Pulmonary Drug Delivery System for inhalation therapy in mechanically ventilated patients

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.

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.

The Use of an Inspiration-Synchronized Vibrating Mesh Nebulizer for Prolonged Inhalative Iloprost Administration in Mechanically Ventilated Patients-An In Vitro Model

Mechanically ventilated patients suffering from acute respiratory distress syndrome (ARDS) frequently receive aerosolized iloprost. Because of prostacyclin's short half-life, prolonged inhalative administration might improve its clinical efficacy. But, this is technically challenging. A solution might be the use of inspiration-synchronized vibrating mesh nebulizers (VMNsyn), which achieve high drug deposition rates while showing prolonged nebulization times. However, there are no data comparing prolonged to bolus iloprost nebulization using a continuous vibrating mesh nebulizer (VMNcont) and investigating the effects of different ventilation modes on inspiration-synchronized nebulization. Therefore, in an in vitro model of mechanically ventilated adults, a VMNsyn and a VMNcont were compared in volume-controlled (VC-CMV) and pressure-controlled continuous mandatory ventilation (PC-CMV) regarding iloprost deposition rate and nebulization time. During VC-CMV, the deposition rate of the VMNsyn was comparable to the rate obtained with the VMNcont, but 10.9% lower during PC-CMV. The aerosol output of the VMNsyn during both ventilation modes was significantly lower compared to the VMNcont, leading to a 7.5 times longer nebulization time during VC-CMV and only to a 4.2 times longer nebulization time during PC-CMV. Inspiration-synchronized nebulization during VC-CMV mode therefore seems to be the most suitable for prolonged inhalative iloprost administration in mechanically ventilated patients.

Not all nebulizers are created equal: Considerations in choosing a nebulizer for aerosol delivery during mechanical ventilation

INTRODUCTION

Aerosol therapy is commonly prescribed in the mechanically ventilated patient. Jet nebulizers (JN) and vibrating mesh nebulizers (VMN) are the most common nebulizer types, however, despite VMN's well established superior performance, JN use remains the most commonly used of the two. In this review, we describe the key differentiators between nebulizer types and how considered selection of nebulizer type may enable successful therapy and the optimization of drug/device combination products.

AREAS COVERED

Following a review of the published literature up to February 2023, the current state of the art in relation to JN and VMN is discussed under the headings of in vitro performance of nebulizers during mechanical ventilation, respective compatibility with formulations for inhalation, clinical trials making use of VMN during mechanical ventilation, distribution of nebulized aerosol throughout the lung, measuring the respective performance of nebulizers in the patient and non-drug delivery considerations in nebulizer choice.

EXPERT OPINION

Whether for standard care, or the development of drug/device combination products, the choice of nebulizer type should not be made without consideration of the unique needs of the combination of each of drug, disease and patient types, as well as target site for deposition, and healthcare professional and patient safety.

Exploring pulmonary distribution of intratracheally instilled liquid foams in excised porcine lungs

The applicability of inhalation therapy to some severe pulmonary conditions is often compromised by limited delivery rates (i.e. total dose) and low deposition efficiencies in the respiratory tract, most notably in the deep pulmonary acinar airways. To circumvent such limitations, alternative therapeutic techniques have relied for instance on intratracheal liquid instillations for the delivery of high-dose therapies. Yet, a longstanding mechanistic challenge with such latter methods lies in delivering solutions homogeneously across the whole lungs, despite an inherent tendency of non-uniform spreading driven mainly by gravitational effects. Here, we hypothesize that the pulmonary distribution of instilled liquid solutions can be meaningfully improved by foaming the solution prior to its instillation, owing to the increased volume and the reduced gravitational bias of foams. As a proof-of-concept, we show in excised adult porcine lungs that liquid foams can lead to significant improvement in homogenous pulmonary distributions compared with traditional liquid instillations. Our ex-vivo results suggest that liquid foams can potentially offer an attractive novel pulmonary delivery modality with applications for high-dose regimens of respiratory therapeutics.

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.

Nebulized antibiotics for ventilator-associated pneumonia: methodological framework for future multicenter randomized controlled trials

PURPOSE OF REVIEW

Although experimental evidence supports the use of nebulized antibiotics in ventilator-associated pneumonia (VAP), two recent multicenter randomized controlled trials (RCTs) have failed to demonstrate any benefit in VAP caused by Gram-negative bacteria (GNB). This review examines the methodological requirements concerning future RCTs.

RECENT FINDINGS

High doses of nebulized antibiotics are required to reach the infected lung parenchyma. Breath-synchronized nebulizers do not allow delivery of high doses. Mesh nebulizers perform better than jet nebulizers. Epithelial lining fluid concentrations do not reflect interstitial lung concentrations in patients receiving nebulized antibiotics. Specific ventilator settings for optimizing lung deposition require sedation to avoid patient's asynchrony with the ventilator.

SUMMARY

Future RCTs should compare a 3-5 day nebulization of amikacin or colistimethate sodium (CMS) to a 7-day intravenous administration of a new cephalosporine/ß-lactamase inhibitor. Inclusion criteria should be a VAP or ventilator-associated tracheobronchitis caused by documented extensive-drug or pandrug resistant GNB. If the GNB remains susceptible to aminoglycosides, nebulized amikacin should be administered at a dose of 40 mg/kg/day. If resistant to aminoglycosides, nebulized CMS should be administered at a dose of 15 millions international units (IU)/day. In VAP caused by pandrug-resistant GNB, 15 millions IU/day nebulized CMS (substitution therapy) should be compared with a 9 millions IU/day intravenous CMS.

The Clinical Practice and Best Aerosol Delivery Location in Intubated and Mechanically Ventilated Patients: A Randomized Clinical Trial

This randomized clinical trial (RCT) is aimed at exploring the best nebulizer position for aerosol delivery within the mechanical ventilation (MV) circuitry. This study enrolled 75 intubated and MV patients with respiratory failure and randomly divided them into three groups. The nebulizer position of patients in group A was between the tracheal tube and Y-piece. For group B, the nebulizer was placed at the inspiratory limb near the ventilator water cup (80 cm away from the Y-piece). For group C, the nebulizer was placed between the ventilator inlet and the heated humidifier. An indirect competitive enzyme-linked immunosorbent assay (ELISA) was used to measure salbutamol drug concentrations in serum and urine. The serum and urine salbutamol concentrations of the three groups were the highest in group B, followed by group C, and the lowest in group A. Serum and urine salbutamol concentrations significantly differed among the three groups (P < 0.05). It was found that the drug was statistically significant between group differences for groups B and A (P = 0.001; P = 0.002, respectively) for both serum and urine salbutamol concentrations. There were no significant differences observed among the other groups. It was found that the drug concentrations were the highest when the nebulizer was placed 80 cm away from the Y-piece, while the location between the tracheal tube and the Y-piece with the higher frequency of nebulizer placement was the location with the lowest drug concentration.

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.

Knowledge and current practices of ICU nurses regarding aerosol therapy for patients treated with invasive mechanical ventilation: a nationwide cross-sectional study

BACKGROUND

Aerosol therapy is a routine operation for intensive care unit (ICU) nurses; however, evidence of the knowledge and current practices of ICU nurses regarding aerosol therapy for patients with invasive mechanical ventilation is insufficient in China.

OBJECTIVE

This study aimed to determine the knowledge and current practices of ICU nurses regarding aerosol therapy for patients with invasive mechanical ventilation in China.

SETTING

A total of 433 hospitals in 92 cities (including 31 capital cities) in 31 provinces in China participated in the study.

METHODS

A questionnaire was used to investigate the knowledge and current practices of ICU nurses regarding aerosol therapy for patients treated with invasive mechanical ventilation, including 42 questions covering five aspects: sociodemographic information, aerosolization devices, atomised drugs, atomisation operation, and atomisation-related knowledge. Descriptive analyses of the distribution of the sample are reported as percentages and medians. Univariate and multivariate analysis was used to detect the factors of the interviewee's atomisation knowledge and practices scores. A STROBE checklist was used to guide the reporting of the research.

RESULTS

Of the 1,995 questionnaires that were returned, 1,978 were analysed. Bronchodilators and glucocorticoids were the most frequently administered drugs. Seventy-four percent of the total respondents reported placing a filter on the expiratory limb during aerosol therapy, and 47% of these reported that the filter was changed once a day. Only 13% of the respondents reported always turning the heating humidifier off during aerosol therapy, and 48% never did. Knowledge about the optimal droplet size or atomisation yield was poor. Work experience in the ICU and frequency of atomisation training were the independent influencing factors for atomisation knowledge and practice scores (F=279.653, P<0.001; F=120.556, P<0.001, respectively).

CONCLUSIONS

The knowledge of ICU nurses about the optimal implementation of aerosol therapy is poor, and the current scientific knowledge about optimal implementation seemed to be applied infrequently. Atomisation-related training should be strengthened, especially for nurses with junior titles and with less work experience.

RELEVANCE TO CLINICAL PRACTICE

Improving the level of ICU nurses' atomization practice ability is helpful to ensure patient safety. In clinical work, atomization expert consensus can be used to carry out relevant training and standardize atomization operation.

Future Trends in Nebulized Therapies for Pulmonary Disease

Aerosol therapy is a key modality for drug delivery to the lungs of respiratory disease patients. Aerosol therapy improves therapeutic effects by directly targeting diseased lung regions for rapid onset of action, requiring smaller doses than oral or intravenous delivery and minimizing systemic side effects. In order to optimize treatment of critically ill patients, the efficacy of aerosol therapy depends on lung morphology, breathing patterns, aerosol droplet characteristics, disease, mechanical ventilation, pharmacokinetics, and the pharmacodynamics of cell-drug interactions. While aerosol characteristics are influenced by drug formulations and device mechanisms, most other factors are reliant on individual patient variables. This has led to increased efforts towards more personalized therapeutic approaches to optimize pulmonary drug delivery and improve selection of effective drug types for individual patients. Vibrating mesh nebulizers (VMN) are the dominant device in clinical trials involving mechanical ventilation and emerging drugs. In this review, we consider the use of VMN during mechanical ventilation in intensive care units. We aim to link VMN fundamentals to applications in mechanically ventilated patients and look to the future use of VMN in emerging personalized therapeutic drugs.

Inhaled amikacin adjunctive to intravenous standard-of-care antibiotics in mechanically ventilated patients with Gram-negative pneumonia (INHALE): a double-blind, randomised, placebo-controlled, phase 3, superiority trial

BACKGROUND

Treatment of ventilated pneumonia is often unsuccessful, even when patients are treated according to established guidelines. Therefore, we aimed to investigate the efficacy of the combination drug device Amikacin Inhale as an adjunctive therapy to intravenous standard-of-care antibiotics for pneumonia caused by Gram-negative pathogens in intubated and mechanically ventilated patients.

METHODS

INHALE was a prospective, double-blind, randomised, placebo-controlled, phase 3 study comprising two trials (INHALE 1 and INHALE 2) done in 153 hospital intensive-care units in 25 countries. Eligible patients were aged 18 years or older; had pneumonia that had been diagnosed by chest radiography and that was documented as being caused by or showing two risk factors for a Gram-negative, multidrug-resistant pathogen; were intubated and mechanically ventilated; had impaired oxygenation within 48 h before screening; and had a modified Clinical Pulmonary Infection Score of at least 6. Patients were stratified by region and disease severity (according to their Acute Physiology and Chronic Health Evaluation [APACHE] II score) and randomly assigned (1:1) via an interactive voice-recognition system to receive 400 mg amikacin (Amikacin Inhale) or saline placebo, both of which were aerosolised, administered every 12 h for 10 days via the same synchronised inhalation system, and given alongside standard-of-care intravenous antibiotics. All patients and all staff involved in administering devices and monitoring outcomes were masked to treatment assignment. The primary endpoint, survival at days 28-32, was analysed in all patients who received at least one dose of study drug, were infected with a Gram-negative pathogen, and had an APACHE II score of at least 10 at diagnosis. Safety analyses were done in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, numbers NCT01799993 and NCT00805168.

FINDINGS

Between April 13, 2013, and April 7, 2017, 807 patients were assessed for eligibility and 725 were randomly assigned to Amikacin Inhale (362 patients) or aerosolised placebo (363 patients). 712 patients received at least one dose of study drug (354 in the Amikacin Inhale group and 358 in the placebo group), although one patient assigned to Amikacin Inhale received placebo in error and was included in the placebo group for safety analyses. 508 patients (255 in the Amikacin Inhale group and 253 in the placebo group) were assessed for the primary endpoint. We found no between-group difference in survival: 191 (75%) patients in the Amikacin Inhale group versus 196 (77%) patients in the placebo group survived until days 28-32 (odds ratio 0·841, 95% CI 0·554-1·277; p=0·43). Similar proportions of patients in the two treatment groups had a treatment-emergent adverse event (295 [84%] of 353 patients in the Amikacin Inhale group vs 303 [84%] of 359 patients in the placebo group) or a serious treatment-emergent adverse event (101 [29%] patients vs 97 [27%] patients).

INTERPRETATION

Our findings do not support use of inhaled amikacin adjunctive to standard-of-care intravenous therapy in mechanically ventilated patients with Gram-negative pneumonia.

FUNDING

Bayer AG.

Vibrating Mesh Nebulisation of Pro-Antimicrobial Peptides for Use in Cystic Fibrosis

Background: There has been considerable interest in the use of antimicrobial peptides (AMPs) as antimicrobial therapeutics in many conditions including cystic fibrosis (CF). The aim of this study is to determine if the prodrugs of AMPs (pro-AMPs) can be delivered to the lung by a vibrating mesh nebuliser (VMN) and whether the pro-AMP modification has any effect on delivery. Methods: Physical characteristics of the peptides (AMP and pro-AMP) and antimicrobial activity were compared before and after nebulisation. Droplet size distribution was determined by laser diffraction and cascade impaction. Delivery to a model lung was determined in models of spontaneously-breathing and mechanically-ventilated patients. Results: The physical characteristics and antimicrobial activities were unchanged after nebulisation. Mean droplet size diameters were below 5 μm in both determinations, with the fine particle fraction approximately 67% for both peptides. Approximately 25% of the nominal dose was delivered in the spontaneously-breathing model for both peptides, with higher deliveries observed in the mechanically-ventilated model. Delivery times were approximately 170 s per mL for both peptides and the residual volume in the nebuliser was below 10% in nearly all cases. Conclusions: These results demonstrate that the delivery of (pro-)AMPs to the lung using a VMN is feasible and that the prodrug modification is not detrimental. They support the further development of pro-AMPs as therapeutics in CF.

Antibacterial Activity of Human Simulated Epithelial Lining Fluid Concentrations of Ceftazidime-Avibactam Alone or in Combination with Amikacin Inhale (BAY41-6551) against Carbapenem-Resistant Pseudomonas aeruginosa and Klebsiella pneumoniae

The role of inhalational combination therapy when treating carbapenem-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae with newer beta-lactam/beta-lactamase inhibitors has not been established. Using a 72-h in vitro pharmacodynamic chemostat model, we simulated the human exposures achieved in epithelial lining fluid (ELF) following intravenous treatment with ceftazidime-avibactam (CZA) 2.5 g every 8 h (q8h) alone and in combination with inhaled amikacin (AMK-I) 400 mg q12h, a reformulated aminoglycoside designed for inhalational administration, against three P. aeruginosa isolates (CZA [ceftazidime/avibactam] MICs, 4/4 to 8/4 μg/ml; AMK-I MICs, 8 to 64 μg/ml) and three K. pneumoniae isolates (CZA MICs, 1/4 to 8/4 μg/ml; AMK-I MICs, 32 to 64 μg/ml). Combination therapy resulted in a significant reduction in 72-h CFU compared with that of CZA monotherapy against two of three P. aeruginosa isolates (-4.14 log₁₀ CFU/ml, P = 0.027; -1.42 log₁₀ CFU/ml, P = 0.020; and -0.4 log₁₀ CFU/ml, P = 0.298) and two of three K. pneumoniae isolates (0.04 log₁₀ CFU/ml, P = 0.963; -4.34 log₁₀ CFU/ml, P < 0.001; and -2.34 log₁₀ CFU/ml, P = 0.021). When measured by the area under the bacterial growth curve (AUBC) over 72 h, significant reductions were observed in favor of the combination regimen against all six isolates tested. AMK-I combination therapy successfully suppressed CZA resistance development in one K. pneumoniae isolate harboring bla_KPC-3 that was observed during CZA monotherapy. These studies suggest a beneficial role for combination therapy with intravenous CZA and inhaled AMK when treating pneumonia caused by carbapenem-resistant Gram-negative bacteria.

Nebulized antibiotics in mechanically ventilated patients: a challenge for translational research from technology to clinical care

Nebulized antibiotic therapy directly targets airways and lung parenchyma resulting in high local concentrations and potentially lower systemic toxicities. Experimental and clinical studies have provided evidence for elevated lung concentrations and rapid bacterial killing following the administration of nebulized antibiotics during mechanical ventilation. Delivery of high concentrations of antibiotics to infected lung regions is the key to achieving efficient nebulized antibiotic therapy. However, current non-standardized clinical practice, the difficulties with implementing optimal nebulization techniques and the lack of robust clinical data have limited its widespread adoption. The present review summarizes the techniques and clinical constraints for optimal delivery of nebulized antibiotics to lung parenchyma during invasive mechanical ventilation. Pulmonary pharmacokinetics and pharmacodynamics of nebulized antibiotic therapy to treat ventilator-associated pneumonia are discussed and put into perspective. Experimental and clinical pharmacokinetics and pharmacodynamics support the use of nebulized antibiotics. However, its clinical benefits compared to intravenous therapy remain to be proved. Future investigations should focus on continuous improvement of nebulization practices and techniques. Before expanding its clinical use, careful design of large phase III randomized trials implementing adequate therapeutic strategies in targeted populations is required to demonstrate the clinical effectiveness of nebulized antibiotics in terms of patient outcomes and reduction in the emergence of antibiotic resistance.

Anti-staphylococcal activity resulting from epithelial lining fluid (ELF) concentrations of amikacin inhale administered via the pulmonary drug delivery system

Background

Amikacin inhale (BAY41-6551), a unique drug—device combination of a specially formulated drug solution and a pulmonary drug delivery system device (AMK-I) is currently under phase III study as an adjunctive therapy to IV antibiotics for the treatment of Gram-negative pneumonia in mechanically ventilated patients. While the epidemiology of nosocomial pneumonia is predominated by Gram-negative pathogens such as Pseudomonas aeruginosa and the Enterobacteriaceae, Staphylococcus aureus is increasingly recognized as a pathogen of concern for these pulmonary based infections. Since the aminoglycosides are historically quite active against S. aureus the use of adjunctive AMK-I may enhance bacterial eradication. Herein, we aimed to characterize the in vitro pharmacodynamic (PD) profile of human-simulated ELF exposures of AMK-I against both methicillin-sensitive (MSSA) and -resistant (MRSA) S. aureus.

Methods

An in vitro model was used to simulate the resultant ELF pharmacokinetic profile of amikacin after the administration of AMK-I 400 mg q12h. The antibacterial activity of this regimen was tested against 7 S. aureus isolates that display MIC profiles encountered clinically (4 MRSA; MIC range 4–64, 3 MSSA; MIC range 8–16 mg/L). Experiments were conducted over 24 h and samples were taken throughout this period to assess the bacterial density in both control and treatments.

Results

The mean ± SD inoculum 0 h bacterial density was 6.4 ± 0.09 which increased to 8.6 ± 0.19 log₁₀ CFU/mL in the control models by the end of 24 h experiments. Simulated ELF concentrations of AMK-I resulted in a rapid, 5 log₁₀ declined in CFU over the initial 12 h for all MRSA and MSSA isolates. After 12 h, all bacterial counts remained below the limit of detection (LOD, 1.7 log₁₀ CFU/mL) and no regrowth was evident at the end of the study.

Conclusion

AMK-I produced an ELF exposure profile that was rapidly bactericidal against S. aureus displaying typical MICs to amikacin irrespective of their phenotypic profile to methicillin. While the Gram-negative organisms are the target pathogens for AMK-I in the ongoing clinical trials, these data suggest that this adjunctive regimen may also have the potential to eradicate both MSSA and MRSA from lower airway which needs to be further evaluated in randomized-controlled clinical trials.

In Vitro Comparison of a Vibrating Mesh Nebulizer Operating in Inspiratory Synchronized and Continuous Nebulization Modes During Noninvasive Ventilation

Backround: Coupling nebulization with noninvasive ventilation (NIV) has been shown to be effective in patients with respiratory diseases. However, a breath-synchronized nebulization option that could potentially improve drug delivery by limiting drug loss during exhalation is currently not available on bilevel ventilators. The aim of this in vitro study was to compare aerosol delivery of amikacin with a vibrating mesh nebulizer coupled to a single-limb circuit bilevel ventilator, using conventional continuous (Conti-Neb) and experimental inspiratory synchronized (Inspi-Neb) nebulization modes.

METHODS

Using an adult lung bench model of NIV, we tested a vibrating mesh device coupled with a bilevel ventilator in both nebulization modes. Inspi-Neb delivered aerosol only during the whole inspiratory phase, whereas Conti-Neb delivered aerosol continuously. The nebulizer was charged with amikacin solution (250 mg/3 mL) and placed at two different positions: between the lung and exhalation port and between the ventilator and exhalation port. Inhaled, expiratory wasted and circuit lost doses were assessed by residual gravimetric method. Particle size distribution of aerosol delivered at the outlet of the ventilator circuit during both nebulization modes was measured by laser diffraction method.

RESULTS

Regardless of the nebulizer position, Inspi-Neb produced higher inhaled dose (p < 0.01; +6.3% to +16.8% of the nominal dose), lower expiratory wasted dose (p < 0.05; -2.7% to -42.6% of the nominal dose), and greater respirable dose (p < 0.01; +8.4% to +15.2% of the nominal dose) than Conti-Neb. The highest respirable dose was found with the nebulizer placed between the lung and exhalation port (48.7% ± 0.3% of the nominal dose).

CONCLUSIONS

During simulated NIV with a single-limb circuit bilevel ventilator, the use of inspiratory synchronized vibrating mesh nebulization improves respirable dose and reduces drug loss of amikacin compared with continuous vibrating mesh nebulization.

Antibacterial activity of achievable epithelial lining fluid exposures of Amikacin Inhale with or without meropenem

OBJECTIVES

While Amikacin Inhale (BAY41-6551), an integrated drug-device combination under development, achieves an estimated amikacin epithelial lining fluid (ELF) concentration of ∼ 5000 mg/L, its target site pharmacodynamics are unknown. We evaluated the pharmacodynamics of ELF exposure of inhaled amikacin ± meropenem.

METHODS

ELF exposures of inhaled amikacin (400 mg every 12 h), intravenous meropenem (2 g every 8 h) and a combination of both were studied in an in vitro pharmacodynamic model. Seven Klebsiella pneumoniae and 10 Pseudomonas aeruginosa with amikacin/meropenem MICs of 1 to 32,768/≤ 0.125 to >128 mg/L were included. Efficacy was assessed over 24-72 h.

RESULTS

The mean ± SD 0 h bacterial density was 6.5 ± 0.1 log10 cfu/mL. Controls grew to 8.0 ± 0.5 log10 cfu/mL by the end of the experiments. Simulation of inhaled amikacin monotherapy rapidly achieved and sustained bactericidal activity near the limit of detection over 24 h for all 13 isolates with amikacin MIC ≤ 256 mg/L except only ∼ 2 log10 cfu/mL reduction was observed in K. pneumoniae 375 (amikacin/meropenem MIC 64/32 mg/L) and P. aeruginosa 1544 (amikacin/meropenem MIC 64/128 mg/L). No activity was seen against the three isolates with amikacin MIC ≥ 2048 mg/L. Among the six isolates tested with meropenem monotherapy, five (meropenem MIC ≥ 16 mg/L) grew similarly to the controls while one (meropenem MIC 2 mg/L) achieved ∼ 2.5 log10 cfu/mL decrease. Among seven isolates tested in combination, four (amikacin/meropenem MIC ≤ 64/32 mg/L), including K. pneumoniae 375, maintained limit of detection until 72 h, whereas P. aeruginosa 1544 sustained a 1 log reduction. Combination therapy had no activity against the two isolates with amikacin MIC ≥ 2048 mg/L.

CONCLUSIONS

Inhaled amikacin monotherapy showed bactericidal activity against most isolates tested with amikacin MICs ≤ 256 mg/L. Adjunct inhaled amikacin plus meropenem sustained this activity for 72 h for the tested isolates with amikacin/meropenem MIC ≤ 64/32 mg/L.

Nebulized antibiotics for ventilator-associated pneumonia: a systematic review and meta-analysis

INTRODUCTION

Nebulized antibiotics are a promising new treatment option for ventilator-associated pneumonia. However, more evidence of the benefit of this therapy is required.

METHODS

The Medline, Scopus, EMBASE, Biological Abstracts, CAB Abstracts, Food Science and Technology Abstracts, CENTRAL, Scielo and Lilacs databases were searched to identify randomized controlled trials or matched observational studies that compared nebulized antibiotics with or without intravenous antibiotics to intravenous antibiotics alone for ventilator-associated pneumonia treatment. Two reviewers independently collected data and assessed outcomes and risk of bias. The primary outcome was clinical cure. Secondary outcomes were microbiological cure, ICU and hospital mortality, duration of mechanical ventilation, ICU length of stay and adverse events. A mixed-effect model meta-analysis was performed. Trial sequential analysis was used for the main outcome of interest.

RESULTS

Twelve studies were analyzed, including six randomized controlled trials. For the main outcome analysis, 812 patients were included. Nebulized antibiotics were associated with higher rates of clinical cure (risk ratio (RR) = 1.23; 95% confidence interval (CI), 1.05 to 1.43; I(2) = 34%; D(2) = 45%). Nebulized antibiotics were not associated with microbiological cure (RR = 1.24; 95% CI, 0.95 to 1.62; I(2) = 62.5), mortality (RR = 0.90; CI 95%, 0.76 to 1.08; I(2) = 0%), duration of mechanical ventilation (standardized mean difference = -0.10 days; 95% CI, -1.22 to 1.00; I(2) = 96.5%), ICU length of stay (standardized mean difference = 0.14 days; 95% CI, -0.46 to 0.73; I(2) = 89.2%) or renal toxicity (RR = 1.05; 95% CI, 0.70 to 1.57; I(2) = 15.6%). Regarding the primary outcome, the number of patients included was below the information size required for a definitive conclusion by trial sequential analysis; therefore, our results regarding this parameter are inconclusive.

CONCLUSIONS

Nebulized antibiotics seem to be associated with higher rates of clinical cure in the treatment of ventilator-associated pneumonia. However, the apparent benefit in the clinical cure rate observed by traditional meta-analysis does not persist after trial sequential analysis. Additional high-quality studies on this subject are highly warranted.

TRIAL REGISTRATION NUMBER

CRD42014009116 . Registered 29 March 2014.

Effect of aerosolized colistin as adjunctive treatment on the outcomes of microbiologically documented ventilator-associated pneumonia caused by colistin-only susceptible gram-negative bacteria

BACKGROUND

The increasing frequency of ventilator-associated pneumonia (VAP) caused by colistin-only susceptible (COS) gram-negative bacteria (GNB) is of great concern. Adjunctive aerosolized (AS) colistin can reportedly increase alveolar levels of the drug without increasing systemic toxicity. Good clinical results have been obtained in patients with cystic fibrosis, but conflicting data have been reported in patients with VAP.

METHODS

We conducted a retrospective, 1:1 matched case-control study to evaluate the efficacy and safety of AS plus IV colistin vs IV colistin alone in 208 patients in the ICU with VAP caused by COS Acinetobacter baumannii, Pseudomonas aeruginosa, or Klebsiella pneumoniae.

RESULTS

Compared with the IV colistin cohort, the AS-IV colistin cohort had a higher clinical cure rate (69.2% vs 54.8%, P = .03) and required fewer days of mechanical ventilation after VAP onset (8 days vs 12 days, P = .001). In the 166 patients with posttreatment cultures, eradication of the causative organism was also more common in the AS-IV colistin group (63.4% vs 50%, P = .08). No between-cohort differences were observed in all-cause ICU mortality, length of ICU stay after VAP onset, or rates of acute kidney injury (AKI) during colistin therapy. Independent predictors of clinical cure were trauma-related ICU admission (P = .01) and combined AS-IV colistin therapy (P = .009). Higher mean Simplified Acute Physiology Score II (P = .002) and Sequential Organ Failure Assessment (P = .05) scores, septic shock (P &lt; .001), and AKI onset during colistin treatment (P = .04) were independently associated with clinical failure.

CONCLUSIONS

Our results suggest that AS colistin might be a beneficial adjunct to IV colistin in the management of VAP caused by COS GNB.

Aerosolized amphotericin B lipid complex as adjunctive treatment for fungal lung infection in patients with cancer-related immunosuppression and recipients of hematopoietic stem cell transplantation

STUDY OBJECTIVE

Aerosolized amphotericin B lipid complex (aeABLC) has been successfully used to prevent fungal disease. Experience with aeABLC as treatment of fungal lung disease is limited.

DESIGN

We evaluated the safety and efficacy of aeABLC adjunct therapy for fungal lung disease in a retrospective study of 32 immunosuppressed adults. All values are given as ± standard deviation.

SETTING

National Cancer Institute-designated Comprehensive Cancer Center.

PATIENTS

Acute leukemia (69%) and severe neutropenia (63%) were common. Fifty-six percent of patients had undergone allogeneic hematopoietic stem cell transplantation 185 ± 424 days prior to aeABLC was commenced.

MEASUREMENT AND MAIN RESULTS

High-dose corticosteroids were administered during aeABLC in 28% of patients. Fungal lung disease was proven or probable in 41% of patients. Most patients (78%) received concurrent systemic antifungal therapy for a median of 14 ± 18 days before aeABLC. The median cumulative aeABLC dose was 1050 ± 2368 mg, and the median duration of aeABLC therapy was 28 ± 130 days. Most patients (78%) received 50 mg aeABLC twice daily. Partial or complete resolution of fungal lung disease was noted in 50% of patients. In three patients (9%) modest cough, mild bronchospasm, and transient chest pain with accompanying nausea and vomiting resolved completely after discontinuation of aeABLC. No patient required hospitalization for drug toxicity or had a serious (grade III or IV) drug-related adverse event.

CONCLUSION

Treatment with aeABLC was tolerated without serious toxicity and may be considered in the setting of severe immunosuppression, cancer, and/or hematopoietic stem cell transplantation in patients with difficult-to-treat fungal lung disease.

Management and prevention of ventilator-associated pneumonia caused by multidrug-resistant pathogens

Ventilator-associated pneumonia (VAP) due to multidrug-resistant (MDR) pathogens is a leading healthcare-associated infection in mechanically ventilated patients. The incidence of VAP due to MDR pathogens has increased significantly in the last decade. Risk factors for VAP due to MDR organisms include advanced age, immunosuppression, broad-spectrum antibiotic exposure, increased severity of illness, previous hospitalization or residence in a chronic care facility and prolonged duration of invasive mechanical ventilation. Methicillin-resistant Staphylococcus aureus and several different species of Gram-negative bacteria can cause MDR VAP. Especially difficult Gram-negative bacteria include Pseudomonas aeruginosa, Acinetobacter baumannii, carbapenemase-producing Enterobacteraciae and extended-spectrum β-lactamase producing bacteria. Proper management includes selecting appropriate antibiotics, optimizing dosing and using timely de-escalation based on antiimicrobial sensitivity data. Evidence-based strategies to prevent VAP that incorporate multidisciplinary staff education and collaboration are essential to reduce the burden of this disease and associated healthcare costs.

Magnetic core-shell nanoparticles for drug delivery by nebulization

BACKGROUND

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

RESULTS

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

CONCLUSION

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

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.

Aerosolized antibiotics in the intensive care unit

This review summarizes recent clinical data examining the use of aerosolized antimicrobial therapy for the treatment of respiratory tract infections in mechanically ventilated patients in the intensive care unit. Aerosolized antibiotics provide high concentrations of drug in the lung without the systemic toxicity associated with the intravenous antibiotics. First introduced in the 1960s as a treatment of tracheobronchitis and bronchopneumonia caused by Pseudomonas aeruginosa, now, more than 40 years later, there is a resurgence of interest in using this mode of delivery as a primary therapy for ventilator-associated tracheobronchitis and an adjunctive therapy for ventilator-associated pneumonia.

BAY41-6551 achieves bactericidal tracheal aspirate amikacin concentrations in mechanically ventilated patients with Gram-negative pneumonia

PURPOSE

To conduct a multicenter, randomized, placebo-controlled, double-blind, phase II study of BAY41-6551 (NCT01004445), an investigational drug-device combination of amikacin, formulated for inhalation, and a proprietary Pulmonary Drug Delivery System, for the treatment of Gram-negative pneumonia in mechanically ventilated patients.

METHODS

Sixty-nine mechanically ventilated patients with Gram-negative pneumonia, a clinical pulmonary infection score ≥6, at risk for multidrug-resistant organisms, were randomized to BAY41-6551 400 mg every 12 h (q12h), 400 mg every 24 h (q24h) with aerosol placebo, or placebo q12h for 7-14 days, plus standard intravenous antibiotics. The combined primary endpoint was a tracheal aspirate amikacin maximum concentration ≥6,400 μg/mL (25 × 256 μg/mL reference minimum inhibitory concentration) and a ratio of area under the aspirate concentration-time curve (0-24 h) to minimum inhibitory concentration ≥100 on day 1.

RESULTS

The primary endpoint was achieved in 50% (6/12) and 16.7% (3/18) of patients in the q12h and q24h groups, respectively. Clinical cure rates, in the 48 patients getting ≥7 days of therapy, were 93.8% (15/16), 75.0% (12/16), and 87.5% (14/16) in the q12h, q24h, and placebo groups, respectively (p = 0.467). By the end of aerosol therapy, the mean number of antibiotics per patient per day was 0.9 in the q12h, 1.3 in the q24h, and 1.9 in the placebo groups, respectively (p = 0.02 for difference between groups). BAY41-6551 was well tolerated and attributed to two adverse events in one patient (mild bronchospasm).

CONCLUSIONS

BAY41-6551 400 mg q12h warrants further clinical evaluation.

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

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

Pharmacokinetics and tolerability of BAY41-6551 in subjects with chronic kidney disease

Abstract Background: BAY41-6551, a drug-device combination in development for adjunctive treatment of Gram-negative pneumonia in mechanically ventilated patients, consists of amikacin formulated for inhalation coupled with the Pulmonary Drug Delivery System (PDDS) Clinical aerosol delivery platform. This study evaluated safety, tolerability, and pharmacokinetics (PK) of BAY41-6551 in subjects with chronic kidney disease (CKD).

METHODS

Single doses of BAY41-6551 (400 mg amikacin) were administered using the PDDS Clinical handheld device to six subjects with mild-to-moderate (Group 1) and six subjects with severe renal impairment (Group 2). Seven subjects with end-stage renal disease (ESRD; Group 3) received single doses of BAY41-6551 on days 1 and 9, with hemodialysis (HD) scheduled 24 h postdose on day 1 and 3 h postdose on day 9. PK analysis was performed on serum, urine, and dialysate samples (Group 3).

RESULTS

Individual serum amikacin concentrations in Groups 1 and 2 were below 6 mg/L at all times [mean maximum serum drug concentration (C(max)) 0.94 mg/L and 2.46 mg/L, respectively). In Group 3, serum amikacin concentrations decreased after each HD session, and amikacin area under the serum concentration-time curve from zero to 72 h (AUC(72)) and C(max) values were lower on day 9 than on day 1 (mean AUC(72) 71.5 mg · h/L vs. 151.5 mg · h/L; mean C(max) 2.09 mg/L vs. 6.16 mg/L). The amounts of amikacin removed by HD and the dialysate clearance rates were similar on days 1 and 9. No serious adverse events were reported.

CONCLUSIONS

Single doses of BAY41-6551 were well tolerated in subjects with CKD. HD effectively removed amikacin from serum in subjects with ESRD, and the timing relative to BAY41-6551 administration was an important determinant of systemic amikacin exposure. Nevertheless, standard precautionary measures for intravenous amikacin should apply for patients receiving BAY41-6551, and dose adjustments and/or dialysis should be considered for subjects with severe renal impairment.

Pharmacokinetics and tolerability of amikacin administered as BAY41-6551 aerosol in mechanically ventilated patients with gram-negative pneumonia and acute renal failure

BACKGROUND

BAY41-6551, a drug-device combination in development for adjunctive treatment of Gram-negative pneumonia in intubated and mechanically ventilated patients, consists of amikacin formulated for inhalation coupled with the Pulmonary Drug Delivery System (PDDS) Clinical aerosol delivery platform. Given the predominantly renal clearance of aminoglycosides, understanding systemic amikacin exposure and safety during administration of BAY41-6551 to patients with acute renal failure (ARF) is clinically important.

METHODS

Seven mechanically ventilated patients with Gram-negative pneumonia and ARF receiving continuous veno-venous hemodiafiltration (CVVHDF) were treated with multiple administrations of BAY41-6551 400 mg amikacin twice daily using the PDDS Clinical on-ventilator device [in addition to standard intravenous (i.v.) antimicrobial therapy]. CVVHDF parameters were recorded and a PK analysis was performed using serum, urine, and bronchoalveolar lavage fluid samples.

RESULTS

Maximum serum amikacin concentration [median 1.93 (range: 0.63-3.99) mg/L] and area under the concentration-time curve from zero to 12 h on day 3 [median 19.32 (range 6.32-36.87) mg · h/L] were elevated compared with mechanically ventilated patients with normal renal function; however, serum amikacin trough concentrations were within accepted safety limits. The median amikacin concentration in epithelial lining fluid [887 (range: 406-12,819) mg/L] was similar to that reported previously in mechanically ventilated patients with normal renal function. BAY41-6551 demonstrated acceptable safety and tolerability with most adverse events (AEs) as expected for the patient population. One serious AE of bronchospasm was attributed to the study medication; no reported AEs were related to the PDDS Clinical device.

CONCLUSIONS

CVVHDF appears to provide adequate clearance of systemically absorbed amikacin in mechanically ventilated patients with ARF, suggesting that dose adjustments for BAY41-6551 are probably not necessary for this patient population. Nonetheless, the standard precautionary measures for critically ill patients receiving i.v. amikacin should be followed for patients with ARF who are treated with BAY41-6551.

Future treatment options for Gram-positive infections--looking ahead

Multidrug-resistant Gram-positive infections remain a significant therapeutic problem, especially those due to Staphylococcus aureus. Antimicrobial choice is only one aspect of the management of these infections. New immunotherapies, exploitation of novel antibiotic targets, topical therapies and new drug delivery systems may have a future role in the management of S. aureus infection. At present, injectable antimicrobials are the main area of drug development and clinical interest. Since 1999, five anti-Gram-positive agents (moxifloxacin, quinupristin-dalfopristin, linezolid, daptomycin and tigecycline) have become available in the EU. At present, three other anti-Gram-positive agents are being considered by the European Medicines Agency (ceftobiprole, gemifloxacin and iclaprim), and a further four have completed phase III clinical trials (ceftaroline, dalbavancin, oritavancin and telavancin). The antibacterial spectra of these agents, their in vitro potencies, bactericidal activities and pharmacokinetics are well known. The safety profiles for those agents that have received regulatory approval and entered clinical practice are also firmly established. Most of the agents are pharmacodynamically promising and effective in clinical trials. As in the past, drug safety is likely to be a major determinant of which of the most recent drugs receive regulatory approval, and, in the long term, which agents will be successful in clinical practice.

Pharmacokinetics and lung delivery of PDDS-aerosolized amikacin (NKTR-061) in intubated and mechanically ventilated patients with nosocomial pneumonia

Introduction

Aminoglycosides aerosolization might achieve better diffusion into the alveolar compartment than intravenous use. The objective of this multicenter study was to evaluate aerosol-delivered amikacin penetration into the alveolar epithelial lining fluid (ELF) using a new vibrating mesh nebulizer (Pulmonary Drug Delivery System (PDDS), Nektar Therapeutics), which delivers high doses to the lungs.

Methods

Nebulized amikacin (400 mg bid) was delivered to the lungs of 28 mechanically ventilated patients with Gram-negative VAP for 7-14 days, adjunctive to intravenous therapy. On treatment day 3, 30 minutes after completing aerosol delivery, all the patients underwent bronchoalveolar lavage in the infection-involved area and the ELF amikacin concentration was determined. The same day, urine and serum amikacin concentrations were determined at different time points.

Results

Median (range) ELF amikacin and maximum serum amikacin concentrations were 976.1 (135.7-16127.6) and 0.9 (0.62-1.73) μg/mL, respectively. The median total amount of amikacin excreted in urine during the first and second 12-hour collection on day 3 were 19 (12.21-28) and 21.2 (14.1-29.98) μg, respectively. During the study period, daily through amikacin measurements were below the level of nephrotoxicity. Sixty-four unexpected adverse events were reported, among which 2 were deemed possibly due to nebulized amikacin: one episode of worsening renal failure, and one episode of bronchospasm.

Conclusions

PDDS delivery of aerosolized amikacin achieved very high aminoglycoside concentrations in ELF from radiography-controlled infection-involved zones, while maintaining safe serum amikacin concentrations. The ELF concentrations always exceeded the amikacin minimum inhibitory concentrations for Gram-negative microorganisms usually responsible for these pneumonias. The clinical impact of amikacin delivery with this system remains to be determined.

Trial Registration

ClinicalTrials.gov Identifier: NCT01021436.

Aerosolized antibiotics in critically ill ventilated patients

PURPOSE OF REVIEW

This review will summarize recent clinical data examining the efficacy of aerosolized antimicrobial therapy in treating respiratory tract infections in mechanically ventilated patients in the ICU.

RECENT FINDINGS

Aerosolized antibiotics provide high levels of drug in the lung and reduce the systemic toxicity associated with intravenous antibiotics. First introduced in the 1970s as a form of prophylaxis for ventilator-associated pneumonia (VAP), now, more than 30 years later, there is a resurgence of interest in using this mode of delivery as primary or adjunctive treatment for ventilator-associated tracheobronchitis (VAT) or VAP. Increasingly resistant organisms are colonizing and infecting critically ill patients, and direct delivery of antibiotic to the lung is being re-evaluated as a means to treat these highly resistant organisms that may not respond to systemic therapy. There are new data emerging that suggest these agents may effectively treat these pathogens when used in targeted, time limited protocols.

SUMMARY

Aerosolized antibiotic therapy may provide an efficacious means of treating respiratory tract infection when targeted at mechanically ventilated patients with proximal airway infection, VAT (with or without VAP) and with highly resistant organisms.

Inhaled colistin as adjunctive therapy to intravenous colistin for the treatment of microbiologically documented ventilator-associated pneumonia: a comparative cohort study

Ventilator-associated pneumonia (VAP) as a result of multidrug-resistant Gram-negative bacteria has contributed to the revival of the use of intravenous (i.v.) colistin. However, the additional administration of inhaled colistin for VAP is controversial. We performed a retrospective cohort study of patients with microbiologically documented VAP who received i.v. colistin with or without inhaled colistin. Seventy-eight patients with VAP received i.v. plus inhaled colistin, whereas 43 patients received i.v. colistin alone. The mean +/- SD daily dosage of i.v. colistin was 7.0 +/- 2.4 and 6.4 +/- 2.3 million international units (IU), respectively (p 0.13); the average daily dosage of inhaled colistin was 2.1 +/- 0.9 million IU. The outcome of infection was cure for 62/78 (79.5%) patients who received i.v. plus inhaled colistin vs. 26/43 (60.5%) patients who received i.v. colistin alone (p 0.025); all-cause in-hospital mortality was 31/78 (39.7%) vs. 19/43 (44.2%), respectively (p 0.63); all-cause intensive care unit (ICU) mortality was 28/78 (35.9%) vs. 17/43 (39.5%), respectively (p 0.92). The use of inhaled colistin was independently associated with the cure of VAP in a multivariable analysis (OR 2.53, 95% CI 1.11-5.76). Independent predictors of mortality were a higher APACHE II score (OR 1.12, 95% CI 1.04-1.20), presence of malignancy (OR 4.11, 95% CI 1.18-14.23) and lower daily dosage of i.v. colistin (OR 0.81, 95% CI 0.68-0.96). The outcome of VAP was better in patients who received inhaled colistin with i.v. colistin than those who received i.v. colistin alone. There was no difference in all-cause in-hospital and ICU mortality between the two groups. Randomized controlled trials are needed to evaluate further the role of inhaled colistin in VAP.

Inhaled therapeutics for prevention and treatment of pneumonia

The lungs are the most common site of serious infection owing to their large surface area exposed to the external environment and minimum barrier defense. However, this architecture makes the lungs readily available for topical therapy. Therapeutic aerosols include those directed towards improving mucociliary clearance of pathogens, stimulation of innate resistance to microbial infection, cytokine stimulation of immune function and delivery of antibiotics. In our opinion inhaled antimicrobials are underused, especially in patients with difficult-to-treat lung infections. The use of inhaled antimicrobial therapy has become an important part of the treatment of airway infection with Pseudomonas aeruginosa in cystic fibrosis and the prevention of invasive fungal infection in patients undergoing heart and lung transplantation. Cytokine inhaled therapy has also been explored in the treatment of neoplastic and infectious disease. The choice of pulmonary drug delivery systems remains critical as air-jet and ultrasonic nebulizer may deliver sub-optimum drug concentration if not used properly. In future development of this field, we recommend an emphasis on the study of the use of aerosolized hypertonic saline solution to reduce pathogen burden in the airways of subjects infected with microbes of low virulence, stimulation of innate resistance to prevent pneumonia in immunocompromised subjects using cytokines or synthetic pathogen-associated molecular pattern analogues and more opportunities for the use of inhaled antimicrobials. These therapeutics are still in their infancy but show great promise.

Aerosolized antibiotics to treat ventilator-associated pneumonia

PURPOSE OF REVIEW

This review summarizes the recent data on antibiotic aerosolization to treat ventilator-associated pneumonia.

RECENT FINDINGS

Most studies on antibiotic aerosolization have been case reports or descriptive studies. The results of a recent randomized, placebo-controlled trial indicated that adjunctive use of nebulized antibiotic with intravenous antibiotics to treat purulent tracheobronchitis was associated with a better outcome than placebo aerosolization. A randomized study, so far published only as an abstract, showed that amikacin aerosolized with a vibrating-mesh nebulizer--a new-generation device--was well distributed in the lung parenchyma and might lead to less intravenous antibiotic use. Several thorough reviews on nebulization devices, techniques and drawbacks have been published recently.

SUMMARY

Despite recent promising findings, the widespread use of aerosolized antibiotics to treat ventilator-associated pneumonia cannot be recommended. It should be restricted to the treatment of multidrug-resistant Gram-negative ventilator-associated pneumonia.

Aerosol antibiotics: considerations in pharmacological and clinical evaluation

Increasing antibiotic resistance and lack of R&D productivity of new classes of antimicrobial agents directed against Gram-negative bacteria necessitate new approaches to maximize the efficacy of existing classes of drugs. Direct administration of drugs to the lung via the inhalational route provides for high concentrations at the target site of action in patients with pulmonary infections. The efficacy of aerosol antibiotic administration has been best demonstrated with aerosolized tobramycin in the management of chronic infections because of Pseudomonas aeruginosa in cystic fibrosis (CF) patients. Unfortunately, inconvenient regimens leading to poor patient adherence to therapy, and the increasing frequency of multidrug-resistant strains have necessitated the search for additional agents. Integration of aerosol science, PK-PD and clinical trial designs are important for the development and evaluation of these new aerosol agents in both chronic infections (e.g. CF and chronic obstructive pulmonary disease (COPD)) as well as acute infections (e.g. bacterial pneumonias). This review outlines important considerations and recent progress in this emerging area.

How best to deliver aerosol medications to mechanically ventilated patients

Pressurized metered-dose inhalers (pMDIs) and nebulizers are employed routinely for aerosol delivery to ventilator-supported patients, but the ventilator circuit and artificial airway previously were thought to be major barriers to effective delivery of aerosols to patients receiving mechanical ventilation. In the past two decades, several investigators have shown that careful attention to many factors, such as the position of the patient, the type of aerosol generator and its configuration in the ventilator circuit, aerosol particle size, artificial airway, conditions in the ventilator circuit, and ventilatory parameters, is necessary to optimize aerosol delivery during mechanical ventilation. The best techniques for aerosol delivery during noninvasive positive-pressure ventilation are not well established as yet, and the efficiency of aerosol delivery in this setting is lower than that during invasive mechanical ventilation. The most efficient methods of using the newer hydrofluoroalkane-pMDIs and vibrating mesh nebulizers in ventilator-supported patients also require further evaluation. When optimal techniques of administration are employed, the efficiency of aerosolized drug delivery in mechanically ventilated patients is comparable to that achieved in ambulatory patients.