Aerosolised antibiotics: a critical appraisal of their use

The pharmacokinetics of antibiotics in cystic fibrosis

INTRODUCTION

Dosing of antibiotics in people with cystic fibrosis (CF) is challenging, due to altered pharmacokinetics, difficulty of lung tissue penetration, and increasing presence of antimicrobial resistance.

AREAS COVERED

The purpose of this work is to critically review original data as well as previous reviews and guidelines on pharmacokinetics of systemic and inhaled antibiotics in CF, with the aim to propose strategies for optimization of antibacterial therapy in both children and adults with CF.

EXPERT OPINION

For systemic antibiotics, absorption is comparable in CF patients and non-CF controls. The volume of distribution (Vd) of most antibiotics is similar between people with CF with normal body composition and healthy individuals. However, there are a few exceptions, like cefotiam and tobramycin. Many antibiotic class-dependent changes in drug metabolism and excretion are reported, with an increased total body clearance for ß-lactam antibiotics, aminoglycosides, fluoroquinolones, and trimethoprim. We, therefore, recommend following class-specific guidelines for CF, mostly resulting in higher dosages per kg bodyweight in CF compared to non-CF controls. Higher local antibiotic concentrations in the airways can be obtained by inhalation therapy, with which eradication of bacteria may be achieved while minimizing systemic exposure and risk of toxicity.

The role of cells and their products in respiratory drug delivery: the past, present, and future

INTRODUCTION

Cell-based delivery systems offer considerable promise as novel and innovative therapeutics to target the respiratory system. These systems consist of cells and/or their extracellular vesicles that deliver their contents, such as anti-microbial peptides, micro RNAs, and even mitochondria to the lung, exerting direct therapeutic effects.

AREAS COVERED

The purpose of this article is to critically review the status of cell-based therapies in the delivery of therapeutics to the lung, evaluate current progress, and elucidate key challenges to the further development of these novel approaches. An overview as to how these cells and/or their products may be modified to enhance efficacy is given. More complex delivery cell-based systems, including cells or vesicles that are genetically modified to (over)express specific therapeutic products, such as proteins and therapeutic nucleic acids are also discussed. Focus is given to the use of the aerosol route to deliver these products directly into the lung.

EXPERT OPINION

The use of biological carriers to deliver chemical or biological agents demonstrates great potential in modern medicine. The next generation of drug delivery systems may comprise 'cell-inspired' drug carriers that are entirely synthetic, developed using insights from cell-based therapeutics to overcome limitations of current generation synthetic carriers.

Evaluation of liposomal ciprofloxacin formulations in a murine model of anthrax

The in vivo efficacy of liposomal encapsulated ciprofloxacin in two formulations, lipoquin and apulmiq, were evaluated against the causative agent of anthrax, Bacillus anthracis. Liposomal encapsulated ciprofloxacin is attractive as a therapy since it allows for once daily dosing and achieves higher concentrations of the antibiotic at the site of initial mucosal entry but lower systemic drug concentrations. The in vivo efficacy of lipoquin and apulmiq delivered by intranasal instillation was studied at different doses and schedules in both a post exposure prophylaxis (PEP) therapy model and in a delayed treatment model of murine inhalational anthrax. In the mouse model of infection, the survival curves for all treatment cohorts differed significantly from the vehicle control. Ciprofloxacin, lipoquin and apulmiq provided a high level of protection (87-90%) after 7 days of therapy when administered within 24 hours of exposure. Reducing therapy to only three days still provided protection of 60-87%, if therapy was provided within 24 hours of exposure. If treatment was initiated 48 hours after exposure the survival rate was reduced to 46-65%. These studies suggest that lipoquin and apulmiq may be attractive therapies as PEP and as part of a treatment cocktail for B. anthracis.

A Breath of Fresh Air in the Fog of Antimicrobial Resistance: Inhaled Polymyxins for Gram-Negative Pneumonia

Despite advancements in therapy, pneumonia remains the leading cause of death due to infectious diseases. Novel treatment strategies are desperately needed to optimize the antimicrobial therapy of patients suffering from this disease. One such strategy that has recently garnered significant attention is the use of inhaled antibiotics to rapidly achieve therapeutic concentrations directly at the site of infection. In particular, there is significant interest in the role of inhaled polymyxins for the treatment of nosocomial pneumonia, including ventilator-associated pneumonia, due to their retained activity against multi-drug resistant Gram-negative pathogens, including Acinetobacter baumannii and Pseudomonas aeruginosa. This review will provide a comprehensive overview of the pharmacokinetic/pharmacodynamic profile, clinical outcomes, safety, and potential role of inhaled polymyxins in clinical practice.

Evaluation of inhaled salbutamol effectiveness under supportive use of electrical impedance tomography in ventilated ICU patients: study protocol for a randomised controlled clinical trial

INTRODUCTION

The inhalative administration of drugs is a non-invasive application form that is regularly used in the treatment of ventilated patients in critical care setting. However, assessment of effectiveness or distribution of nebulised drugs is one of the lacking cornerstones of modern intensive care monitoring. Electrical impedance tomography (EIT) may provide a promising new monitoring and guiding tool for an adequate optimisation of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and evaluate associated pathologies at bedside. This study aims to elucidate the extent to which the effectiveness of inhaled salbutamol can be increased by the additional use of EIT for optimisation of respirator settings.

METHODS AND ANALYSIS

This study is a randomised, open-label, superiority trial conducted on an intensive care unit of a German university hospital, comparing two groups of mechanically ventilated patients with an acute or chronic bronchial airway obstruction according to the effectiveness of inhaled salbutamol with (intervention) or without (control) additional use of EIT for optimising ventilator settings. The primary outcome is change in airway resistance 30 min after salbutamol inhalation.

ETHICS AND DISSEMINATION

The study has received approval from the Ethics Committee of the Medical Faculty of Ruhr-University Bochum (17-6306). The results will be made available to critical care survivors, their caregivers, the funders, the critical care societies and other researchers by publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

DRKS00014706; Pre-results.

A perspective on magnetic core-shell carriers for responsive and targeted drug delivery systems

Magnetic core-shell nanocarriers have been attracting growing interest owing to their physicochemical and structural properties. The main principles of magnetic nanoparticles (MNPs) are localized treatment and stability under the effect of external magnetic fields. Furthermore, these MNPs can be coated or functionalized to gain a responsive property to a specific trigger, such as pH, heat, or even enzymes. Current investigations have been focused on the employment of this concept in cancer therapies. The evaluation of magnetic core-shell materials includes their magnetization properties, toxicity, and efficacy in drug uptake and release. This review discusses some categories of magnetic core-shell drug carriers based on Fe2O3 and Fe3O4 as the core, and different shells such as poly(lactic-co-glycolic acid), poly(vinylpyrrolidone), chitosan, silica, calcium silicate, metal, and lipids. In addition, the review addresses their recent potential applications for cancer treatment.

Nebulized Versus IV Amikacin as Adjunctive Antibiotic for Hospital and Ventilator-Acquired Pneumonia Postcardiac Surgeries: A Randomized Controlled Trial

OBJECTIVE

Nebulized antibiotics offer high efficacy due to significant local concentrations and safety with minimal blood levels. This study evaluates the efficacy and nephrotoxicity of nebulized versus IV amikacin in postcardiothoracic surgical patients with nosocomial pneumonia caused by multidrug-resistant Gram- negative bacilli.

DESIGN

Prospective, randomized, controlled study on surgical patients divided into two groups.

SETTING

Postcardiac surgery ICU.

INTERVENTIONS

The first gtroup was administered IV amikacin 20 mg/kg once daily. The second group was prescribed amikacin nebulizer 400 mg twice daily. Both groups were co-administered IV piperacillin/tazobactam empirically.

PATIENTS

Recruited patients were diagnosed by either hospital-acquired pneumonia or ventilator-associated pneumonia where 56 (42.1%) patients were diagnosed with hospital-acquired pneumonia, 51 (38.34%) patients were diagnosed with early ventilator-associated pneumonia, and 26 (19.54%) patients with late ventilator-associated pneumonia.

MEASUREMENTS AND MAIN RESULTS

Clinical cure in both groups assessed on day 7 of treatment was the primary outcome. Efficacy was additionally evaluated through assessing the length of hospital stay, ICU stay, days on amikacin, days on mechanical ventilator, mechanical ventilator-free days, days to reach clinical cure, and mortality rate. Lower nephrotoxicity in the nebulized group was observed through significant preservation of kidney function (p < 0.001). Although both groups were comparable regarding length of hospital stay, nebulizer group showed shorter ICU stay (p = 0.010), lower number of days to reach complete clinical cure (p = 0.001), fewer days on mechanical ventilator (p = 0.035), and fewer days on amikacin treatment (p = 0.022).

CONCLUSION

Nebulized amikacin showed better clinical cure rates, less ICU stay, and fewer days to reach complete recovery compared to IV amikacin for surgical patients with nosocomial pneumonia. It is also a less nephrotoxic option associated with less deterioration in kidney function.

The efficacy, safety, and feasibility of inhaled amikacin for the treatment of difficult-to-treat non-tuberculous mycobacterial lung diseases

Background

In multidrug regimens, including an intravenous aminoglycoside (e.g. amikacin [AMK]) is recommended for difficult-to-treat non-tuberculous mycobacterial (NTM) lung diseases. We aimed to evaluate the efficacy, safety, and feasibility of inhaled AMK therapy in patients with difficult-to-treat NTM lung diseases in a retrospective chart review.

Methods

The study population consisted of patients with NTM lung diseases who received combination therapy, including inhaled AMK therapy, at Keio University Hospital (Tokyo, Japan), from January 2014 through May 2016. A total of 26 cases, consisting of 23 Mycobacterium avium complex (MAC) and three Mycobacterium abscessus complex (MABC) infections cases, were included in this study. The efficacy, safety, and feasibility of inhaled AMK therapy were retrospectively investigated. The Research Ethics Committee of Keio University Hospital approved this study, and informed consent was obtained from all patients.

Results

All 26 patients were culture-positive at enrolment. Twenty-three of the 26 patients (88.5%), including 21/23 MAC patients (91.3%) and 2/3 MABC patients (66.7%), were administered inhaled AMK therapy for >3 months. The proportion of patients who had clinical symptoms, including, cough and sputum, declined after inhalation AMK therapy. Ten of the 23 patients (43.5%) who received AMK inhalation, including 8/21 MAC (38.1%) and 2/2 MABC patients (100%), showed sputum conversion, defined as at least three consecutive negative sputum cultures. Seven of the 23 patients, including, 5/21 MAC and 2/2 MABC patients, showed improvements in high-resolution computed tomography imaging of the chest. In addition, the serum AMK trough levels before the second inhalation were <1.2 μg/mL in all 26 patients, with no occurrence of severe adverse events, such as renal toxicity. One patient (3.8%) experienced auditory toxicity, in the form of tinnitus. However, this symptom was reversible, after temporary interruption of AMK, the patient was able to safely resume the therapy.

Conclusions

Inhaled AMK therapy is an effective and feasible therapy for difficult-to-treat NTM lung disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2665-5) contains supplementary material, which is available to authorized users.

Potential Toxicity of Polymyxins in Human Lung Epithelial Cells

Inhaled polymyxins are of considerable utility in achieving optimal exposure in the respiratory tract for the treatment of lung infections caused by multidrug-resistant Gram-negative pathogens. Current inhaled polymyxin therapy is empirical, and often large doses are used that may lead to potential pulmonary adverse effects. This study aimed to investigate the effect of polymyxins on human lung epithelial (A549) cells. The viability of A549 cells was examined after treatment with polymyxins by flow cytometry. Activation of caspases 3, 8, and 9, expression of Fas ligand (FasL), loss of mitochondrial membrane potential, and mitochondrial oxidative stress induced by polymyxin B were evaluated. The concentration of polymyxin B required to induce 50% of maximal cell death was 1.74 mM (95% confidence interval, 1.60 to 1.90 mM). Colistin was at least 2-fold less toxic than polymyxin B, while colistimethate was nontoxic. With 2.0 mM polymyxin B, 30.6% ± 11.5% (mean ± standard deviation) of the cells were apoptotic at 8 h and this increased to 71.3% ± 3.72% at 24 h. Concentration- and time-dependent activation of caspases 3, 8, and 9 was evident, while the activation of caspase 9 was more dramatic. Furthermore, polymyxin B caused concentration- and time-dependent FasL expression, production of mitochondrial reactive oxygen species, and changes in mitochondrial membrane potential. This is the first study to demonstrate that both extrinsic death receptor and intrinsic mitochondrial pathways are involved in polymyxin-induced toxicity in A549 cells. This knowledge base is critical for the development of novel strategies for the safe and effective inhalation therapy of polymyxins against Gram-negative "superbugs."

Tobramycin inhalation powder for the treatment of pulmonary Pseudomonas aeruginosa infection in patients with cystic fibrosis: a review based on clinical evidence

Chronic airway infection with Pseudomonas aeruginosa is a major cause of increased morbidity and mortality in patients with cystic fibrosis (CF). The development and widespread use of nebulized antibacterial therapies, including tobramycin inhalation solution (TIS), has led to improvements in lung function and quality of life. However, the use of nebulizers is associated with various challenges, including extended administration times and the need for frequent device cleaning and disinfection. Multiple therapies are required for patients with CF, which poses a considerable burden to patients, and adherence to the recommended treatments remains a challenge. Tobramycin inhalation powder (TIP), delivered via the T-326 Inhaler, has been shown to have similar clinical efficacy and safety as compared to TIS, with improved patient convenience, satisfaction, and treatment adherence. Long-term safety studies have shown that TIP was well tolerated with no unexpected adverse events in patients with CF. This review of the TIP pivotal and postmarketing studies reinforces the well-established efficacy and safety profile of TIP and its ease of use.

Inhaled Antibiotics for Gram-Negative Respiratory Infections

Gram-negative organisms comprise a large portion of the pathogens responsible for lower respiratory tract infections, especially those that are nosocomially acquired, and the rate of antibiotic resistance among these organisms continues to rise. Systemically administered antibiotics used to treat these infections often have poor penetration into the lung parenchyma and narrow therapeutic windows between efficacy and toxicity. The use of inhaled antibiotics allows for maximization of target site concentrations and optimization of pharmacokinetic/pharmacodynamic indices while minimizing systemic exposure and toxicity. This review is a comprehensive discussion of formulation and drug delivery aspects, in vitro and microbiological considerations, pharmacokinetics, and clinical outcomes with inhaled antibiotics as they apply to disease states other than cystic fibrosis. In reviewing the literature surrounding the use of inhaled antibiotics, we also highlight the complexities related to this route of administration and the shortcomings in the available evidence. The lack of novel anti-Gram-negative antibiotics in the developmental pipeline will encourage the innovative use of our existing agents, and the inhaled route is one that deserves to be further studied and adopted in the clinical arena.

Antibiotic treatment for nontuberculous mycobacterial lung disease

Pulmonary infections are the most frequent diseases caused by nontuberculous mycobacteria (NTM). Common causative organisms of pulmonary infection are slowly growing mycobacteria including Mycobacterium avium complex and Mycobacterium kansasii, and rapidly growing mycobacteria including Mycobacterium abscessus complex. Clinical concern has been raised over the increasing incidence of NTM lung disease combined with the poor treatment outcomes of these chronic infectious diseases. Since treatment guidelines of the American Thoracic Society/Infectious Disease Society of America were published in 2007 there have been continuous efforts to improve the outcomes of NTM lung disease, albeit slowly and with limitations. Here, we focus on recent advances in the antibiotic treatment of NTM lung disease.

Perspective on Nanoparticle Technology for Biomedical Use

This review gives a short overview on the widespread use of nanostructured and nanocomposite materials for disease diagnostics, drug delivery, imaging and biomedical sensing applications. Nanoparticle interaction with a biological matrix/entity is greatly influenced by its morphology, crystal phase, surface chemistry, functionalization, physicochemical and electronic properties of the particle. Various nanoparticle synthesis routes, characterization, and functionalization methodologies to be used for biomedical applications ranging from drug delivery to molecular probing of underlying mechanisms and concepts are described with several examples (150 references).

Inhaled anti-infective chemotherapy for respiratory tract infections: successes, challenges and the road ahead

One of the most common causes of illnesses in humans is from respiratory tract infections caused by bacterial, viral or fungal pathogens. Inhaled anti-infective drugs are crucial for the prophylaxis and treatment of respiratory tract infections. The benefit of anti-infective drug delivery via inhalation is that it affords delivery of sufficient therapeutic dosages directly to the primary site of infection, while minimizing the risks of systemic toxicity or avoiding potential suboptimal pharmacokinetics/pharmacodynamics associated with systemic drug exposure. This review provides an up-to-date treatise of approved and novel developmental inhaled anti-infective agents, with particular attention to effective strategies for their use, pulmonary pharmacokinetic properties and safety.

Inhalation of macrolides: a novel approach to treatment of pulmonary infections

Systemic antibiotic treatment is established for many pulmonary diseases, e.g., cystic fibrosis (CF), bronchiectasis and chronic obstructive pulmonary disease (COPD) where recurrent bacterial infections cause a progressive decline in lung function. In the last decades inhalative administration of antibiotics was introduced into clinical routine, especially tobramycin, colistin, and aztreonam for treatment of CF and bronchiectasis. Even though they are important in systemic treatment of these diseases due to their antimicrobial spectrum and anti-inflammatory and immunomodulatory properties, macrolides (e.g., azithromycin, clarithromycin, erythromycin, and telithromycin) up to now are not administered by inhalation. The number of in vitro aerosol studies and in vivo inhalation studies is also sparse. We analyzed publications on preparation and administration of macrolide aerosols available in PUBMED focusing on recent publications. Studies with solutions and dry powder aerosols were published. Publications investigating physicochemical properties of aerosols demonstrated that macrolide aerosols may serve for inhalation and will achieve sufficient lung deposition and that the bitter taste can be masked. In vivo studies in rats demonstrated high concentrations and areas under the curve sufficient for antimicrobial treatment in alveolar macrophages and epithelial lining fluid without lung toxicity. The obtained data demonstrate the feasibility of macrolide inhalation which should be further investigated.

Comparison of two tobramycin nebuliser solutions: pharmacokinetic, efficacy and safety profiles of T100 and TNS

BACKGROUND

Tobramycin inhalation is an accepted treatment of chronic pseudomonal infection in cystic fibrosis (CF) patients. Twice daily inhalation is efficacious, but time-consuming.

METHODS

In this randomized, open-label, multicentre, two-period, crossover study, 58 patients with CF and chronic Pseudomonas aeruginosa (PA) infection received two tobramycin nebuliser solutions: T100/eFlow or TNS/PARI LC PLUS. The primary objective was to demonstrate the equivalence of both treatments with respect to pharmacokinetics (area under the concentration-time curve and maximum concentration in plasma). Secondary endpoints were tobramycin sputum pharmacokinetics, reduction in PA colony forming units, improvement of lung function, incidence of adverse drug reactions and reduction of inhalation times.

RESULTS

Tobramycin plasma AUC and Cmax were lower after administration of T100 than after TNS. The study failed to demonstrate systemic bioequivalence of the two treatments. After T100 administration, tobramycin sputum AUC and Cmax achieved higher values than after TNS. Changes in efficacy parameters from baseline were similar. Safety profiles were not different or unexpected. Inhalation time per inhalation was shorter during treatment with T100.

CONCLUSION

The lower systemic drug burden and the higher local drug deposition together with a comparable efficacy/safety profile and a shorter inhalation time render T100/eFlow an attractive treatment option for CF patients. (www.controlled-trials.com/ISRCTN85410458).

Biopharmaceutical characterization of nebulized antimicrobial agents in rats: 1. Ciprofloxacin, moxifloxacin, and grepafloxacin

The aim of this study was to evaluate the biopharmaceutical characteristics of three fluoroquinolones (FQs), ciprofloxacin (CIP), moxifloxacin (MXF), and grepafloxacin (GRX), after delivery via a nebulized aerosol to rats. Bronchoalveolar lavages (BAL) were conducted 0.5, 2, 4, and 6 h after FQ intravenous administration and nebulized aerosol delivery to estimate epithelial lining fluid (ELF) drug concentrations. Plasma drug concentrations were also measured, and profiles of drug concentrations versus time after intravenous administration and nebulized aerosol delivery were virtually superimposable, attesting for rapid and complete systemic absorption of FQs. ELF drug concentrations were systematically higher than corresponding plasma drug concentrations, whatever the route of administration, and average ELF-to-unbound plasma drug concentration ratios post-distribution equilibrium did not change significantly between the ways of administration and were equal: 4.0 ± 5.3 for CIP, 12.6 ± 7.3 for MXF, and 19.1 ± 10.5 for GRX (means ± standard deviations). The impact of macrophage lysis on estimated ELF drug concentrations was significant for GRX but reduced for MXF and CIP; therefore, simultaneous pharmacokinetic modeling of plasma and ELF drug concentrations was only performed for the latter two drugs. The model was characterized by a fixed volume of ELF (VELF), passive diffusion clearance (QELF), and active efflux clearance (CLout) between plasma and ELF, indicating active efflux transport systems. In conclusion, this study demonstrates that ELF drug concentrations of these three FQs are several times higher than plasma drug concentrations, probably due to the presence of efflux transporters at the pulmonary barrier level, but no biopharmaceutical advantage of FQ nebulization was observed compared with intravenous administration.

Biopharmaceutical characterization of nebulized antimicrobial agents in rats: 2. Colistin

The purpose of this study was to investigate the pharmacokinetic properties of colistin following intrapulmonary administration of colistin sulfate in rats. Colistin was infused or delivered in nebulized form at a dose of 0.35 mg/kg of body weight in rats, and plasma drug concentrations were measured for 4 h after administration. Bronchoalveolar lavages (BAL) were also conducted at 0.5, 2, and 4 h after intravenous (i.v.) administration and administration via nebulized drug to estimate epithelial lining fluid (ELF) drug concentrations. Unbound colistin plasma concentrations at distribution equilibrium (2 h postdosing) were almost identical after i.v. infusion and nebulized drug inhalation. ELF drug concentrations were undetectable in BAL samples after i.v. administration, but they were about 1,800 times higher than unbound plasma drug levels at 2 h and 4 h after administration of the nebulized drug. Simultaneous pharmacokinetic modeling of plasma and ELF drug concentrations was performed with a model characterized by a fixed physiological volume of ELF (VELF), a passive diffusion clearance (QELF) between plasma and ELF, and a nonlinear influx transfer from ELF to the central compartment, which was assessed by reducing the nebulized dose of colistin by 10-fold (0.035 mg kg(-1)). The km was estimated to be 133 μg ml(-1), and the Vmax, in-to-Km ratio was equal to 2.5 × 10(-3) liter h(-1) kg(-1), which was 37 times higher than the QELF (6.7 × 10(-5) liter h(-1) kg(-1)). This study showed that with the higher ELF drug concentrations after administration via nebulized aerosol than after intravenous administration, for antibiotics with low permeability such as colistin, nebulization offers a real potential over intravenous administration for the treatment of pulmonary infections.

Antibiotics for treatment and prevention of exacerbations of chronic obstructive pulmonary disease

Acute exacerbations (AE) can be recurrent problems for patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) increasing morbidity and mortality. Evidence suggests that ≥50% of acute exacerbations involve bacteria requiring treatment with an antibiotic which should have high activity against the causative pathogens. However, sputum analysis is not a pre-requisite for antibiotic prescription in outpatients as results are delayed and patients are likely to be colonised with bacteria in the stable state. Clinicians rely on the clinical symptoms, sputum appearance and the patient's medical history to decide if an AE-COPD should be treated with antibiotics. This article reviews the available data of antibiotic trials in AE-COPD. Management of frequent exacerbators is particularly challenging for physicians. This may include antibiotic prophylaxis, especially macrolides because of anti-inflammatory properties; though successful in reducing exacerbations, concerns about resistance development remain. Inhalation of antibiotics achieves high local concentrations and minimal systemic exposure; therefore, it may represent an attractive alternative for antibiotic prophylaxis in certain COPD patients. Inhaled antibiotic prophylaxis has been successfully used in other respiratory conditions such as non-cystic fibrosis bronchiectasis which itself might be present in COPD patients who have chronic bacterial infection, particularly with Pseudomonas aeruginosa.

Magnetic core-shell nanoparticles for drug delivery by nebulization

BACKGROUND

Aerosolized therapeutics hold great potential for effective treatment of various diseases including lung cancer. In this context, there is an urgent need to develop novel nanocarriers suitable for drug delivery by nebulization. To address this need, we synthesized and characterized a biocompatible drug delivery vehicle following surface coating of Fe3O4 magnetic nanoparticles (MNPs) with a polymer poly(lactic-co-glycolic acid) (PLGA). The polymeric shell of these engineered nanoparticles was loaded with a potential anti-cancer drug quercetin and their suitability for targeting lung cancer cells via nebulization was evaluated.

RESULTS

Average particle size of the developed MNPs and PLGA-MNPs as measured by electron microscopy was 9.6 and 53.2 nm, whereas their hydrodynamic swelling as determined using dynamic light scattering was 54.3 nm and 293.4 nm respectively. Utilizing a series of standardized biological tests incorporating a cell-based automated image acquisition and analysis procedure in combination with real-time impedance sensing, we confirmed that the developed MNP-based nanocarrier system was biocompatible, as no cytotoxicity was observed when up to 100 μg/ml PLGA-MNP was applied to the cultured human lung epithelial cells. Moreover, the PLGA-MNP preparation was well-tolerated in vivo in mice when applied intranasally as measured by glutathione and IL-6 secretion assays after 1, 4, or 7 days post-treatment. To imitate aerosol formation for drug delivery to the lungs, we applied quercitin loaded PLGA-MNPs to the human lung carcinoma cell line A549 following a single round of nebulization. The drug-loaded PLGA-MNPs significantly reduced the number of viable A549 cells, which was comparable when applied either by nebulization or by direct pipetting.

CONCLUSION

We have developed a magnetic core-shell nanoparticle-based nanocarrier system and evaluated the feasibility of its drug delivery capability via aerosol administration. This study has implications for targeted delivery of therapeutics and poorly soluble medicinal compounds via inhalation route.

Elevated tobramycin concentrations following endotracheal administration in a premature infant

The following case report describes a 1-month-old, 34-week-gestation premature neonate who had compromised renal function. The neonate received endotracheally administered tobramycin (300 mg every 12 hours) via a PARI PLUS reusable nebulizer to treat a documented Gram-negative tracheostomy infection. The patient also received systemic tobramycin (2.5 mg/kg intravenously every 18 hours). The tobramycin serum concentration obtained 45 hours after the last intravenous dose and 11.5 hours after the second nebulized dose was 17.6 mg/L. The tobramycin nebulizations were stopped.

Multidisciplinary approach to the treatment of invasive fungal infections in adult patients. Prophylaxis, empirical, preemptive or targeted therapy, which is the best in the different hosts?

The high morbidity, mortality, and health care costs associated with invasive fungal infections, especially in the critical care setting and immunocompromised host, have made it an excellent target for prophylactic, empiric, and preemptive therapy interventions principally based on early identification of risk factors. Early diagnosis and treatment are associated with a better prognosis. In the last years there have been important developments in antifungal pharmacotherapy. An approach to the new diagnosis tools in the clinical mycology laboratory and an analysis of the use new antifungal agents and its application in different clinical situations has been made. Furthermore, an attempt of developing a state of the art in each clinical scenario (critically ill, hematological, and solid organ transplant patients) has been performed, trying to choose the best strategy for each clinical situation (prophylaxis, pre-emptive, empirical, or targeted therapy). The high mortality rates in these settings make mandatory the application of early de-escalation therapy in critically ill patients with fungal infection. In addition, the possibility of antifungal combination therapy might be considered in solid organ transplant and hematological patients.

Inhaled antibiotic therapy for ventilator-associated tracheobronchitis and ventilator-associated pneumonia: an update

Ventilator-associated pneumonia (VAP) remains a leading cause of morbidity and mortality in mechanically-ventilated patients in the Intensive Care Unit (ICU). Ventilator-associated tracheobronchitis (VAT) was previously believed to be an intermediate stage between colonization of the lower respiratory tract and VAP. More recent data, however, suggest that VAT may be a separate entity that increases morbidity and mortality, independently of the occurrence of VAP. Some, but not all, patients with VAT progress to develop VAP. Although inhaled antibiotics alone could be effective for the treatment of VAP, the current consensus of opinion favors their role as adjuncts to systemic antimicrobial therapy for VAP. Inhaled antibiotics are increasingly employed for salvage therapy in patients with VAP due to multi-drug resistant Gram-negative bacteria. In contrast to VAP, VAT could be effectively treated with inhaled antibiotic therapy alone or in combination with systemic antimicrobials.

Clinical perspective on aztreonam lysine for inhalation in patients with cystic fibrosis

Progressive obstructive lung disease is a characteristic component of cystic fibrosis (CF). It is the pulmonary manifestations, including obstruction and endobronchial infection, which directly contribute to the premature mortality of patients affected with CF. Due to the devastating effects on the pulmonary system, interest abounds in ways to improve antimicrobial delivery to the lungs and to impact clinical patient outcomes positively, whilst minimizing systemic toxicities. Recently, aztreonam lysine for inhalation solution, a new monobactam formulation, was approved by the US Food and Drug Administration for use in a subgroup of CF patients with Pseudomonas aeruginosa to improve respiratory symptoms. The purpose of this review is to present a summary of relevant pharmacologic, microbiologic, and clinical data related to the use of aztreonam lysine for inhalation in patients with CF.

Antimicrobial prophylaxis for primary immunodeficiencies

PURPOSE OF REVIEW

Antibiotic prophylaxis is one of the mainstays of therapy of primary immunodeficiencies. We aim to summarize what is known about antibiotic prophylaxis for select primary immunodeficiencies.

RECENT FINDINGS

In recent years, there has been a push towards more evidence-based practices for antimicrobial prophylaxis for many conditions such as antifungal prophylaxis for extremely premature neonates and antibiotic prophylaxis for neutropenia associated with chemotherapy. However, there are remarkably few data regarding antibiotic prophylaxis in primary immunodeficiencies and regimens vary greatly between practices.

SUMMARY

Currently, antibiotic prophylaxis is guided by the common microbial pathogens seen in specific immunodeficiencies, and experience with other chronic illnesses such as cystic fibrosis, HIV, and immunosuppression from transplantation. Controlled studies are necessary to address the preferred antimicrobial and immunomodulator regimens for most of the primary immunodeficiencies.

Clinical pharmacology and lesion penetrating properties of second- and third-line antituberculous agents used in the management of multidrug-resistant (MDR) and extensively-drug resistant (XDR) tuberculosis

Failure of first-line chemotherapy to cure tuberculosis (TB) patients occurs, in part, because of the development of resistance to isoniazid (INH) and rifampicin (RIF) the two most sterilizing agents in the four-drug regimen used to treat primary infections. Strains resistant to both INH and RIF are termed multidrug-resistant (MDR). Treatment options for MDR patients involve a complex array of twenty different drugs only two classes of which are considered to be highly effective (fluoroquinolones and aminoglycosides). Resistance to these two classes results in strains known as extensively drug-resistant (XDR) and these types of infections are becoming increasingly common. Many of the remaining agents have poorly defined pharmacology but nonetheless are widely used in the treatment of this disease. Several of these agents are known to have highly variable exposures in healthy volunteers and little is known in the patients in which they must be used. Therapeutic drug monitoring (TDM) is infrequently used in the management of MDR or XDR disease yet the clinical pharmacokinetic studies that have been done suggest this might have a large impact on disease outcome. We review what is known about the pharmacologic properties of each of the major classes of second- and third-line antituberculosis agents and suggest where judicious use of TDM would have the maximum possible impact. We summarize the state of knowledge of drug-drug interactions (DDI) in these classes of agents and those that are currently in clinical trials. Finally we consider what little is known about the ability of TB drugs to reach their ultimate site of action--the interior of a granuloma by penetrating the diseased lung area. Careful consideration of the pharmacology of these agents is essential if we are to avoid further fueling the growing epidemic of highly drug-resistant TB and critical in the development of new antituberculosis drugs.

Evaluation of the Target Inhalation Mode (TIM) breathing maneuver in simulated nebulizer therapy in patients with cystic fibrosis

BACKGROUND

Adaptive Aerosol Delivery (AAD) systems provide efficient drug delivery and improved lung deposition over conventional nebulizers by combining real-time analyses of patient breathing patterns and precisely timed aerosol delivery. Delivery and deposition are further enhanced by breathing techniques involving slow, deep inhalations.

METHODS

This exploratory study assessed the acceptability of slow, deep inhalations in 20 patients with cystic fibrosis (CF) during up to eight simulated nebulizer treatments with the I-neb AAD System. The breathing maneuver, Target Inhalation Mode (TIM) breathing, involved the lengthening of the patient's inhalation time over successive breaths with guidance from auditory and tactile (vibratory) feedback from the device.

RESULTS

At the end of the first treatment, most patients felt that the instructions were easy to understand (90%) and that the vibratory feedback was pleasant (65%). Half of the patients found the procedure to be comfortable. At the end of the final treatment, most patients felt that the breathing maneuver was easy to understand (90%) and use (80%), but that the duration of the breath was too long (100%). Logged data revealed that 90% of patients were able to comply with the breathing maneuver. The two patients unable to comply had a forced vital capacity of <1.75 L. The average treatment time decreased from 288.4 to 141.6 sec during the first and final treatments, respectively.

CONCLUSIONS

This study provides preliminary evidence of the acceptability of the TIM breathing maneuver in patients with CF and their ability to perform repeated TIM breathing during simulated nebulizer therapy with the I-neb AAD System.

Pharmacokinetics and safety of tobramycin administered by the PARI eFlow rapid nebulizer in cystic fibrosis

BACKGROUND

Nebulization times have been identified as an issue in patient compliance with tobramycin solution for inhalation (TSI) therapy in cystic fibrosis (CF).

METHODS

In this randomized, open-label, multicentre, two-period, crossover study, patients (n=25) with CF and chronic pulmonary pseudomonal infection received TSI for 15 days via eFlow rapid or LC PLUS nebulizer. Nebulization times and sputum/serum tobramycin concentrations were determined, and safety evaluated.

RESULTS

Nebulization times were significantly shorter for eFlow rapid versus LC PLUS on Day 1 (least squares mean estimate of the difference -10.5 min, 95% confidence intervals [CI] -12.6, -8.3, p<0.0001) and Day 15 (difference -7.7 min, 95% CI -9.0, -6.5, p<0.0001). Broadly comparable sputum/systemic exposure to tobramycin was observed and the incidence of adverse events was similar for both nebulizers.

CONCLUSION

Use of the eFlow rapid nebulizer reduced TSI nebulization time. The systemic exposure to tobramycin appeared to be broadly similar in this exploratory study.

Disease guided optimization of the respiratory delivery of microparticulate formulations

BACKGROUND

Inhalation of microparticulate dosage forms can be effectively used in the treatment of respiratory and systemic diseases.

OBJECTIVE

Disease states investigated for treatment by inhalation of microparticles were reviewed along with the drugs' pharmacological, pharmacokinetic and physical chemical properties to identify the advantages of microparticulate inhalation formulations and to identify areas for further improvement.

METHODS

Microbial infections of the lung, asthma, diabetes, lung transplantation and lung cancer were examined, with a focus on those systems intended to provide a sustained release.

CONCLUSION

In developing microparticulate formulations for inhalation in the lung, there is a need to understand the pharmacology of the drug as the key to revealing the optimal concentration time profile, the disease state, and the pharmacokinetic properties of the pure drug as determined by IV administration and inhalation. Finally, in vitro release studies will allow better identification of the best dosing strategy to be used in efficacy and safety studies.

Targeted delivery of magnetic aerosol droplets to the lung

The inhalation of medical aerosols is widely used for the treatment of lung disorders such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, respiratory infection and, more recently, lung cancer. Targeted aerosol delivery to the affected lung tissue may improve therapeutic efficiency and minimize unwanted side effects. Despite enormous progress in optimizing aerosol delivery to the lung, targeted aerosol delivery to specific lung regions other than the airways or the lung periphery has not been adequately achieved to date. Here, we show theoretically by computer-aided simulation, and for the first time experimentally in mice, that targeted aerosol delivery to the lung can be achieved with aerosol droplets comprising superparamagnetic iron oxide nanoparticles--so-called nanomagnetosols--in combination with a target-directed magnetic gradient field. We suggest that nanomagnetosols may be useful for treating localized lung disease, by targeting foci of bacterial infection or tumour nodules.

Novel tobramycin inhalation powder in cystic fibrosis subjects: pharmacokinetics and safety

Aerosolized antibiotics are associated with a high treatment burden that can result in non-adherence to chronic therapy. We evaluated the pharmacokinetics (PK) and safety of tobramycin inhalation powder (TIP), a novel dry-powder formulation designed to deliver a high payload of tobramycin topically to the lungs for management of chronic Pseudomonas aeruginosa infections. This was a multi-center, open-label, sequential-cohort, single-dose, dose-escalation study using the standard 300 mg dose of tobramycin solution for inhalation (TSI) as an active control. Subjects were randomized to TIP or TSI in a 3:1 ratio in each of five cohorts. Measurements included serum and sputum tobramycin concentrations, administration time, serum chemistries, acute change in lung function, and adverse events (AEs). Out of 90 randomized subjects, 86 had data for safety analysis; and 84 had data for PK analysis. Serum tobramycin PK profiles were similar for TIP and TSI. Four capsules of 28 mg TIP (total tobramycin dose 112 mg) produced comparable systemic exposure to 300 mg TSI, in less than one-third the administration time. The most common AEs associated with TIP were cough (20%) and dysgeusia (17%). TIP allows for faster and more efficient pulmonary delivery of tobramycin than TSI and has a safety profile that supports continued clinical investigation. The increased rate of local respiratory tract irritation noted with TIP is not unexpected with a high-payload powder formulation. The development of dry powder inhaled antibiotics may represent an important advance in the treatment of chronic lung infections.

Tobramycin solution for inhalation in cystic fibrosis patients: a review of the literature

Cystic fibrosis patients suffer increased sputum production and a notable decline in respiratory function throughout the progression of their disease. Patients are left vulnerable to respiratory colonization/infection from a number of pathogens, including Pseudomonas aeruginosa. At present, the only antibiotic formulation that is FDA approved for aerosolized delivery is tobramycin solution for inhalation (TSI). TSI allows for targeted antibiotic delivery to the lungs and is indicated for maintenance therapy in cystic fibrosis patients infected with P. aeruginosa. Studies demonstrate that cyclical treatment with TSI is associated with an increase in respiratory function and a decrease in sputum density in cystic fibrosis patients. Additional benefits include fewer hospitalizations and a decreased need for systemic antibiotics. However, because of the need for chronic administration, issues such as emergence of resistant organisms and toxicity are a potential concern and have also been evaluated. This review details the pharmacology of TSI and literature involving its use in cystic fibrosis patients.