of the prepared micelles. The in vitro pulmonary profile of polymeric micelles was studied by an air-jet nebulizer connected to a twin stage impinger.

Results

The polymeric micelles prepared in this study could entrap up to 43.2±2.27 μg of ITRA per milliliter. All micelles showed mean diameter between 120–200 nm. The critical micelle concentration of the stearic acid grafted chitosan was found to be 1.58×10^-2 mg/ml. The nebulization efficiency was up to 89% and the fine particle fraction (FPF) varied from 38% to 47%. The micelles had enough stability to remain encapsulation of the drug during nebulization process.

Conclusions

In vitro data showed that stearic acid grafted chitosan based polymeric micelles has a potential to be used as nanocarriers for delivery of itraconazole through inhalation.

Chitosan-Grafted Copolymers and Chitosan-Ligand Conjugates as Matrices for Pulmonary Drug Delivery

Recently, much attention has been given to pulmonary drug delivery by means of nanosized systems to treat both local and systemic diseases. Among the different materials used for the production of nanocarriers, chitosan enjoys high popularity due to its inherent characteristics such as biocompatibility, biodegradability, and mucoadhesion, among others. Through the modification of chitosan chemical structure, either by the addition of new chemical groups or by the functionalization with ligands, it is possible to obtain derivatives with advantageous and specific characteristics for pulmonary administration. In this paper, we discuss the advantages of using chitosan for nanotechnology-based pulmonary delivery of drugs and summarize the most recent and promising modifications performed to the chitosan molecule in order to improve its characteristics.