Rapid pulmonary delivery of inhaled tobramycin for Pseudomonas infection in cystic fibrosis: a pilot project

Efficacy and Safety of Dry Powder Antibiotics: A Narrative Review

The use of inhaled antibiotics was initially almost exclusively confined to patients with cystic fibrosis (CF). However, it has been extended in recent decades to patients with non-CF bronchiectasis or chronic obstructive pulmonary disease who present with chronic bronchial infection by potentially pathogenic microorganisms. Inhaled antibiotics reach high concentrations in the area of infection, which enhances their effect and enables their long-term administration to defeat the most resistant infections, while minimizing possible adverse effects. New formulations of inhaled dry powder antibiotics have been developed, providing, among other advantages, faster preparation and administration of the drug, as well as avoiding the requirement to clean nebulization equipment. In this review, we analyze the advantages and disadvantages of the different types of devices that allow the inhalation of antibiotics, especially dry powder inhalers. We describe their general characteristics, the different inhalers on the market and the proper way to use them. We analyze the factors that influence the way in which the dry powder drug reaches the lower airways, as well as aspects of microbiological effectiveness and risks of resistance development. We review the scientific evidence on the use of colistin and tobramycin with this type of device, both in patients with CF and with non-CF bronchiectasis. Finally, we discuss the literature on the development of new dry powder antibiotics.

Nuclear medicine imaging methods as novel tools in the assessment of pulmonary drug disposition

INTRODUCTION

Drugs for the treatment of respiratory diseases are commonly administered by oral inhalation. Yet surprisingly little is known about the pulmonary pharmacokinetics of inhaled molecules. Nuclear medicine imaging techniques (i.e. planar gamma scintigraphy, single-photon emission computed tomography [SPECT] and positron emission tomography [PET]) enable the noninvasive dynamic measurement of the lung concentrations of radiolabeled drugs or drug formulations. This review discusses the potential of nuclear medicine imaging techniques in inhalation biopharmaceutical research.

AREAS COVERED

(i) Planar gamma scintigraphy studies with radiolabeled inhalation formulations to assess initial pulmonary drug deposition; (ii) imaging studies with radiolabeled drugs to assess their intrapulmonary pharmacokinetics; (iii) receptor occupancy studies to quantify the pharmacodynamic effect of inhaled drugs.

EXPERT OPINION

Imaging techniques hold potential to bridge the knowledge gap between animal models and humans with respect to the pulmonary disposition of inhaled drugs. However, beyond the mere assessment of the initial lung deposition of inhaled formulations with planar gamma scintigraphy, imaging techniques have rarely been employed in pulmonary drug development. This may be related to several technical challenges encountered with such studies. Considering the wealth of information that can be obtained with imaging studies their use in inhalation biopharmaceutics should be further investigated.

Indian Guidelines on Nebulization Therapy

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

Status of inhalable antimicrobial agents for lung infection: progress and prospects

Introduction: Available parenteral and oral administration of antimicrobial agents (AMAs) in respiratory infections often show less penetration into the lung parenchyma. Due to inappropriate dose availability, the rate of antibiotic resistance is increasing gradually. Inhaled antibiotics intensely improve the availability of drugs at the site of respiratory infections. This targeted delivery minimizes systemic exposure and associated toxicity.Area covers: This review was performed by searching in the scientific database like PubMed and several trusted government sites like fda.gov, cdc.gov, ClinicalTrials.gov, etc. For better understanding, AMAs are classified in different stages of approval. Mechanism and characterization of pulmonary drug deposition section helps to understand the effective delivery of AMAs to the respiratory tract. There is a need for proper adoption of delivery devices for inhalable AMAs. Thus, delivery devices are extensively explained. Inspiratory flow has a remarkable impact on the delivery device that has been explained in detail.Expert opinion: Pulmonary delivery restricts the bulk administration of drugs in comparison with other routes. Therefore, novel AMAs with higher bactericidal activity at lower concentrations need to be synthesized. Extensive research is indeed in developing innovative delivery devices that would able to deliver higher doses of AMAs through the pulmonary route.

Challenges and opportunities for antiviral monoclonal antibodies as COVID-19 therapy

To address the COVID-19 pandemic, there has been an unprecedented global effort to advance potent neutralizing mAbs against SARS-CoV-2 as therapeutics. However, historical efforts to advance antiviral monoclonal antibodies (mAbs) for the treatment of other respiratory infections have been met with categorical failures in the clinic. By investigating the mechanism by which SARS-CoV-2 and similar viruses spread within the lung, along with available biodistribution data for systemically injected mAb, we highlight the challenges faced by current antiviral mAbs for COVID-19. We summarize some of the leading mAbs currently in development, and present the evidence supporting inhaled delivery of antiviral mAb as an early intervention against COVID-19 that could prevent important pulmonary morbidities associated with the infection.

Pharmacokinetics and pharmacodynamics of high doses of inhaled dry powder drugs

For many years, administration of drugs by inhalation has been the mainstay treatment for obstructive respiratory disorders such as asthma and chronic obstructive pulmonary disease. Antibiotics and other drugs have been administered for decades as aerosols to treat other pulmonary disease in a clinical setting, but it was until the early 1980's that colistin was formally marketed as a solution for nebulization in Europe (Colomycin, Pharmax, Bexley). The solubility of other drugs and the size of the dose required to achieve therapeutic concentrations at the site of action, made treatment times long and difficult to be performed at home. High dose dry powder delivery is a potentially effective way to deliver low potency drugs such as antibiotics. There are three major barriers to achieving the desired pharmacodynamic effect with these compounds: aerosol delivery, lung deposition and clearance. The powder formulation and device technology influence aerosol generation and may influence the size of the dose that can be achieved by inhalation in one puff. The site of deposition in the lungs is dictated by mechanisms of deposition which are influenced by the aerosol properties, particularly aerodynamic particle size distribution and the anatomy and physiology of the lungs. Finally, mechanisms of clearance dictate the local and systemic disposition of the drug, which in turn affects its pharmacokinetics and ultimately the pharmacodynamic effect and efficacy of treatment. Each of these factors will be considered and the implications for antimicrobial agent delivery as a high dose delivery example will be given.

Mesh nebulizers have become the first choice for new nebulized pharmaceutical drug developments

In the 24 years since first being marketed, the mesh nebulizer has been developed by five main manufacturers into a viable solution for the delivery of high-value nebulized drugs. Mesh nebulizers provide increased portability, convenience and energy efficiency along with similar lung deposition and increased ease of use compared with jet nebulizers. An analysis of EU and US clinical trial databases has shown that mesh nebulizers are now preferred over jet nebulizers for clinical trials sponsored by pharmaceutical companies. The results show a strong preference for the use of mesh nebulizers in trials involving high cost and niche therapy areas. Built-in capability to optimize the way patients use their mesh nebulizer and manage their disease will further increase uptake.

[Formula: see text]

Aerosol delivery during invasive mechanical ventilation: a systematic review

BACKGROUND

This systematic review aimed to assess inhaled drug delivery in mechanically ventilated patients or in animal models. Whole lung and regional deposition and the impact of the ventilator circuit, the artificial airways and the administration technique for aerosol delivery were analyzed.

METHODS

In vivo studies assessing lung deposition during invasive mechanical ventilation were selected based on a systematic search among four databases. Two investigators independently assessed the eligibility and the risk of bias.

RESULTS

Twenty-six clinical and ten experimental studies were included. Between 30% and 43% of nominal drug dose was lost to the circuit in ventilated patients. Whole lung deposition of up to 16% and 38% of nominal dose (proportion of drug charged in the device) were reported with nebulizers and metered-dose inhalers, respectively. A penetration index inferior to 1 observed in scintigraphic studies indicated major proximal deposition. However, substantial concentrations of antibiotics were measured in the epithelial lining fluid (887 (406-12,819) μg/mL of amikacin) of infected patients and in sub-pleural specimens (e.g., 197 μg/g of amikacin) dissected from infected piglets, suggesting a significant distal deposition. The administration technique varied among studies and may explain a degree of the variability of deposition that was observed.

CONCLUSIONS

Lung deposition was lower than 20% of nominal dose delivered with nebulizers and mostly occurred in proximal airways. Further studies are needed to link substantial concentrations of antibiotics in infected pulmonary fluids to pulmonary deposition. The administration technique with nebulizers should be improved in ventilated patients in order to ensure an efficient but safe, feasible and reproducible technique.

Aerosol Delivery with Two Nebulizers Through High-Flow Nasal Cannula: A Randomized Cross-Over Single-Photon Emission Computed Tomography-Computed Tomography Study

BACKGROUND

High-flow nasal cannula use is developing in ICUs. The aim of this study was to compare aerosol efficiency by using two nebulizers through a high-flow nasal cannula: the most commonly used jet nebulizer (JN) and a more efficient vibrating-mesh nebulizer (VN).

METHODS

Aerosol delivery of diethylenetriaminepentaacetic acid labeled with technetium-99m (4 mCi/4 mL) to the lungs by using a VN (Aerogen Solo^®; Aerogen Ltd., Galway, Ireland) and a constant-output JN (Opti-Mist Plus Nebulizer^®; ConvaTec, Bridgewater, NJ) through a high-flow nasal cannula (Optiflow^®; Fisher & Paykel, New Zealand) was compared in six healthy subjects. Flow rate was set at 30 L/min through the heated humidified circuit. Pulmonary and extrapulmonary deposition was measured by single-photon emission computed tomography combined with a low-dose computed tomographic scan and by planar scintigraphy.

RESULTS

Lung deposition was only 3.6 (2.1-4.4) and 1 (0.7-2)% of the nominal dose with the VN and the JN, respectively (p < 0.05). The JN showed higher retained doses than the VN. However, both nebulizers were associated with substantial deposition in the single limb circuit, the humidification chamber, and the nasal cannula [58.2 (51.6-61.6)% of the nominal dose with the VN versus 19.2 (15.8-22.9)% of the nominal dose with the JN, p < 0.05] and in the upper respiratory tract [17.6 (13.4-27.9)% of the nominal dose with the VN and 8.6 (6.0-11.0)% of the nominal dose with the JN, p < 0.05], especially in the nasal cavity.

CONCLUSIONS

In the specific conditions of the study, pulmonary drug delivery through the high-flow nasal cannula is about 1%-4% of the initial amount of drugs placed in the nebulizer, despite the higher efficiency of the VN as compared with the JN.

SPECT-CT Comparison of Lung Deposition using a System combining a Vibrating-mesh Nebulizer with a Valved Holding Chamber and a Conventional Jet Nebulizer: a Randomized Cross-over Study

PURPOSE

To compare in vivo the total and regional pulmonary deposition of aerosol particles generated by a new system combining a vibrating-mesh nebulizer with a specific valved holding chamber and constant-output jet nebulizer connected to a corrugated tube.

METHODS

Cross-over study comparing aerosol delivery to the lungs using two nebulizers in 6 healthy male subjects: a vibrating-mesh nebulizer combined with a valved holding chamber (Aerogen Ultra®, Aerogen Ltd., Galway, Ireland) and a jet nebulizer connected to a corrugated tube (Opti-Mist Plus Nebulizer®, ConvaTec, Bridgewater, NJ). Nebulizers were filled with diethylenetriaminepentaacetic acid labelled with technetium-99 m (^99mTc-DTPA, 2 mCi/4 mL). Pulmonary deposition of ^99mTc-DTPA was measured by single-photon emission computed tomography combined with a low dose CT-scan (SPECT-CT).

RESULTS

Pulmonary aerosol deposition from SPECT-CT analysis was six times increased with the vibrating-mesh nebulizer as compared to the jet nebulizer (34.1 ± 6.0% versus 5.2 ± 1.1%, p < 0.001). However, aerosol penetration expressed as the three-dimensional normalized ratio of the outer and the inner regions of the lungs was similar between both nebulizers.

CONCLUSIONS

This study demonstrated the high superiority of the new system combining a vibrating-mesh nebulizer with a valved holding chamber to deliver nebulized particles into the lungs as comparted to a constant-output jet nebulizer with a corrugated tube.

Protein stability in pulmonary drug delivery via nebulization

Protein inhalation is a delivery route which offers high potential for direct local lung application of proteins. Liquid formulations are usually available in early stages of biopharmaceutical development and nebulizers are the device of choice for atomization avoiding additional process steps like drying and enabling fast progression to clinical trials. While some proteins were proven to remain stable throughout aerosolization e.g. DNase, many biopharmaceuticals are more susceptible towards the stresses encountered during nebulization. The main reason for protein instability is unfolding and aggregation at the air-liquid interface, a problem which is of particular challenge in the case of ultrasound and jet nebulizers due to recirculation of much of the generated droplets. Surfactants are an important formulation component to protect the sensitive biomolecules. A second important challenge is warming of ultrasound and vibrating mesh devices, which can be overcome by overfilling, precooled solutions or cooling of the reservoir. Ultimately, formulation development has to go hand in hand with device evaluation.

Faraday instability-based micro droplet ejection for inhalation drug delivery

We report here the technology and the underlying science of a new device for inhalation (pulmonary) drug delivery which is capable of fulfilling needs unmet by current commercial devices. The core of the new device is a centimeter-size clog-free silicon-based ultrasonic nozzle with multiple Fourier horns in resonance at megahertz (MHz) frequency. The dramatic resonance effect among the multiple horns and high growth rate of the MHz Faraday waves excited on a medicinal liquid layer together facilitate ejection of monodisperse droplets of desirable size range (2-5 µm) at low electrical drive power (<1.0 W). The small nozzle requiring low drive power has enabled realization of a pocket-size (8.6 × 5.6 × 1.5 cm³) ultrasonic nebulizer. A variety of common pulmonary drugs have been nebulized using the pocket-size unit with desirable aerosol sizes and output rate. These results clearly provide proof-of-principle for the new device and confirm its potential for commercialization.

Modeling breath-enhanced jet nebulizers to estimate pulmonary drug deposition

BACKGROUND

Predictable delivery of aerosol medication for a given patient and drug-device combination is crucial, both for therapeutic effect and to avoid toxicity. The gold standard for measuring pulmonary drug deposition (PDD) is gamma scintigraphy. However, these techniques expose patients to radiation, are complicated, and are relevant for only one patient and drug-device combination, making them less available. Alternatively, in vitro experiments have been used as a surrogate to estimate in vivo performance, but this is time-consuming and has few "in vitro to in vivo" correlations for therapeutics delivered by inhalation. An alternative method for determining inhaled mass and PDD is proposed by deriving and validating a mathematical model, for the individual breathing patterns of normal subjects and drug-device operating parameters. This model was evaluated for patients with cystic fibrosis (CF).

METHODS

This study is comprised of three stages: mathematical model derivation, in vitro testing, and in vivo validation. The model was derived from an idealized patient's respiration cycle and the steady-state operating characteristics of a drug-device combination. The model was tested under in vitro dynamic conditions that varied tidal volume, inspiration-to-expiration time, and breaths per minute. This approach was then extended to incorporate additional physiological parameters (dead space, aerodynamic particle size distribution) and validated against in vivo nuclear medicine data in predicting PDD in both normal subjects and those with CF.

RESULTS

The model shows strong agreement with in vitro testing. In vivo testing with normal subjects yielded good agreement, but less agreement for patients with chronic obstructive lung disease and bronchiectasis from CF.

CONCLUSIONS

The mathematical model was successful in accommodating a wide range of breathing patterns and drug-device combinations. Furthermore, the model has demonstrated its effectiveness in predicting the amount of aerosol delivered to "normal" subjects. However, challenges remain in predicting deposition in obstructive lung disease.

Lung imaging - two dimensional gamma scintigraphy, SPECT, CT and PET

This review will cover the principles of imaging the deposition of inhaled drugs and some of the state-of-the art imaging techniques being used today. Aerosol deposition can be imaged and quantified by the addition of a radiolabel to the aerosol formulation. The subsequent imaging of the inhaled deposition pattern can be acquired by different imaging techniques. Specifically, this review will focus on the use of two-dimensional planar, gamma scintigraphy, SPECT, CT and PET. This review will look at how these imaging techniques are used to investigate the mechanisms of drug delivery in the lung and how the lung anatomy and physiology have the potential to alter therapeutic outcomes.

Technological and behavioral strategies to reduce treatment burden and improve adherence to inhaled antibiotics in cystic fibrosis

Aerosolized antibiotics are a common treatment option for patients with cystic fibrosis and chronic airway infection, as high doses can be delivered topically to the site of the infection while systemic exposure is minimized. Patients also use other aerosolized therapies (e.g. mucus-active agents, airway-wetting agents, and bronchodilators), adding significantly increase timed and complexity to their daily regimen, and often leading to lower adherence rates. A number of novel technological strategies are available that may reduce dose frequency and increase the speed of drug delivery. Psychologically based therapies may also be used to help modify behavior and thus improve adherence to treatment. Clinicians need to explore both technological and psychological strategies that will assist in the successful maintenance of treatment requirements.

Higher tobramycin concentration and vibrating mesh technology can shorten antibiotic treatment time in cystic fibrosis

Poor adherence to recommended therapy in cystic fibrosis (CF) is often because of the time demands of therapy. Tobramycin (TOBI®, 300 mg at 60 mg/ml) inhaled from the PARI LC PLUS® nebulizer requires about 20 min. This study determined if equivalent levels of pulmonary deposition could be achieved in shorter time using 1.5 ml of 100 mg/ml tobramycin solution delivered by an investigational eFlow® nebulizer. Sixteen males with stable CF, 8 children and 8 adults, and an FEV(1)  > 45% predicted inhaled both preparations on two occasions with (99m) Tc-DTPA added to the tobramycin. Blood samples were taken for quantification of tobramycin in the serum. The PARI LC PLUS® delivered 45.4 (39.3-51.6), mean and 95% CI, mg to the lungs in 17.0 ± 2.5 min (mean ± SD) with serum levels of 1,089 ± 388 µg/L. The investigational eFlow® delivered 46.3(40.3-51.7) mg in 4.0 ± 1.0 min with blood levels of 909 ± 458 µg/L. Only the time of delivery was significantly different with P < 0.0001 (paired t-test). Tolerability of the treatment was comparable for both inhalation regimes, but the shorter treatment was preferred by all patients. These results demonstrate the possibility of delivering equivalent levels of tobramycin much faster into the lungs of CF patients when using eFlow®, a very efficient electronic nebulizer.

Have inadequate delivery systems hampered the clinical success of inhaled disodium cromoglycate? Time for reconsideration

IMPORTANCE OF THE FIELD

Disodium cromoglycate (DSCG) fits with the perception of a safe drug, but conclusions from questionable meta-analyses reduced its use. In addition, drug delivery aspects, such as hygroscopicity and the poor performance of delivery systems, were not considered to be important determinants of therapeutic failures.

AREAS COVERED IN THIS REVIEW

Drug delivery aspects and parameters affecting lung deposition and distribution, important parameters for therapeutic efficacy, are addressed. In addition, the distribution and ratio of mast cell tryptase and chymase-positive phenotypes in the lungs and their role in the prostaglandin and leukotriene pathway are discussed.

WHAT THE READER WILL GAIN

Information on why in vitro data are an excellent tool to understand better therapeutic failures associated with the moisture sensitivity of DSCG and the difficulty in handling and operating DSCG delivery systems in a therapeutically reliable way.

TAKE HOME MESSAGE

Pharmacological efficacy of DSCG has been demonstrated in animals and humans. If the drug is delivered to the site of inflammation in an effective dose, a reliable therapeutic effect can be expected. DSCG has extra properties and potential unspecific antiviral properties and may offer new therapeutic treatment aspects for asthma and viral-induced bronchiolitis in early childhood.

A comparison of amount and speed of deposition between the PARI LC STAR® jet nebulizer and an investigational eFlow® nebulizer

BACKGROUND

The potency and physical properties of many of the drugs used in the treatment of cystic fibrosis necessitates the use of nebulization, a relatively time-consuming pulmonary delivery method. Newer, faster, and more efficient delivery systems are being proposed. The purposes of this study was to compare the length of time it took to deliver the equivalent of normal saline nebulized for 10 min in a PARI LC STAR(®) nebulizer to that of an investigational PARI eFlow(®).

METHODS

Six normal adults inhaled a 4-mL (36-mg) charge volume of saline from the LC STAR(®) or a 2.5-mL (22.5-mg) charge volume from the investigational eFlow(®). The saline was mixed with (99m)Tc-DTPA to allow two-dimensional imaging. The inhalation was preceded by a xenon equilibration scan to allow more accurate separation of deposition into central and peripheral lung regions.

RESULTS

The investigational eFlow(®) delivered 8.6 ± 1.0 mg, approximately 90% of the lung dose compared to the LC STAR(®), 9.6 ± 1.0 mg, but did in less than half the time (p < 0.02 for both). There were no differences in central versus peripheral distribution for either device.

CONCLUSIONS

In conclusion the investigational eFlow(®) was both faster and more efficient than the LC STAR(®).

New antimicrobial strategies in cystic fibrosis

With more antibiotic resistance and emerging pathogens in cystic fibrosis (CF) patients, the need for new strategies in the lifelong treatment of pulmonary infection has increased. Most of the focus is on chronic infection with Pseudomonas aeruginosa, which is still thought to be the main pathogen leading to advanced CF lung disease. Other bacterial species are also recognized in the pathogenesis of CF lung disease, even though their definitive role is not well established yet. Clearly, expansion of treatment options is urgently needed. This article focuses on recent developments in the field of new antimicrobial strategies for CF. It is clear that studies on new classes of antibiotics or antimicrobial-like drugs are scarce, and that most studies involve new (inhalation) formulations, new routes of delivery, or analogs of existing classes of antibiotics. Studies of new antibiotic-like drugs are, in most cases, in preclinical phases of development and only a few of these agents may reach the market. Importantly, new inhaled antibiotics, e.g. aztreonam, levofloxacin, and fosfomycin, and new, more efficient delivery systems such as dry powder inhalation and liposomes for current antibiotics are in the clinical phase of development. These developments will be of great importance in improving effective treatment and reducing the treatment burden for CF patients in the near future.

Sputum induction in routine clinical care of children with cystic fibrosis

OBJECTIVE

To determine the microbiological yield of induced sputum (IS) samples compared with conventional airway samples, spontaneously expectorated sputum and throat swabs, in children with cystic fibrosis (CF) attending an outpatient clinic.

STUDY DESIGN

Ninety-five children with CF (75 able to spontaneously expectorate sputum) were included in this prospective cross-sectional comparative study. After obtaining expectorated sputum or throat swabs samples, IS was obtained by performing the sputum induction procedure using an eFlow device (PARI, Starnberg, Germany). CF bacterial culture results were compared between the two procedures.

RESULTS

Differences in culture results between samples were observed in 25 of 94 (27%) patients. IS had a significantly higher yield for CF pathogens, with 80% of the differences being due to detection of additional organisms in IS samples. Overall, SI was well tolerated, but 12 of 95 cases had a >20% postinduction decline in forced expiratory volume in 1 second. The whole SI procedure took 30 to 85 minutes of clinic time, and its estimated additional cost was $150 (US)/patient.

CONCLUSIONS

Induced sputum has a higher microbiological yield compared with the conventional samples in children with CF, even in patients capable of expectorating sputum spontaneously. Although sputum induction is safe and tolerable, it is time-consuming and expensive in routine clinical settings.

Miniaturized multiple Fourier-horn ultrasonic droplet generators for biomedical applications

Here we report micro-electro-mechanical system (MEMS)-based miniaturized silicon ultrasonic droplet generators of a new and simple nozzle architecture with multiple Fourier horns in resonance but without a central channel. The centimetre-sized nozzles operate at one to two MHz and a single vibration mode which readily facilitates temporal instability of Faraday waves to produce monodisperse droplets. Droplets with diameter range 2.2-4.6 μm are produced at high throughput of 420 μl min(-1) and very low electrical drive power of 80 mW. We also report the first theoretical prediction of the droplet diameter. The resulting MHz ultrasonic devices possess important advantages and demonstrate superior performance over earlier devices with a central channel and thus have high potential for biomedical applications such as efficient and effective delivery of inhaled medications and encapsulated therapy to the lung.