Factors affecting aerosol performance during nebulization with jet and ultrasonic nebulizers

Development and Characterization of Novel Combinations and Compositions of Nanostructured Lipid Carrier Formulations Loaded with Trans-Resveratrol for Pulmonary Drug Delivery

BACKGROUND/OBJECTIVES

This study aimed to fabricate, optimize, and characterize nanostructured lipid carriers (NLCs) loaded with trans-resveratrol (TRES) as an anti-cancer drug for pulmonary drug delivery using medical nebulizers.

METHODS

Novel TRES-NLC formulations (F1-F24) were prepared via hot, high-pressure homogenization. One solid lipid (Dynasan 116) was combined with four liquid lipids (Capryol 90, Lauroglycol 90, Miglyol 810, and Tributyrin) in three different ratios (10:90, 50:50, and 90:10 w/w), with a surfactant (Tween 80) in two different concentrations (0.5 and 1.5%), and a co-surfactant, soya phosphatidylcholine (SPC S-75; 50 mg).

RESULTS

Amongst the analyzed 24 TR-NLC formulations, F8, F14, and F22 were selected based on their physicochemical stability when freshly prepared and following storage (4 weeks 25 °C), as well as in terms of particle size (<145 nm), polydispersity index (PDI; <0.21) and entrapment efficiency (>96%). Furthermore, F14 showed greater stability at 4 and 25 °C for six months and exhibited enhanced aerosolization performance, demonstrating the greater deposition of TRES in the later stages of the next-generation impactor (NGI) when using an air-jet nebulizer than when using an ultrasonic nebulizer. The F14 formulation exhibited greater stability and release in acetate buffer (pH 5.4), with a cumulative release of 95%.

CONCLUSIONS

Overall, formulation F14 in combination with an air-jet nebulizer was identified as a superior combination, demonstrating higher emitted dose (ED; 80%), fine particle dose (FPD; 1150 µg), fine particle fraction (FPF; 24%), and respirable fraction (RF; 94%). These findings are promising in the optimization and development of NLC formulations, highlighting their versatility and targeting the pulmonary system via nebulization.

Respiratory Delivery of Lacticaseibacillus rhamnosus GG by Vibrating-Mesh and Jet Nebulisation

BACKGROUND

The use of probiotic bacteria to improve lung health has been gaining interest. Although the oral delivery of probiotics and their effects are well documented, there is currently limited knowledge on the respiratory delivery of probiotics.

OBJECTIVES

This study aimed to investigate whether nebulisation is suitable for delivering Lacticaseibacillus rhamnosus GG (LGG) into the lungs for the potential treatment of bacterial pulmonary infections.

METHODS

It compared the dose output and aerosol performance of a vibrating-mesh nebuliser (VMN) and a jet nebuliser (JN) in nebulising LGG suspended in de Man Rogosa Sharpe (MRS) broth, phosphate-buffered saline (PBS), or normal saline (0.9% w/v sodium chloride in water).

RESULTS

The VMN consistently produced a higher output than the JN for all liquid media, indicating that VMN was more efficient. The fine-particle fractions of both nebulisers were comparable for a given medium. The highest fine-particle fraction was achieved with LGG suspended in MRS broth for both nebulisers (20.5 ± 2.8% for VMN; 18.7 ± 3.4% for JN). This suggests that the aerosol performance of nebulised probiotics may depend on the medium in which the probiotic bacteria were suspended.

CONCLUSIONS

Therefore, this study demonstrated that the nebulisation efficiency of LGG depended on the nebuliser type and liquid medium of the probiotic suspension.

Administration of airborne pathogens in non-human primates

PURPOSE

Airborne pathogen scan penetrate in human respiratory tract and can cause illness. The use of animal models to predict aerosol deposition and study respiratory disease pathophysiology is therefore important for research and a prerequisite to test and study the mechanism of action of treatment. NHPs are relevant animal species for inhalation studies because of their similarities with humans in terms of anatomical structure, respiratory parameters and immune system.

MATERIALS AND METHODS

The aim of this review is to provide an overview of the state of the art of pathogen aerosol studies performed in non-human primates (NHPs). Herein, we present and discuss the deposition of aerosolized bacteria and viruses. In this review, we present important advantages of using NHPs as model for inhalation studies.

RESULTS

We demonstrate that deposition in the respiratory tract is not only a function of aerosol size but also the technique of administration influences the biological activity and site of aerosol deposition. Finally, we observe an influence of a region of pathogen deposition in the respiratory tract on the development of the pathophysiological effect in NHPs.

CONCLUSION

The wide range of methods used for the delivery of pathogento NHP respiratory airways is associated with varying doses and deposition profiles in the airways.

Pulmonary delivery of icariin-phospholipid complex prolongs lung retention and improves therapeutic efficacy in mice with acute lung injury/ARDS

Icariin has been shown the promising therapeutic potential to treat inflammatory airway diseases, yet its poor lung distribution and retention restrict the clinical applications. To this end, this work aimed to prepare an icariin-phospholipid complex (IPC) formulation for sustained nebulization delivery that enabled excellent inhalability, improved lung exposure and prolonged duration of action. Icariin was found to react with soybean phospholipid to form supramolecular IPC, which was able to self-assemble into nanoparticle suspension. The suspension was stable during steam sterilization and nebulization processes, and its aerosols generated by a commercial nebulizer exhibited excellent aerodynamic properties and delivery efficiency. In vitro studies showed that the formation of complex sustained drug release, enhanced lung affinity and slowed lung clearance. The drug distribution in lung epithelial lining fluid (ELF) also demonstrated in vivo sustained release after intratracheal administration to mice. In addition, compared to free icariin, IPC improved the drug exposure to lung tissues and immune cells in the ELF by 4.61-fold and 39.5-fold, respectively. This resulted in improved and prolonged local anti-inflammatory effects up to 24 h in mice with lipopolysaccharide (LPS)-induced acute lung injury. Moreover, IPC improved survival rate of mice with acute respiratory distress syndrome (ARDS). Overall, the present phospholipid complex represented a promising formulation of icariin for the treatment of acute lung injury/ARDS by nebulization delivery.

Antisense oligonucleotides and their technical suitability to nebulization

In vivo studies investigating the inhalative efficacy of biotherapeutics, such as nucleic acids, usually do not perform an aerosolization step, rather the solution is directly administered into the lungs e.g. intratracheally. In addition, there is currently very little information on the behavior of nucleic acid solutions when subjected to the physical stress of the nebulization process. In this study, the aim was to assess the technical suitability of Locked Nucleic Acids (LNAs), as a model antisense oligonucleotide, towards nebulization using two commercially available nebulizers. A jet nebulizer (Pari LC Plus) and a vibrating mesh nebulizer (Aerogen Solo) were employed and solutions of five different LNAs investigated in terms of their physical and chemical stability to nebulization and the quality of the generated aerosols. The aerosol properties of the Aerogen Solo were mainly influenced by the viscosity of the solutions with the output rate and the droplet size decreasing with increasing viscosity. The Pari LC Plus was less susceptible to viscosity and overall the droplet size was smaller. The LNAs tolerated both nebulization processes and the integrity of the molecules was shown. Chemical stability of the molecules from the Aerogen Solo was confirmed, whereas aerosol generation with the Pari LC Plus jet nebulizer led to a slight increase of phosphodiester groups in a fully phosphorothiolated backbone of the LNAs. Overall, it could be shown that nebulization of different LNAs is possible and inhalation can therefore be considered a potential route of administration.

Nebulizers

Nebulizers generate aerosols from liquid-based solutions and suspensions. Nebulizers are particularly well suited to delivering larger doses of medication than is practical with inhalers and are used with a broad range of liquid formulations. When the same drug is available in liquid or inhaler form, nebulizers are applicable for use with patients who will not or cannot reliably use a pressurized metered-dosed inhaler (pMDI) or dry powder inhaler (DPI) due to poor lung function, hand-breath coordination, cognitive abilities (e.g., infants, elderly) or device preference. In a nebulizer, liquid medication is placed in a reservoir and fed to an aerosol generator to produce the droplets. A series of tubes and channels direct the aerosol to the patient via an interface such as mouthpiece, mask, tent, nasal prongs or artificial airway. All nebulizers contain these basic parts, although the technology and design used can vary widely and can result in significant difference in ergonomics, directions for use, and performance. While many types of nebulizers have been described, the three categories of modern clinical nebulizers include: (1) pneumatic jet nebulizers (JN); (2) ultrasonic nebulizers (USN); and (3) vibrating mesh nebulizers (VMN). Nebulizers are also described in terms of their reservoir size. Small volume nebulizers (SVNs), most commonly used for medical aerosol therapy, can hold 5 to 20 mL of medication and may be jet, ultrasonic, or mesh nebulizers. Large volume nebulizers, typically jet or ultrasonic nebulizers, hold up to 200 mL and may be used for either bland aerosol therapy or continuous drug administration.

Aerosol drug therapy in critically ill patients (Aero-in-ICU study): A multicentre prospective observational cohort study

BACKGROUND

In recent years, a significant understanding of delivering optimal aerosol therapy and the availability of various drugs and devices have led to an increase in its use in clinical practice. There are only a few studies available regarding their use in critically ill patients from a few parts of the world. We aimed to study the practice pattern of aerosol therapy in critically ill patients from Indian intensive care units (ICUs).

METHODS

After ethical approval, this multi-centric prospective observational study was performed over a study period of four weeks. Newly admitted adult patients considered who had an artificial airway and/or ventilation (including non-invasive). Patients were followed up for the next 14 days or until ICU discharge/death (whichever came first) for details of each aerosol therapy, including ongoing respiratory support, drug type, and aerosol-generating device.

RESULTS

From the nine participating centers across India, 218 patients were enrolled. Of 218 enrolled patients, 72.48% received 4884 aerosols with 30.91 ± 27.15 (95%CI: 26.6-35.1) aerosols per patient over 1108 patient days. Approximately 62.7% during IMV, 30.2% during NIV, 2.3% in spontaneously breathing patients with an artificial airway during weaning, and 4.7% were given without an artificial airway after weaning or decannulation. In 59%, a single drug was used, and bronchodilators were the most frequent. The jet nebulizer was the most common, followed by the ultrasonic and vibrating mesh aerosol generator. The ventilator setting was changed in only 6.6% of the aerosol sessions with IMV and none with NIV.

CONCLUSION

Aerosol therapy is frequently used with a wide variation in practices; bronchodilators are the most commonly used drugs, and jet nebulizers are the most widely used.

Novel inhalation therapy in pulmonary fibrosis: principles, applications and prospects

Pulmonary fibrosis (PF) threatens millions of people worldwide with its irreversible progression. Although the underlying pathogenesis of PF is not fully understood, there is evidence to suggest that the disease can be blocked at various stages. Inhalation therapy has been applied for lung diseases such as asthma and chronic obstructive pulmonary disease, and its application for treating PF is currently under consideration. New techniques in inhalation therapy, such as the application of microparticles and nanoparticles, traditional Chinese medicine monomers, gene therapy, inhibitors, or agonists of signaling pathways, extracellular vesicle interventions, and other specific drugs, are effective in treating PF. However, the safety and effectiveness of these therapeutic techniques are influenced by the properties of inhaled particles, biological and pathological barriers, and the type of inhalation device used. This review provides a comprehensive overview of the pharmacological, pharmaceutical, technical, preclinical, and clinical experimental aspects of novel inhalation therapy for treating PF and focus on therapeutic methods that significantly improve existing technologies or expand the range of drugs that can be administered via inhalation. Although inhalation therapy for PF has some limitations, the advantages are significant, and further research and innovation about new inhalation techniques and drugs are encouraged.

Nebulised delivery of RNA formulations to the lungs: From aerosol to cytosol

In the past decade RNA-based therapies such as small interfering RNA (siRNA) and messenger RNA (mRNA) have emerged as new and ground-breaking therapeutic agents for the treatment and prevention of many conditions from viral infection to cancer. Most clinically approved RNA therapies are parenterally administered which impacts patient compliance and adds to healthcare costs. Pulmonary administration via inhalation is a non-invasive means to deliver RNA and offers an attractive alternative to injection. Nebulisation is a particularly appealing method due to the capacity to deliver large RNA doses during tidal breathing. In this review, we discuss the unique physiological barriers presented by the lung to efficient nebulised RNA delivery and approaches adopted to circumvent this problem. Additionally, the different types of nebulisers are evaluated from the perspective of their suitability for RNA delivery. Furthermore, we discuss recent preclinical studies involving nebulisation of RNA and analysis in in vitro and in vivo settings. Several studies have also demonstrated the importance of an effective delivery vector in RNA nebulisation therefore we assess the variety of lipid, polymeric and hybrid-based delivery systems utilised to date. We also consider the outlook for nebulised RNA medicinal products and the hurdles which must be overcome for successful clinical translation. In summary, nebulised RNA delivery has demonstrated promising potential for the treatment of several lung-related conditions such as asthma, COPD and cystic fibrosis, to which the mode of delivery is of crucial importance for clinical success.

Towards More Precise Targeting of Inhaled Aerosols to Different Areas of the Respiratory System

Pharmaceutical aerosols play a key role in the treatment of lung disorders, but also systemic diseases, due to their ability to target specific areas of the respiratory system (RS). This article focuses on identifying and clarifying the influence of various factors involved in the generation of aerosol micro- and nanoparticles on their regional distribution and deposition in the RS. Attention is given to the importance of process parameters during the aerosolization of liquids or powders and the role of aerosol flow dynamics in the RS. The interaction of deposited particles with the fluid environment of the lung is also pointed out as an important step in the mass transfer of the drug to the RS surface. The analysis presented highlights the technical aspects of preparing the precursors to ensure that the properties of the aerosol are suitable for a given therapeutic target. Through an analysis of existing technical limitations, selected strategies aimed at enhancing the effectiveness of targeted aerosol delivery to the RS have been identified and presented. These strategies also include the use of smart inhaling devices and systems with built-in AI algorithms.

Advances in Aerogels Formulations for Pulmonary Targeted Delivery of Therapeutic Agents: Safety, Efficacy and Regulatory Aspects

Aerogels are the 3D network of organic, inorganic, composite, layered, or hybrid-type materials that are used to increase the solubility of Class 1 (low solubility and high permeability) and Class 4 (poor solubility and low permeability) molecules. This approach improves systemic drug absorption due to the alveoli's broad surface area, thin epithelial layer, and high vascularization. Local therapies are more effective and have fewer side effects than systemic distribution because inhalation treatment targets the specific location and raises drug concentration in the lungs. The present manuscript aims to explore various aspects of aerogel formulations for pulmonary targeted delivery of active pharmaceutical agents. The manuscript also discusses the safety, efficacy, and regulatory aspects of aerogel formulations. According to projections, the global respiratory drug market is growing 4-6% annually, with short-term development potential. The proliferation of literature on pulmonary medicine delivery, especially in recent years, shows increased interest. Aerogels come in various technologies and compositions, but any aerogel used in a biological system must be constructed of a material that is biocompatible and, ideally, biodegradable. Aerogels are made via "supercritical processing". After many liquid phase iterations using organic solvents, supercritical extraction, and drying are performed. Moreover, the sol-gel polymerization process makes inorganic aerogels from TMOS or TEOS, the less hazardous silane. The resulting aerogels were shown to be mostly loaded with pharmaceutically active chemicals, such as furosemide-sodium, penbutolol-hemisulfate, and methylprednisolone. For biotechnology, pharmaceutical sciences, biosensors, and diagnostics, these aerogels have mostly been researched. Although aerogels are made of many different materials and methods, any aerogel utilized in a biological system needs to be made of a substance that is both biocompatible and, preferably, biodegradable. In conclusion, aerogel-based pulmonary drug delivery systems can be used in biomedicine and non-biomedicine applications for improved sustainability, mechanical properties, biodegradability, and biocompatibility. This covers scaffolds, aerogels, and nanoparticles. Furthermore, biopolymers have been described, including cellulose nanocrystals (CNC) and MXenes. A safety regulatory database is necessary to offer direction on the commercialization potential of aerogelbased formulations. After that, enormous efforts are discovered to be performed to synthesize an effective aerogel, particularly to shorten the drying period, which ultimately modifies the efficacy. As a result, there is an urgent need to enhance the performance going forward.

Influence of mesh nebulizer characteristics on aerosol delivery in non-human primates

Non-Human Primates (NHPs) are particularly relevant for preclinical studies during the development of inhaled biologics. However, aerosol inhalation in NHPs is difficult to evaluate due to a low lung deposition fraction and high variability. The objective of this study was to evaluate the influence of mesh nebulizer parameters to improve lung deposition in macaques. We developed a humidified heated and ventilated anatomical 3D printed macaque model of the upper respiratory tract to reduce experiments with animals. The model was compared to in vivo deposition using 2D planar scintigraphy imaging in NHPs and demonstrated good predictivity. Next, the anatomical model was used to evaluate the position of the nebulizer on the mask, the aerosol particle size and the aerosol flow rate on the lung deposition. We showed that placing the mesh-nebulizer in the upper part of the mask and in proximal position to the NHP improved lung delivery prediction. The lower the aerosol size and the lower the aerosol flow rate, the better the predicted aerosol deposition. In particular, for 4.3 ± 0.1 µm in terms of volume mean diameter, we obtained 5.6 % ± 0.2 % % vs 19.2 % ± 2.5 % deposition in the lung model for an aerosol flow rate of 0.4 mL/min vs 0.03 mL/min and achieved 16 % of the nebulizer charge deposited in the lungs of macaques. Despite the improvement of lung deposition efficiency in macaques, its variability remained high (6-21 %).

Nebulizers effectiveness on pulmonary delivery of alpha-1 antitrypsin

The nebulization of alpha-1 antitrypsin (AAT) for its administration to the lung could be an interesting alternative to parenteral infusion for patients suffering from AAT genetic deficiency (AATD). In the case of protein therapeutics, the effect of the nebulization mode and rate on protein conformation and activity must be carefully considered. In this paper two types of nebulizers, i.e., a jet and a mesh vibrating system, were used to nebulize a commercial preparation of AAT for infusion and compared. The aerosolization performance, in terms of mass distribution, respirable fraction, and drug delivery efficiency, as well as the activity and aggregation state of AAT upon in vitro nebulization were investigated. The two nebulizers demonstrated equivalent aerosolization performances, but the mesh nebulizer provided a higher efficiency in the delivery of the dose. The activity of the protein was acceptably preserved by both nebulizers and no aggregation or changes in its conformation were identified. This suggests that nebulization of AAT represents a suitable administration strategy ready to be translated to the clinical practice for delivering the protein directly to the lungs in AATD patients, either as a support therapy to parenteral administration or for subjects with a precocious diagnosis, to prevent the onset of pulmonary symptoms.

Aerosolization Performance of Immunoglobulin G by Jet and Mesh Nebulizers

Recently, many preclinical and clinical studies have been conducted on the delivery of therapeutic antibodies to the lungs using nebulizers, but standard treatment guidelines have not yet been established. Our objective was to compare nebulization performance according to the low temperature and concentration of immunoglobulin G (IgG) solutions in different types of nebulizers, and to evaluate the stability of IgG aerosols and the amount delivered to the lungs. The output rate of the mesh nebulizers decreased according to the low temperature and high concentration of IgG solution, whereas the jet nebulizer was unaffected by the temperature and concentration of IgG. An impedance change of the piezoelectric vibrating element in the mesh nebulizers was observed because of the lower temperature and higher viscosity of IgG solution. This affected the resonance frequency of the piezoelectric element and lowered the output rate of the mesh nebulizers. Aggregation assays using a fluorescent probe revealed aggregates in IgG aerosols from all nebulizers. The delivered dose of IgG to the lungs in mice was highest at 95 ng/mL in the jet nebulizer with the smallest droplet size. Evaluation of the performance of IgG solution delivered to the lungs by three types of nebulizers could provide valuable parameter information for determination on dose of therapeutic antibody by nebulizers.

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.

In vitro interactions of aerosol formulations with human nasal epithelium using real-time monitoring of drug transport in a nasal mucosa-on-a-chip

The current organ-on-chip platforms used for studying respiratory drug delivery are limited to the administration of drug solutions and suspensions, lacking the in vivo aerosol drug administration and aerosol interaction with the respiratory tract barrier. Moreover, they mostly rely on conventional assays that require sample collection and 'off the chip' analyses, which can be labor-intensive and costly. In this study, a human nasal epithelial mucosa (NEM)-on-a-chip is developed that enables the deposition of aerosolized nasal formulations while emulating realistic shear stresses (0.23 and 0.78 Pa), exerted to the inferior and middle turbinate of the human nasal cavity. Under these different dynamic conditions in the donor channel of the NEM-on-a-chip, the deposited dose of aerosols and particle size distributions varied. In addition, the increase in the shear stress to 0.78 Pa adversely affected the cells' viability, reflected by a 36.9 ± 5.4% reduction in the transepithelial electrical resistance. The epithelial transport profiles of aerosolized ibuprofen formulations under 0.23 Pa shear stress were successfully monitored in real-time by an electrochemical sensor embedded in the acceptor channel, where the NEM-on-a-chip was able to monitor the effect of permeation enhancer in the test formulation on the rate of drug transport. The novel NEM-on-a-chip can potentially be a promising physiologically relevant tool for reliable nasal aerosol testing in vitro.

Understanding the influence of the bioaerosol source on the distribution of airborne bacteria in hospital indoor air

The composition and concentration of airborne microorganisms in hospital indoor air has been reported to contain airborne bacteria and fungi concentrations ranged 10¹-10³ CFU/m³ in inpatients facilities which mostly exceed recommendations from the World Health Organization (WHO). In this work, a deeper knowledge of the performance of airborne microorganisms would allow improving the designs of the air-conditioning installations to restrict hospital-acquired infections (HAIs). A solution containing Escherichia coli (E. coli) as a model of airborne bacteria was nebulized using the Collison nebulizer to simulate bioaerosols in various hospital areas such as patients' rooms or bathrooms. Results showed that the bioaerosol source had a significant influence on the airborne bacteria concentrations since 4.00 10², 6.84 10³ and 1.39 10⁴ CFU mL^-1 were monitored during the aerosolization for 10 min of urine, saliva and urban wastewater, respectively. These results may be explained considering the quite narrow distribution profile of drop sizes around 1.10-1.29 μm obtained for urban wastewater, with much vaster distribution profiles during the aerosolization of urine or saliva. The airborne bacteria concentration may increase up to 10⁷ CFU mL^-1 for longer sampling times and higher aerosolization pressures, causing several cell damages. The cell membrane damage index (I_D) can vary from 0 to 1, depending on the genomic DNA releases from bacteria. In fact, the I_D of E. coli was more than two times higher (0.33 vs. 0.72) when increasing the pressure of air flow was applied from 1 to 2 bar. Finally, the ventilation air flow also affected the distribution of bioaerosols due to its direct relationship with the relative humidity of indoor air. Specifically, the airborne bacteria concentration diminished almost below 3-logs by applying more than 10 L min^-1 during the aerosolization of urine due to their inactivation by an increase in their osmotic pressure.

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.

State-of-the-Art Review of The Application and Development of Various Methods of Aerosol Therapy

Aerosol therapy is a rapidly developing field of science. Due to a number of advantages, the administration of drugs to the body with the use of aerosol therapy is becoming more and more popular. Spraying drugs into the patient's lungs has a significant advantage over other methods of administering drugs to the body, including injection and oral methods. In order to conduct proper and effective aerosol therapy, it is necessary to become familiar with the basic principles and applications of aerosol therapy under various conditions. The effectiveness of inhalation depends on many factors, but most of all on: the physicochemical properties of the sprayed system, the design of the medical inhaler and its correct application, the dynamics of inhalation (i.e. the frequency of breathing and the volume of inhaled air). It is worth emphasizing that respiratory system diseases are one of the most frequently occurring and fastest growing diseases in the world. Accordingly, in recent years, a significant increase in the number of new spraying devices and pharmaceutical drugs for spraying has appeared on the market. It should also be remembered that the process of spraying a liquid is a complicated and complex process, and its efficiency is very often characterized by the use of micro- and macro parameters (including average droplet diameters or the spectrum of droplet diameter distribution). In order to determine the effectiveness of the atomization process and in the delivery of drugs to the patient's respiratory tract, the analysis of the size of the generated aerosol droplets is most often performed. Based on the proposed literature review, it has been shown that many papers dealt with the issues related to aerosol therapy, the selection of an appropriate spraying device, the possibility of modifying the spraying devices in order to increase the effectiveness of inhalation, and the possibility of occurrence of certain discrepancies resulting from the use of various measurement methods to determine the characteristics of the generated aerosol. The literature review presented in the paper was prepared in order to better understand the spraying process. Moreover, it can be helpful in choosing the right medical inhaler for a given liquid with specific rheological properties. The experimental data contained in this study are of great cognitive importance and may be of interest to entities involved in pharmaceutical product engineering (in particular in the case of the production of drugs containing liquids with complex rheological properties).

Modification of Apremilast from Pills to Aerosol a Future Concept

BACKGROUND

Inhaled drugs have been available in the market for several years and for several diseases. Drugs for chronic obstructive pulmonary disease, cystic fibrosis, and diabetes have been used for several years. In the field of drug modification, these drugs range from tablets to aerosol.

METHODS

Milling as used to break down the tablets to powder and nebulisers are used to produce aerosol droplets. A mastersizer was used to measure the mass median aerodynamic diameter of the aerosol droplets.

RESULTS

Apremilast produced mmad diameters (2.43 μm) without any statistical difference between the different jet-nebulizers. The residual cup B contributed to greater mmad diameters as the 95% interval of mean values, based on those the ANOVA mean square clearly indicated, followed by cups C and F. The previous interval plot is much better clarified when the interaction means between drug and residual cap are plotted. The residual cups B, C and F produce mmad between (2.0-3.2).

CONCLUSION

In the current research study we demonstrated our methodology to create apremilast powder and produce apremilast aerosol droplets with different nebulisers and residual cups.

Evaluation of Aerosol Drug Delivery Options during Adult Mechanical Ventilation in the COVID-19 Era

Drug delivery devices used for aerosol therapy during mechanical ventilation to ease the symptoms of respiratory diseases provide beneficial treatment but can also pose challenges. Reflecting the significant changes in global guidance around aerosol usage and lung-protective ventilation strategies, seen in response to the COVID-19 pandemic, for the first time, we describe the drug delivery performance of commonly used devices under these conditions. Here, vibrating mesh nebuliser (VMN), jet nebuliser (JN) and pressurised metered-dose inhaler (pMDI) performance was assessed during simulated adult mechanical ventilation. Both standard test breathing patterns and those representatives of low tidal volume (LTV) ventilation with concurrent active and passive humidification were investigated. Drug delivery using a VMN was significantly greater than that with a JN and pMDI for both standard and LTV ventilation. Humidification type did not affect the delivered dose across all device types for standard ventilation. Significant variability in the pMDI dosing was evident, depending on the timing of actuation and the adapter type used. pMDI actuation synchronised with inspiration resulted in a higher delivered drug dose. The type of adapter used for pMDI actuation influenced drug delivery, with the highest dose observed using the CombiHaler.

Evaluation of Aerosol Therapy during the Escalation of Care in a Model of Adult Cystic Fibrosis

Lung disease is the main cause of morbidity and mortality in cystic fibrosis (CF). CF patients inhale antibiotics regularly as treatment against persistent bacterial infections. The goal of this study was to investigate the effect of clinical intervention on aerosol therapy during the escalation of care using a bench model of adult CF. Droplet size analysis of selected antibiotics was completed in tandem with the delivered aerosol dose (% of total dose) assessments in simulations of various interventions providing oxygen supplementation or ventilatory support. Results highlight the variability of aerosolised dose delivery. In the homecare setting, the vibrating mesh nebuliser (VMN) delivered significantly more than the jet nebuliser (JN) (16.15 ± 0.86% versus 6.51 ± 2.15%). In the hospital setting, using VMN only, significant variability was seen across clinical interventions. In the emergency department, VMN plus mouthpiece (no supplemental oxygen) was seen to deliver (29.02 ± 1.41%) versus low flow nasal therapy (10 L per minute (LPM) oxygen) (1.81 ± 0.47%) and high flow nasal therapy (50 LPM oxygen) (3.36 ± 0.34%). In the ward/intensive care unit, non-invasive ventilation recorded 19.02 ± 0.28%, versus 22.64 ± 1.88% of the dose delivered during invasive mechanical ventilation. These results will have application in the design of intervention-appropriate aerosol therapy strategies and will be of use to researchers developing new therapeutics for application in cystic fibrosis and beyond.

Aerosol delivery via invasive ventilation: a narrative review

In comparison with spontaneously breathing non-intubated subjects, intubated, mechanically ventilated patients encounter various challenges, barriers, and opportunities in receiving medical aerosols. Since the introduction of mechanical ventilation as a part of modern critical care medicine during the middle of the last century, aerosolized drug delivery by jet nebulizers has become a common practice. However, early evidence suggested that aerosol generators differed in their efficacies, and the introduction of newer aerosol technology (metered dose inhalers, ultrasonic nebulizer, vibrating mesh nebulizers, and soft moist inhaler) into the ventilator circuit opened up the possibility of optimizing inhaled aerosol delivery during mechanical ventilation that could meet or exceed the delivery of the same aerosols in spontaneously breathing patients. This narrative review will catalogue the primary variables associated with this process and provide evidence to guide optimal aerosol delivery and dosing during mechanical ventilation. While gaps exist in relation to the appropriate aerosol drug dose, discrepancies in practice, and cost-effectiveness of the administered aerosol drugs, we also present areas for future research and practice. Clinical practice should expand to incorporate these techniques to improve the consistency of drug delivery and provide safer and more effective care for patients.

Pulmonary drug delivery with aerogels: engineering of alginate and alginate-hyaluronic acid microspheres

In this study, the aerogel technology was used to prepare pulmonary drug carriers consisting of alginate and alginate-hyaluronic acid by an emulsion gelation technique and supercritical CO₂ drying. During the preparation process, the emulsification rate and inner phase viscosity were varied to control the diameter of aerogel microspheres. Results showed that the aerogel microspheres were highly porous (porosity > 98%) with low densities in the range between 0.0087 and 0.0634 g/cm³ as well as high surface areas between 354 and 759 m²/g. The obtained microspheres showed aerodynamic diameter below 5 µm making them suitable for pulmonary drug delivery. An in vitro drug release study with the model drug sodium naproxen was conducted and a non-Fickian drug release mechanism was observed, with no significant difference between the release profiles of alginate and alginate-hyaluronic acid microspheres. During the emulsion gelation step, the feasibility of using the capillary number to estimate the largest stable droplet size in the emulsions was also studied and it was found that using this number, the droplet size in the emulsions may well be predicted.

Comparison of pulmonary deposition of nebulized 99m technetium-diethylenetriamine-pentaacetic acid through 3 inhalation devices in healthy dogs

Background

Inhalation treatment frequently is used in dogs and cats with chronic respiratory disease. Little is known however about the performance of delivery devices and the distribution of aerosolized drugs in the lower airways.

Objective

To assess the performance of 3 delivery devices and the impact of variable durations of inhalation on the pulmonary and extrapulmonary deposition of nebulized ^99mtechnetium‐diethylenetriamine‐pentaacetic acid (^99mTc‐DTPA).

Animals

Ten university‐owned healthy Beagle dogs.

Methods

Prospective crossover study. Dogs inhaled the radiopharmaceutical for 5 minutes either through the Aerodawg spacer with a custom‐made nose‐muzzle mask, the Aerochamber spacer with the same mask, or the Aerodawg spacer with its original nose mask. In addition, dogs inhaled for 1 and 3 minutes through the second device. Images were obtained by 2‐dimensional planar scintigraphy. Radiopharmaceutical uptake was calculated as an absolute value and as a fraction of the registered dose in the whole body.

Results

Mean (±SD) lung deposition for the 3 devices was 9.2% (±5.0), 11.4% (±4.9), and 9.3% (±4.6), respectively. Differences were not statistically significant. Uptake in pulmonary and extrapulmonary tissues was significantly lower after 1‐minute nebulization, but the mean pulmonary/extrapulmonary deposition ratio (0.38 ± 0.27) was significantly higher than after 5‐minute nebulization (0.16 ± 0.1; P = .03). No significant differences were detected after 3‐ and 5‐minute nebulization.

Conclusion and Clinical Importance

The performance of a pediatric spacer with a custom‐made mask is comparable to that of a veterinary device. One‐minute nebulization provides lower pulmonary uptake but achieves a better pulmonary/extrapulmonary deposition ratio than does 5‐minute nebulization.

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.

Repurposing of Plasminogen: An Orphan Medicinal Product Suitable for SARS-CoV-2 Inhalable Therapeutics

The SARS-CoV-2 infection is associated with pulmonary coagulopathy, which determines the deposition of fibrin in the air spaces and lung parenchyma. The resulting lung lesions compromise patient pulmonary function and increase mortality, or end in permanent lung damage for those who have recovered from the COVID-19 disease. Therefore, local pulmonary fibrinolysis can be efficacious in degrading pre-existing fibrin clots and reducing the conversion of lung lesions into lasting scars. Plasminogen is considered a key player in fibrinolysis processes, and in view of a bench-to-bedside translation, we focused on the aerosolization of an orphan medicinal product (OMP) for ligneous conjunctivitis: human plasminogen (PLG-OMP) eye drops. As such, the sterile and preservative-free solution guarantees the pharmaceutical quality of GMP production and meets the Ph. Eur. requirements of liquid preparations for nebulization. PLG-OMP aerosolization was evaluated both from technological and stability viewpoints, after being submitted to either jet or ultrasonic nebulization. Jet nebulization resulted in a more efficient delivery of an aerosol suitable for pulmonary deposition. The biochemical investigation highlighted substantial protein integrity maintenance with the percentage of native plasminogen band > 90%, in accordance with the quality specifications of PLG-OMP. In a coherent way, the specific activity of plasminogen is maintained within the range 4.8–5.6 IU/mg (PLG-OMP pre-nebulization: 5.0 IU/mg). This is the first study that focuses on the technological and biochemical aspects of aerosolized plasminogen, which could affect both treatment efficacy and clinical dosage delivery. Increasing evidence for the need of local fibrinolytic therapy could merge with the availability of PLG-OMP as an easy handling solution, readily aerosolizable for a fast translation into an extended clinical efficacy assessment in COVID-19 patients.

Can bacteriophage endolysins be nebulised for inhalation delivery against Streptococcus pneumoniae?

Endolysins are bacteriophage-derived protein molecules highly effective for bacterial killing. Cpl-1 and ClyJ-3 are native and chimeric endolysins, respectively, having antimicrobial activity against Streptococcus pneumoniae which causes lung infections. We conducted the first feasibility study on nebulisation of Cpl-1 and ClyJ-3, with a focus on the antimicrobial activity, structural changes of the proteins and aerosol performance. Bacterial colony counts, live cell imaging and Fourier-transform infrared(FTIR) spectroscopy were used to evaluate the proteins before and after jet or vibrating mesh nebulisation. These nebulised aerosols were inhalable with a volume median size of 3.8-4.2 µm (span 1.1-2.3) measured by laser diffraction. How-ever, neb-u-li-sa-tion caused al-most com-plete loss in bioac-tiv-ity of ClyJ-3, which were corroborated with the live cell imaging observation and protein structural damage with a large intensity reduction in the amide absorption bands between 1300 and 1700 cm^-1. In contrast, the bactericidal activity of Cpl-1 showed no significant difference (p ≥ 0.05) before and after mesh nebulisation with 4.9 and 4.6-log10 bacterial count reduction, respectively. However, jet nebulisation reduced the bioactivity of Cpl-1 and the effect was time-dependent showing 1.7, 1.0-log10 bacterial count reduction at 7 and 14 min with complete loss of antimicrobial activity at 21 min after nebulisation, respectively. The results were consistent with time-dependent changes in live cell images and FTIR amide band changes at 1655, 1640, 1632 and 1548 cm^-1. In conclusion, it is feasible to nebulise endolysins for inhalation delivery but it depends on both the protein and the nebuliser, with the mesh nebuliser being the preferred choice.

Proliposome powder or tablets for generating inhalable liposomes using a medical nebulizer

Purpose

The aim of this study was to develop and compare proliposome powder and proliposome tablet formulations for drug delivery from a Pari-LC Sprint nebulizer.

Methods

Proliposome powders were prepared by the slurry method and sorbitol or mannitol carbohydrate carrier were used in a 1:10 and 1:15 w/w lipid phase to carrier ratio. Beclometasone dipropionate (BDP; 2 mol%) was incorporated in the lipid phase. Proliposome powders were compressed into tablets, and liposomes were generated from proliposome powders or tablets within the nebulizer reservoir for subsequent aerosolization.

Results

Comparatively, shorter sputtering times were reported for the tablet formulations (≈ < 2.7±0.45 min), indicating uniform aerosolization. Post-nebulization, liposomes size was larger in the nebulizer reservoir in the range of 7.79±0.48 µm–9.73±1.53 µm for both powder and tablet formulations as compared to freshly prepared liposomes (5.38±0.73 µm–5.85±0.86 µm), suggesting liposome aggregation/fusion in the nebulizer’s reservoir. All formulations exhibited more than 80% mass output regardless of formulation type, but greater BDP proportions (circa 50%) were delivered to the Two-stage Impinger when tablet formulations were used. Moreover, the nebulized droplet median size and size distribution were lower for all tablet formulations in comparison to the powder formulations. Proliposome tablet and powdered formulations demonstrated the ability to generate vesicles that sustained the release of BDP.

Conclusion

Overall, this study showed that proliposome tablets could be disintegrated within a Pari-LC Sprint nebulizer to generate inhalable aerosol, with high drug output and hence can be manufactured on large scale to overcome the storage problems associated with powder formulations.

A Stimulus-Responsive Polymer Composite Surface with Magnetic Field-Governed Wetting and Photocatalytic Properties

With the increasing demand for liquid manipulation and microfluidic techniques, surfaces with real-time tunable wetting properties are becoming the focus of materials science researches. In this study, we present a simple preparation method for a 0.5-4 µm carbonyl iron (carbonyl Fe) loaded polydimethylsiloxane (PDMS)-based magnetic composite coating with magnetic field-tailored wetting properties. Moreover, the embedded 6.3-16.7 wt.% Ag-TiO₂ plasmonic photocatalyst (d~50 nm) content provides additional visible light photoreactivity to the external stimuli-responsive composite grass surfaces, while the efficiency of this photocatalytic behavior also turned out to be dependent on the external magnetic field. The inclusion of the photocatalyst introduced hierarchical surface roughness to the micro-grass, resulting in the broadening of the achievable contact and sliding angle ranges. The photocatalyst-infused coatings are also capable of catching and releasing water droplets, which alongside their multifunctional (photocatalytic activity and tunable wetting characteristics) nature makes surfaces of this kind the novel sophisticated tools of liquid manipulation.

Aerosol Delivery of Dornase Alfa Generated by Jet and Mesh Nebulizers

Recent reports on mesh nebulizers suggest the possibility of stable nebulization of various therapeutic protein drugs. In this study, the in vitro performance and drug stability of jet and mesh nebulizers were examined for dornase alfa and compared with respect to their lung delivery efficiency in BALB/c mice. We compared four nebulizers: two jet nebulizers (PARI BOY SX with red and blue nozzles), a static mesh nebulizer (NE-U150), and a vibrating mesh nebulizer (NE-SM1). The enzymatic activity of dornase alfa was assessed using a kinetic fluorometric DNase activity assay. Both jet nebulizers had large residual volumes between 24% and 27%, while the volume of the NE-SM1 nebulizer was less than 2%. Evaluation of dornase alfa aerosols produced by the four nebulizers showed no overall loss of enzymatic activity or protein content and no increase in aggregation or degradation. The amount of dornase alfa delivered to the lungs was highest for the PARI BOY SX-red jet nebulizer. This result confirmed that aerosol droplet size is an important factor in determining the efficiency of dornase alfa delivery to the lungs. Further clinical studies and analysis are required before any conclusions can be drawn regarding the clinical safety and efficacy of these nebulizers.

Inactivation of airborne porcine reproductive and respiratory syndrome virus (PRRSv) by a packed bed dielectric barrier discharge non-thermal plasma

Porcine reproductive and respiratory syndrome virus (PRRSv) is one of the most significant airborne viruses impacting the pork industry in the US. Non-thermal plasmas (NTPs) are electrical discharges comprised of reactive radicals and excited species that inactivate viruses and bacteria. Our previous experiments using a packed bed NTP reactor demonstrated effective inactivation of bacteriophage MS2 as a function of applied voltage and power. The present study examined the effectiveness of the same reactor in inactivating aerosolized PRRSv. A PRRSv solution containing ∼10⁵ TCID₅₀/ml of PRRSv VR2332 strain was aerosolized at 3 ml/min by an air-jet nebulizer and introduced into 5 or 12 cfm air flow followed by NTP exposure in the reactor. Twin impingers upstream and downstream of the reactor collected samples of the virus-laden air flow for subsequent TCID₅₀ assay and qPCR analyses. An optical particle sizer measured upstream and downstream aerosol size distributions, giving estimates of aerosol filtration by the reactor. The results showed that PRRSv was inactivated to a similar degree as MS2 at the same conditions, with the maximum 1.3-log inactivation of PRRSv achieved at 20 kV and 12 cfm air flow rate. The results demonstrate the potential of properly optimized NTPs in controlling PRRSv transmission.

A Facile and Novel Approach to Manufacture Paclitaxel-Loaded Proliposome Tablet Formulations of Micro or Nano Vesicles for Nebulization

Purpose

The aim of this study was to develop novel paclitaxel-loaded proliposome tablet formulations for pulmonary drug delivery.

Method

Proliposome powder formulations (i.e. F1 – F27) were prepared employing Lactose monohydrate (LMH), Microcrystalline cellulose (MCC) or Starch as a carbohydrate carriers and Soya phosphatidylcholine (SPC), Hydrogenated soya phosphatidylcholine (HSPC) or Dimyristoly phosphatidylcholine (DMPC) as a phospholipid. Proliposome powder formulations were prepared in 1:5, 1:15 or 1:25 w/w lipid phase to carrier ratio (lipid phase; comprising of phospholipid and cholesterol in 1:1 M ratio) and Paclitaxel (PTX) was used as model anticancer drug.

Results

Based on flowability studies, out of 27 formulations; F3, F6, and F9 formulations were selected as they exhibited an excellent angle of repose (AOR) (17.24 ± 0.43, 16.41 ± 0.52 and 15.16 ± 0.72°), comparatively lower size of vesicles (i.e. 5.35 ± 0.76, 6.27 ± 0.59 and 5.43 ± 0.68 μm) and good compressibility index (14.81 ± 0.36, 15.01 ± 0.35 and 14.56 ± 0.14) via Carr’s index. The selected formulations were reduced into Nano (N) vesicles via probe sonication, followed by spray drying (SD) to get a dry powder of these formulations as F3SDN, F6SDN and F9SDN, and gave high yield (>53%) and exhibited poor to very poor compressibility index values via Carr’s Index. Post tablet manufacturing, F3 tablets formulation showed uniform weight uniformity (129.40 ± 3.85 mg), good crushing strength (14.08 ± 1.95 N), precise tablet thickness (2.33 ± 0.51 mm) and a short disintegration time of 14.35 ± 0.56 min, passing all quality control tests in accordance with British Pharmacopeia (BP). Upon nebulization of F3 tablets formulation, Ultrasonic nebulizer showed better nebulization time (8.75 ± 0.86 min) and high output rate (421.06 ± 7.19 mg/min) when compared to Vibrating mesh nebulizer. PTX-loaded F3 tablet formulations were identified as toxic (60% cell viability) to cancer MRC-5 SV2 cell lines while safe to normal MRC-5 cell lines.

Conclusion

Overall, in this study LMH was identified as a superior carbohydrate carrier for proliposome tablet manufacturing in a 1:25 w/w lipid to carrier ratio for in-vitro nebulization via Ultrasonic nebulizer.

Electronic supplementary material

The online version of this article (10.1007/s11095-020-02840-w) contains supplementary material, which is available to authorized users.

Relationship Between Geometric and Aerodynamic Particle Size Distributions in the Formulation of Solution and Suspension Metered-Dose Inhalers

The relationship between the geometric particle size distribution (GPSD) and the aerodynamic particle size distribution (APSD) of commercial solution and suspension metered-dose inhaler (MDI) formulations was assessed to clarify the use of GPSD to estimate the APSD. The size distribution of particles discharged from four suspension and four solution MDIs was measured using the Inas®100 light-scattering spectrometer and a Next Generation Impactor. The conversion factor was calculated by measuring the GPSD and APSD of MDIs. The morphology and physical properties of MDIs were studied using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Six of the eight MDIs showed similar conversion factor profiles, irrespective of their composition and formulation types. Applying the conversion factor obtained from one of the six MDIs resulted in a particle size distribution comparable to each APSD except for some formulations. The two other solution MDIs, which contained citric acid, had much higher and variable conversion factors. SEM images and DSC scans of the solids obtained by nebulization of the solutions containing beclomethasone and/or citric acid showed the formation of a paste-like amorphous solid. These results indicated that APSD of solution and suspension MDIs that form rigid particles may be estimated by using the conversion factor and GPSD. Contrarily, the estimation is more difficult in formulations that tend to lose the particle structure during the measurement.

Inhaled chemotherapy adverse effects: mechanisms and protection methods

Lung cancer is still diagnosed at a late stage due to a lack of symptoms. Although there are novel therapies, many patients are still treated with chemotherapy. In an effort to reduce adverse effects associated with chemotherapy, inhaled administration of platinum analogs has been investigated. Inhaled administration is used as a local route in order to reduce the systemic adverse effects; however, this treatment modality has its own adverse effects. In this mini review, we present drugs that were administered as nebulized droplets or dry powder aerosols for non-small-cell lung cancer. We present the adverse effects and methods to overcome them.

Size Distribution of Colistin Delivery by Different Type Nebulizers and Concentrations During Mechanical Ventilation

Although aerosol delivery through mechanical ventilators has been used to administer various medications, little is known of administration with colistin. This in vitro evaluation aimed to evaluate size distribution of colistin delivery by different types of nebulizers and concentrations during mechanical ventilation. Colistin methanesulfonate (colistin) for injection was dissolved in 6 mL of distilled water to produce a low concentration (L; 156 mg) and a high concentration (H; 312 mg). A dose volume of 6 mL was placed in a vibrating mesh nebulizer (VMN) and a jet nebulizer (JN). The inhaled mass (mean ± SD) of the VMN-L (53.80 ± 14.79 mg) was greater than both the JN-L (19.82 ± 3.34 mg, P = 0.001) and JN-H (31.72 ± 4.48 mg, P = 0.017). The nebulization time of the VMN-L (42.35 ± 2.30 min) was two times longer than the JN-L (21.12 ± 0.8 min) or JN-H (21.65 ± 0.42 min; P < 0.001). The mass median aerodynamic distal to the endotracheal tube was within a similar range at 2.03 to 2.26 μm (P = 0.434), independent of neb or formulation concentration. In conclusion, the VMN-L yields greater inhaled mass than the JN with either concentration. Therefore, a standard nominal dose of colistin results in a higher delivered dose during mechanical ventilation with a VMN compared with a JN and may be considered the preferred device. If JN must be used, multiple doses of low concentration colistin may compensate for poor delivery performance.

Aerosol Therapy for Pneumonia in the Intensive Care Unit

Antibiotic aerosolization in patients with ventilator-associated pneumonia (VAP) allows very high concentrations of antimicrobial agents in the respiratory secretions, far more than those achievable using the intravenous route. However, data in critically ill patients with pneumonia are limited. Administration of aerosolized antibiotics might increase the likelihood of clinical resolution, but no significant improvements in important outcomes have been consistently documented. Thus, aerosolized antibiotics should be restricted to the treatment of extensively resistant gram-negative pneumonia. In these cases, the use of a vibrating-mesh nebulizer seems to be more efficient, but specific settings and conditions are required to improve lung delivery.

Inhaled Cisplatin for NSCLC: Facts and Results

Although we have new diagnostic tools for non-small cell lung cancer, diagnosis is still made in advanced stages of the disease. However, novel treatments are being introduced in the market and new ones are being developed. Targeted therapies and immunotherapy have brought about a bloom in the treatment of non-small cell lung cancer. Still we have to find ways to administer drugs in a more efficient and safe method. In the current review, we will focus on the administration of inhaled cisplatin based on published data.

Acute effects of hypertonic saline inhalation on nitric oxide pulmonary diffusing capacity in healthy adults

We investigated acute effects of inhalation of hypertonic saline solution (HSS) and oxygen (O₂, control exposure) on pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO). In a randomized crossover study, 20 healthy, non-smoking subjects were allocated to short-term inhalation of HSS or O₂. Spirometry [(forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC)] and combined single-breath DLNO-DLCO measurements were performed before and immediately after inhalation of either HSS or O₂. Percent changes were presented as median values (interquartile range). After HSS inhalation, DLNO, FEV₁ and FVC were decreased by -3.0% (-7.3, 0.5), -3.1% (-4.2, -1.6) and -1.2% (-3.3, 0.6), respectively (all P < 0.05), without significant effect on DLCO. No changes in spirometry and diffusing capacity were observed following O₂ inhalation. Acute inhalation of HSS causes a slight decrease in membrane conductance, probably as a result of fluid imbalance at the alveolar surface and interstitial fluid accumulation, both of which could impair gas exchange.

Nebulization of Cyclic Arginine-Glycine-(D)-Aspartic Acid-Peptide Grafted and Drug Encapsulated Liposomes for Inhibition of Acute Lung Injury

PURPOSE

Acute lung injury (ALI) is a fatal syndrome in critically ill patients. It is characterized by lung edema and inflammation. Numerous pro-inflammatory mediators are released into alveoli. Among them, interleukin-1beta (IL-1β) causes an increase in solute permeability across the alveolar-capillary barrier leading to edema. It activates key effector cells (alveolar epithelial and endothelial cells) releasing inflammatory chemokines and cytokines. The purpose of the study was to demonstrate that nebulized liposomes inhibit ALI in vivo.

METHODS

In vivo ALI model was simulated through intra-tracheal instillation of IL-1β solution (100 μg/mL in PBS, pH 7.2, 200 μL) in male Sprague-Dawley rats. Various formulations were tested in ALI induced rats. These formulations include plain liposomes (PL), methylprednisolone sodium succinate solution (MPS solution), cRGD-peptide grafted liposomes (L^cRGD) and methylprednisolone sodium succinate encapsulated and cRGD-peptide grafted liposomes (MPS-L^cRGD). Formulations were nebulized in vivo in rats using micro-pump nebulizer.

RESULTS

Liposome formulations exhibited higher levels of drug concentration in lungs. The physicochemical parameters demonstrated that the liposome formulations were stable. On the basis of aerodynamic droplet-size, nebulized formulations were estimated to deposit in different regions of respiratory tract, especially alveolar region, Among the formulations, MPS-L^cRGD caused significant reduction of edema, neutrophil infiltration and inflammation biochemical marker levels.

CONCLUSION

From the results, it can be inferred that nebulization of targeted liposomes had facilitated spatial and temporal modulation of drug delivery resulting in alleviation of ALI.

The analysis of pneumatic atomization of Newtonian and non-Newtonian fluids for different medical nebulizers

OBJECTIVE

The article contains results of the experimental studies on atomization process of inhaled drugs and aqueous solutions of glycerol with aqueous solutions of glycerol polyacrylamide (Rokrysol WF1) in pneumatic nebulizers. In experiments, the different concentration of aqueous solutions of glycerol polyacrylamide have been tested. In addition, the effect of nebulizer design on atomization process has been determined. The one of the main elements of medical pneumatic nebulizer is nebulizer cup.

SIGNIFICANCE

The experiment with this scope is new and is very important from the point of view of aerosol therapy.

METHODS

The results have been obtained by the use of the digital microphotography technique. In order to determine a physicochemical properties of tested liquids, a rheological measurements and measurements of the surface tension were carried out.

RESULTS

The differences between characteristics of aerosol for the liquids have been observed. The analysis of the droplets size distributions shows that the different diameters of droplets for Newtonian and non-Newtonian fluids have been formed during atomization in pneumatic nebulizers equipped with different nebulizer cups. The effect of the mouthpiece location on the droplets diameters has been shown.

CONCLUSIONS

Precise design of nebulizer and nebulizer cups, and also physicochemical properties of atomized liquids are of high importance in order to the effectiveness of drug delivery to patient's respiratory tracts.

Estimation of critical supersaturation solubility ratio for predicting diameters of dry particles prepared by air-jet atomization of solutions

Air-jet atomization of solution into droplets followed by controlled drying is increasingly being used for producing nanoparticles for drug delivery applications. Nanoparticle size is an important parameter that influences the stability, bioavailability and efficacy of the drug. In air-jet atomization technique, dry particle diameters are generally predicted by using solute diffusion models involving the key concept of critical supersaturation solubility ratio (Sc) that dictates the point of crust formation within the droplet. As no reliable method exists to determine this quantity, the present study proposes an aerosol based method to determine Sc for a given solute-solvent system and process conditions. The feasibility has been demonstrated by conducting experiments for stearic acid in ethanol and chloroform as well as for anti-tubercular drug isoniazid in ethanol. Sc values were estimated by combining the experimentally observed particle and droplet diameters with simulations from a solute diffusion model. Important findings of the study were: (i) the measured droplet diameters systematically decreased with increasing precursor concentration (ii) estimated Sc values were 9.3±0.7, 13.3±2.4 and 18±0.8 for stearic acid in chloroform, stearic acid and isoniazid in ethanol respectively (iii) experimental results pointed at the correct interfacial tension pre-factor to be used in theoretical estimates of Sc and (iv) results showed a consistent evidence for the existence of induction time delay between the attainment of theoretical Sc and crust formation. The proposed approach has been validated by testing its predictive power for a challenge concentration against experimental data. The study not only advances spray-drying technique by establishing an aerosol based approach to determine Sc, but also throws considerable light on the interfacial processes responsible for solid-phase formation in a rapidly supersaturating system. Until satisfactory theoretical formulae for predicting CSS are developed, the present approach appears to offer the best option for engineering nanoparticle size through solute diffusion models.

Key considerations on nebulization of antimicrobial agents to mechanically ventilated patients

Nebulized antibiotics have an established role in patients with cystic fibrosis or bronchiectasis. Their potential benefit to treat respiratory infections in mechanically ventilated patients is receiving increasing interest. In this consensus statement of the European Society of Clinical Microbiology and Infectious Diseases, the body of evidence of the therapeutic utility of aerosolized antibiotics in mechanically ventilated patients was reviewed and resulted in the following recommendations: Vibrating-mesh nebulizers should be preferred to jet or ultrasonic nebulizers. To decrease turbulence and limit circuit and tracheobronchial deposition, we recommend: (a) the use of specifically designed respiratory circuits avoiding sharp angles and characterized by smooth inner surfaces, (b) the use of specific ventilator settings during nebulization including use of a volume controlled mode using constant inspiratory flow, tidal volume 8 mL/kg, respiratory frequency 12 to 15 bpm, inspiratory:expiratory ratio 50%, inspiratory pause 20% and positive end-expiratory pressure 5 to 10 cm H₂O and (c) the administration of a short-acting sedative agent if coordination between the patient and the ventilator is not obtained, to avoid patient's flow triggering and episodes of peak decelerating inspiratory flow. A filter should be inserted on the expiratory limb to protect the ventilator flow device and changed between each nebulization to avoid expiratory flow obstruction. A heat and moisture exchanger and/or conventional heated humidifier should be stopped during the nebulization period to avoid a massive loss of aerosolized particles through trapping and condensation. If these technical requirements are not followed, there is a high risk of treatment failure and adverse events in mechanically ventilated patients receiving nebulized antibiotics for pneumonia.

Influence of concentration on distribution properties of stretched-DNA in the MEC studied with fluorescence imaging and drop shape analyzing

Stretching and manipulating DNA efficiently is significant for exploring the properties and applications of single DNA molecules. Here, the influence of concentrations of buffer and DNA on properties of stretched DNA molecules in the molecular evaporation combing (MEC) is investigated systematically with the single molecule fluorescence imaging microscopy and the high-precision drop shape analyzing technology. The stretched degree and uniformity of combed DNA molecules decrease as the buffer concentration are increased from 7 to 20mM. When the buffer concentration changes from 12 to 15mM, the stretched DNA molecules are apt to form a ringlike pattern. During the MEC process, there exist two kinds of evaporation modes, i.e., the constant contact angle mode and the constant contact radius mode. The former only takes effect in the lower concentration of buffer and DNA, enabling the uniform stretching. While the latter plays the leading role in the higher concentration, promoting the formation of the ringlike pattern of DNA molecules.

Cytotoxic effect of different treatment parameters in pressurized intraperitoneal aerosol chemotherapy (PIPAC) on the in vitro proliferation of human colonic cancer cells

Background

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) has been recently reported as a new approach for intraperitoneal chemotherapy (IPC). By means of a patented micropump, the liquid chemotherapy is delivered into the peritoneal cavity as an aerosol which is supposed to achieve “gas-like” distribution. However, recent data report that the fraction of the submicron aerosol (gas-like) is less than 3 vol% of the total amount of aerosolized chemotherapy. Until today, possible modifications of treatment parameters during PIPAC with the aim of improving therapeutic outcomes have not been studied yet.

This study aims to establish an in vitro PIPAC model to explore the cytotoxic effect of the submicron aerosol fraction and to investigate the impact of different application parameters on the cytotoxic effect of PIPAC on human colonic cancer cells.

Methods

An in vitro model using HCT8 colon adenocarcinoma wild-type cells (HCT8^WT) and multi-chemotherapy refractory subline (HCT8^RT) was established. Different experimental parameters such as pressure, drug dosage, time exposure, and system temperature were monitored in order to search for the conditions with a higher impact on cell toxicity. Cell proliferation was determined by means of colorimetric MTT assay 48 h following PIPAC exposures.

Results

Standard operational parameters applied for PIPAC therapy depicted a cytotoxic effect of the submicron aerosol fraction generated by the PIPAC micropump. We also observed that increasing pressure significantly enhanced tumor cell toxicity in both wild-type and chemotherapy-resistant cells. A maximum of cytotoxicity was observed at 15 mmHg. Pressure >15 mmHg did not show additional cytotoxic effect on cells. Increased oxaliplatin dosage resulted in progressively higher cell toxicity as expected. However, in resistant cells, a significant effect was only found at higher drug concentrations. Neither an extension of exposure time nor an increase in temperature of the aerosolized chemotherapy solution added an improvement in cytotoxicity.

Conclusions

In this in vitro PIPAC model, the gas-like PIPAC aerosol fraction showed a cytotoxic effect which was enhanced by higher intra-abdominal pressure with a maximum at 15 mmHg. Similar findings were observed for drug dose escalation. A phase I dose escalation study is currently performed at our institution. However, increasing the intra-abdominal pressure might be a first and simple way to enhance the cytotoxic effect of PIPAC therapy which needs further clinical investigations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12957-017-1109-4) contains supplementary material, which is available to authorized users.

Inhalation Properties and Stability of Nebulized Naked siRNA Solution for Pulmonary Therapy

The use of naked unmodified small interfering RNA (N-siRNA) without vector has previously been investigated as a pulmonary therapy. However, little is known regarding stabilities and aerodynamic particle sizes of N-siRNA-containing droplets; nebulizers have not yet been optimized for N-siRNA solutions. Thus, in this study, we investigated the feasibility of inhaled N-siRNA solutions for pulmonary therapy using nebulization. Various nebulizers and N-siRNA concentrations were assessed in terms of siRNA integrity after nebulization, and inhalation properties including aerodynamic particle size were examined. In comparison with ultrasonic-, air-jet-, and vibrating-mesh nebulizers, N-siRNA integrity was not affected by nebulization. Thus, in further experiments, performances of N-siRNA aerosols with different nebulizers and N-siRNA concentrations were evaluated and screened using an aerodynamic particle sizer (APS) which employed the time-of-flight principle or a cascade impactor. Mean mass aerodynamic diameters of N-siRNA-containing droplets from vibrating-mesh nebulizers tended to decrease with increasing N-siRNA concentrations, reflecting the influence of N-siRNA solutions on surface tension, as indicated by contact angles. These data indicate the utility of APS instruments for investigating the nebulized characteristics of expensive drugs including siRNAs and may facilitate the development of N-siRNA inhalation formulations.