Long-term safety and efficacy of tobramycin in the management of cystic fibrosis

Nanoparticle-based platforms for targeted drug delivery to the pulmonary system as therapeutics to curb cystic fibrosis: A review

Cystic fibrosis (CF) is a genetic disorder of the respiratory system caused by mutation of the Cystic Fibrosis Trans-Membrane Conductance Regulator (CFTR) gene that affects a huge number of people worldwide. It results in difficulty breathing due to a large accumulation of mucus in the respiratory tract, resulting in serious bacterial infections, and subsequent death. Traditional drug-based treatments face hindered penetration at the site of action due to the thick mucus layer. Nanotechnology offers possibilities for developing advanced and effective treatment platforms by focusing on drugs that can penetrate the dense mucus layer, fighting against the underlying bacterial infections, and targeting the genetic cause of the disease. In this review, current nanoparticle-mediated drug delivery platforms for CF, challenges in therapeutics, and future prospects have been highlighted. The effectiveness of the different types of nano-based systems conjugated with various drugs to combat the symptoms and the challenges of treating CF are brought into focus. The toxic effects of these nano-medicines and the various factors that are responsible for their effectiveness are also highlighted.

Alginate/Chitosan Particle-Based Drug Delivery Systems for Pulmonary Applications

Cystic fibrosis (CF) is a complex, potentially life-threatening disease that is most effectively treated through the administration of antibiotics (e.g., colistimethate sodium). Chronic infection with Pseudomonas aeruginosa is one of the most significant events in the pathogenesis of cystic fibrosis, and tobramycin is the treatment of choice for those patients with chronic P. aeruginosa infection who are deteriorating despite regular administration of colistimethate sodium. Effective treatment can be challenging due to the accumulation of thickened mucus in the pulmonary environment, and here we describe the results of our investigation into the development of alginate/chitosan particles prepared via precipitation for such environments. Tobramycin loading and release from the alginate/chitosan particles was investigated, with evidence of both uptake and release of sufficient tobramycin to inhibit P. aeruginosa in vitro. Functionalisation of the alginate/chitosan particles with secretory leukocyte protease inhibitor (SLPI) was shown to help inhibit the inflammatory response associated with lung infections (via inhibition of neutrophil elastase activity) and enhance their interaction with cystic fibrosis mucus (assayed via reduction of the depth of particle penetration into the mucus) in vitro, which have prospects to enhance their efficacy in vivo.

Pharmacokinetics and safety of tobramycin nebulization with the I-neb and PARI-LC Plus in children with cystic fibrosis: A randomized, crossover study

AIMS

We aimed to compare the pharmacokinetics (PK) and safety profile of tobramycin inhalation solution (TIS) using the I-neb device to the standard PARI-LC Plus nebulizer in children with cystic fibrosis.

METHODS

A randomized, open-label, crossover study was performed. In 2 separate study visits, blood samples from 22 children were collected following TIS nebulization with I-neb (75 mg) and PARI-LC Plus (300 mg). Study visits were separated by 1 month, in which 1 of the study nebulizers was used twice daily. Tobramycin PK for both nebulizers was established using measured tobramycin concentrations and Bayesian PK modelling software. Hearing and renal function tests were performed to test for aminoglycoside associated toxicity. In addition to standard estimated glomerular filtration rate values, biomarkers for tubular injury (KIM-1 and NAG) were measured. Patient and nebulizer satisfaction were assessed.

RESULTS

Inhalations were well tolerated and serum trough concentrations below the predefined toxic limit were reached with no significant differences in PK parameters between nebulizers. Results of audiometry and estimated glomerular filtration rate revealed no abnormalities. However, increased urinary NAG/creatinine ratios at visit 2 for both nebulizers suggest TIS-induced subclinical tubular kidney injury. Nebulization time was 50% shorter and patient satisfaction was significantly higher with the I-neb.

CONCLUSIONS

Nebulization of 75 mg TIS with the I-neb in children with cystic fibrosis resulted in comparable systemic exposure to 300 mg TIS with the PARI-LC Plus and was well tolerated and preferred over the PARI-LC Plus. Long-term safety of TIS nebulization should be monitored clinically, especially regarding the effects on tubular kidney injury.

The effects of cycled inhaled aztreonam on the cystic fibrosis (CF) lung microbiome

BACKGROUND

To improve clinical outcomes, cystic fibrosis (CF) patients with chronic Pseudomonas aeruginosa infections are prescribed inhaled anti-pseudomonal antibiotics. Although, a diverse microbial community exists within CF airways, little is known about how the CF microbiota influences patient outcomes. We hypothesized that organisms within the CF microbiota are affected by inhaled-antibiotics and baseline microbiome may be used to predict therapeutic response.

METHODS

Adults with chronic P. aeruginosa infection from four clinics were observed during a single 28-day on/off inhaled-aztreonam cycle. Patients performed serial sputum collection, CF-respiratory infection symptom scores (CRISS), and spirometry. Patients achieving a decrease of ≥2 CRISS by day 28 were categorized as subjective responders (SR). The airway microbiome was defined by Illumina MiSeq analysis of the 16S rRNA gene.

RESULTS

Thirty-seven patients (median 37.4 years and FEV₁ 44% predicted) were enrolled. No significant cohort-wide changes in the microbiome were observed between on/off AZLI cycles in either alpha- or beta-diversity metrics. However, at an individual level shifts were apparent. Twenty-one patients (57%) were SR and fourteen patients did not subjectively respond. While alpha-diversity metrics did not associate with response, patients who did not subjectively respond had a higher abundance of Staphylococcus and Streptococcus, and lower abundance of Haemophilus.

CONCLUSIONS

The CF microbiome is relatively resilient to AZLI perturbations. However, associated changes were observed at the individual patient level. The relative abundance of key "off-target" organisms associated with subjective improvements suggesting that the microbiome may be used as a tool to predict patient response - potentially improving outcomes.

Quinoxaline protects zebrafish lateral line hair cells from cisplatin and aminoglycosides damage

Hair cell (HC) death is the leading cause of hearing and balance disorders in humans. It can be triggered by multiple insults, including noise, aging, and treatment with certain therapeutic drugs. As society becomes more technologically advanced, the source of noise pollution and the use of drugs with ototoxic side effects are rapidly increasing, posing a threat to our hearing health. Although the underlying mechanism by which ototoxins affect auditory function varies, they share common intracellular byproducts, particularly generation of reactive oxygen species. Here, we described the therapeutic effect of the heterocyclic compound quinoxaline (Qx) against ototoxic insults in zebrafish HCs. Animals incubated with Qx were protected against the deleterious effects of cisplatin and gentamicin, and partially against neomycin. In the presence of Qx, there was a reduction in the number of TUNEL-positive HCs. Since Qx did not block the mechanotransduction channels, based on FM1-43 uptake and microphonic potentials, this implies that Qx’s otoprotective effect is at the intracellular level. Together, these results unravel a novel therapeutic role for Qx as an otoprotective drug against the deleterious side effects of cisplatin and aminoglycosides, offering an alternative option for patients treated with these compounds.

Economic Evaluation of Tobramycin Inhalation Powder for the Treatment of Chronic Pulmonary Pseudomonas aeruginosa Infection in Patients with Cystic Fibrosis

Background

Chronic lung infection with Pseudomonas aeruginosa occurs in approximately 50% of patients with cystic fibrosis (CF). This infection further compromises lung function, and significantly contributes to the increased healthcare costs.

Objectives

Inhaled tobramycin, used to manage P. aeruginosa infection in CF patients, is available as powder (tobramycin inhalation powder, TIP) and solution (tobramycin inhalation solution, TIS). Evidence suggests increased adherence with the use of TIP over TIS. Hence, this analysis aimed to evaluate the potential pharmacoeconomic benefit of increased adherence with TIP over TIS in the US setting.

Methods

A patient-level simulation model was developed to compare TIP with TIS. Both costs and benefits were predicted over a 10-year time horizon from a payer’s perspective, and were discounted annually at 3%. All costs were presented in 2016 US dollars.

Results

TIP was associated with greater quality-adjusted life-years (by 0.27) and lower total costs (by US$36,168) as compared with TIS over a 10-year time horizon. TIP-treated patients experienced a decreased mean number of exacerbations than TIS-treated patients (39.24 vs 50.20). Furthermore, administration of TIP via the T-326 Inhaler was associated with significant cost savings per patient, because of the nebulizer required for administering TIS (by US$1596) and exacerbation costs (by US$76,531). Probabilistic sensitivity analysis showed that TIP was dominant over TIS in 100% of the simulations.

Conclusion

TIP is likely to be a more cost-effective treatment than TIS, and therefore may reduce the economic burden of CF.

Aerosolized tobramycin for Pseudomonas aeruginosa ventilator-associated pneumonia in patients with acute respiratory distress syndrome

BACKGROUND

Ventilator-associated pneumonia (VAP) due to Pseudomonas aeruginosa has a high mortality and recurrence rate, especially in patients with acute respiratory distress syndrome (ARDS). Therefore, new therapeutic strategies against severe pneumonia are needed. This study evaluated the efficacy of aerosolized tobramycin for P. aeruginosa VAP in ARDS patients.

METHODS

A retrospective analysis was performed on patients who developed VAP caused by P. aeruginosa during the course of ARDS at the intensive care unit (ICU) of Kumamoto University Hospital. Aerosolized tobramycin inhalation solution (TIS) 240 mg was administered daily for 14 days in addition to systemic antibiotics.

RESULTS

A total of 44 patients (TIS group, n = 22; control group, n = 22) were included in the analysis. No significant differences were found between the two groups in terms of clinical characteristics, including acute physiology and chronic health evaluation II score upon ICU admission. The TIS group had significantly lower recurrence of P. aeruginosa VAP (22.7% vs. 52.4%, P = 0.04) and ICU mortality (22.7% vs. 63.6%, P < 0.01) than the control group. Bacterial concentration in tracheal aspirate (mean log 10 cfu/mL ± SD on days 2-5: 1.2 ± 1.3 vs. 5.0 ± 2.3, P < 0.01) decreased more rapidly and markedly in the TIS group compared with the control group.

CONCLUSION

Aerosolized tobramycin was an effective therapeutic strategy for P. aeruginosa VAP patients with ARDS.

Fundamentals of aerosol therapy in critical care

Drug dosing in critically ill patients is challenging due to the altered drug pharmacokinetics–pharmacodynamics associated with systemic therapies. For many drug therapies, there is potential to use the respiratory system as an alternative route for drug delivery. Aerosol drug delivery can provide many advantages over conventional therapy. Given that respiratory diseases are the commonest causes of critical illness, use of aerosol therapy to provide high local drug concentrations with minimal systemic side effects makes this route an attractive option. To date, limited evidence has restricted its wider application. The efficacy of aerosol drug therapy depends on drug-related factors (particle size, molecular weight), device factors, patient-related factors (airway anatomy, inhalation patterns) and mechanical ventilation-related factors (humidification, airway). This review identifies the relevant factors which require attention for optimization of aerosol drug delivery that can achieve better drug concentrations at the target sites and potentially improve clinical outcomes.

Natural Bizbenzoquinoline Derivatives Protect Zebrafish Lateral Line Sensory Hair Cells from Aminoglycoside Toxicity

Moderate to severe hearing loss affects 360 million people worldwide and most often results from damage to sensory hair cells. Hair cell damage can result from aging, genetic mutations, excess noise exposure, and certain medications including aminoglycoside antibiotics. Aminoglycosides are effective at treating infections associated with cystic fibrosis and other life-threatening conditions such as sepsis, but cause hearing loss in 20–30% of patients. It is therefore imperative to develop new therapies to combat hearing loss and allow safe use of these potent antibiotics. We approach this drug discovery question using the larval zebrafish lateral line because zebrafish hair cells are structurally and functionally similar to mammalian inner ear hair cells and respond similarly to toxins. We screened a library of 502 natural compounds in order to identify novel hair cell protectants. Our screen identified four bisbenzylisoquinoline derivatives: berbamine, E6 berbamine, hernandezine, and isotetrandrine, each of which robustly protected hair cells from aminoglycoside-induced damage. Using fluorescence microscopy and electrophysiology, we demonstrated that the natural compounds confer protection by reducing antibiotic uptake into hair cells and showed that hair cells remain functional during and after incubation in E6 berbamine. We also determined that these natural compounds do not reduce antibiotic efficacy. Together, these natural compounds represent a novel source of possible otoprotective drugs that may offer therapeutic options for patients receiving aminoglycoside treatment.

Tobramycin inhalation powder (TOBI Podhaler) for the treatment of lung infection in patients with cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive inherited disease secondary to a defect in the CF transmembrane conductance regulator gene (CFTR). Mortality in CF is associated with impairment of lung function in which bacterial infection plays a fundamental role. The microorganism Pseudomonas aeruginosa (P. aeruginosa) is a marker of poor prognosis. Tobramycin was the first parenteral antibiotic to be used as inhaled medication in CF. Owing to its beneficial effects; it was subsequently used in designed inhaled formulations. The first formulation was the inhalation solution, which improved lung function, lowered hospitalization rates, and reduced the courses of intravenous antibiotic. However, the high associated costs and time necessary to administer the medication negatively affected quality of life. The recent development of tobramycin inhalation powder has optimized treatment. The dry powder inhaler is a simple device that reduces administration time and improves adherence. As there is no risk of bacterial contamination, disinfection is unnecessary.