Suitability of Caspofungin for Aerosol Delivery

Inhaled Antifungal Agents for the Treatment and Prophylaxis of Pulmonary Mycoses

Pulmonary mycoses are associated with high morbidity and mortality. The current standard treatment by systemic administration is limited by inadequate local bioavailability and systemic toxic effects. Aerosolisation of antifungals is an attractive approach to overcome these problems, but no inhaled antifungal formulation is currently available for the treatment of pulmonary mycoses. Hence, the development of respirable antifungals formulations is of interest and in high demand. In this review, the recent advances in the development of antifungal formulations for pulmonary delivery are discussed, including both nebulised and dry powder formulations. Although the clinical practices of nebulised parenteral amphotericin B and voriconazole formulations (off-label use) are reported to show promising therapeutic effects with few adverse effects, there is no consensus about the dosage regimen (e.g. the dose, frequency, and whether they are used as single or combination therapy). To maximise the benefits of nebulised antifungal therapy, it is important to establish standardised protocol that clearly defines the dose and specifies the device and the administration conditions. Dry powder formulations of antifungal agents such as itraconazole and voriconazole with favourable physicochemical and aerosol properties are developed using various powder engineering technologies, but it is important to consider their suitability for use in patients with compromised lung functions. In addition, more biological studies on the therapeutic efficacy and pharmacokinetic profile are needed to demonstrate their clinical potential.

Status of inhalable antimicrobial agents for lung infection: progress and prospects

Introduction: Available parenteral and oral administration of antimicrobial agents (AMAs) in respiratory infections often show less penetration into the lung parenchyma. Due to inappropriate dose availability, the rate of antibiotic resistance is increasing gradually. Inhaled antibiotics intensely improve the availability of drugs at the site of respiratory infections. This targeted delivery minimizes systemic exposure and associated toxicity.Area covers: This review was performed by searching in the scientific database like PubMed and several trusted government sites like fda.gov, cdc.gov, ClinicalTrials.gov, etc. For better understanding, AMAs are classified in different stages of approval. Mechanism and characterization of pulmonary drug deposition section helps to understand the effective delivery of AMAs to the respiratory tract. There is a need for proper adoption of delivery devices for inhalable AMAs. Thus, delivery devices are extensively explained. Inspiratory flow has a remarkable impact on the delivery device that has been explained in detail.Expert opinion: Pulmonary delivery restricts the bulk administration of drugs in comparison with other routes. Therefore, novel AMAs with higher bactericidal activity at lower concentrations need to be synthesized. Extensive research is indeed in developing innovative delivery devices that would able to deliver higher doses of AMAs through the pulmonary route.

Pharmacokinetic and Pharmacodynamic Comparison of Intravenous and Inhaled Caspofungin

Background: Aspergillosis is a serious fungal lung infection caused by Aspergillus spp. and is often fatal in immunocompromised patients. Current antifungal drug treatment and delivery results in modest efficacy in these patients may be due to low drug distribution to the lung. A comparison of intravenous (IV) caspofungin and lung-targeted inhaled caspofungin was conducted in rats. The goal was to determine the concentrations of drug at the site of infection and systemic distribution that leads to toxicity. This was performed to understand the difference in the in vitro activity of caspofungin and modest in vivo efficacy. Methods: Caspofungin was delivered to rats through IV injection and nose-only inhalation. Each cohort received a single 2 mg/kg dose of drug. Plasma and tissue samples were analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) and drug levels were compared. Results: The lung drug level was above the minimum effective concentration for 168 hours in the inhaled group but <24 hours in the IV cohort. The lung C_max and area under curve (AUC) in the inhaled group was 20 times higher than in the IV group. Lung-targeted delivery doubled lung drug half-life compared with IV delivery. Systemic distribution to the liver and kidney was 45% lower for the inhaled cohort than the IV group of animals. Conclusions: Based on pharmacokinetic and pharmacodynamic indices, lung-targeted inhaled caspofungin is likely to provide an improved therapeutic benefit without any increase in systemic toxicities. Furthermore, inhaled delivery supports a weekly dosing regimen instead of daily IV dosing.

Combination of urea-crosslinked hyaluronic acid and sodium ascorbyl phosphate for the treatment of inflammatory lung diseases: An in vitro study

This in vitro study evaluated, for the first time, the safety and the biological activity of a novel urea-crosslinked hyaluronic acid component and sodium ascorbyl phosphate (HA-CL - SAP), singularly and/or in combination, intended for the treatment of inflammatory lung diseases. The aim was to understand if the combination HA-CL - SAP had an enhanced activity with respect to the combination native hyaluronic acid (HA) - SAP and the single SAP, HA and HA-CL components. Sample solutions displayed pH, osmolality and viscosity values suitable for lung delivery and showed to be not toxic on epithelial Calu-3 cells at the concentrations used in this study. The HA-CL - SAP displayed the most significant reduction in interleukin-6 (IL-6) and reactive oxygen species (ROS) levels, due to the combined action of HA-CL and SAP. Moreover, this combination showed improved cellular healing (wound closure) with respect to HA - SAP, SAP and HA, although at a lower rate than HA-CL alone. These preliminary results showed that the combination HA-CL - SAP could be suitable to reduce inflammation and oxidative stress in lung disorders like acute respiratory distress syndrome, asthma, emphysema and chronic obstructive pulmonary disease, where inflammation is prominent.

Inhaled anti-infective chemotherapy for respiratory tract infections: successes, challenges and the road ahead

One of the most common causes of illnesses in humans is from respiratory tract infections caused by bacterial, viral or fungal pathogens. Inhaled anti-infective drugs are crucial for the prophylaxis and treatment of respiratory tract infections. The benefit of anti-infective drug delivery via inhalation is that it affords delivery of sufficient therapeutic dosages directly to the primary site of infection, while minimizing the risks of systemic toxicity or avoiding potential suboptimal pharmacokinetics/pharmacodynamics associated with systemic drug exposure. This review provides an up-to-date treatise of approved and novel developmental inhaled anti-infective agents, with particular attention to effective strategies for their use, pulmonary pharmacokinetic properties and safety.

Treatment of asthma exacerbations with the human-powered nebuliser: a randomised parallel-group clinical trial

Background:

Nebulisers aid the treatment of respiratory diseases, including asthma, but they require electricity and are often cost-prohibitive for low- and middle-income countries.

Aims:

The aim of this study was to compare a low-cost, human-powered nebuliser compressor with an electric nebuliser compressor for the treatment of mild to moderate asthma exacerbations in adults and children.

Methods:

This was a non-blinded, parallel-group, equivalence study, with 110 subjects between 6 and 65 years of age, conducted in the emergency department of a district hospital in Ilopango, El Salvador. Participants were assigned by random allocation to receive a 2.5-mg dose of salbutamol from the experimental human-powered nebuliser or the electric nebuliser control. All assigned participants completed treatment and were included in analysis. The study was not blinded as this was clinically unfeasible; however, data analysis was blinded.

Results:

The mean improvement in peak flow of the experimental and control groups was 37.5 (95% confidence interval (CI) 26.7–48.2) l/min and 38.7 (95% CI, 26.1–51.3) l/min, respectively, with a mean difference of 1.3 (95% CI, −15.1 to 17.7) l/min. The mean improvement in percent-expected peak flow for the experimental and control groups was 12.3% (95% CI, 9.1–15.5%) and 13.8% (95% CI, 9.8–17.9%), respectively, with a mean difference of 1.5% (95% CI, −3.6 to 6.6%).

Conclusions:

The human-powered nebuliser compressor is equivalent to a standard nebuliser compressor for the treatment of mild-to-moderate asthma. (Funded by the Opus Dean’s Fund, Marquette University College of Engineering; ClinicalTrials.gov NCT01795742.)

Nebulizer Choice Affects the Airway Targeting of Amphotericin B Lipid Complex Aerosols

Background: Although amphotericin B is highly effective against fungal infections, it has serious adverse effects. Encapsulation of amphotericin B in liposomes reduces its potential for systemic side effects. Administration of liposomal amphotericin via aerosols to the lungs (a main portal of fungal infections) further reduces its toxicity while increasing its therapeutic index and prophylactic efficacy. However, the effectiveness of aerosol therapy depends on the dose deposited and the distribution of the drug within the lungs. The size of the aerosol particle is an important factor that affects the distribution of the drug within the lungs and the effectiveness of therapy. Objective: This study aims to determine the physicochemical suitability of amphotericin B lipid complex (ABLC) for aerosolization and to compare the performance of 3 commercially available air jet nebulizers in generating ABLC aerosols in terms of aerosol output (mg/min) and drug amount aerosolized within various particle-size ranges, the latter of which affects airway deposition. Methods: We aerosolized 2 concentrations (5 mg/mL and 10 mg/mL) of ABLC and evaluated their physicochemical properties, including osmolality, pH, and viscosity. The aerosolization performances of Pulmo-Aide/Micromist, Envoy/Sidestream, and Proneb/Pari LC Star systems were then evaluated in terms of output rate (mg/min), percent aerosolized, and milligram per minute of drug aerosolized within particle-size ranges of 1 to 3.5 µm, 3.5 to 6 µm, and 1 to 6 µm. Results: The output rate increased with higher drug concentration regardless of device. Pulmo-Aide/Micromist and Envoy/Sidestream showed high output rates. Proneb/Pari LC Star and Envoy/Sidestream delivered the highest percentages of aerosolized particles within the 1 to 3.5 µm particle-size range, favoring deposition within the alveolar/distal end area of the airways. Pulmo-Aide/Micromist delivered a higher percentage of aerosol within the 3.5 to 6 µm than the 1 to 3.5 µm particle-size range, favoring deposition in the central airways. Conclusion: The present study shows that different nebulizers produced different size ranges of aerosolized particles of ABLC preferentially targeting different parts of the airways. Thus, effective aerosol therapies may require the evaluation of different nebulizers for optimal targeting.

Preparation and evaluation of inhalable itraconazole chitosan based polymeric micelles

Background

This study evaluated the potential of chitosan based polymeric micelles as a nanocarrier system for pulmonary delivery of itraconazole (ITRA).

Methods

Hydrophobically modified chitosan were synthesized by conjugation of stearic acid to the hydrophilic depolymerized chitosan. FTIR and ¹HNMR were used to prove the chemical structure and physical properties of the depolymerized and the stearic acid grafted chitosan. ITRA was entrapped into the micelles and physicochemical properties of the micelles were investigated. Fluorescence spectroscopy, dynamic laser light scattering and transmission electron microscopy were used to characterize the physicochemical properties of the prepared micelles. The in vitro pulmonary profile of polymeric micelles was studied by an air-jet nebulizer connected to a twin stage impinger.

Results

The polymeric micelles prepared in this study could entrap up to 43.2±2.27 μg of ITRA per milliliter. All micelles showed mean diameter between 120–200 nm. The critical micelle concentration of the stearic acid grafted chitosan was found to be 1.58×10^-2 mg/ml. The nebulization efficiency was up to 89% and the fine particle fraction (FPF) varied from 38% to 47%. The micelles had enough stability to remain encapsulation of the drug during nebulization process.

Conclusions

In vitro data showed that stearic acid grafted chitosan based polymeric micelles has a potential to be used as nanocarriers for delivery of itraconazole through inhalation.

Multidisciplinary approach to the treatment of invasive fungal infections in adult patients. Prophylaxis, empirical, preemptive or targeted therapy, which is the best in the different hosts?

The high morbidity, mortality, and health care costs associated with invasive fungal infections, especially in the critical care setting and immunocompromised host, have made it an excellent target for prophylactic, empiric, and preemptive therapy interventions principally based on early identification of risk factors. Early diagnosis and treatment are associated with a better prognosis. In the last years there have been important developments in antifungal pharmacotherapy. An approach to the new diagnosis tools in the clinical mycology laboratory and an analysis of the use new antifungal agents and its application in different clinical situations has been made. Furthermore, an attempt of developing a state of the art in each clinical scenario (critically ill, hematological, and solid organ transplant patients) has been performed, trying to choose the best strategy for each clinical situation (prophylaxis, pre-emptive, empirical, or targeted therapy). The high mortality rates in these settings make mandatory the application of early de-escalation therapy in critically ill patients with fungal infection. In addition, the possibility of antifungal combination therapy might be considered in solid organ transplant and hematological patients.

Nebulizer delivery of micafungin aerosols

STUDY OBJECTIVES

To determine the optimal nebulization system for aerosolizing micafungin and to further assess the physiochemical properties of aerosolized micafungin.

DESIGN

In vitro experiment.

SETTING

University research center. NEBULIZERS: Pari LC Star, Hudson Updraft, Small Volume Nebulizer, and Aeroclipse II.

MEASUREMENTS AND MAIN RESULTS

Using a commercially available cascade impactor, the four nebulizers were tested for their ability to deliver micafungin to the lungs. Mass median aerodynamic diameter (MMAD) and fine particle fraction (FPF) percent less than 3.3 μm (FPF(3.3)) and less than 5.8 μm (FPF(5.8)) were determined during two sampling periods for each of three trials of all nebulizers. The mean ± standard error of the mean MMAD for the nebulizers ranged from 1.93 ± 0.09 to 2.49 ± 0.25 μm; FPF(3.3) and FPF(5.8) were approximately 50% and 90%, respectively, for all nebulizers.

CONCLUSION

Although all nebulizers appeared acceptable to deliver micafungin to the lungs, the Pari LC Star had the smallest MMAD and highest FPF(3.3) and FPF(5.8). These properties of the Pari LC Star should result in greater delivery of the aerosol to the lungs. Additional research on pulmonary delivery and clinical tolerability is warranted.

Aerosolized Delivery of Antifungal Agents

Pulmonary infections caused by Aspergillus species are associated with significant morbidity and mortality in immunocompromised patients. Although the treatment of pulmonary fungal infections requires the use of systemic agents, aerosolized delivery is an attractive option in prevention because the drug can concentrate locally at the site of infection with minimal systemic exposure. Current clinical evidence for the use of aerosolized delivery in preventing fungal infections is limited to amphotericin B products, although itraconazole, voriconazole, and caspofungin are under investigation. Based on conflicting results from clinical trials that evaluated various amphotericin B formulations, the routine use of aerosolized delivery cannot be recommended. Further research with well-designed clinical trials is necessary to elucidate the therapeutic role and risks associated with aerosolized delivery of antifungal agents. This article provides an overview of aerosolized delivery systems, the intrapulmonary pharmacokinetic properties of aerosolized antifungal agents, and key findings from clinical studies.

Fungal infections after lung transplantation

PURPOSE OF REVIEW

Lung transplant's Achilles heel is chronic rejection. This is the reason why high immunosuppression is used, which leads to the development of infections. Fungal infections are a great obstacle in lung transplant patients' progress, not only because of their impact on patient survival, but also because fungal infections indirectly have an influence on the graft's progress. This review highlights the changing spectrum of invasive fungal infections as well as the most recent developments in diagnosis, prophylaxis, treatment and monitoring of lung transplantation.

RECENT FINDINGS

Fungal infections have a bimodal presentation: early onset, in relation to difficult postsurgeries and prior colonizations, and late onset, primarily in relation to chronic rejection and terminal renal insufficiency. The clinical impact of non-Aspergillus moulds is still unknown. Recent efforts have focused on nonculture-based methods to establish a rapid diagnosis. However, multicentre studies are needed to establish the diagnostic value of galactomannan antigen assay in invasive aspergillosis in lung transplantation. In addition, studies of the sensitivity and specificity of PCR assays are required to establish their diagnostic value. Unfortunately, only some advances in the diagnosis of aspergillosis have been achieved.

SUMMARY

Prophylaxis should be tailored according to the different individual patient's risk status. Combined treatments, including surgical therapy, may be useful in some patients.

Nanodisks derived from amphotericin B lipid complex

The goal of this study was to determine the effect of apolipoproteins on Amphotericin B lipid complex (ABLC). We report that incubation of ABLC with recombinant human apolipoprotein A-I (apoA-I) induces solubilization of ABLC by transforming the micron sized phospholipid/AMB assemblies into discrete nanoscale disk-shaped complexes termed nanodisks (ND). ApoA-I induced changes in ABLC solubility and morphology were monitored by spectroscopy and electron microscopy. AMB efficacy was evaluated in yeast and pathogenic fungi growth inhibition assays and the effect of AMB formulation on cell toxicity was assessed in cultured Hep3B cells. AMB associated with ND were more efficiently nebulized than AMB associated with ABLC. Thus, transformation of ABLC into ND preserves the potent biological activity of AMB as well as the reduced toxicity of the ABLC formulation. ABLC derived AMB-ND offer advantages over conventional ABLC in terms of stability, storage, nebulization efficiency and provides an intrinsic "handle" for tissue specific targeting via genetic engineering of its protein component.

[Administration of anti-infective agents through the inhaled route]

OBJECTIVE

To report the doses of inhaled anti-infective agents described in the literature for both the adult and paediatric population. In the case of anti-infective agents which were not approved for inhaled administration, to propose the optimum manner in which these should be prepared in order to achieve osmolality and pH values as similar as possible to physiological values.

METHOD

A search was carried out of Pubmed (between 1960 and 2005) for each of the anti-infective agents using the words "inhalation OR inhaled OR aerosol OR aerosolized OR nebulized". We also consulted text books, Micromedex and the technical specifications of the pharmaceutical products. Nebulised solutions were prepared using the drugs for which information was found. The drugs approved for inhaled administration were prepared according to the manufacturers recommendations. For anti-infective agents which were not approved for inhaled administration, the raw materials and the branded drug products for intravenous administration available at our hospital were diluted using physiological saline solution and/or water for injection up to a final volume of 4-5 ml. The osmolality and pH values of all the solutions were measured. The optimum form of preparation was considered to be one with values as close as possible to between 150 and 550 mOsm/kg for osmolatity osmolality and 7 +/- 0.5 for pH.

RESULTS

Information about doses of 18 inhaled anti-infective agents was found (12 antibiotics, 5 antifungals and 1 antiviral); paediatric doses were described in 9 of these. Three of the anti-infective agents reviewed were approved for inhaled use in adult patients and four in paediatric patients. Of the 48 recommendations for dilution suggested for administration, two had an osmolality > 1,100 mOsm/kg and 5 an osmolality of < 100 mOsm/kg. Two dilutions had a pH > 8 and 14 a pH < 5.

CONCLUSIONS

There is limited literature regarding the doses of anti-infective agents for inhaled administration. The majority of anti-infective agents are not approved for inhaled administration. The dilution of the raw material or proprietary drugs with water or physiological saline solution for intravenous administration achieved solutions with appropriate osmolality in the majority of cases. Some of the solutions have extreme osmolality and/or pH levels, implying that it is reasonable to expect a greater risk of bronchospasm.

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.

The echinocandins: comparison of their pharmacokinetics, pharmacodynamics and clinical applications

Caspofungin, micafungin and anidulafungin are three drugs of the echinocandin class of antifungals available for intravenous treatment of invasive candidiasis and aspergillosis. They exhibit high in vitro and in vivo activities against Candida spp. and Aspergillus spp. In various clinical studies investigating candidemia and invasive candidiasis, Candida esophagitis, and fever in neutropenia, the clinical efficacy of the echinocandin tested was similar to that of established antifungals. Antifungal activity against strains no longer susceptible to conventional antifungal agents, such as fluconazole and amphotericin B suggests that echinocandins can be used as salvage therapy in life-threatening fungal infections. There is no cross-resistance to other antifungals. Excellent safety and tolerability of treatment with caspofungin has been documented over a total of 4.3 million patient days. Echinocandins are poor substrates of the cytochrome P450 enzyme family and can be safely co-administered with most drugs without the need for dosage adaptation. No dose reduction is required in renal impairment. A reduction in the daily maintenance dose has been recommended for caspofungin, but not for micafungin and anidulafungin in patients presenting with mild to moderate hepatic failure.