Non-invasive pulmonary aerosol delivery in mice by the endotracheal route

In this report we present in detail a non-invasive pulmonary application method that can be a useful tool in studying drug and vaccine delivery to the lower airways. In this method the formulation is sprayed directly into the lungs of mice via the endotracheal route using a MicroSprayer™ aerolizer. Mean droplet size produced was 8 μm, appropriate for deposition in the large airways. Endotracheal application of suspension of fluorescent nanospheres, 200 nm in size, by this method resulted in nanoparticle deposition in the smaller airways (bronchi and bronchioles). Mice showed full recovery one day after administration of 50 μl of formulation. Furthermore, no mortality was observed as a result of the technique. We conclude that this endotracheal application is a useful tool for studying pulmonary drug delivery in mice. The technique is especially useful for the pulmonary application of vaccines, since it enables multiple administrations without a need for analgesics.     

Nanocluster budesonide formulations enhance drug delivery through endotracheal tubes

The pulmonary system is an attractive route for drug delivery because the lungs have a large accessible surface area for treatment. For ventilated patients, an endotracheal tube is required for delivering drugs into the lungs. Such tubes are generally poor conduits for delivering traditional aerosol formulations. Both the formulation and the properties of the endotracheal tube are important effectors of delivery efficiency. In this study, agglomerates of budesonide nanoparticles (NanoClusters) were formulated with or without l-leucine or lactose. Teflon tubing was compared with commercial endotracheal tubes as a conduit for delivering budesonide powders into a cascade impactor. The effects of volumetric flow rate, tube size, and humidity were also investigated. NanoCluster budesonide (NC-Bud) formulations had a considerably higher emitted dose and fine particle fraction compared with stock budesonide and the commercial Flexhaler powder when applied through endotracheal tubes. Tubing material did not significantly affect powder performance, but decreasing tubing diameter or increasing volumetric flow rates yielded a smaller mass median aerodynamic diameter for NC-Bud. Engineered NC-Bud powders may dramatically improve drug delivery through endotracheal tubes when using proper ventilator settings.     

Condensational growth of combination drug-excipient submicrometer particles for targeted high-efficiency pulmonary delivery: evaluation of formulation and delivery device

Objectives The objective of this study was to investigate the in‐vitro particle‐size growth of combination drug and excipient submicrometer aerosols generated from a series of formulations and two aerosol delivery devices. Methods Submicrometer combination drug and excipient particles were generated experimentally using both the capillary aerosol generator and the Respimat inhaler. Budesonide and albuterol sulfate were used as model drugs and were formulated with sodium chloride, citric acid and mannitol as excipients in various ratios. Aerosol growth was evaluated in‐vitro in a coiled‐tube geometry designed to provide residence times and thermodynamic conditions consistent with the airways. Key findings Submicrometer combination drug : excipient aerosols when exposed to simulated respiratory conditions increased to micrometer size suitable for pulmonary deposition. It was possible to control the aerosol growth ratio by altering: (1) the hygroscopic excipient, (2) the drug : excipient ratio and (3) the drug. The applicability of this approach was demonstrated using the capillary aerosol generator and the Respimat inhaler. Conclusions The enhanced excipient growth approach may enable the delivery of submicrometer aerosol particles that increase in size within the airways and result in high percentages of pulmonary deposition.     

Design and Characterization of Atorvastatin Dry Powder Formulation as a potential Lung Cancer Treatment

Lung cancer is the leading cause of cancer death. Many studies have shown the beneficial effects of Atorvastatin in decreasing the mortality risk and improving survival among patients with lung cancer. This research paper focuses on improving AVT cytotoxic activity and cellular uptake by developing mannitol microcarriers as a promising drug delivery system for lung cancer treatment and, studying the impact of improving inhalation deposition on the delivery and Dry Powder formulations efficiency. The AVT loaded mannitol (AM) microparticles (AVT-AM) formulation was prepared by spray drying and characterized for its physicochemical properties and aerodynamic deposition. The results revealed that the AVT-AM formulation has good flow properties and aerosol deposition with a particle size of 3418 nm ± 26.86. The formulation was also assessed in vitro for cytotoxicity effects (proliferation, apoptosis, and cell cycle progression) on A549 human lung adenocarcinoma. Compared with free AVT, the AVT-AM formulation has significantly higher cellular uptake and anti-cancer properties by disrupting cell cycle progression via either apoptosis or cell cycle arrest in the G2/M phase. This study shows that AVT loaded mannitol microcarriers may provide a potentially effective and sustained pulmonary drug delivery for lung cancer treatment.     

A new Pharmaceutical Aerosol Deposition Device on Cell Cultures (PADDOCC) to evaluate pulmonary drug absorption for metered dose dry powder formulations

Absorption studies with aerosol formulation delivered by metered dose inhalers across cell- and tissue-based in vitro models of the pulmonary epithelia are not trivial due to the complexity of the processes involved: (i) aerosol generation and deposition, (ii) drug release from the carrier, and (iii) absorption across the epithelial air-blood barrier. In contrast to the intestinal mucosa, pulmonary epithelia are only covered by a thin film of lining fluid. Submersed cell culture systems would not allow to studying the deposition of aerosol particles and their effects on this delicate epithelial tissue.We developed a new Pharmaceutical Aerosol Deposition Device on Cell Cultures (PADDOCC) to mimic the inhalation of a single metered aerosol dose and its subsequent deposition on filter-grown pulmonary epithelial cell monolayers exposed to an air-liquid interface. The reproducibility of deposition of these dry powder aerosols and subsequent drug transport across Calu-3 monolayers with commercially available dry powder inhalers containing salbutamol sulphate or budesonide could be demonstrated.In the context of developing new dry powder aerosol formulations, PADDOCC appears as a useful tool, allowing reducing animal testing and faster translation into clinical trials.     

In vivo assessment of temozolomide local delivery for lung cancer inhalation therapy

The aim of this study was to compare the efficacy of local drug delivery by inhalation to intravenous delivery in a B16F10 melanoma metastatic lung model. Temozolomide was formulated as a suspension, which was elaborated and evaluated in terms of particle size, shape and agglomeration. An endotracheal administration device was used to aerosolise the suspension. This mode of delivery was evaluated at different temozolomide concentrations and was optimized for the uniformity of delivered dose, the droplet size distribution and the distribution of droplets in vivo. Of the particles in the stabilised suspension, 79% were compatible with the human respirable size range, and this formulation retained 100% in vitro anticancer activity as compared to temozolomide alone in three distinct cancer cell lines. The pulmonary delivery device provided good reproducibility in terms of both the dose delivered and the droplet size distribution. Most of the lung tissues that were exposed to aerosol droplets contained the particles, as revealed by fluorescent microscopy techniques. The global in vivo antitumour activity of the inhaled temozolomide provided a median survival period similar to that for intravenous temozolomide delivery, and three out of 27 mice (11%) survived with almost complete eradication of the lung tumours. The present study thus shows that inhalation of a simple liquid formulation is well tolerated and active against a very biologically aggressive mouse melanoma pulmonary pseudo-metastatic model. This inhalation delivery could be used to deliver other types of anticancer drugs.     

Characterization of regional and local deposition of inhaled aerosol drugs in the respiratory system by computational fluid and particle dynamics methods.

The present work describes the local deposition patterns of therapeutic aerosols in the oropharyngeal airways, healthy and diseased bronchi and alveoli using computational fluid and particle dynamics techniques. A user-enhanced computational fluid dynamics commercial finite- volume software package was used to compute airflow fields, deposition efficiencies, and deposition patterns of therapeutic aerosols along the airways. Adequate numerical meshes, generated in different airway sections, enabled us to more precisely define trajectories and local deposition patterns of inhaled particles than before. Deposition patterns show a high degree of heterogeneity of deposition along the airways, being more uniform for nanoparticles compared to micro-particles in the whole respiratory system at all inspiratory flow rates. Extrathoracic and tracheobronchial deposition fractions of nanoparticles decrease with increasing flow rates. However, vice versa happens to the micron-size particles, that is, the deposition fraction is higher at high flow rates. Both airway constrictions and the presence of tumors significantly increased the deposition efficiencies compared to the deposition efficiencies in healthy airways by a factor ranging from 1.2 to 4.4. In alveoli, the deposition patterns are strongly influenced by particle size and direction of gravity. This study demonstrated that numerical modeling can be a powerful tool in the aerosol drug delivery optimization. Present results may be integrated in future aerosol drug therapy protocols.     

Inhalation therapy for infants

Delivering aerosolised drugs to infants poses a number of challenges. It is clear that drug delivery is possible via the inhaled route but to date it has been difficult to demonstrate clearly therapeutic benefit from the use of any conventional therapy in the vast majority of infants. This is probably related to the nature of pulmonary disease in this age group. While most aerosol scientists focus on factors such as aerosol size and airways geometry drug delivery, as in all age groups, is most dependent upon patient behaviour. A small amount of drug reaches the lungs of distressed infants. Consideration of patient device interactions is vital if successful drug delivery is to be achieved and this includes consideration of mask design. Doses reaching the lungs are generally very low when considered in terms of the nominal dose but when considered in terms of dose delivered per kilogram body weight drug delivery to the lungs is generally similar to or greater than in adults. Upper airways deposition is relatively greater than in older subjects, in large part because of nasal breathing, and this will affect the 'therapeutic index' of some drugs.     

Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC) for pulmonary application: A review of the state of the art

Drug delivery by inhalation is a noninvasive means of administration that has following advantages for local treatment for airway diseases: reaching the epithelium directly, circumventing first pass metabolism and avoiding systemic toxicity. Moreover, from the physiological point of view, the lung provides advantages for systemic delivery of drugs including its large surface area, a thin alveolar epithelium and extensive vasculature which allow rapid and effective drug absorption. Therefore, pulmonary application is considered frequently for both, the local and the systemic delivery of drugs. Lipid nanoparticles – Solid Lipid Nanoparticles and Nanostructured Lipid Carriers – are nanosized carrier systems in which solid particles consisting of a lipid matrix are stabilized by surfactants in an aqueous phase. Advantages of lipid nanoparticles for the pulmonary application are the possibility of a deep lung deposition as they can be incorporated into respirables carriers due to their small size, prolonged release and low toxicity. This paper will give an overview of the existing literature about lipid nanoparticles for pulmonary application. Moreover, it will provide the reader with some background information for pulmonary drug delivery, i.e., anatomy and physiology of the respiratory system, formulation requirements, application forms, clearance from the lung, pharmacological benefits and nanotoxicity.     

Inhaled bronchodilator administration during mechanical ventilation: how to optimize it, and for which clinical benefit?

Bronchodilators are frequently used in ICU patients, and are the most common medications administered by inhalation during mechanical ventilation. The amount of bronchodilator that deposits at its site of action depends on the amount of drug, inhaled mass, deposited mass, and particle size distribution. Mechanical ventilation challenges both inhaled mass and lung deposition by specific features, such as a ventilatory circuit, an endotracheal tube, and ventilator settings. Comprehensive in vitro studies have shown that an endotracheal tube is not as significant a barrier for the drug to travel as anticipated. Key variables of drug deposition are attachments of the inhalation device in the inspiratory line 10 to 30 cm to the endotracheal tube, use of chamber with metered-dose inhaler, dry air, high tidal volume, low respiratory frequency, and low inspiratory flow, which can increase the drug deposition. In vivo studies showed that a reduction by roughly 15% of the respiratory resistance was achieved with inhaled bronchodilators during invasive mechanical ventilation. The role of ventilatory settings is not as clear in vivo, and primary factors for optimal delivery and physiologic effects were medication dose and device location. Nebulizers and pressurized metered-dose inhalers can equally achieve physiologic end points. The effects of bronchodilators should be carefully evaluated, which can easily be done with the interrupter technique. With the non-invasive ventilation, the data regarding drug delivery and physiologic effects are still limited. With the bilevel ventilators the inhalation device should be located between the leak port and face mask. Further studies should investigate the effects of inhaled bronchodilators on patient outcome and methods to optimize delivery of inhaled bronchodilators during non-invasive ventilation.     

Regional distribution and kinetics of inhaled pharmaceuticals

Drug biodistribution is often secondary to drug action. However, drugs that have a topical action and are deposited into the airway by inhalation are dependent on effective deposition at the intended site of action. Measurement of the distribution of such drugs in the airway is a useful tool. Distribution data can help to interpret clinical results, to evaluate products relative to each other, to optimize a new drug formulation, and to choose effective drug delivery methods. Imaging of radiotracers is the only means available to measure drug deposition throughout the lungs, nasal passages, and sinuses. There are several approaches to imaging drug deposition. Planar imaging has been the most used method, but SPECT and PET imaging are beginning to be applied effectively. The properties of non-drug tracers, labeling of drugs, evaluation of distribution patterns, and quantification of deposited drugs are important issues that have been addressed. Imaging has been shown to be a powerful technique to evaluate and to speed development of inhaled drugs. This review explores the most recent advances and issues with an emphasis on drug development.     

Development of vitamin loaded topical liposomal formulation using factorial design approach: drug deposition and stability

Long-term exposure of the skin to UV light causes degenerative effects, which can be minimized by using antioxidant formulations. The major challenge in this regard is that a significant amount of antioxidant should reach at the site for effective photoprotection. However, barrier properties of the skin limit their use. In the present study, Vitamin E acetate was encapsulated into liposome for improving its topical delivery. However preparation of liposomes is very difficult due to number of formulation variables involved therein. In the present work systematic statistical study for the formulation of liposomes for topical delivery of Vitamin E using the factorial design approach was undertaken. Amount of phospholipid (PL) and cholesterol (CH) were taken at three different levels and liposomes were prepared using ethanol injection method. Liposomes were characterized for encapsulation efficiency, vesicle size, zeta potential, and drug deposition in the rat skin. Gels containing liposomal dispersion (batch with higher skin deposition of VE) were prepared in Carbopol^® 980 NF and were characterized for gel strength, viscosity and drug deposition in the rat skin. Stability of liposome dispersion and gel formulation was studied at 30 °C/65% RH for 3 months. Results of regression analysis revealed that vesicle size and drug deposition in the rat skin were dependant on the lipid concentration and lipid:drug ratio. Drug deposition in rat skin had an inverse relationship with respect to PL and CH concentration. Prepared liposomal dispersion (50 mg PL:6 mg CH) showed seven-fold increase in drug deposition compared to control (plain drug dispersion). Gel formulation demonstrated six-fold and four-fold increase in drug deposition compared to control gel and marketed cream, respectively. Liposome dispersion and gel formulation were found to be stable for 3 months. Factorial design was found to be well suited to identify the key variables affecting drug deposition. Improved drug deposition from liposomal preparations demonstrates its potential for dermal delivery.     

Development,characterisation and pharmacoscintigraphic evaluation of nano-fluticasone propionate dry powder inhalation as potential antidote against inhaled toxic gases

Acute lung injuries caused due to inhalation of toxic irritant gases such as ammonia, chlorine, hot smoke and burning plastic fumes predominantly affect the airways, causing tracheitis, bronchitis, and other inflammatory responses. The purpose was to develop and characterise nanoparticle based fluticasone propionate (FP) DPI formulation and assess its in vitro and in vivo pulmonary deposition using pharmacoscintigraphy. FP nanoparticles were prepared by nanoprecipitation method. Optimisation was carried out with the help of Box–Behnken statistical design. Nanoparticles were characterised with the help of SEM, FT-IR, DSC and XRD. Anderson cascade impaction showed that nano-FP exhibited significantly higher respirable fraction of 60.3?±?2.41 as compared to 16.4?±?0.66 for micronised form. Ventilation lung scintigraphy in human volunteers confirmed significant increase in drug delivery till alveolar region with nano-FP in comparison to micronised drug. Results indicate that the developed formulation may have a potential prophylactic/therapeutic role against toxic, irritant gas inhalation.     

PEG conjugation of a near-infrared fluorescent probe for noninvasive dual imaging of lung deposition and gene expression by pulmonary gene delivery

Dual imaging of lung deposition and gene expression following the pulmonary delivery of a gene formulation is useful for a precise analysis of gene transfection efficiency in vivo. As a novel probe for evaluating lung deposition, in this study, a poly(ethylene glycol)-conjugated near-infrared fluorescent probe (PEG-NIRF) was newly synthesized, and compared with indocyanine green (ICG), for application to pDNA/polyethyleneimine (PEI) complex. PEG-NIRF had superior characteristics including a larger Stokes shift (absorption maximum, 662?nm; emission maximum, 772?nm) and relatively equivalent fluorescence intensity compared with ICG. ICG affected the physicochemical properties of pDNA/PEI complex with a loss of fluorescence intensity, while PEG-NIRF did not. Experiments in mice demonstrated that PEG-NIRF showed greater lung localization than ICG following pulmonary co-delivery with pDNA/PEI complex, indicating the possibility of accurately evaluating lung deposition. Moreover, it was clarified that the evaluation of lung deposition by PEG-NIRF even at 60?min could be significantly correlated with gene expression in each mouse following pulmonary co-delivery with pDNA/PEI complex. These results suggest that PEG-NIRF is widely applicable to the dual imaging of the lung deposition and gene expression of inhaled gene formulations.     

Evaluation of metered dose inhaler spray velocities using phase Doppler anemometry (PDA)

Droplet velocity is an important parameter which can significantly influence inhalation drug delivery performance. Together with the droplet size, this parameter determines the efficiency of the deposition of MDI products at different sites within the lungs. In this study, Phase Doppler Anemometry (PDA) was used to investigate the instantaneous droplet velocity emitted from MDIs as well as the corresponding droplet size distribution. The nine commercial MDI products surveyed showed significantly different droplet velocities, indicating that droplet velocity could be used as a discriminating parameter for in vitro testing of MDI products. The droplet velocity for all tested MDI products decreased when the testing distance was increased from 3 cm to 6 cm from the front of mouthpiece, with CFC formulations showing a larger decrease than HFA formulations. The mean droplet diameters of the nine MDIs were also significantly different from one-another. Droplet size measurements made using PDA (a number-based technique) could not be directly compared to results obtained using laser light scattering measurements (a volume-based technique). This work demonstrates that PDA can provide unique information useful for characterizing MDI aerosol plumes and evaluating MDI drug delivery efficiency. PDA could also aid the evaluation of in vitro equivalence in support of formulation or manufacturing changes and in evaluation of abbreviated new drug applications (ANDAs) for MDIs.     

肽类和蛋白质类药物肺部给药的体内外评价方法

目的介绍肽类和蛋白质类药物肺部给药的体内外评价方法。方法对肽类和蛋白质药物肺部给药研究中的给药方法、药动学评价、药效学评价、肺部沉积、体外评价及安全性评价方法进行综述。结果根据研究的不同阶段选择合适的动物给药模型,采用特异性强、灵敏度高的分析方法是肽类和蛋白质药物肺部给药系统体内评价的关键。肺内沉积是对剂型和给药装置递送效果的综合考察。具有良好体内外相关性的体外评价方法的建立与安全性评价在肺部给药制剂开发中具有十分重要的意义。结论肽类和蛋白质类药物肺部给药的体内外评价方法与其他给药途径有较大区别,在研究和开发中应根据需要选取适当的方法。     

Pulmonary delivery of therapeutic siRNA

Small interfering RNA (siRNA) has a huge potential for the treatment or prevention of various lung diseases. Once the RNA molecules have successfully entered the target cells, they could inhibit the expression of specific gene sequence through RNA interference (RNAi) mechanism and generate therapeutic effects. The biggest obstacle to translating siRNA therapy from the laboratories into the clinics is delivery. An ideal delivery agent should protect the siRNA from enzymatic degradation, facilitate cellular uptake and promote endosomal escape inside the cells, with negligible toxicity. Lung targeting could be achieved by systemic delivery or pulmonary delivery. The latter route of administration could potentially enhance siRNA retention in the lungs and reduce systemic toxic effects. However the presence of mucus, the mucociliary clearance actions and the high degree branching of the airways present major barriers to targeted pulmonary delivery. The delivery systems need to be designed carefully in order to maximize the siRNA deposition to the diseased area of the airways. In most of the pulmonary siRNA therapy studies in vivo, siRNA was delivered either intratracheally or intranasally. Very limited work was done on the formulation of siRNA for inhalation which is believed to be the direction for future development. This review focuses on the latest development of pulmonary delivery of siRNA for the treatment of various lung diseases.     

In-vivo Monitoring of Dosage Forms*

The use of imaging techniques including gamma scintigraphy to follow the behaviour of drug formulations has revolutionized our knowledge of absorption and distribution in drug delivery. The development of gamma camera techniques as physiological tools to explore organ function became routine by the mid-seventies. Several research groups started to explore the applications of technique in drug delivery. Within 5 years, the utility of the technique became obvious and scintigraphy is now widely accepted as an important investigation tool in formulation research. Gamma scintigraphy is especially useful in exploring sources of inter-subject variation, especially in examining food effects in pharmacokinetic estimations and establishing windows of absorption for oral delivery. As a tool to examine drug delivery to the lung and to the eye, scintigraphy is the method of choice. Magnetic Resonance Imaging (MRI) became more generally employed in medicine two decades after the gamma camera. The superior soft-tissue contrast and resolution compared to computed X-ray tomography rapidly established MRI in clinical investigation. Recent applications in oral drug research has allowed the pharmaceutical scientist to explore new facets of delivery and ultimately combine MRI and scintigraphy in human clinical trials.     

Nasal delivery systems and their effect on deposition and absorption

Due to nasal anatomy and physiology, with a non-ciliated area in the anterior part of the nasal cavity and a ciliated region in the more posterior part of the nose, the site of deposition is of importance for the nasal mucociliary clearance and retainment of a formulation in the nose. Many drug delivery devices for nasal application of liquid, semisolid and solid formulations were investigated in respect to their deposition in the nasal cavity. The site of deposition and the deposition area depend on several parameters which are related to the delivery device, such as mode of administration, particle size of the formulation and velocity of the delivered particles. Several in vitro and in vivo methods have been used to study distribution and clearance of intranasally delivered therapeutics. The relationship between deposition, absorption and related bioavailability of the nasally applied formulation has been shown.