Nebulization and anti-Pseudomonas aeruginosa activity of colistin

Establishment of a prognostic risk model for prostate cancer based on Gleason grading and cuprotosis related genes

INTRODUCTION

Prostate cancer (PCa) is common in aging males, diagnosed via the Gleason grading system. The study explores the unexamined prognostic value of cuprotosis, a distinct cell death type, alongside Gleason grades in PCa.

METHODS

We explored Cuprotosis-related genes (CRGs) in prostate cancer (PCa), using NMF on TCGA-PRAD data for patient classification and WGCNA to link genes with Gleason scores and prognosis. A risk model was crafted via LASSO Cox regression. STX3 knockdown in PC-3 cells, analyzed for effects on cell behaviors and tumor growth in mice, highlighted its potential therapeutic impact.

RESULTS

We identified five genes crucial for a prognostic risk model, with higher risk scores indicating worse prognosis. Survival analysis and ROC curves confirmed the model's predictive accuracy in TCGA-PRAD and GSE70769 datasets. STX3 was a key adverse prognostic factor, with its knockdown significantly reducing mRNA and protein levels, impairing PC-3 cell functions. In vivo, STX3 knockdown in PC-3 cells led to significantly smaller tumors in nude mice, underscoring its potential therapeutic value.

CONCLUSION

Our prognostic model, using five genes linked to Gleason scores, effectively predicts prostate cancer outcomes, offering a novel treatment strategy angle.

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.

Pharmacokinetics of Colistin Methansulphonate (CMS) and Colistin after CMS Nebulisation in Baboon Monkeys

PURPOSE

The objective of this study was to compare two different nebulizers: Eflow rapid® and Pari LC star® by scintigraphy and PK modeling to simulate epithelial lining fluid concentrations from measured plasma concentrations, after nebulization of CMS in baboons.

METHODS

Three baboons received CMS by IV infusion and by 2 types of aerosols generators and colistin by subcutaneous infusion. Gamma imaging was performed after nebulisation to determine colistin distribution in lungs. Blood samples were collected during 9 h and colistin and CMS plasma concentrations were measured by LC-MS/MS. A population pharmacokinetic analysis was conducted and simulations were performed to predict lung concentrations after nebulization.

RESULTS

Higher aerosol distribution into lungs was observed by scintigraphy, when CMS was nebulized with Pari LC® star than with Eflow Rapid® nebulizer. This observation was confirmed by the fraction of CMS deposited into the lung (respectively 3.5% versus 1.3%).CMS and colistin simulated concentrations in epithelial lining fluid were higher after using the Pari LC star® than the Eflow rapid® system.

CONCLUSIONS

A limited fraction of CMS reaches lungs after nebulization, but higher colistin plasma concentrations were measured and higher intrapulmonary colistin concentrations were simulated with the Pari LC Star® than with the Eflow Rapid® system.

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

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

Inhaled antibiotics for Gram-negative respiratory infections

Several disease states create conditions that lead to opportunistic Gram-negative respiratory infections. Inhalation is the most direct and, until recently, underutilized means of antimicrobial drug targeting for respiratory tract infections. All approved antimicrobial agents for administration by inhalation are indicated for Pseudomonas aeruginosa infections in patients with cystic fibrosis. These inhaled therapies have directly contributed to a significant reduction in exacerbations and hospitalizations in this patient population over the last few decades. The relentless adaptation of pathogenic organisms to current treatment options demands that the pharmaceutical industry continue designing next-generation antimicrobial agents over 70 years after they were first introduced. Recent technological advances in inhalation devices and drug formulation techniques have broadened the scope of antimicrobial structural classes that can be investigated by inhalation; however, there is an urgent need to discover novel compounds with improved resistance profiles relative to those drugs that are already marketed.

Occupational asthma due to colistin in a pharmaceutical worker

To our knowledge, this is the first case report of a 24-year-old man working in a pharmaceutical company transporting and storing raw materials who developed occupational asthma (OA) to colistin. The specific inhalation challenge confirmed the diagnosis of OA to colistin. Specific IgE was not detected, because dot-blot analysis was negative at all colistin concentrations tested. To our knowledge, OA due to a peptide antibiotic has not previously been described. This antibiotic should be listed as a trigger of OA.

Aerosol drug delivery in lung transplant recipients

BACKGROUND

Inhaled drug delivery after lung transplantation provides a unique opportunity for direct treatment of a solid organ transplant. At present, no inhaled therapies are approved for this population though several have received some development. Primary potential applications include inhaled immunosuppressive and anti-infective drugs.

OBJECTIVES

The objective of this article is to review potential applications of inhaled medications for lung transplant recipients, the techniques used to develop inhaled drugs and the challenges of aerosol delivery in this specific population.

METHODS

The results of relevant studies are reviewed and two developmental examples are presented.

RESULTS/CONCLUSIONS

Inhaled medications may provide significant advantages for lung transplant recipients. Past studies with inhaled cyclosporine and amphotericin-B provide useful guidance for clinical development of new preparations.

[Will we still have antibiotics tomorrow?]

Since the discovery of antibiotics, it has been generally believed that these antimicrobials are capable of curing almost all bacterial infections. More recently, the appearance of increasing resistance to antibiotics and the emergence of multiresistant microorganisms have given rise to growing concern among physicians, and that concern has now started to filter through to society in general. The problem is further aggravated by a situation that not many people are currently aware of, that is, the limited prospects for future development of new antibiotics in the short to medium term. Appropriate use of available antibiotics based on a thorough understanding of their in vivo activity and the emergence of new forms of administration, such as inhalers, may help to alleviate the problem.

Unlabeled uses of nebulized medications

PURPOSE

The uses, dosing recommendations, benefits, and disadvantages of unlabeled drugs administered by nebulization are reviewed.

SUMMARY

Nebulization is gaining popularity as a treatment alternative, and many drugs are used unlabeled in a nebulized form, including the opioids, lidocaine, magnesium sulfate, amphotericin B, and colistin. The opioids are frequently used to treat dyspnea in end-stage diseases. Common dosages include 1-2 mg every two hours as needed for hydromorphone and 25-50 microg every two hours for fentanyl citrate. Lidocaine can be used to relieve bronchoconstriction and cough symptoms as well as acting as a local anesthetic. It is typically given in a dose between 20 and 160 mg. Nebulized magnesium sulfate can be used in managing acute asthma and is given in dosages between 125 and 250 mg every 20 minutes, with no more than four consecutive doses. Nebulized amphotericin B can be used to prevent infections in immunocompromised patients. A typical amphotericin B regimen is 25 mg every 24 hours. Nebulized colistin is being studied in the prevention and treatment of gram-negative infections and in patients awaiting lung transplants. Colistin is often given as 75 mg every 12 hours to combat infections.

CONCLUSION

Unlabeled nebulization of opioids, lidocaine, magnesium, amphotericin B, and colistin is an alternative method of treatment for patients with pulmonary problems or infections or for those undergoing bronchoscopy. More research is needed to develop guidelines for their use since nebulization may provide benefits to many patients who otherwise cannot be treated or would be at risk of systemic adverse effects of the drugs.

Aerosolised antibacterials for the prevention and treatment of hospital-acquired pneumonia

Aerosolised administration of antibacterials remains theoretically attractive for the prevention and treatment of hospital-acquired pneumonia (HAP) because of the ability to generate high drug concentrations at the site of infection. There is renewed interest in this area because of the shortcomings of current therapies and increasing multidrug resistance in Gram-negative organisms. Clinical trials of aerosolised or endotracheally administered antibacterials for HAP prevention have generally been positive; however, early trials were hampered by the development of resistance related to indiscriminate use. More recent trials have shown efficacy at HAP prevention without adverse effects on microflora as a result of more limited usage. However, prophylactic aerosolised antibacterials still need to be studied in large randomised trials before they could enter widespread use. The treatment of HAP with aerosolised antibacterials has mostly been reported in case series without control groups. Both early reports with aminoglycosides and the more recent use of colistin have reported very good response rates; even with organisms such as Pseudomonas aeruginosa and Acinetobacter baumannii. Aerosolised antibacterials were almost always added to intravenous therapy. On the basis of these reports, the current HAP guidelines allow the addition of aerosolised antibacterials in selected patients with multidrug-resistant organisms. This seems to be a reasonable recommendation until large trials are performed. Overall, toxicity was relatively low in the publications reviewed. Aerosolised drug administration in mechanically ventilated patients requires attention to a number of factors in order to maximise drug deposition in the lung.

Efficacy of aerosolized peroxyacetic acid as a sanitizer of lettuce leaves

Aerosolized sanitizer was investigated as a potential alternative to aqueous and gaseous sanitizers for produce. Peroxyacetic acid was aerosolized (5.42 to 11.42 microm particle diameter) by a commercially available nebulizer into a model cabinet. Iceberg lettuce leaves were inoculated with three strains each of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium and then treated with aerosolized peroxyacetic acid for 10, 30, or 60 min in a model aerosol cabinet at room temperature (22 +/- 2 degrees C). After treatment, surviving healthy and injured bacterial cells were enumerated on appropriate selective agars or using the overlay agar method. Inoculated iceberg lettuce leaves exposed to aerosolized peroxyacetic acid for 10 min exhibited a 0.8-log reduction in E. coli O157:H7, a 0.3-log reduction in Salmonella Typhimurium, and a 2.5-log reduction in L. monocytogenes when compared with the control. After 30 min of treatment, the three pathogens were reduced by 2.2, 3.3, and 2.7 log, and after 60 min, the reductions were 3.4, 4.5, and 3.8 log, respectively. Aerosolization may be a new and convenient method for sanitizing produce for storage or shipping.

Bronchial constriction and inhaled colistin in cystic fibrosis

STUDY OBJECTIVE

Inhaled colistin is used for the treatment of Pseudomonas aeruginosa infection in cystic fibrosis (CF) patients despite reports of chest tightness and bronchospasm. The main objective of the study was to assess whether bronchospasm occurred in pediatric CF patients with or without clinical evidence of airway hyperreactivity.

DESIGN AND METHODS

A prospective placebo-controlled clinical trial with crossover design was devised using challenge tests with 75 mg colistin in 4 mL saline solution and a placebo solution of the same osmolarity using a breath-enhanced nebulizer for administration. Subjects were recruited as follows: high risk (HR) for bronchospasm due to a personal history of recurrent wheezing, a family history of asthma and/or atopy, or bronchial lability, as demonstrated in pulmonary function tests; or low risk (LR) without these characteristics.

RESULTS

The mean FEV(1) (expressed as the mean [+/- SD] fall from baseline) of the HR group (n = 12) fell 12 +/- 9% after placebo was administered, and fell 17 +/- 10% after colistin was administered. For the LR group (n = 8), the mean FEV(1) fell 9 +/- 4% following placebo administration and 13 +/- 8% following colistin administration. There was a greater number of subjects in the HR group compared to the LR group, which had a mean fall in FEV(1) of >/= 15% (p < 0.01) after inhaling colistin. The differences between placebo and colistin therapy in the LR group were not significant.

CONCLUSION

The results demonstrated that colistin can cause bronchospasm, particularly in those patients with coexisting CF and asthma.

Residual Gravimetric Method to Measure Nebulizer Output

The aim of this study was to assess a residual gravimetric method based on weighing dry filters to measure the aerosol output of nebulizers. This residual gravimetric method was compared to assay methods based on spectrophotometric measurement of terbutaline (Bricanyl, Astra Zeneca, France), high-performance liquid chromatography (HPLC) measurement of tobramycin (Tobi, Chiron, U.S.A.), and electrochemical measurements of NaF (as defined by the European standard). Two breath-enhanced jet nebulizers, one standard jet nebulizer, and one ultrasonic nebulizer were tested. Output produced by the residual gravimetric method was calculated by weighing the filters both before and after aerosol collection and by filter drying corrected by the proportion of drug contained in total solute mass. Output produced by the electrochemical, spectrophotometric, and HPLC methods was determined after assaying the drug extraction filter. The results demonstrated a strong correlation between the residual gravimetric method (x axis) and assay methods (y axis) in terms of drug mass output (y = 1.00 x -0.02, r(2) = 0.99, n = 27). We conclude that a residual gravimetric method based on dry filters, when validated for a particular agent, is an accurate way of measuring aerosol output.

Pseudomonas acquisition in young patients with cystic fibrosis: pathophysiology, diagnosis, and management

PURPOSE OF REVIEW

To summarize the pathophysiology of, risk factors for, and outcomes of early Pseudomonas aeruginosa (Pa) infection in CF; to review the results of trials of early intervention and to describe treatment options for early Pa infection.

RECENT FINDINGS

Chronic lower airway Pa infection is associated with significant morbidity and mortality among CF patients. However, first acquisition of Pa does not appear to cause an immediate and rapid decline in lung function. Early Pa isolates are generally non-mucoid, antibiotic-sensitive, and present at low density, suggesting a possible "window of opportunity" for early intervention.

SUMMARY

Anti-pseudomonal therapy for early infection results in transient Pa eradication, but re-infection with Pa appears inevitable despite early aggressive treatment. There are no controlled trials demonstrating clinical benefit in young children. There is a critical need for further investigation of the clinical outcomes associated with early intervention, the long-term safety profile, and the optimal drug regimen.

Characteristics of EPI-hNE4 aerosol: a new elastase inhibitor for treatment of cystic fibrosis

The purpose of this study was to define nebulization conditions providing delivery of aerosols of EPI-hNE4, an inhibitor of human neutrophil elastase (HNE). EPI-hNE4 was nebulized with Pari LC Star and tested at three concentrations (2.5, 5, and 10 mg/mL). The inhaled mass was measured over 15 min. Particle size distribution was measured by cascade impaction. The effect was also tested of mixing EPI-hNE4 with a (99m)Tc human serum albumin (HSA) tracer on the aerodynamic properties of the aerosol. The inhibitory activity of EPI-hNE4 after nebulization was assessed on purified HNE. The inhaled mass was 32.3 +/- 3.5% (mean +/- SD) after 10 min and 44.2 +/- 3.8% (mean +/- SD) after 15 min. Mass median aerodynamic diameter ranged between 1.2 and 1.8 microm. The (99m)Tc HSA EPI-hNE4 aerosol was similar in terms of particle size distribution (y = 1.0338x - 0.003, r = 0.83). (99m)Tc activity was predictive of EPI-hNE4 mass distribution (y = 1.0278x - 1.6991, r = 0.89). The inhibitory capacity of aerosolized samples remained unchanged after up to 10 min of nebulization. EPI-hNE4 can be nebulized efficiently without decrease in its activity. Mixing this inhibitor with (99m)Tc HSA should allow quantification of its deposition in CF patients.

Aerosols and anti-infectious agents

Anti-infectious agents such as pentamidine, antibiotics (mainly colistine and aminoglycosides), and amphotericin B can be administered by aerosol. Apart from pentamidine and Tobi, this route of administration is not officially approved and it constitutes an empirical approach, which has benefited from recent research summarized hereafter. The most fundamental question is related to the potentially deleterious effects of nebulization processes, especially ultrasound, on the anti-infectious properties of the drugs. Colimycin, which was chosen as a reference because its polypeptide structure makes it unstable a priori, proved to be resistant to high frequency ultrasound, which is encouraging for other molecules such as aminoglycosides or betalactamins. The nebulizer characteristics also have to be taken into account. An aerosol can be produced from an amphotericin B suspension and from colistine using both an ultrasonic nebulizer and a jet nebulizer. Differentiating between good and bad nebulizers is not dependent upon the physical process involved to nebulize the drug, but on the intrinsic characteristics of the device and its performance with a known drug. The inhaled mass of an aerosol in the respirable range must be high and dosimetric nebulizers represent significant progress. Finally, administration of anti-infectious aerosols requires a new pharmacological approach to monitor treatment, and urinary assays are promising for this purpose.

Nebulizer choice for inhaled colistin treatment in cystic fibrosis

STUDY OBJECTIVES

To develop practical ways of nebulizing colistin by determining the rate of drug output, total drug output, and particle-size distribution of two commercially available jet nebulizers, the disposable Hudson 1730 Updraft II (Hudson Respiratory Care; Temecula, CA) and the reusable Pari LC Star breath-enhanced nebulizer (Pari Respiratory Equipment; Midlothian, VA).

METHODS

The nebulizers contained colistin, 75 mg, in 4 mL of isotonic solution. Particle-size distribution was measured by helium-neon laser diffraction, allowing calculation of the respirable fraction (RF), the mass of aerosol comprised of droplets < 5 microm.

RESULTS

The mean (95% confidence interval [CI]) total rate of output of the Updraft II was 2.6 mg/min (2.0, 3.1; n = 4) with 1.3 mg/min (1.0, 1.5) mg/min within the RF. The rate of output of the LC Star increased in a quadratic relationship to the inspiratory flow, delivering 1.8 mg/min (0.7, 2.0; n = 4) with 1.4 mg/min (1.3, 1.6) within the RF, and 6.2 mg/min (5.6, 6.8) with 5.3 mg/min (4.8, 5.7) within the RF, at 0 L/min and 20 L/min inspiratory flows, respectively. Efficiency, as the rate of expected pulmonary deposition divided by rate of total output, was then calculated. The LC Star estimated 56% (51, 61) efficiency, with pulmonary delivery of 29% (26, 32) of the charge of the nebulizer, compared to the Updraft II at 22% (22, 23) efficiency and expected pulmonary deposition of 10% (10, 10) of the dose.

CONCLUSIONS

Colistin can be successfully nebulized with both nebulizers tested. This study provides an estimate of in vivo efficiency and expected pulmonary deposition that may be used in future trials.

High-performance liquid chromatographic method for the determination of colistin in serum

Inhalation therapy of colistin is widespread in patients with cystic fibrosis. To date, no pharmacokinetic data of colistin after inhalation are available. To optimize the inhalation therapy, pharmacokinetic data of colistin are necessary. In this study, the authors describe a chromatographic analysis for measurement of colistin concentrations in serum. After protein precipitation, the colistin sample is treated with orthophthalaldehyde for derivatization. The sum of the peak areas of the two main components of colistin (polymyxin E1 and E2) were used for quantitation. The performance of the analytical method was assessed by determining the lower limit of quantitation, the selectivity of the method, the intra-assay variation, the reproducibility, the interassay variation, and the accuracy. The lower limit of quantitation was 28 microg/L. Ceftazidime, aztreonam, piperacilline, or tobramycin showed no interference with the colistin assay. In a pilot study, the authors found a trough value of approximately 10 microg/L and peak values of approximately 100 microg/L after inhalation of 160 mg colistin in serum samples of a representative patient. These values show that the method can be used to design further experiments. The applicability of the method was also tested on urine and sputum samples. Colistin was detectable but further validation experiments are required to confirm the usefulness of the method in these biologic matrices. To the authors' knowledge this is the first study in which serum concentrations are described after inhalation of colistin in patients with cystic fibrosis.

Basis for nebulized antibiotics: droplet characterization and in vitro antimicrobial activity versus Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa

The aims of this study were to (1) quantify the particle size characteristics of several antibiotics considered suitable for aerosol therapy after aerosolization with the PARI IS/2 nebulizer (Pari GmbH, Sarnberg, Germany) and (2) determine the degree to which in vitro antimicrobial activity of these antibiotics is maintained after nebulization. The aerosolized drugs were tobramycin sulfate, streptomycin, and imipenem, with saline solution as the control. Mean mass aerodynamic diameter of the nebulized drugs was 3.25 microns for tobramycin, 2.26 microns for imipenem, and 2.38 microns for streptomycin. In vitro tests showed that tobramycin and imipenem were unaltered in their bacteriostatic activity against strains of Escherichia coli (American Type Culture Collection [ATCC] 25922) and Staphylococcus aureus (ATCC 29213) as well as against Pseudomonas aeruginosa (ATCC 27853) with minimal inhibitory concentration (MIC) values less than 0.3 microgram/mL. Nebulized streptomycin showed significantly higher MIC values against P. aeruginosa (ATCC 27853). These results suggest that tobramycin and imipenem may be prescribed as an aerosol generated by jet nebulization (PARI IS/2) to treat S. aureus, E. coli, and P. aeruginosa infections without any risk of altering the drugs minimum bacteriostatic activity by the nebulization process. Aerosolization of streptomycin with this nebulizer may not be as effective against P. aeruginosa because it seems to alter the bacteriostatic activity.

Current status of topical nasal antimicrobial agents

The nasal cavity and paranasal sinuses are probably one of the last frontiers in the head and neck region where the use of topical antimicrobial agents is not yet established. Although the anatomy of the nasal cavity and the paranasal sinuses can theoretically be exploited for the administration of antimicrobials in rhinosinusitis, very few studies have been conducted to test the feasibility of this mode of therapy. We review the anatomical and physiological factors that should be considered in the use of topical nasal antimicrobial agents and the current status of topical nasal antimicrobial usage, and we make recommendations for the administration of topical nasal antimicrobial agents.