Delivery Efficacy of a Vibrating Mesh Nebulizer and a Jet Nebulizer under Different Configurations

Nano-Formulations for Pulmonary Delivery: Past, Present, and Future Perspectives

With the development of nanotechnology and confronting the problems of traditional pharmaceutical formulations in treating lung diseases, inhalable nano-formulations have attracted interest. Inhalable nano-formulations for treating lung diseases allow for precise pulmonary drug delivery, overcoming physiological barriers, improving aerosol lung deposition rates, and increasing drug bioavailability. They are expected to solve the difficulties faced in treating lung diseases. However, limited success has been recorded in the industrialization translation of inhalable nano-formulations. Only one relevant product has been approved by the FDA to date, suggesting that there are still many issues to be resolved in the clinical application of inhalable nano-formulations. These systems are characterized by a dependence on inhalation devices, while the adaptability of device formulation is still inconclusive, which is the most important issue impeding translational research. In this review, we categorized various inhalable nano-formulations, summarized the advantages of inhalable nano-formulations over conventional inhalation formulations, and listed the inhalable nano-formulations undergoing clinical studies. We focused on the influence of inhalation devices on nano-formulations and analyzed their adaptability. After extensive analysis of the drug delivery mechanisms, technical processes, and limitations of different inhalation devices, we concluded that vibrating mesh nebulizers might be most suitable for delivering inhalable nano-formulations, and related examples were introduced to validate our view. Finally, we presented the challenges and outlook for future development. We anticipate providing an informative reference for the field.

Comparison of amikacin lung delivery between AKITA® and eFlow rapid® nebulizers in healthy controls and patients with CF: A randomized cross-over trial

INTRODUCTION

Nebulization plays a key role in the treatment of cystic fibrosis. The Favorite function couple to jet nebulizers (AKITA®) emerged recently. The aim of this study was to assess the efficiency of the lung delivery by the AKITA® by comparing the urinary concentration of amikacin after nebulization with the AKITA® and the eFlow rapid®, in healthy subjects and patients with CF (PwCF).

METHOD

The two samples (healthy subjects and PwCF) were randomized (cross-over 1:1) for two nebulizations (500 mg of amikacin diluted in 4 mL of normal saline solution), with the AKITA® and with the eFlow rapid®. The primary endpoint was the amount of urinary excretion of amikacin over 24 h. The constant of elimination (Ke) was calculated based on the maximal cumulative urinary amikacin excretion plotted over time.

RESULTS

The total amount of urinary amikacin excretion was greater when AKITA® was used in PwCF (11.7 mg (8.2-14.1) vs 6.1 mg (3.7-13.3); p = 0.02) but not different in healthy subjects (14.5 mg (11.7-18.5) vs 12.4 mg (8.0-17.1); p = 0.12). The duration of the nebulization was always shorter with eFlow rapid® than with AKITA® (PwCF: 6.5 ± 0.6 min vs 9.2 ± 1.8 min; p = 0.001 - Healthy: 4.7 ± 1.3 min vs 9.7 ± 1.6 min; p = 0.03). The constant of elimination was similar between the two modalities in CF subjects (0.153 (0.071-0.205) vs 0.149 (0.041-0.182); p = 0.26) and in healthy subjects (0.166 (0.130-0.218) vs 0.167 (0.119-0.210), p = 0.25).

CONCLUSION

the Favorite inhalation is better to deliver a specific amount of drug than a mesh nebulizer (eFlow rapid®) in PwCF but not in healthy subjects.

Predicting Inhaled Drug Dose Generated by Mesh Nebulizers

Background: The lung dose of nebulized drugs for spontaneous breathing is influenced by breathing patterns and nebulizer performance. This study aimed to develop a system for measuring breath patterns and a formula for estimating inhaled drugs, and then to validate the hypothesized prediction formula. Methods: An in vitro model was first used to determine correlations among the delivered dose, breath patterns, and doses deposited on the accessories and reservoirs testing with a breathing simulator to generate 12 adult breathing patterns (n = 5). A pressure sensor was developed to measure breathing parameters and used along with a prediction formula that accounted for the initial charge dose, respiratory pattern, and dose on the accessory and reservoir of a nebulizer. Three brands of nebulizers were tested by placing salbutamol (5.0 mg/2.5 mL) in the drug holding chamber. Ten healthy individuals participated in the ex vivo study to validate the prediction formula. The agreement between the predicted and inhaled doses was analyzed using the Bland-Altman plot. Results: The in vitro model showed that the inspiratory time to total respiratory cycle time (Ti/Ttotal; %) was significantly directly correlated with the delivered dose among the respiratory factors, followed by inspiratory flow, respiratory rate, and tidal volume. The ex vivo model showed that Ti/Ttotal was significantly directly correlated with the delivered dose among the respiratory factors, in addition to the nebulization time and accessory dose. The Bland-Altman plots for the ex vivo model showed similar results between the two methods. Large differences in inhaled dose measured at the mouth were observed among the subjects, ranging from 12.68% to 21.68%; however, the difference between the predicted dose and inhaled dose was lower, at 3.98%-5.02%. Conclusions: The inhaled drug dose could be predicted with the hypothesized estimation formula, which was validated by the agreement between the inhaled and predicted doses of breathing patterns of healthy individuals.

Low-dose intrapulmonary drug delivery device for studies on next-generation therapeutics in mice

Although nebulizers have been developed for delivery of small molecules in human patients, no tunable device has been purpose-built for targeted delivery of modern large molecule and temperature-sensitive therapeutics to mice. Mice are used most of all species in biomedical research and have the highest number of induced models for human-relevant diseases and transgene models. Regulatory approval of large molecule therapeutics, including antibody therapies and modified RNA highlight the need for quantifiable dose delivery in mice to model human delivery, proof-of-concept studies, efficacy, and dose-response. To this end, we developed and characterized a tunable nebulization system composed of an ultrasonic transducer equipped with a mesh nebulizer fitted with a silicone restrictor plate modification to control the nebulization rate. We have identified the elements of design that influence the most critical factors to targeted delivery to the deep lungs of BALB/c mice. By comparing an in silico model of the mouse lung with experimental data, we were able to optimize and confirm the targeted delivery of over 99% of the initial volume to the deep portions of the mouse lung. The resulting nebulizer system provides targeted lung delivery efficiency far exceeding conventional nebulizers preventing waste of expensive biologics and large molecules during proof-of-concept and pre-clinical experiments involving mice. (Word Count =207).

Optimization of formulation and atomization of lipid nanoparticles for the inhalation of mRNA

Lipid nanoparticles (LNPs) have demonstrated efficacy and safety for mRNA vaccine administration by intramuscular injection; however, the pulmonary delivery of mRNA encapsulated LNPs remains challenging. The atomization process of LNPs will cause shear stress due to dispersed air, air jets, ultrasonication, vibrating mesh etc., leading to the agglomeration or leakage of LNPs, which can be detrimental to transcellular transport and endosomal escape. In this study, the LNP formulation, atomization methods and buffer system were optimized to maintain the LNP stability and mRNA efficiency during the atomization process. Firstly, a suitable LNP formulation for atomization was optimized based on the in vitro results, and the optimized LNP formulation was AX4, DSPC, cholesterol and DMG-PEG_2K at a 35/16/46.5/2.5 (%) molar ratio. Subsequently, different atomization methods were compared to find the most suitable method to deliver mRNA-LNP solution. Soft mist inhaler (SMI) was found to be the best for pulmonary delivery of mRNA encapsulated LNPs. The physico-chemical properties such as size and entrapment efficiency (EE) of the LNPs were further improved by adjusting the buffer system with trehalose. Lastly, the in vivo fluorescence imaging of mice demonstrated that SMI with proper LNPs design and buffer system hold promise for inhaled mRNA-LNP therapies.

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.

In vitro delivery efficiencies of nebulizers for different breathing patterns

BACKGROUND

Nebulizers are medical devices that deliver aerosolized medication directly to lungs to treat a variety of respiratory diseases. However, breathing patterns, respiration rates, airway diameters, and amounts of drugs delivered by nebulizers may be respiratory disease dependent.

METHOD

In this study, we developed a respiratory simulator consisting of an airway model, an artificial lung, a flow sensor, and an aerosol collecting filter. Various breathing patterns were generated using a linear actuator and an air cylinder. We tested six home nebulizers (jet (2), static (2), and vibrating mesh nebulizers (2)). Nebulizers were evaluated under two conditions, that is, for the duration of nebulization and at a constant output 1.3 mL using four breathing patterns, namely, the breathing pattern specified in ISO 27427:2013, normal adult, asthmatic, and COPD.

RESULTS

One of the vibrating mesh nebulizers had the highest dose delivery efficiency. The drug delivery efficiencies of nebulizers were found to depend on breathing patterns.

CONCLUSION

We suggest a quantitative drug delivery efficiency evaluation method and calculation parameters that include considerations of constant outputs and residual volumes. The study shows output rates and breathing patterns should be considered when the drug delivery efficiencies of nebulizers are evaluated.

Active pulmonary targeting against tuberculosis (TB) via triple-encapsulation of Q203, bedaquiline and superparamagnetic iron oxides (SPIOs) in nanoparticle aggregates

Tuberculosis (TB) has gained attention over the past few decades by becoming one of the top ten leading causes of death worldwide. This infectious disease of the lungs is orally treated with a medicinal armamentarium. However, this route of administration passes through the body’s first-pass metabolism which reduces the drugs’ bioavailability and toxicates the liver and kidneys. Inhalation therapy represents an alternative to the oral route, but low deposition efficiencies of delivery devices such as nebulizers and dry powder inhalers render it challenging as a favorable therapy. It was hypothesized that by encapsulating two potent TB-agents, i.e. Q203 and bedaquiline, that inhibit the oxidative phosphorylation of the bacteria together with a magnetic targeting component, superparamagnetic iron oxides, into a poly (D, L-lactide-co-glycolide) (PDLG) carrier using a single emulsion technique, the treatment of TB can be a better therapeutic alternative. This simple fabrication method achieved a homogenous distribution of 500 nm particles with a magnetic saturation of 28 emu/g. Such particles were shown to be magnetically susceptible in an in-vitro assessment, viable against A549 epithelial cells, and were able to reduce two log bacteria counts of the Bacillus Calmette-Guerin (BCG) organism. Furthermore, through the use of an external magnet, our in-silico Computational Fluid Dynamics (CFD) simulations support the notion of yielding 100% deposition in the deep lungs. Our proposed inhalation therapy circumvents challenges related to oral and respiratory treatments and embodies a highly favorable new treatment regime.

Aerosolization Performance of Jet Nebulizers and Biopharmaceutical Aspects

In this work, 13 jet nebulizers, some of which in different configurations, were investigated in order to identify the biopharmaceutical constraints related to the quality attributes of the medicinal products, which affect their safety, efficiency, compliance, and effectiveness. The aerosolization parameters, including the aerosol output, aerosol output rate, mass median aerodynamic diameter, and fine particle fraction, were determined according to the European Standard EN 13544-1, using sodium fluoride as a reference formulation. A comparison between the aerosol output nebulization time and the fine particle fraction displayed a correlation between the aerosol quality and the nebulization rate. Indeed, the quality of the nebulization significantly increased when the rate of aerosol emission was reduced. Moreover, the performance of the nebulizers was analyzed in terms of respirable delivered dose and respirable dose delivery rate, which characterize nebulization as the rate and amount of respirable product that could be deposited into the lungs. Depending on which of these two latter parameters was used, the nebulizers showed different performances. The differences, in terms of the rate and amount of delivered aerosol, could provide relevant information for the appropriate choice of nebulizer as a function of drug product, therapy, and patient characteristics.

Devices for Improved Delivery of Nebulized Pharmaceutical Aerosols to the Lungs

Nebulizers have a number of advantages for the delivery of inhaled pharmaceutical aerosols, including the use of aqueous formulations and the ability to deliver process-sensitive proteins, peptides, and biological medications. A frequent disadvantage of nebulized aerosols is poor lung delivery efficiency, which wastes valuable medications, increases delivery times, and may increase side effects of the medication. A focus of previous development efforts and previous nebulizer reviews, has been an improvement of the underlying nebulization technology controlling the breakup of a liquid into droplets. However, for a given nebulization technology, a wide range of secondary devices and strategies can be implemented to significantly improve lung delivery efficiency of the aerosol. This review focuses on secondary devices and technologies that can be implemented to improve the lung delivery efficiency of nebulized aerosols and potentially target the region of drug delivery within the lungs. These secondary devices may (1) modify the aerosol size distribution, (2) synchronize aerosol delivery with inhalation, (3) reduce system depositional losses at connection points, (4) improve the patient interface, or (5) guide patient inhalation. The development of these devices and technologies is also discussed, which often includes the use of computational fluid dynamic simulations, three-dimensional printing and rapid prototype device and airway model construction, realistic in vitro experiments, and in vivo analysis. Of the devices reviewed, the implementation of streamlined components may be the most direct and lowest cost approach to enhance aerosol delivery efficiency within nonambulatory nebulizer systems. For applications involving high-dose medications or precise dose administration, the inclusion of active devices to control aerosol size, guide inhalation, and synchronize delivery with inhalation hold considerable promise.

Exploring the fate of inhaled monoclonal antibody in the lung parenchyma by microdialysis

Therapeutic antibodies (Abs) are emerging as major drugs to treat respiratory diseases, and inhalation may provide substantial benefits for their delivery. Understanding the behavior of Abs after pulmonary deposition is critical for their development. We investigated the pharmacokinetics of a nebulized Ab by continuous sampling in lung parenchyma using microdialysis in non-human primates. We defined the optimal conditions for microdialysis of Ab and demonstrated that lung microdialysis of Ab is feasible over a period of several days. The concentration-profile indicated a two-phase non-linear elimination and/or distribution of inhaled mAbX. Lung exposition was higher than the systemic one over a period of 33 hours and above MabX affinity for its target. The microdialysis results were supported by an excellent relationship with dosages from lung extracts.

Nebulization of Single-Chain Tissue-Type and Single-Chain Urokinase Plasminogen Activator for Treatment of Inhalational Smoke-Induced Acute Lung Injury

Single-chain tissue-type plasminogen activator (sctPA) and single-chain urokinase plasminogen activator (scuPA) have attracted interest as enzymes for the treatment of inhalational smoke-induced acute lung injury (ISALI). In this study, the pulmonary delivery of commercial human sctPA and lyophilized scuPA and their reconstituted solution forms were demonstrated using vibrating mesh nebulizers (Aeroneb® Pro (active) and EZ Breathe® (passive)). Both the Aeroneb® Pro and EZ Breathe® vibrating mesh nebulizers produced atomized droplets of protein solution of similar size of less than about 5 μm, which is appropriate for pulmonary delivery. Enzymatic activities of scuPA and of sctPA were determined after nebulization and both remained stable (88.0% and 93.9%). Additionally, the enzymatic activities of sctPA and tcuPA were not significantly affected by excipients, lyophilization or reconstitution conditions. The results of these studies support further development of inhaled formulations of fibrinolysins for delivery to the lungs following smoke-induced acute pulmonary injury.

Detectable Concentrations of Inhaled Tobramycin in Critically Ill Children Without Cystic Fibrosis: Should Routine Monitoring Be Recommended?

OBJECTIVES

To determine the percentage of detectable tobramycin troughs and acute kidney injury in critically ill children without cystic fibrosis on inhaled therapy.

DESIGN

Historic cohort.

SETTING

Academic hospital.

PATIENTS

Forty children less than 18 years receiving inhaled tobramycin across 6.5 years.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary objective was to determine the percentage of detectable tobramycin troughs greater than or equal to 0.5 µg/mL. Secondary objectives included a comparison of acute kidney injury in children with and without detectable troughs. Twenty-two (55%) had trough concentrations obtained. Ten of these (45.5%) had detectable concentrations, with a median of 0.85 µg/mL (interquartile range, 0.5-2.0). There was no statistical significance between the detectable and nondetectable groups in age, gender, and method of administration. However, patients in the detectable group tended to be younger than nondetectable group and more likely to have a tracheotomy. There was a clinically significant decrease in estimated glomerular filtration rate in the detectable trough group.

CONCLUSIONS

Detectable troughs were noted in almost half of patients with concentrations obtained. A clinically significant decrease in estimated glomerular filtration rate was noted in patients with detectable concentrations. Continued work should be directed to better understand outcomes and monitoring in children requiring inhaled tobramycin.

Inhaled colistin monotherapy for respiratory tract infections in adults without cystic fibrosis: a systematic review and meta-analysis

BACKGROUND

Inhaled colistin is becoming increasingly popular against respiratory tract infections caused by multidrug resistant (MDR) Gram-negative bacteria because it may overcome the problems associated with intravenous (IV) administration.

OBJECTIVE

To investigate the effectiveness and safety of inhaled colistin as monotherapy (without concomitant IV administration of colistin) in the treatment of respiratory tract infections caused by MDR or colistin-only susceptible Gram-negative bacteria.

METHODS

PubMed and Scopus databases were searched. A systematic review and meta-analysis were conducted.

RESULTS

Twelve studies (373 patients receiving inhaled colistin for respiratory tract infection) were included. Ten studies evaluated patients with pneumonia (including 8 studies with ventilator-associated pneumonia) and 2 studies evaluated patients with ventilator-associated tracheobronchitis. Patients with infections due to MDR Acinetobacter baumannii and Pseudomonas aeruginosa were mainly studied. Daily dose of inhaled colistin and treatment duration varied in the individual studies. The pooled all-cause mortality was 33.8% (95% CI 24.6% - 43.6%), clinical success was 70.4% (58.5% - 81.1%) and eradication of Gram-negative bacteria was shown in 71.3% (57.6% - 83.2%) of cases.

CONCLUSIONS

Inhaled colistin monotherapy may deserve further consideration as a mode for colistin administration for the treatment of respiratory tract infections caused by MDR A. baumannii and P. aeruginosa.

Development of a drug delivery system for efficient alveolar delivery of a neutralizing monoclonal antibody to treat pulmonary intoxication to ricin

The high toxicity of ricin and its ease of production have made it a major bioterrorism threat worldwide. There is however no efficient and approved treatment for poisoning by ricin inhalation, although there have been major improvements in diagnosis and therapeutic strategies. We describe the development of an anti-ricin neutralizing monoclonal antibody (IgG 43RCA-G1) and a device for its rapid and effective delivery into the lungs for an application in humans. The antibody is a full-length IgG and binds to the ricin A-chain subunit with a high affinity (KD=53pM). Local administration of the antibody into the respiratory tract of mice 6h after pulmonary ricin intoxication allowed the rescue of 100% of intoxicated animals. Specific operational constraints and aerosolization stresses, resulting in protein aggregation and loss of activity, were overcome by formulating the drug as a dry-powder that is solubilized extemporaneously in a stabilizing solution to be nebulized. Inhalation studies in mice showed that this formulation of IgG 43RCA-G1 did not induce pulmonary inflammation. A mesh nebulizer was customized to improve IgG 43RCA-G1 deposition into the alveolar region of human lungs, where ricin aerosol particles mostly accumulate. The drug delivery system also comprises a semi-automatic reconstitution system to facilitate its use and a specific holding chamber to maximize aerosol delivery deep into the lung. In vivo studies in monkeys showed that drug delivery with the device resulted in a high concentration of IgG 43RCA-G1 in the airways for at least 6h after local deposition, which is consistent with the therapeutic window and limited passage into the bloodstream.

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.

Influence of Tracheostomy on Lung Deposition in Spontaneously Breathing Patients

BACKGROUND

Nebulized drugs are frequently administrated through tracheostomy in clinical routine. So far, the amount of drug deposited into the lung in these patients remains unknown. The aim of our pharmacokinetic study was to compare lung delivery of amikacin in the same subjects in two settings: spontaneously breathing through a tracheostomy and through the mouth.

METHODS

Lung delivery was measured by amikacin urinary drug concentration in nine patients who were transitory tracheostomized for the need of a head and neck oncologic surgery. Patients performed two nebulization sessions: with a mouthpiece (MB) and through tracheostomy (TB) using a adapted jet nebulizer (Sidestream^®).

RESULTS AND CONCLUSION

Lung delivery was similar with the two conditions of nebulization (6.5 ± 2.5% vs. 6.3 ± 2.0% of the nominal mass of amikacin, respectively, for MB and TB; p = 0.95). Duration of nebulization was also comparable (19.7 ± 1.6 vs. 20.1 ± 1.8 min, respectively, for mouth and tracheostomy breathing; p = 0.307). The half-life and elimination rate constant were not different between the two settings. We conclude that nebulized therapy can be administered in spontaneously breathing tracheostomized adults patients, with a similar amount of drug delivered to the lung compared with spontaneously mouth breathing patients.

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.

In vitro comparison of five nebulizers during noninvasive ventilation: analysis of inhaled and lost doses

BACKGROUND

Few studies on performance comparison of nebulizer systems coupled with a single-limb circuit bilevel ventilator are available. Most of these data compared the aerosol drug delivery for only two different systems. Using an adult lung bench model of noninvasive ventilation, we compared inhaled and lost doses of three nebulizer systems coupled with a single-limb circuit bilevel ventilator, as well as the influence of the nebulizer position.

METHOD

Three vibrating mesh nebulizers (Aeroneb(®) Pro, Aeroneb(®) Solo, and NIVO(®)), one jet nebulizer (Sidestream(®)), and one ultrasonic nebulizer (Servo Ultra Nebulizer 145(®)) coupled with a bilevel ventilator were tested. They were charged with amikacin solution (500 mg/4 mL) and operated at two different positions: before and after the exhalation port (starting from the lung). The inhaled dose, the expiratory wasted dose, and the estimated lost dose were assessed by the residual gravimetric method.

RESULTS

The doses varied widely among the nebulizer types and position. When the nebulizer was positioned before the exhalation port, the vibrating mesh nebulizer delivered the highest inhaled dose (p<0.001), the jet nebulizer the highest expiratory wasted dose (p<0.001), and the ultrasonic device the highest total lost dose (p<0.001). When the nebulizer was positioned after the exhalation port, the vibrating mesh nebulizers delivered the highest inhaled (p<0.001) and expiratory wasted doses (p<0.001), and the ultrasonic device the highest total lost dose (p<0.001). The most efficient nebulizers were NIVO and Aeroneb Solo when placed before the exhalation port.

CONCLUSIONS

In a single-limb circuit bilevel ventilator, vibrating mesh nebulizers positioned between the exhalation port and lung model are more efficient for drug delivery compared with jet or ultrasonic nebulizers. In this position, the improved efficiency of vibrating mesh nebulizers was due to an increase in the inhaled dose and a reduction in the exhaled wasted dose compared with placement between the ventilator and the expiratory port. Because of the high total lost dose, the ultrasonic device should not be recommended. Nebulizer placement before the exhalation port increased the inhaled dose and decreased the expiratory wasted dose, except for the jet nebulizer.

Delivering antibiotics to the lungs of patients with ventilator-associated pneumonia: an update

Ventilator-associated pneumonia is a serious hospital-acquired infection, with 20-70% crude mortality and 10-40% estimated attributable mortality. Insufficient antibiotic concentrations at the infection site when these drugs are given intravenously may lead to poor outcomes, particularly when difficult-to-treat pathogens are responsible; for example, Pseudomonas aeruginosa, extended spectrum beta lactamase-producing Gram-negative bacilli, Acinetobacter spp. and/or methicillin-resistant Staphylococcus aureus. Direct drug delivery to the infection site via aerosolization combined with intravenous administration achieves concentrations exceeding MICs of the pathogens, even those with impaired susceptibility. Experimental and recent clinical results demonstrated our markedly improved ability to deliver aerosolized antibiotics to the lung with new-generation devices, for example, vibrating-mesh nebulizers. Convincing clinical data from a large randomized trial are still lacking to support the routine administration of aerosolized antibiotics to treat ventilator-associated pneumonia, even though some small-randomized trials' observations are encouraging.

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.

Establishing the optimal nebulization system for paclitaxel, docetaxel, cisplatin, carboplatin and gemcitabine: back to drawing the residual cup

BACKGROUND

Chemotherapy drugs have still the major disadvantage of non-specific cytotoxic effects. Although, new drugs targeting the genome of the tumor are already in the market, doublet chemotherapy regimens still remain the cornerstone of lung cancer treatment. Novel modalities of administration are under investigation such as; aerosol, intratumoral and intravascular.

MATERIALS AND METHODS

In the present study five chemotherapy drugs; paclitaxel, docetaxel, gemcitabine, carboplatin and cisplatin were nebulized with three different jet nebulizers (Maxineb(®), Sunmist(®), Invacare(®)) and six different residual cups at different concentrations. The purpose of the study was to identify the "ideal" combination of nebulizer-residual cup design-drug-drug loading for a future concept of aerosol chemotherapy in lung cancer patients. The Mastersizer(®) 2000 was used to evaluate the aerosol droplet mass median aerodynamic diameter.

RESULTS

The drug, nebulizer and residual cup design greatly influences the producing droplet size (p<0.005, in each case). However; the design of the residual cup is the most important factor affecting the produced droplet size (F=834.6, p<0.001). The drug loading plays a vital role in the production of the desired droplet size (F=10.42, p<0.001). The smallest droplet size was produced at 8 ml loading (1.26 μm), while it remained the same at 2, 4 and 6 mls of drug loading.

CONCLUSION

The ideal nebulizer would be Maxineb(®), with a large residual cup (10 ml maximum loading capacity) and 8 mls loading and the drug with efficient pulmonary deposition would be docetaxel.

Aerosol delivery to the lung is more efficient using an extension with a standard jet nebulizer than an open-vent jet nebulizer

BACKGROUND

Open-vent jet nebulizers are frequently used to promote drug deposition in the lung, but their clinical efficacy and indications are not clear. Our study compared lung deposition of amikacin using two different configurations of a jet nebulizer (Sidestream(®)): one vented (N1) and one unvented with a corrugated piece of tubing (N2).

METHODS

In vitro nebulizer performance was assessed by laser diffraction and filtering. Lung delivery was evaluated by scintigraphy in baboons as a child model, and by amikacin urinary drug concentration in seven healthy spontaneously breathing volunteers. Subjects were randomly assigned to the two nebulizer systems (N1 and N2).

RESULTS AND CONCLUSIONS

In vitro results showed a higher efficiency of N2 than N1 in terms of lung deposition prediction (95±3 mg vs. 70±0 mg; p<0.0001). Radioactivity deposition in the baboons' lungs was lower with N1 than with N2 (1.8% vs. 4.7% of nebulizer charge; p<0.05). The total daily amount of amikacin urinary excretion was lower with N1 than with N2 (29.5 mg vs. 40.1 mg; p<0.01). Conversely, in vivo drug output rate was higher with N1 than with N2 (3.1 mg/min vs. 2.2 mg/min; p<0.05). Using a corrugated piece of tubing with standard jet nebulizers delivers higher doses to the lungs than open-vent jet nebulizers. The open-vent jet nebulizer might be recommended for rapid administration of a lower dose to the lungs and the standard jet nebulizer with corrugated piece of tubing for a higher dose in the lungs.

Production of Inhalable Submicrometer Aerosols from Conventional Mesh Nebulizers for Improved Respiratory Drug Delivery

Submicrometer and nanoparticle aerosols may significantly improve the delivery efficiency, dissolution characteristics, and bioavailability of inhaled pharmaceuticals. The objective of this study was to explore the formation of submicrometer and nanometer aerosols from mesh nebulizers suitable for respiratory drug delivery using experiments and computational fluid dynamics (CFD) modeling. Mesh nebulizers were coupled with add-on devices to promote aerosol drying and the formation of submicrometer particles, as well as to control the inhaled aerosol temperature and relative humidity. Cascade impaction experiments were used to determine the initial mass median aerodynamic diameters of 0.1% albuterol aerosols produced by the AeroNeb commercial (4.69 μm) and lab (3.90 μm) nebulizers and to validate the CFD model in terms of droplet evaporation. Through an appropriate selection of flow rates, nebulizers, and model drug concentrations, submicrometer and nanometer aerosols could be formed with the three devices considered. Based on CFD simulations, a wire heated design was shown to overheat the airstream producing unsafe conditions for inhalation if the aerosol was not uniformly distributed in the tube cross-section or if the nebulizer stopped producing droplets. In comparison, a counter-flow heated design provided sufficient thermal energy to produce submicrometer particles, but also automatically limited the maximum aerosol outlet temperature based on the physics of heat transfer. With the counter-flow design, submicrometer aerosols were produced at flow rates of 5, 15, and 30 LPM, which may be suitable for various forms of oral and nasal aerosol delivery. Thermodynamic conditions of the aerosol stream exiting the counter-flow design were found be in a range of 21-45 °C with relative humidity greater than 40% in some cases, which was considered safe for direct inhalation and advantageous for condensational growth delivery.

Inhalation therapy in patients receiving mechanical ventilation: an update

Incremental gains in understanding the influence of various factors on aerosol delivery in concert with technological advancements over the past 2 decades have fueled an ever burgeoning literature on aerosol therapy during mechanical ventilation. In-line use of pressurized metered-dose inhalers (pMDIs) and nebulizers is influenced by a host of factors, some of which are unique to ventilator-supported patients. This article reviews the impact of various factors on aerosol delivery with pMDIs and nebulizers, and elucidates the correlation between in-vitro estimates and in-vivo measurement of aerosol deposition in the lung. Aerosolized bronchodilator therapy with pMDIs and nebulizers is commonly employed in intensive care units (ICUs), and bronchodilators are among the most frequently used therapies in mechanically ventilated patients. The use of inhaled bronchodilators is not restricted to mechanically ventilated patients with chronic obstructive pulmonary disease (COPD) and asthma, as they are routinely employed in other ventilator-dependent patients without confirmed airflow obstruction. The efficacy and safety of bronchodilator therapy has generated a great deal of interest in employing other inhaled therapies, such as surfactant, antibiotics, prostacyclins, diuretics, anticoagulants and mucoactive agents, among others, in attempts to improve outcomes in critically ill ICU patients receiving mechanical ventilation.

Aerosol delivery through tracheostomy tubes: an in vitro study

BACKGROUND

Our study investigated the influence of the cannula's inner diameter (ID) and of its removal on the expected respiratory dose of amikacin, using three different jet nebulizer configurations (Sidestream(®)): vented (N1), unvented with a piece of corrugated tubing attached to the expiratory limb of the T attachment (N2), and unvented alone (N3).

METHODS

The jet nebulizer was filled with amikacin (500 mg/4 mL) and was attached to the tracheostomy tube. A lung model simulating spontaneous breathing was connected to the tracheostomy tube. A filter was connected between the nebulizer and the tracheostomy tube to measure the inhaled dose, and between the tracheostomy tube and the lung model to measure the respiratory dose. Different cannula IDs were tested (6.5, 8, 8.5, and 10 mm), and aerosol lost in the cannulas was determined.

RESULTS AND CONCLUSIONS

Respiratory dose varied between 96±1 mg and 44±3 mg, with higher values observed with N2. The aerosol lost in the cannula was significant and represented up to 63% of the inhaled dose. There was a negative correlation between the cannula's ID and the aerosol lost in the cannula. After removal of the internal cannula, an increase in the respiratory dose of up to 31.3% was observed. We recommend removing the inner tracheostomy cannula to nebulize a larger amount of drug through a tracheostomy tube. Among the three jet nebulizer configurations studied, we recommend the unvented one with a piece of corrugated tubing attached to the expiratory limb of the T attachment.