Bronchial provocation testing with dry powder mannitol in children with cystic fibrosis

Comparison of inhaled mannitol/dornase alfa combination and daily dornase alfa alone in children with cystic fibrosis

OBJECTIVES

Inhaled recombinant human deoxyribonuclease (dornase alfa) and osmotic agents such as inhaled mannitol are used for improving the clearance of secretions of cystic fibrosis (CF) patients. We aimed to evaluate the long-term clinical effects of adding dry powder inhaled (DPI) mannitol in subjects with CF who are taking daily dornase alfa.

METHOD

We conducted a retrospective case-control study on subjects with CF. The effect of DPI mannitol was assessed by comparing DPI mannitol and dornase alfa combination with daily dornase alfa alone in children with CF during a 12-month period. The primary outcome measures of the study were absolute changes in percent predicted forced expiratory volume in 1 s (FEV1) and FEV1 z-scores and the secondary outcomes included other spirometry indices, body mass index, frequency of pulmonary exacerbations, SPO₂ , and sputum microbiology.

RESULT

Of a total of 28 patients who committed to use DPI mannitol treatments during the study period, five had a positive challenge with DPI mannitol and two were aged over 18 years. Therefore, the mannitol treatment group consisted of 21 patients. However, the effect of DPI mannitol was analyzed using 15 patients in the mannitol treatment group who received DPI mannitol for at least 12 months, and 18 patients who only used dornase alfa constituted the control group. The median absolute change in FEV1 between baseline and the third month; and baseline and the 12th month were significantly higher in the mannitol treatment group (p = 0.038, p = 0.004, respectively). When the groups are compared with respect to absolute z-score changes, all spirometry indices, except FVC at the end of 3 months, showed statistically significant improvements in the mannitol treatment group. Some secondary outcomes like pulmonary exacerbation frequency during the study year and median absolute body mass index z-score changes from baseline to the end of the study showed no significant differences between the groups (p = 0.735, p = 0.161, respectively). No colonization changes were observed in the treatment group.

CONCLUSIONS

This study showed that in those patients who tolerated long-term (12 months) treatment with DPI mannitol and dornase alfa made greater improvements in FEV1, FVC, FEV1/FVC, FEF25-75 z-scores than treatment with dornase alfa alone in children with CF.

Cough as an adverse effect on inhalation pharmaceutical products

Cough is an adverse effect that may hinder the delivery of drugs into the lungs. Chemical or mechanical stimulants activate the transient receptor potential in some airway afferent nerves (C-fibres or A-fibres) to trigger cough. Types of inhaler device and drug, dose, excipients and formulation characteristics, including pH, tonicity, aerosol output and particle size may trigger cough by stimulating the cough receptors. Release of inflammatory mediators may increase the sensitivity of the cough receptors to stimulants. The cough-provoking effect of aerosols is enhanced by bronchoconstriction in diseased airways and reduces drug deposition in the target pulmonary regions. In this article, we review the factors by which inhalation products may cause cough.

Asthma and cystic fibrosis: a tangled web

Successfully diagnosing concomitant asthma in people with cystic fibrosis (CF) is a challenging proposition, and the utility of conventional diagnostic criteria of asthma in CF populations remains uncertain. Nonetheless, the accurate identification of individuals with CF and asthma allows appropriate tailoring of therapy, and should reduce the unnecessary use of asthma medication in broader CF cohorts. In this review, we discuss the diagnostic challenge posed by asthma in CF, both in terms of clinical evaluation, and of interpretation of pulmonary function testing and non-invasive markers of airway inflammation. We also examine how the role of cross-sectional thoracic imaging in CF and asthma can assist in the diagnosis of asthma in these patients. Finally, we critically appraise the evidence base behind the use of asthma medications in CF populations, with a particular focus on the use of inhaled corticosteroids and bronchodilators. As shall be discussed, the gaps in the current literature make further high-quality research in this field imperative.

Challenges in enzymatic route of mannitol production

Mannitol is an important biochemical often used as medicine and in food sector, yet its biotechnological is not preffered in Industry for large scale production, which may be due to the multistep mechanism involved in hydrogenation and reduction. This paper is a comparative preview covering present chemical and biotechnological approaches existing today for mannitol production at industrial scale. Biotechnological routes are suitable for adaptation at industrial level for mannitol production, and whatever concerns are there had been discussed in detail, namely, raw materials, broad range of enzymes with high activity at elevated temperature suitable for use in reactor, cofactor limitation, reduced by-product formation, end product inhibition, and reduced utilization of mannitol for enhancing the yield with maximum volumetric productivity.

Safety assessment of nebulized xylitol in beagle dogs

Xylitol, a potential cystic fibrosis treatment, lowers the salt concentration of airway surface liquid and enhances innate immunity of human airways. The study objective was to evaluate the potential toxicity/recovery from a 14-consecutive day (7 days/week), facemask inhalation administration of nebulized xylitol solution in Beagle dogs. Aerosolized xylitol was generated through three Aerotech II nebulizers operating at approximately 40 psi driving pressure. Test article groups were exposed to the same concentration of aerosolized xylitol for 1, 0.5, or 0.25 h for the high, mid, and low exposures, respectively. A control group was exposed for 1 h to a nebulized normal saline solution. Animals were sacrificed the day following the last exposure or subsequently after 14 non-exposure days. Study endpoints included clinical observations, body weights, ophthalmology, and physical examinations, food consumption, clinical pathology, urinalyses, organ weights, and histopathology. Mean xylitol aerosol concentrations for all groups were approximately 3.5 mg/l. Mean total deposited doses to the pulmonary region were estimated as 21, 11, and 5 mg/kg, for the high-, mid-, and low-exposure groups, respectively. All dogs survived to the scheduled necropsy. No treatment-related findings were observed due to xylitol exposure in any end point examined. Lung findings (mild interstitial infiltration, macrophage hyperplasia, alveolitis, and bronchitis) were consistent among exposed and control groups. No exposure-related effect of xylitol in any parameter assessed was seen during or after the 14-day exposure in Beagle dogs. The No Observed Effect Level was the high-exposure level and suggests that inhaled xylitol is safe for clinical administration.

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.

Airway-rehydrating agents for the treatment of cystic fibrosis: past, present, and future

OBJECTIVE

To review and evaluate airway-rehydrating agents used for the treatment of cystic fibrosis (CF).

DATA SOURCES

Literature was retrieved through MEDLINE (1977-August 2010), Cochrane Library, and International Pharmaceutical Abstracts (1977-August 2010). Search terms used included hypertonic saline, inhaled mannitol, denufosol, Moli1901, lancovutide, and cystic fibrosis. Reference citations from selected articles were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All articles published in English identified from the data sources were evaluated for inclusion. Clinical trials in humans and relevant review articles were evaluated for each airway-rehydrating agent.

DATA SYNTHESIS

Use of airway-rehydrating agents for the treatment of CF is an expanding area. Hypertonic saline (7% NaCl) is currently the only commercially available airway-rehydrating agent recommended for chronic therapy in patients with CF and is being evaluated in younger patients. Inhaled mannitol is an investigational dry-powder inhalation agent that improves mucus clearance in a similar manner to hypertonic saline and produced a statistically significant increase in forced expiratory volume in 1 second in a Phase 3 trial. Denufosol, a P2Y(2) agonist, rehydrates the airway surface liquid bypassing the basic CF transmembrane conductance regulator (CFTR) protein defect. It produces improvement in pulmonary function and is being further evaluated in a Phase 3 trial. Lancovutide (Moli1901) is an investigational agent in early-phase trials that activates a calcium-dependent chloride channel, allowing chloride to enter the airway.

CONCLUSIONS

Hypertonic saline is the primary airway-rehydrating agent used in the treatment of CF. Inhaled mannitol may become an alternative to hypertonic saline since it is faster and easier to administer. It remains unclear whether denufosol and lancovutide will be synergistic or antagonistic with hypertonic saline. Both agents have a unique mechanism of action that bypasses the basic CFTR defect.

Hypertonic Saline Therapy in Cystic Fibrosis: Do Population Shifts Caused by the Osmotic Sensitivity of Infecting Bacteria Explain the Effectiveness of this Treatment?

Cystic fibrosis (CF) is caused by a defect in the CF transmembrane regulator that leads to depletion and dehydration of the airway surface liquid (ASL) of the lung epithelium, providing an environment that can be infected by bacteria leading to increased morbidity and mortality. Pseudomonas aeruginosa chronically infects more than 80% of CF patients and one hallmark of infection is the emergence of a mucoid phenotype associated with a worsening prognosis and more rapid decline in lung function. Hypertonic saline (HS) is a clinically proven treatment that improves mucociliary clearance through partial rehydration of the ASL of the lung. Strikingly, while HS therapy does not alter the prevalence of P. aeruginosa in the CF lung it does decrease the frequency of episodes of acute, severe illness known as infective exacerbations among CF patients. In this article, we propose a hypothesis whereby the positive clinical effects of HS treatment are explained by the osmotic sensitivity of the mucoid sub-population of P. aeruginosa in the CF lung leading to selection against this group in favor of the osmotically resistant non-mucoid variants.

Emerging treatments in cystic fibrosis

There are a number of potential drugs for the treatment of cystic fibrosis (CF) currently undergoing clinical studies. A number of antibacterials formulated for delivery by inhalation are at various stages of study; these include dry-powder inhaler versions of colistin, tobramycin and ciprofloxacin, and formulations of azteonam, amikacin, levofloxacin, ciprofloxacin and fosfomycin/tobramycin for nebulization. Clinical trials of anti-inflammatory agents, including glutathione, phosphodiesterase-5 inhibitors such as sildenafil, oral acetylcysteine, simvastatin, methotrexate, docosahexaenoic acid, hydroxychloroquine, pioglitazone and alpha1-antitrypsin, are ongoing. Ion channel modulating agents, such as lancovutide (Moli1901, duramycin) and denufosol, which activate alternate (non-CF transmembrane regulator [CFTR]) chloride channels, and GS 9411, a sodium channel antagonist, are now at the stages of clinical study and if successful, will offer a new category of therapeutic agent for the treatment of CF. Correction of the underlying gene effect, either by agents that help to correct the dysfunctional CFTR, such as ataluren, VX-770 and VX-809, or by gene transfer (gene therapy), is a particularly exciting prospect as a new therapy for CF and clinical studies are ongoing. This article reviews the exciting potential drug treatments for CF currently being evaluated in clinical studies, and also highlights some of the challenges faced by research and clinical teams in assessing the efficacy of potential new therapies for CF.