Inhaled mannitol in patients with cystic fibrosis: A randomised open-label dose response trial

A Novel Combined Dry Powder Inhaler Comprising Nanosized Ketoprofen-Embedded Mannitol-Coated Microparticles for Pulmonary Inflammations: Development, In Vitro-In Silico Characterization, and Cell Line Evaluation

Pulmonary inflammations such as chronic obstructive pulmonary disease and cystic fibrosis are widespread and can be fatal, especially when they are characterized by abnormal mucus accumulation. Inhaled corticosteroids are commonly used for lung inflammations despite their considerable side effects. By utilizing particle engineering techniques, a combined dry powder inhaler (DPI) comprising nanosized ketoprofen-embedded mannitol-coated microparticles was developed. A nanoembedded microparticle system means a novel advance in pulmonary delivery by enhancing local pulmonary deposition while avoiding clearance mechanisms. Ketoprofen, a poorly water-soluble anti-inflammatory drug, was dispersed in the stabilizer solution and then homogenized by ultraturrax. Following this, a ketoprofen-containing nanosuspension was produced by wet-media milling. Furthermore, co-spray drying was conducted with L-leucine (dispersity enhancer) and mannitol (coating and mucuactive agent). Particle size, morphology, dissolution, permeation, viscosity, in vitro and in silico deposition, cytotoxicity, and anti-inflammatory effect were investigated. The particle size of the ketoprofen-containing nanosuspension was ~230 nm. SEM images of the spray-dried powder displayed wrinkled, coated, and nearly spherical particles with a final size of ~2 µm (nano-in-micro), which is optimal for pulmonary delivery. The mannitol-containing samples decreased the viscosity of 10% mucin solution. The results of the mass median aerodynamic diameter (2.4-4.5 µm), fine particle fraction (56-71%), permeation (five-fold enhancement), and dissolution (80% release in 5 min) confirmed that the system is ideal for local inhalation. All samples showed a significant anti-inflammatory effect and decreased IL-6 on the LPS-treated U937 cell line with low cytotoxicity. Hence, developing an innovative combined DPI comprising ketoprofen and mannitol by employing a nano-in-micro approach is a potential treatment for lung inflammations.

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.

Inhaled Dry Powder Mannitol Treatment in Pediatric Patients with Cystic Fibrosis: Evaluation of Clinical Data in a Real-World Setting

Background: Cystic fibrosis (CF) is a genetic disorder, in which defective clearance of airway secretions leads to progressive lung function loss. Inhaled mannitol is used to increase sputum and mucociliary clearance. There are little data from real-world studies on the effectiveness of mannitol in children. Our objective was to evaluate the spirometry and clinical results of mannitol in pediatric patients. Methods: We retrospectively reviewed the records of 30 children and adolescents with CF receiving inhaled mannitol who were already on recombinant human deoxyribonuclease (rhDNase) treatment. The change in forced expiratory volume in 1 second (FEV₁) from baseline at 2-4 months was the primary outcome. Secondary measures were other spirometry results, body mass index (BMI), hospital admissions, sputum characteristics, and positive bacterial colonization. Results: Compared to baseline, we found significant improvement in percent predicted FEV₁ at 2-4 months of treatment; 84.50 (58.00-99.00) vs. 96.00 (66.00-106.00) (P = 0.0007). The absolute change in FEV₁ was +11.5% at 2-4 months, +6.5% at 5-7 months, and +4% at 8-12 months. Also, significant improvements in other spirometry results were observed. Adolescents had significantly lower FEV₁ results, but the improvement in their lung function was sustained for a more extended period than children. Mannitol provided easier sputum removal, increased sputum volume, significant decline in hospitalizations, and significantly fewer patients with positive sputum cultures. A significant increase in BMI at 8-12 months was observed. Cough was the most frequent adverse effect. Conclusion: In a real-world setting, our results demonstrated that adding mannitol to rhDNase therapy is tolerable in pediatric patients with CF and may provide improved spirometry and clinical outcomes. In addition, our results showed that mannitol provided recovery in overall lung function at 2-4 months, which was sustained up to 12 months together with improved BMI, easier sputum removal, and a decline in bacterial colonization and hospital admissions. However, cough was the most frequent side effect.

Inhaled Medicines: Past, Present, and Future

The purpose of this review is to summarize essential pharmacological, pharmaceutical, and clinical aspects in the field of orally inhaled therapies that may help scientists seeking to develop new products. After general comments on the rationale for inhaled therapies for respiratory disease, the focus is on products approved approximately over the last half a century. The organization of these sections reflects the key pharmacological categories. Products for asthma and chronic obstructive pulmonary disease include β -2 receptor agonists, muscarinic acetylcholine receptor antagonists, glucocorticosteroids, and cromones as well as their combinations. The antiviral and antibacterial inhaled products to treat respiratory tract infections are then presented. Two "mucoactive" products-dornase α and mannitol, which are both approved for patients with cystic fibrosis-are reviewed. These are followed by sections on inhaled prostacyclins for pulmonary arterial hypertension and the challenging field of aerosol surfactant inhalation delivery, especially for prematurely born infants on ventilation support. The approved products for systemic delivery via the lungs for diseases of the central nervous system and insulin for diabetes are also discussed. New technologies for drug delivery by inhalation are analyzed, with the emphasis on those that would likely yield significant improvements over the technologies in current use or would expand the range of drugs and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of approved orally inhaled drug products for a variety of respiratory diseases and for systemic administration should be helpful in making judicious decisions about the development of new or improved inhaled drugs. These aspects include the choices of the active ingredients, formulations, delivery systems suitable for the target patient populations, and, to some extent, meaningful safety and efficacy endpoints in clinical trials.

Microencapsulated Chitosan-Based Nanocapsules: A New Platform for Pulmonary Gene Delivery

In this work, we propose chitosan (CS)-based nanocapsules (NCs) for pulmonary gene delivery. Hyaluronic acid (HA) was incorporated in the NCs composition (HA/CS NCs) aiming to promote gene transfection in the lung epithelium. NCs were loaded with a model plasmid (pCMV-βGal) to easily evaluate their transfection capacity. The plasmid encapsulation efficiencies were of approx. 90%. To facilitate their administration to the lungs, the plasmid-loaded NCs were microencapsulated in mannitol (Ma) microspheres (MS) using a simple spray-drying technique, obtaining dry powders of adequate properties. In vivo, the MS reached the deep lung, where the plasmid-loaded CS-based NCs were released and transfected the alveolar cells more homogeneously than the control formulation of plasmid directly microencapsulated in Ma MS. The HA-containing formulation achieved the highest transfection efficiency, in a more extended area and more homogeneously distributed than the rest of tested formulations. The new micro-nanostructured platform proposed in this work represents an efficient strategy for the delivery of genetic material to the lung, with great potential for the treatment of genetic lung diseases.

The effects of sildenafil on ciliary beat frequency in patients with pulmonary non-tuberculous mycobacteria disease: phase I/II trial

Rationale

Pulmonary non-tuberculous mycobacterial (PNTM) disease has increased over the past several decades, especially in older women. Abnormal mucociliary clearance and abnormal nasal nitric oxide (nNO) have been associated with PNTM disease in other patient cohorts. Mucociliary clearance can be affected by NO-cyclic guanosine monophosphate signalling and, therefore, modulation of the pathway may be possible with phosphodiesterase inhibitors such as sildenafil as a novel therapeutic approach.

Objective

To define ex vivo characteristics of PNTM disease affected by sildenafil.

Methods

Subjects with PNTM infections were recruited into an open-label dose-escalation trial of sildenafil. Laboratory measurements and mucociliary measurements—ciliary beat frequency, nNO and 24-hour sputum production—were collected throughout the study period. Patients received sildenafil daily during the study period, with escalation from 20 to 40 mg three times per day.

Measurements and main results

Increased ciliary beat frequency occurred after a single dose of 40 mg sildenafil and after extended dosing of 40 mg sildenafil. The increase ciliary beat frequency was not seen with 20 mg sildenafil dosing. There were no changes in sputum production, nNO production, Quality of Life-Bronchiectasis-NTM module (QOL-B-NTM) questionnaire or the St George’s Respiratory Questionnaire during the study period.

Conclusion

Sildenafil, 40 mg, increased ciliary beat frequency acutely as well as with extended administration.

Efficacy and safety of inhaled dry-powder mannitol in adults with cystic fibrosis: An international, randomized controlled study

BACKGROUND

Mannitol is a mucoactive hyperosmotic agent used as add-on therapy in patients with cystic fibrosis (CF), administered twice-daily (BID) via a small, portable, breath-actuated dry-powder inhaler. This study was conducted to provide confirmatory evidence of mannitol's efficacy and safety in adults.

METHODS

This multicenter, double-blind, randomized, parallel-group, controlled clinical trial recruited adults (aged ≥18 years) with CF, and forced expiratory volume in 1 second (FEV₁) 40-90% predicted. Subjects received either mannitol 400 mg or mannitol 50 mg (control), BID via dry-powder inhaler for 26 weeks. Primary endpoint: FEV₁ averaged over the 26-week treatment period.

RESULTS

Of 423 subjects randomized (209 or 214 receiving mannitol 400 mg BID or control, respectively), 373 (88.2%) completed the study, with a similar proportion completing in the two groups. For FEV₁ averaged over 26 weeks, mannitol 400 mg BID was statistically superior to control (adjusted mean difference 54 mL [95% CI 8, 100 mL]; p = 0.020). This was supported by sensitivity analyses of the primary endpoint, and by observed improvements in secondary pulmonary function endpoints (eg, absolute adjusted mean difference in percent predicted FEV₁ averaged over 26 weeks 1.21% [0.07%, 2.36%]; p = 0.037). Adverse events were mainly mild or moderate in severity, with treatment-related adverse events in 15.5 and 12.2% of subjects receiving mannitol 400 mg BID and control, respectively.

CONCLUSIONS

In adults with CF, mannitol 400 mg BID inhaled as a dry-powder statistically significantly improved lung function (FEV₁) compared with control, with this improvement supported by sensitivity analyses and secondary pulmonary function endpoints. Mannitol had a good overall safety and tolerability profile. ClinicalTrials.gov: NCT02134353.

Mucociliary Respiratory Epithelium Integrity in Molecular Defense and Susceptibility to Pulmonary Viral Infections

Mucociliary defense, mediated by the ciliated and goblet cells, is fundamental to respiratory fitness. The concerted action of ciliary movement on the respiratory epithelial surface and the pathogen entrapment function of mucus help to maintain healthy airways. Consequently, genetic or acquired defects in lung defense elicit respiratory diseases and secondary microbial infections that inflict damage on pulmonary function and may even be fatal. Individuals living with chronic and acute respiratory diseases are more susceptible to develop severe coronavirus disease-19 (COVID-19) illness and hence should be proficiently managed. In light of the prevailing pandemic, we review the current understanding of the respiratory system and its molecular components with a major focus on the pathophysiology arising due to collapsed respiratory epithelium integrity such as abnormal ciliary movement, cilia loss and dysfunction, ciliated cell destruction, and changes in mucus rheology. The review includes protein interaction networks of coronavirus infection-manifested implications on the molecular machinery that regulates mucociliary clearance. We also provide an insight into the alteration of the transcriptional networks of genes in the nasopharynx associated with the mucociliary clearance apparatus in humans upon infection by severe acute respiratory syndrome coronavirus-2.

Inhaled mannitol for cystic fibrosis

BACKGROUND

Several agents are used to clear secretions from the airways of people with cystic fibrosis. Mannitol increases mucociliary clearance, but its exact mechanism of action is unknown. The dry powder formulation of mannitol may be more convenient and easier to use compared with established agents which require delivery via a nebuliser. Phase III trials of inhaled dry powder mannitol for the treatment of cystic fibrosis have been completed and it is now available in Australia and some countries in Europe. This is an update of a previous review.

OBJECTIVES

To assess whether inhaled dry powder mannitol is well tolerated, whether it improves the quality of life and respiratory function in people with cystic fibrosis and which adverse events are associated with the treatment.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic databases, handsearching relevant journals and abstracts from conferences. Date of last search: 12 December 2019.

SELECTION CRITERIA

All randomised controlled studies comparing mannitol with placebo, active inhaled comparators (for example, hypertonic saline or dornase alfa) or with no treatment.

DATA COLLECTION AND ANALYSIS

Authors independently assessed studies for inclusion, carried out data extraction and assessed the risk of bias in included studies. The quality of the evidence was assessed using GRADE.

MAIN RESULTS

Six studies (reported in 36 unique publications) were included with a total of 784 participants. Duration of treatment in the included studies ranged from 12 days to six months, with open-label treatment for an additional six months in two of the studies. Five studies compared mannitol with control (a very low dose of mannitol or non-respirable mannitol) and the final study compared mannitol to dornase alfa alone and to mannitol plus dornase alfa. Two large studies had a similar parallel design and provided data for 600 participants, which could be pooled where data for a particular outcome and time point were available. The remaining studies had much smaller sample sizes (ranging from 22 to 95) and data could not be pooled due to differences in design, interventions and population. Pooled evidence from the two large parallel studies was judged to be of low to moderate quality and from the smaller studies was judged to be of low to very low quality. In all studies, there was an initial test to see if participants tolerated mannitol, with only those who could tolerate the drug being randomised; therefore, the study results are not applicable to the cystic fibrosis population as a whole. While the published papers did not provide all the data required for our analysis, additional unpublished data were provided by the drug's manufacturer and the author of one of the studies. Pooling the large parallel studies comparing mannitol to control, up to and including six months, lung function (forced expiratory volume at one second) measured in both mL and % predicted was significantly improved in the mannitol group compared to the control group (moderate-quality evidence). Beneficial results were observed in these studies in adults and in both concomitant dornase alfa users and non-users in these studies. In the smaller studies, statistically significant improvements in lung function were also observed in the mannitol groups compared to the non-respirable mannitol groups; however, we judged this evidence to be of low to very low quality. For the comparisons of mannitol and control, we found no consistent differences in health-related quality of life in any of the domains except for burden of treatment, which was less for mannitol up to four months in the two pooled studies of a similar design; this difference was not maintained at six months. It should be noted that the tool used to measure health-related quality of life was not designed to assess mucolytics and pooling of the age-appropriate tools (as done in some of the included studies) may not be valid so results were judged to be low to very low quality and should be interpreted with caution. Cough, haemoptysis, bronchospasm, pharyngolaryngeal pain and post-tussive vomiting were the most commonly reported side effects in both treatment groups. Where rates of adverse events could be compared, statistically no significant differences were found between mannitol and control groups; although some of these events may have clinical relevance for people with CF. For the comparisons of mannitol to dornase alfa alone and to mannitol plus dornase alfa, very low-quality evidence from a 12-week cross-over study of 28 participants showed no statistically significant differences in the recorded domains of health-related quality of life or measures of lung function. Cough was the most common side effect in the mannitol alone arm but there was no occurrence of cough in the dornase alfa alone arm and the most commonly reported reason of withdrawal from the mannitol plus dornase alfa arm was pulmonary exacerbations. In terms of secondary outcomes of the review (pulmonary exacerbations, hospitalisations, symptoms, sputum microbiology), evidence provided by the included studies was more limited. For all comparisons, no consistent statistically significant and clinically meaningful differences were observed between mannitol and control treatments (including dornase alfa).

AUTHORS' CONCLUSIONS

There is moderate-quality evidence to show that treatment with mannitol over a six-month period is associated with an improvement in some measures of lung function in people with cystic fibrosis compared to control. There is low to very low-quality evidence suggesting no difference in quality of life for participants taking mannitol compared to control. This review provides very low-quality evidence suggesting no difference in lung function or quality of life comparing mannitol to dornase alfa alone and to mannitol plus dornase alfa. The clinical implications from this review suggest that mannitol could be considered as a treatment in cystic fibrosis; but further research is required in order to establish who may benefit most and whether this benefit is sustained in the longer term. Furthermore, studies comparing its efficacy against other (established) mucolytic therapies need to be undertaken before it can be considered for mainstream practice.

Inhaled mannitol for cystic fibrosis

BACKGROUND

Several agents are used to clear secretions from the airways of people with cystic fibrosis. Mannitol increases mucociliary clearance, but its exact mechanism of action is unknown. The dry powder formulation of mannitol may be more convenient and easier to use compared with established agents which require delivery via a nebuliser. Phase III trials of inhaled dry powder mannitol for the treatment of cystic fibrosis have been completed and it is now available in Australia and some countries in Europe. This is an update of a previous review.

OBJECTIVES

To assess whether inhaled dry powder mannitol is well tolerated, whether it improves the quality of life and respiratory function in people with cystic fibrosis and which adverse events are associated with the treatment.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic databases, handsearching relevant journals and abstracts from conferences.Date of last search: 28 September 2017.

SELECTION CRITERIA

All randomised controlled studies comparing mannitol with placebo, active inhaled comparators (for example, hypertonic saline or dornase alfa) or with no treatment.

DATA COLLECTION AND ANALYSIS

Authors independently assessed studies for inclusion, carried out data extraction and assessed the risk of bias in included studies. The quality of the evidence was assessed using GRADE.

MAIN RESULTS

Six studies (reported in 50 publications) were included with a total of 784 participants.Duration of treatment in the included studies ranged from 12 days to six months, with open-label treatment for an additional six months in two of the studies. Five studies compared mannitol with control (a very low dose of mannitol or non-respirable mannitol) and the final study compared mannitol to dornase alfa alone and to mannitol plus dornase alfa. Two large studies had a similar parallel design and provided data for 600 participants, which could be pooled where data for a particular outcome and time point were available. The remaining studies had much smaller sample sizes (ranging from 22 to 95) and data could not be pooled due to differences in design, interventions and population.Pooled evidence from the two large parallel studies was judged to be of low to moderate quality and from the smaller studies was judged to be of low to very low quality. In all studies, there was an initial test to see if participants tolerated mannitol, with only those who could tolerate the drug being randomised; therefore, the study results are not applicable to the cystic fibrosis population as a whole.While the published papers did not provide all the data required for our analysis, additional unpublished data were provided by the drug's manufacturer and the author of one of the studies.Pooling the large parallel studies comparing mannitol to control, up to and including six months, lung function (forced expiratory volume at one second) measured in both mL and % predicted was significantly improved in the mannitol group compared to the control group (moderate-quality evidence). Beneficial results were observed in these studies in adults and in both concomitant dornase alfa users and non-users in these studies. In the smaller studies, statistically significant improvements in lung function were also observed in the mannitol groups compared to the non-respirable mannitol groups; however, we judged this evidence to be of low to very low quality.For the comparisons of mannitol and control, we found no consistent differences in health-related quality of life in any of the domains except for burden of treatment, which was less for mannitol up to four months in the two pooled studies of a similar design; this difference was not maintained at six months. It should be noted that the tool used to measure health-related quality of life was not designed to assess mucolytics and pooling of the age-appropriate tools (as done in some of the included studies) may not be valid so results were judged to be low to very low quality and should be interpreted with caution. Cough, haemoptysis, bronchospasm, pharyngolaryngeal pain and post-tussive vomiting were the most commonly reported side effects in both treatment groups. Where rates of adverse events could be compared, statistically no significant differences were found between mannitol and control groups; although some of these events may have clinical relevance for people with CF.For the comparisons of mannitol to dornase alfa alone and to mannitol plus dornase alfa, very low-quality evidence from a 12-week cross-over study of 28 participants showed no statistically significant differences in the recorded domains of health-related quality of life or measures of lung function. Cough was the most common side effect in the mannitol alone arm but there was no occurrence of cough in the dornase alfa alone arm and the most commonly reported reason of withdrawal from the mannitol plus dornase alfa arm was pulmonary exacerbations.In terms of secondary outcomes of the review (pulmonary exacerbations, hospitalisations, symptoms, sputum microbiology), evidence provided by the included studies was more limited. For all comparisons, no consistent statistically significant and clinically meaningful differences were observed between mannitol and control treatments (including dornase alfa).

AUTHORS' CONCLUSIONS

There is moderate-quality evidence to show that treatment with mannitol over a six-month period is associated with an improvement in some measures of lung function in people with cystic fibrosis compared to control. There is low to very low-quality evidence suggesting no difference in quality of life for participants taking mannitol compared to control. This review provides very low-quality evidence suggesting no difference in lung function or quality of life comparing mannitol to dornase alfa alone and to mannitol plus dornase alfa.The clinical implications from this review suggest that mannitol could be considered as a treatment in cystic fibrosis; but further research is required in order to establish who may benefit most and whether this benefit is sustained in the longer term. Furthermore, studies comparing its efficacy against other (established) mucolytic therapies need to be undertaken before it can be considered for mainstream practice.

New drug developments in the management of cystic fibrosis lung disease

INTRODUCTION

Therapies for cystic fibrosis (CF) pulmonary disease have, until recently, all targeted downstream manifestations rather than the root cause of the disease. A step-change in our approach has been achieved in the last few years, with novel small-molecule CFTR modulating drugs entering the clinic.

AREAS COVERED

In this article, we will discuss the field of drug development for CF lung disease. The case will be made for the potential benefits of basic defect-targeted strategies, which will be described in detail. Novel therapies directed at the downstream pulmonary manifestations of CF - infection, inflammation, and mucus impaction - will be reviewed. Finally, we will speculate on future directions and challenges.

EXPERT OPINION

CF drug development is in an exciting phase, catalysed by the impressive results seen in patients with ivacaftor-responsive CFTR mutations. The research field is active with trials of novel therapies targeting the basic defect, alongside drugs targeting downstream effects. In order to detect potentially small improvements due to novel therapies, especially in the context of treating young patients with early disease, sensitive outcome measures and the coordinated efforts of collaborative research networks are crucial.

Inhaled mannitol for cystic fibrosis

BACKGROUND

Several agents are used to clear secretions from the airways of people with cystic fibrosis. Inhaled dry powder mannitol is now available in Australia and some countries in Europe. The exact mechanism of action of mannitol is unknown, but it increases mucociliary clearance. Phase III trials of inhaled dry powder mannitol for the treatment of cystic fibrosis have been completed. The dry powder formulation of mannitol may be more convenient and easier to use compared with established agents which require delivery via a nebuliser.

OBJECTIVES

To assess whether inhaled dry powder mannitol is well tolerated, whether it improves the quality of life and respiratory function in people with cystic fibrosis and which adverse events are associated with the treatment.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic databases, handsearching relevant journals and abstracts from conferences.Date of last search: 16 April 2015.

SELECTION CRITERIA

All randomised controlled studies comparing mannitol with placebo, active inhaled comparators (for example, hypertonic saline or dornase alfa) or with no treatment.

DATA COLLECTION AND ANALYSIS

Authors independently assessed studies for inclusion, carried out data extraction and assessed the risk of bias in included studies.

MAIN RESULTS

The searches identified nine separate studies (45 publications), of which four studies (36 publications) were included with a total of 667 participants, one study (only available as an abstract) is awaiting assessment and two studies are ongoing. Duration of treatment in the included studies ranged from two weeks to six months with open-label treatment for an additional six months in two of the studies. Three studies compared mannitol with control (a very low dose of mannitol or non-respirable mannitol); two of these were parallel studies with a similar design and data could be pooled, where data for a particular outcome and time point were available; also, one short-term cross-over study supplied additional results. The fourth study compared mannitol to dornase alfa alone and to mannitol plus dornase alfa. There was generally a low risk of bias in relation to randomisation and blinding; evidence from the parallel studies was judged to be of low to moderate quality and from the cross-over studies was judged to be of low to very low quality. While the published papers did not provide all the data required for our analysis, additional unpublished data were provided by the drug's manufacturer and the author of one of the studies. There was an initial test to see if participants tolerated mannitol, with only those who could tolerate the drug being randomised to the studies; therefore the study results are not applicable to the cystic fibrosis population as a whole.For the comparison of mannitol and control, we found no consistent differences in health-related quality of life in any of the domains, except for burden of treatment, which was less for mannitol up to four months in the two pooled studies of a similar design; this difference was not maintained at six months. Up to and including six months, lung function in terms of forced expiratory volume at one second (millilitres) and per cent predicted were significantly improved in all three studies comparing mannitol to control. Beneficial results were observed in these studies in adults and in both concomitant dornase alfa users and non users. A significant reduction was shown in the incidence of pulmonary exacerbations in favour of mannitol at six months; however, the estimate of this effect was imprecise so it is unclear whether the effect is clinically meaningful. Cough, haemoptysis, bronchospasm, pharyngolaryngeal pain and post-tussive vomiting were the most commonly reported side effects on both treatments. Mannitol was not associated with any increase in isolation of bacteria over a six-month period.In the 12-week cross-over study (28 participants), no significant differences were found in the recorded domains of health-related quality of life or measures of lung function between mannitol versus dornase alfa alone and versus mannitol plus dornase alfa. There seemed to be a higher rate of pulmonary exacerbations in the mannitol plus dornase alfa arm compared with dornase alfa alone; although not statistically significant, this was the most common reason for stopping treatment in this arm. Cough was the most common side effect in the mannitol alone arm but there was no occurrence of cough in the dornase alfa alone arm and the most commonly reported reason of withdrawal from the mannitol plus dornase alfa arm was pulmonary exacerbations. Mannitol (with or without dornase alfa) was not associated with any increase in isolation of bacteria over the 12-week period.

AUTHORS' CONCLUSIONS

There is evidence to show that treatment with mannitol over a six-month period is associated with an improvement in some measures of lung function in people with cystic fibrosis compared to control. There is no evidence that quality of life is improved for participants taking mannitol compared to control; a decrease in burden of treatment was observed up to four months on mannitol compared to control but this difference was not maintained to six months. Randomised information regarding the burden of adding mannitol to an existing treatment is limited. There is no randomised evidence of improvement in lung function or quality of life comparing mannitol to dornase alfa alone and to mannitol plus dornase alfa.Mannitol as a single or concomitant treatment to dornase alfa may be of benefit to people with cystic fibrosis, but further research is required in order to establish who may benefit most and whether this benefit is sustained in the longer term.The clinical implications from this review suggest that mannitol could be considered as a treatment in cystic fibrosis; however, studies comparing its efficacy against other (established) mucolytic therapies need to be undertaken before it can be considered for mainstream practice.

Hyper-osmolarity and calcium chelation: Effects on cystic fibrosis mucus

A non-functional Cystic Fibrosis Transmembrane conductance Regulator (CFTR) leads to the disease cystic fibrosis (CF). Although the CFTR is expressed in multiple organs, pulmonary disease is the major cause of illness and death in patients with CF. Stagnant mucus, causing airway obstruction, bacterial overgrowth, persistent inflammation and tissue destruction characterizes the disease, but how the defect in CFTR function is coupled to the mucus phenotype is still controversial. We have recently shown that bicarbonate ions passing through CFTR are necessary for proper unfolding of the MUC2 mucin, thus highlighting the importance of bicarbonate ion transport via the CFTR and the ability of these ions to raise the pH and chelate calcium bound to the mucin as the important steps in forming normal mucus. In order to find potential CF treatments and expand our knowledge about the usefulness of bicarbonate as an active ingredient in formulations to alleviate mucus plugging, we used an Ussing-type chamber and explants from the F508del-CFTR mutant mouse ileum to test the effect of calcium chelators on mucus attachment, either in isolation or in combination with osmolytes such as mannitol or hypertonic saline. We found that increasing the concentration of bicarbonate, both alone or in combination with increased osmolarity of the solution, detached the otherwise attached CF mucus.

Therapeutic options for hydrating airway mucus in cystic fibrosis

BACKGROUND

In cystic fibrosis (CF), genetic mutations in the CF transmembrane conductance regulator (CFTR) gene cause reduced chloride efflux from ciliated airway epithelial cells. This results in a reduction in periciliary liquid (PCL) depth of the airway surface liquid due to associated reduced water efflux. PCL layer dehydration reduces mucociliary clearance (MCC), leading to airway obstruction (reduced airflow and inflammation due to pathogen invasion) with mucus plug formation.

SUMMARY

Rehydrating mucus increases MCC. Mucus hydration can be achieved by direct hydration (administering osmotic agents to set up an osmotic gradient), using CFTR modulators to correct dysfunctional CFTR, or it can be achieved pharmacologically (targeting other ion channels on airway epithelial cells). Key Messages: The molecular mechanisms of several therapies are discussed in the context of pre-clinical and clinical trial studies. Currently, only the osmotic agent 7% hypertonic saline and the CFTR 'potentiator' VX-770 (ivacaftor) are used clinically to hydrate mucus. Emerging therapies include the osmotic agent mannitol (Bronchitol), the intracellular Ca(2+)-raising agent Moli1901/lancovutide, the CFTR potentiator sildenafil [phosphodiesterase type 5 (PDE5) inhibitor] and the CFTR 'corrector' VX-809 (lumacaftor). Other CFTR correctors (e.g. 'chemical chaperones') are also showing pre-clinical promise.

Inhaled mannitol for non-cystic fibrosis bronchiectasis: a randomised, controlled trial

RATIONALE

Bronchiectasis is characterised by excessive production of mucus and pulmonary exacerbations. Inhaled osmotic agents may enhance mucociliary clearance, but few long-term clinical trials have been conducted.

OBJECTIVES

To determine the impact of inhaled mannitol on exacerbation rates in patients with non-cystic fibrosis (CF) bronchiectasis. Secondary endpoints included time to first exacerbation, duration of exacerbations, antibiotic use for exacerbations and quality of life (QOL) (St George's Respiratory Questionnaire, SGRQ).

METHODS

Patients with non-CF bronchiectasis and a history of chronic excess production of sputum and ≥2 pulmonary exacerbations in the previous 12 months were randomised (1:1) to 52 weeks treatment with inhaled mannitol 400 mg or low-dose mannitol control twice a day. Patients were 18-85 years of age, baseline FEV1 ≥40% and ≤85% predicted and a baseline SGRQ score ≥30.

MAIN RESULTS

461 patients (233 in the mannitol and 228 in the control arm) were treated. Baseline demographics were similar in the two arms. The exacerbation rate was not significantly reduced on mannitol (rate ratio 0.92, p=0.31). However, time to first exacerbation was increased on mannitol (HR 0.78, p=0.022). SGRQ score was improved on mannitol compared with low-dose mannitol control (-2.4 units, p=0.046). Adverse events were similar between groups.

CONCLUSIONS

Mannitol 400 mg inhaled twice daily for 12 months in patients with clinically significant bronchiectasis did not significantly reduce exacerbation rates. There were statistically significant improvements in time to first exacerbation and QOL. Mannitol therapy was safe and well tolerated.

TRIAL REGISTRATION NUMBER

NCT00669331.

Design, characterization, and aerosol dispersion performance modeling of advanced spray-dried microparticulate/nanoparticulate mannitol powders for targeted pulmonary delivery as dry powder inhalers

BACKGROUND

The purpose was to design and characterize inhalable microparticulate/nanoparticulate dry powders of mannitol with essential particle properties for targeted dry powder delivery for cystic fibrosis mucolytic treatment by dilute organic solution spray drying, and, in addition, to tailor and correlate aerosol dispersion performance delivered as dry powder inhalers based on spray-drying conditions and solid-state physicochemical properties.

METHODS

Organic solution advanced spray drying from dilute solution followed by comprehensive solid-state physicochemical characterization and in vitro dry powder aerosolization were used.

RESULTS

The particle size distribution of the spray-dried (SD) powders was narrow, unimodal, and in the range of ∼500 nm to 2.0 μm. The particles possessed spherical particle morphology, relatively smooth surface morphology, low water content and vapor sorption (crystallization occurred at exposure above 65% relative humidity), and retention of crystallinity by polymorphic interconversion. The emitted dose, fine particle fraction (FPF), and respirable fraction (RF) were all relatively high. The mass median aerodynamic diameters were below 4 μm for all SD mannitol aerosols.

CONCLUSION

The in vitro aerosol deposition stage patterns could be tailored based on spray-drying pump rate. Positive linear correlation was observed between both FPF and RF values with spray-drying pump rates. The interplay between various spray-drying conditions, particle physicochemical properties, and aerosol dispersion performance was observed and examined, which enabled tailoring and modeling of high aerosol deposition patterns.

Emerging drugs for cystic fibrosis

INTRODUCTION

Cystic fibrosis is an autosomal recessive disease, which is the result of a genetic defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Pulmonary disease accounts for over 90% of the morbidity and mortality associated with the disease. Conventionally, CF treatment has focused on symptomatic therapy.

AREAS COVERED

In the past, the emphasis for the development of CF therapeutics has previously been on addressing complications of the manifestations rather than on the underlying disease process. However, in the past few decades there has been a paradigm shift with new attention on the underlying biological mechanisms and therapies targeted at curing the disease rather than simply controlling it. This review summarizes the current CF therapeutics pipeline. These developing therapies include CFTR gene therapy, CFTR pharmacotherapeutics, osmotically active agents and anti-inflammatory therapies, as well as novel inhaled antibiotics.

EXPERT OPINION

The CF therapeutics pipeline currently holds great promise both for novel therapies directly targeting the underlying biological mechanisms of CFTR dysfunction and new symptomatic therapies. While CFTR-directed therapy has the highest potential to improve patients' outcome, it is important to continue to develop better treatment options for all aspects of CF lung disease.

Growth on mannitol-rich media elicits a genome-wide transcriptional response in Burkholderia multivorans that impacts on multiple virulence traits in an exopolysaccharide-independent manner

In common with other members of the Burkholderia cepacia complex (BCC), Burkholderia multivorans is capable of producing exopolysaccharide (EPS) when grown on certain mannitol-rich media. The significance of the resulting mucoid phenotype and the genome-wide response to mannitol has never been characterized despite its clinical relevance following the approval of a dried-powder preparation of mannitol as an inhaled osmolyte therapy for cystic fibrosis (CF) patients. In the present study we defined the transcriptional response of B. multivorans ATCC 17616, a model genome-sequenced strain of environmental origin, to growth on mannitol-rich yeast extract media (MYEM). EPS-dependent and -independent impact of MYEM on virulence-associated traits was assessed in both strain ATCC 17616 and the CF isolate B. multivorans C1576. Our studies revealed a significant transcriptional response to MYEM encompassing approximately 23 % of predicted genes within the genome. Strikingly, this transcriptional response identified that EPS induction occurs in ATCC 17616 without the upregulation of the bce-I and bce-II EPS gene clusters, despite their pivotal role in EPS biosynthesis. Of approximately 20 differentially expressed putative virulence factors, 16 exhibited upregulation including flagella, ornibactin, oxidative stress proteins and phospholipases. MYEM-grown B. multivorans also exhibited enhanced motility, biofilm formation and epithelial cell invasion. In contrast to these potential virulence enhancements, MYEM-grown B. multivorans C1576 showed attenuated virulence in the Galleria mellonella infection model. All of the observed phenotypic responses occurred independently of EPS production, highlighting the profound impact that mannitol-based growth has on the physiology and virulence of B. multivorans.

Effect of inhaled dry powder mannitol on mucus and its clearance

Insufficient hydration at the airway surface can make mucus adherent and poorly cleared. Cough, the major mechanism of mucus clearance in disease, is ineffective when mucus is adhesive. Inhaled mannitol creates an osmotic drive for water to move into the airway lumen. The consequent increased hydration of the airway surface decreases the adherence of mucus to the epithelium, facilitates the coupling of mucus and cilia thereby increasing mucus clearance. Inhaled mannitol also promotes effective coughing and stimulates mucociliary clearance. The beneficial effect of mannitol on mucus and its clearance has been demonstrated in patients with asthma, bronchiectasis and cystic fibrosis. Inhaled dry powder mannitol (Bronchitol™) is promising to be an effective treatment for the clearance of retained airway secretions.

New pulmonary therapies directed at targets other than CFTR

Our current understanding of the pathogenesis of cystic fibrosis (CF) lung disease stresses the importance of the physical and chemical properties of the airway surface liquid (ASL). In particular, the loss of cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel function in CF reduces the volume and fluidity of the ASL, thus impairing mucociliary clearance and innate antimicrobial mechanisms. Besides direct approaches to restoring mutant CFTR function, alternative therapeutic strategies may also be considered to correct the basic defect of impaired salt and water transport. Such alternative strategies are focused on the restoration of mucociliary transport by (1) reducing sodium and fluid absorption by inhibiting the ENaC channel; (2) activating alternative chloride channels; and (3) increasing airway surface hydration with osmotic agents. Therapeutic approaches directed at targets other than CFTR are attractive because they are potentially useful to all patients irrespective of their genotype. Clinical trials are underway to test the efficacy of these approaches.

Mannitol promotes adherence of an outbreak strain of Burkholderia multivorans via an exopolysaccharide-independent mechanism that is associated with upregulation of newly identified fimbrial and afimbrial adhesins

Burkholderia multivorans, a member of the Burkholderia cepacia complex (Bcc), is an important pathogen of the cystic fibrosis (CF) lung. Mannitol, approved as an inhaled osmolyte therapy for use in CF patients, promotes exopolysaccharide (EPS) production by the Bcc. In the present study, we investigated the role of mannitol-induced EPS in the adherence of B. multivorans. We report that mannitol promoted adherence of two representative B. multivorans strains. However, whilst this enhanced adherence was largely EPS-dependent in an environmental isolate, it was EPS-independent within a CF outbreak strain, suggesting strain-to-strain variation in adhesins. Genome sequencing of the outbreak strain enabled the identification of two distinct loci encoding putative fimbrial and afimbrial adhesins. The putative fimbriae-encoding locus was found to be widely distributed amongst clinical and environmental B. multivorans. In contrast, the locus encoding the putative afimbrial adhesin (of the filamentous haemagglutinin family, FHA) was restricted to clinical isolates. Both loci contributed to biofilm formation and mucin adherence. Furthermore, we report that mannitol promoted expression of both loci, and that the locus encoding the putative FHA-family adhesin is a key determinant of the enhanced adherence observed following growth in mannitol. Our studies provide the first characterization, to our knowledge, of B. multivorans adhesins, and in so doing highlight the strain-dependent role of EPS in the Bcc and the difficulties in assigning phenotypic traits to Bcc EPS due to the wider response to mannitol. Our observations also highlight the need to monitor the microbiological effects of inhaled mannitol therapy in Bcc-infected CF patients.

Pooled analysis of two large randomised phase III inhaled mannitol studies in cystic fibrosis

BACKGROUND

To evaluate safety and efficacy of inhaled mannitol treatment in subgroups of a large global CF population.

METHODS

Data were pooled from two multicentre, double-blind, randomised, controlled, parallel group phase III studies in which 600 patients inhaled either mannitol (400 mg) or control (mannitol 50 mg) twice a day for 26 weeks.

RESULTS

Both the mean absolute change in FEV(1) (mL) and relative change in FEV(1) by % predicted from baseline for mannitol (400 mg) versus control were statistically significant (73.42 mL, 3.56%, both p<0.001). Increases in FEV(1) were observed irrespective of rhDNase use. Significant improvements in FEV1 occurred in adults but not children (6-11) or adolescents (aged 12-17). Pulmonary exacerbation incidence was reduced by 29% (p=0.039) in the mannitol (400 mg) group.

CONCLUSIONS

Sustained six-month improvements in lung function and decreased pulmonary exacerbation incidence indicate that inhaled mannitol is an important additional drug in the treatment of CF.

Cystic fibrosis: a mucosal immunodeficiency syndrome

Cystic fibrosis transmembrane conductance regulator (CFTR) functions as a channel that regulates the transport of ions and the movement of water across the epithelial barrier. Mutations in CFTR, which form the basis for the clinical manifestations of cystic fibrosis, affect the epithelial innate immune function in the lung, resulting in exaggerated and ineffective airway inflammation that fails to eradicate pulmonary pathogens. Compounding the effects of excessive neutrophil recruitment, the mutant CFTR channel does not transport antioxidants to counteract neutrophil-associated oxidative stress. Whereas mutant CFTR expression in leukocytes outside of the lung does not markedly impair their function, the expected regulation of inflammation in the airways is clearly deficient in cystic fibrosis. The resulting bacterial infections, which are caused by organisms that have substantial genetic and metabolic flexibility, can resist multiple classes of antibiotics and evade phagocytic clearance. The development of animal models that approximate the human pulmonary phenotypes-airway inflammation and spontaneous infection-may provide the much-needed tools to establish how CFTR regulates mucosal immunity and to test directly the effect of pharmacologic potentiation and correction of mutant CFTR function on bacterial clearance.

Long-term inhaled dry powder mannitol in cystic fibrosis: an international randomized study

RATIONALE

New treatment strategies are needed to improve airway clearance and reduce the morbidity and the time burden associated with cystic fibrosis (CF).

OBJECTIVES

To determine whether long-term treatment with inhaled mannitol, an osmotic agent, improves lung function and morbidity.

METHODS

Double-blind, randomized, controlled trial of inhaled mannitol, 400 mg twice a day (n = 192, "treated" group) or 50 mg twice a day (n = 126, "control" group) for 26 weeks, followed by 26 weeks of open-label treatment.

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was absolute change in FEV(1) from baseline in treated versus control groups, averaged over the study period. Secondary endpoints included other spirometric measurements, pulmonary exacerbations, and hospitalization. Clinical, microbiologic, and laboratory safety were assessed. The treated group had a mean improvement in FEV(1) of 105 ml (8.2% above baseline). The treated group had a relative improvement in FEV(1) of 3.75% (P = 0.029) versus the control group. Adverse events and sputum microbiology were similar in both treatment groups. Exacerbation rates were low, but there were fewer in the treated group (hazard ratio, 0.74; 95% confidence interval, 0.42-1.32; P = 0.31), although this was not statistically significant. In the 26-week open-label extension study, FEV(1) was maintained in the original treated group, and improved in the original control group to the same degree.

CONCLUSIONS

Inhaled mannitol, 400 mg twice a day, resulted in improved lung function over 26 weeks, which was sustained after an additional 26 weeks of treatment. The safety profile was also acceptable, demonstrating the potential role for this chronic therapy for CF. Clinical trial registered with www.clinicaltrials.gov (NCT 00630812).