Efficacy of inhaled ciprofloxacin in the management of non-cystic fibrosis bronchiectasis

Ciprofloxacin-Loaded Inhalable Formulations against Lower Respiratory Tract Infections: Challenges, Recent Advances, and Future Perspectives

Inhaled ciprofloxacin (CFX) has been investigated as a treatment for lower respiratory tract infections (LRTIs) associated with cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), and bronchiectasis. The challenges in CFX effectiveness for LRTI treatment include poor aqueous solubility and therapy resistance. CFX dry powder for inhalation (DPI) formulations were well-tolerated, showing a remarkable decline in overall bacterial burden compared to a placebo in bronchiectasis patients. Recent research using an inhalable powder combining Pseudomonas phage PEV20 with CFX exhibited a substantial reduction in bacterial density in mouse lungs infected with clinical P. aeruginosa strains and reduced inflammation. Currently, studies suggest that elevated biosynthesis of fatty acids could serve as a potential biomarker for detecting CFX resistance in LRTIs. Furthermore, inhaled CFX has successfully addressed various challenges associated with traditional CFX, including the incapacity to eliminate the pathogen, the recurrence of colonization, and the development of resistance. However, further exploration is needed to address three key unresolved issues: identifying the right patient group, determining the optimal treatment duration, and accurately assessing the risk of antibiotic resistance, with additional multicenter randomized controlled trials suggested to tackle these challenges. Importantly, future investigations will focus on the effectiveness of CFX DPI in bronchiectasis and COPD, aiming to differentiate prognoses between these two conditions. This review underscores the importance of CFX inhalable formulations against LRTIs in preclinical and clinical sectors, their challenges, recent advancements, and future perspectives.

Nanoparticle-modified microrobots for in vivo antibiotic delivery to treat acute bacterial pneumonia

Bioinspired microrobots capable of actively moving in biological fluids have attracted considerable attention for biomedical applications because of their unique dynamic features that are otherwise difficult to achieve by their static counterparts. Here we use click chemistry to attach antibiotic-loaded neutrophil membrane-coated polymeric nanoparticles to natural microalgae, thus creating hybrid microrobots for the active delivery of antibiotics in the lungs in vivo. The microrobots show fast speed (>110 µm s^-1) in simulated lung fluid and uniform distribution into deep lung tissues, low clearance by alveolar macrophages and superb tissue retention time (>2 days) after intratracheal administration to test animals. In a mouse model of acute Pseudomonas aeruginosa pneumonia, the microrobots effectively reduce bacterial burden and substantially lessen animal mortality, with negligible toxicity. Overall, these findings highlight the attractive functions of algae-nanoparticle hybrid microrobots for the active in vivo delivery of therapeutics to the lungs in intensive care unit settings.

Pulmonary biofilm-based chronic infections and inhaled treatment strategies

Certain pulmonary diseases, such as cystic fibrosis (CF), non-CF bronchiectasis, chronic obstructive pulmonary disease, and ventilator-associated pneumonia, are usually accompanied by respiratory tract infections due to the physiological alteration of the lung immunological defenses. Recurrent infections may lead to chronic infection through the formation of biofilms. Chronic biofilm-based infections are challenging to treat using antimicrobial agents. Therefore, effective ways to eradicate biofilms and thus relieve respiratory tract infection require the development of efficacious agents for biofilm destruction, the design of delivery carriers with biofilm-targeting and/or penetrating abilities for these agents, and the direct delivery of them into the lung. This review provides an in-depth description of biofilm-based infections caused by pulmonary diseases and focuses on current existing agents that are administered by inhalation into the lung to treat biofilm, which include i) inhalable antimicrobial agents and their combinations, ii) non-antimicrobial adjuvants such as matrix-targeting enzymes, mannitol, glutathione, cyclosporin A, and iii) liposomal formulations of anti-biofilm agents. Finally, novel agents that have shown promise against pulmonary biofilms as well as traditional and new devices for pulmonary delivery of anti-biofilm agents into the lung are also discussed.

Ciprofloxacin nanocrystals liposomal powders for controlled drug release via inhalation

This study was conducted to evaluate the feasibility of developing inhalable dry powders of liposomal encapsulated ciprofloxacin nanocrystals (LECN) for controlled drug release. Dry powders of LECN were produced by freeze-thaw followed by spray drying. The formulations contained sucrose as a lyoprotectant in different weight ratios (0.75:1, 1:1 and 2:1 sucrose to lipids), along with 2% magnesium stearate and 5% isoleucine as aerosolization enhancers. The powder physical properties (particle size, morphology, crystallinity, moisture content), in vitro aerosolization performance, drug encapsulation efficiency and in vitro drug release were investigated. The spray dried powders were comprised of spherical particles with a median diameter of ∼1 µm, partially crystalline, with a low water content (∼2% mass) and did not undergo recrystallization at high relative humidity. When dispersed by an Osmohaler® inhaler at 100 L/min, the powders showed a high aerosol performance with a fine particle fraction (% wt. <5 µm) of 66-70%. After reconstitution of the powders in saline, ciprofloxacin nanocrystals were confirmed by cryo-electron microscopy. The drug encapsulation efficiency of the reconstituted liposomes was 71-79% compared with the stock liquid formulation. Of the three formulations, the one containing a sucrose to lipids wt. ratio of 2:1 demonstrated a prolonged release of ciprofloxacin from the liposomes. In conclusion, ciprofloxacin nanocrystal liposomal powders were prepared that were suitable for inhalation aerosol delivery and controlled drug release.

An evaluation of inhaled antibiotic liposome versus antibiotic nanoplex in controlling infection in bronchiectasis

Inhaled antibiotic nanoparticles have emerged as an effective strategy to control infection in bronchiectasis lung owed to their mucus-penetrating ability. Using ciprofloxacin (CIP) as the model antibiotic, we evaluated dry powder inhaler (DPI) formulations of two classes of antibiotic nanoparticles (i.e. liposome and nanoplex) in their (1) physical characteristics (i.e. size, zeta potential, CIP payload, preparation efficiency), (2) dissolution in artificial sputum medium, (3) ex vivo mucus permeability, (4) antimicrobial activity against Pseudomonas aeruginosa in mucus, (5) cytotoxicity towards human lung epithelium cells, and (6) in vitro aerosolization efficiency. The results showed that the CIP nanoplex exhibited fast dissolution with CIP supersaturation generation, in contrast to the slower release of the liposome (80 versus 30% dissolution after 1 h). Both nanoparticles readily overcame the mucus barrier attributed to their nanosize and mucus-inert surface (50% permeation after 1 h), leading to their similarly high antipseudomonal activity. The CIP liposome, however, possessed much lower CIP payload than the nanoplex (84% versus 3.5%), resulting in high lipid contents in its DPI formulation that led to higher cytotoxicity and lower aerosolization efficiency. The CIP nanoplex thus represented a superior formulation owed to its simpler preparation, higher CIP payload hence lower dosage, better aerosolization, and lower cytotoxicity.

Novel Inhalable Ciprofloxacin Dry Powders for Bronchiectasis Therapy: Mannitol-Silk Fibroin Binary Microparticles with High-Payload and Improved Aerosolized Properties

Non-cystic fibrosis bronchiectasis (NCFB) is a chronic respiratory disease associated with the high morbidity and mortality. Long-term intermittent therapy by inhalable antibiotics has recently emerged as an effective approach for NCFB treatment. However, the effective delivery of antibiotics to the lung requires administering a high dose to the site of infection. Herein, we investigated the novel inhalable silk-based microparticles as a promising approach to deliver high-payload ciprofloxacin (CIP) for NCFB therapy. Silk fibroin (SF) was applied to improve drug-payload and deposit efficiency of the dry powder particles. Mannitol was added as a mucokinetic agent. The dry powder inhaler (DPI) formulations of CIP microparticles were evaluated in vitro in terms of the aerodynamic performance, particle size distribution, drug loading, morphology, and their solid state. The optimal formulation (highest drug loading, 80%) exhibited superior aerosolization performance in terms of fine particle fraction (45.04 ± 0.84%), emitted dose (98.10 ± 1.27%), mass median aerodynamic diameter (3.75 ± 0.03 μm), and geometric standard deviation (1.66 ± 0.10). The improved drug loading was due to the electrostatic interactions between the SF and CIP by adsorption, and the superior aerosolization efficiency would be largely attributed to the fluffy and porous cotton-like property and low-density structure of SF. The presented results indicated the novel inhalable silk-based DPI microparticles of CIP could provide a promising strategy for the treatment of NCFB.

Spotlight on inhaled ciprofloxacin and its potential in the treatment of non-cystic fibrosis bronchiectasis

Non-cystic fibrosis bronchiectasis (NCFB) is a severe chronic illness characterized by irreversible dilation of airways and thickening of bronchial walls, chronic inflammation, repeated infections, and progressive obstruction of the airways. In contrast to cystic fibrosis bronchiectasis (CFB), which is a well-defined genetic disorder, NCFB is a heterogeneous disease caused by many different medical entities. Inhaled antibiotics are effective for patients with CFB, but their efficacy in NCFB has not been proven. The main pathogens involved in the colonization of patients with bronchiectasis are Haemophilus influenza, Moraxella catarrhalis, Staphylococcus aureus, and Pseudomonas aeruginosa. The latter is associated with increased morbidity and mortality. In addition, in NCFB, P. aeruginosa strains are frequently more resistant than those in CFB. At present, there are no approved inhaled antibiotic therapies for NCFB patients. Inhaled ciprofloxacin has been under investigation in the last few years. In two phase II randomized, double-blind, placebo-controlled trials, the use of inhaled ciprofloxacin was significantly associated with reduction in sputum bacterial density and greater eradication rates. In four phase III randomized, double-blind, placebo-controlled trials, the results regarding the time of the first exacerbation and the rate of exacerbations were inconsistent. Specifically, ORBIT-4 and RESPIRE-1 trials showed clinical benefit (prolongation of the time of the first exacerbation and reduced rate of exacerbations in the treatment group compared to the placebo group), whereas the ORBIT-3 and RESPIRE-2 failed to achieve their primary endpoints. The RESPIRE-1 was the first trial that examined the 14-days on/off course separate from the standard 28-days on/off regimen, which is based on CFB protocol treatments. The current data on the efficacy of inhaled ciprofloxacin are encouraging, but further evaluation is needed to determine the appropriate target group and the ideal duration of treatment.

A new therapeutic avenue for bronchiectasis: Dry powder inhaler of ciprofloxacin nanoplex exhibits superior ex vivo mucus permeability and antibacterial efficacy to its native ciprofloxacin counterpart

Non-cystic fibrosis bronchiectasis (NCFB) characterized by permanent bronchial dilatation and recurrent infections has been clinically managed by long-term intermittent inhaled antibiotic therapy among other treatments. Herein we investigated dry powder inhaler (DPI) formulation of ciprofloxacin (CIP) nanoplex with mannitol/lactose as the excipient for NCFB therapy. The DPI of CIP nanoplex was evaluated against DPI of native CIP in terms of their (1) dissolution characteristics in artificial sputum medium, (2) ex vivo mucus permeability in sputum from NCFB and healthy individuals, (3) antibacterial efficacy in the presence of sputum against clinical Pseudomonas aeruginosa strains (planktonic and biofilm), and (4) cytotoxicity towards human lung epithelial cells. Despite their similarly fast dissolution rates in sputum, the DPI of CIP nanoplex exhibited superior mucus permeability to the native CIP (5-7 times higher) attributed to its built-in ability to generate highly supersaturated CIP concentration in the sputum. The superior mucus permeability led to the CIP nanoplex's higher antibacterial efficacy (>3 log₁₀ CFU/mL). The DPI of CIP nanoplex exhibited similar cytotoxicity towards the lung epithelial cells as the native CIP indicating its low risk of toxicity. These results established the promising potential of DPI of CIP nanoplex as a new therapeutic avenue for NCFB.

Inhaled Antibiotic Therapy in Chronic Respiratory Diseases

The management of patients with chronic respiratory diseases affected by difficult to treat infections has become a challenge in clinical practice. Conditions such as cystic fibrosis (CF) and non-CF bronchiectasis require extensive treatment strategies to deal with multidrug resistant pathogens that include Pseudomonas aeruginosa, Methicillin-resistant Staphylococcus aureus, Burkholderia species and non-tuberculous Mycobacteria (NTM). These challenges prompted scientists to deliver antimicrobial agents through the pulmonary system by using inhaled, aerosolized or nebulized antibiotics. Subsequent research advances focused on the development of antibiotic agents able to achieve high tissue concentrations capable of reducing the bacterial load of difficult-to-treat organisms in hosts with chronic respiratory conditions. In this review, we focus on the evidence regarding the use of antibiotic therapies administered through the respiratory system via inhalation, nebulization or aerosolization, specifically in patients with chronic respiratory diseases that include CF, non-CF bronchiectasis and NTM. However, further research is required to address the potential benefits, mechanisms of action and applications of inhaled antibiotics for the management of difficult-to-treat infections in patients with chronic respiratory diseases.

Efficacy of the Novel Antibiotic POL7001 in Preclinical Models of Pseudomonas aeruginosa Pneumonia

The clinical development of antibiotics with a new mode of action combined with efficient pulmonary drug delivery is a priority against untreatable Pseudomonas aeruginosa lung infections. POL7001 is a macrocycle antibiotic belonging to the novel class of protein epitope mimetic (PEM) molecules with selective and potent activity against P. aeruginosa We investigated ventilator-associated pneumonia (VAP) and cystic fibrosis (CF) as indications of the clinical potential of POL7001 to treat P. aeruginosa pulmonary infections. MICs of POL7001 and comparators were measured for reference and clinical P. aeruginosa strains. The therapeutic efficacy of POL7001 given by pulmonary administration was evaluated in murine models of P. aeruginosa acute and chronic pneumonia. POL7001 showed potent in vitro activity against a large panel of P. aeruginosa isolates from CF patients, including multidrug-resistant (MDR) isolates with adaptive phenotypes such as mucoid or hypermutable phenotypes. The efficacy of POL7001 was demonstrated in both wild-type and CF mice. In addition to a reduced bacterial burden in the lung, POL7001-treated mice showed progressive body weight recovery and reduced levels of inflammatory markers, indicating an improvement in general condition. Pharmacokinetic studies indicated that POL7001 reached significant concentrations in the lung after pulmonary administration, with low systemic exposure. These results support the further evaluation of POL7001 as a novel therapeutic agent for the treatment of P. aeruginosa pulmonary infections.

Dry powders for oral inhalation free of lactose carrier particles

Dry powder inhaler (DPI) products have traditionally comprised a simple formulation of micronised drug mixed with a carrier excipient, typically lactose monohydrate. The presence of the carrier is aimed at overcoming issues of poor flowability and dispersibility, associated with the cohesive nature of small, micronised active pharmaceutical ingredient (API) particles. Both the powder blend and the DPI device must be carefully designed so as to ensure detachment of the micronised drug from the carrier excipient on inhalation. Over the last two decades there has been a significant body of research undertaken on the design of carrier-free formulations for DPI products. Many of these formulations are based on sophisticated particle engineering techniques; a common aim in formulation design of carrier-free products being to reduce the intrinsic cohesion of the particles, while maximising dispersion and delivery from the inhaler. In tandem with the development of alternative formulations has been the development of devices designed to ensure the efficient delivery and dispersion of carrier-free powder on inhalation. In this review we examine approaches to both the powder formulation and inhaler design for carrier-free DPI products.