Advancements in dry powder delivery to the lung

Dry Powder Inhaler with the technical and practical obstacles, and forthcoming platform strategies

A Dry Powder Inhaler (DPI) is a technique as well as a device used to inhale formulation which is in the form of dry powder, and is inhaled through the nose or mouth. It was developed for the purpose of treating conditions like chronic obstructive pulmonary disease (COPD), Asthma, and even cystic fibrosis etc. The aim of the review is to discuss the different methods of preparation of dry powders along with the characterization of DPI. Here we present the outline of different methods like supercritical fluid extraction (SCF), spray drying, and milling. The review focussed on various devices including single and multi-dose devices used in the DPI. It also highlights on recent advances in the DPI including nano particulate system, siRNA-based medication, liposomes, and pro-liposomes based delivery. In COVID-19 silver nanoparticles-based DPIs provide very prominent results in the infected lungs. Moreover, this review states that the AI-based DPI development provides and improvement in the bioavailability and effectiveness of the drug along with the role of artificial neural networks (ANN). The study also showed that nasally administered drugs (nose to brain) can easily cross the blood-brain barrier (BBB) and enter the central nervous system (CNS) through the olfactory and trigeminal pathway which provides effective CNS concentrations at lower dosage. It is suggested that DPIs not only target respiratory complications but also treat CNS complications too. This review provides support and guides the researcher in the recent development and evaluation of DPI.

Respirable spray dried vancomycin coated magnetic nanoparticles for localized lung delivery

Bacterial pneumonia is a common pulmonary infection responsible for premature death. Biomaterials based-carriers loaded with antibiotics enhance drug potency through localizing the therapy, minimizing the associated adverse effects, and improving patient compliance. Herein, this study reports the preparation of an inhalable dry powder formulation composed of a nano-in-microparticles. Vancomycin was adsorbed on the core of magnetic nanoparticles followed by spray drying into lactose/dextran to optimize the aerodynamic performance and allow the local delivery of the drug into the bacterial pneumonia infection site. Lactose and Dextran are polysaccharides commonly used for pulmonary delivery due to their optimum aerodynamic performance and biocompatibility. The preparation of the nano-in-micro particles with optimum properties was confirmed using FTIR, TEM, SEM, Laser-diffraction, ICP-AES and TGA. The TEM micrographs confirmed the formation of spherical magnetic nanoparticles with a diameter 14.7 ± 5.9 nm and a coating thickness 3 - 16 nm, while laser diffraction showed that outer microparticles exhibited a mean diameter < 5 µm. The formulations demonstrated a promising activity against S. aureus and MRSA and better biocompatibility using MTT assay. In vivo safety and pharmacokinetic studies confirmed the localization of VAN in lung tissue and minimized adverse effects compared to free VAN. Therefore, the developed nano-in-microparticles confers a good potential for eradication of lung infections.

Developing Insulin Delivery Devices with Glucose Responsiveness

Individuals with type 1 and advanced type 2 diabetes require daily insulin therapy to maintain blood glucose levels in normoglycemic ranges to prevent associated morbidity and mortality. Optimal insulin delivery should offer both precise dosing in response to real-time blood glucose levels as well as a feasible and low-burden administration route to promote long-term adherence. A series of glucose-responsive insulin delivery mechanisms and devices have been reported to increase patient compliance while mitigating the risk of hypoglycemia. This review discusses currently available insulin delivery devices, overviews recent developments towards the generation of glucose-responsive delivery systems, and provides commentary on the opportunities and barriers ahead regarding the integration and translation of current glucose-responsive insulin delivery designs.

Pulmonary route of administration is instrumental in developing therapeutic interventions against respiratory diseases

Pulmonary route of drug delivery has drawn significant attention due to the limitations associated with conventional routes and available treatment options. Drugs administered through pulmonary route has been an important research area that focuses on to developing effective therapeutic interventions for asthma, chronic obstructive pulmonary disease, tuberculosis, lung cancer etc. The intravenous route has been a natural route of delivery of proteins and peptides but associated with several issues including high cost, needle-phobia, pain, sterility issues etc. These issues might be addressed by the pulmonary administration of macromolecules to achieving an effective delivery and efficacious therapeutic impact. Efforts have been made to develop novel drug delivery systems (NDDS) such as nanoparticles, microparticles, liposomes and their engineered versions, polymerosomes, micelles etc to achieving targeted and sustained delivery of drug(s) through pulmonary route. Further, novel approaches such as polymer-drug conjugates, mucoadhesive particles and mucus penetrating particles have attracted significant attention due to their unique features for an effective delivery of drugs. Also, use of semi flourinated alkanes is in use for improvising the pulmonary delivery of lipophilic drugs. Present review focuses on to unravel the mechanism of pulmonary absorption of drugs for major pulmonary diseases. It summarizes the development of interventional approaches using various particulate and vesicular drug delivery systems. In essence, the orchestrated attempt presents an inflammatory narrative on the advancements in the field of pulmonary drug delivery.

Design of ciprofloxacin-loaded nano-and microcomposite particles for dry powder inhaler formulations: preparation, in vitro characterisation, and antimicrobial efficacy

In this study, ciprofloxacin hydrochloride (CIP)-loaded poly-ε-caprolactone (PCL) nanoparticles were prepared for pulmonary administration. CIP-loaded PCL nanoparticles were prepared using solid-in-oil-in-water (s/o/w) emulsion solvent evaporation method, and the effects of various formulation parameters on the physicochemical properties of the nanoparticles were investigated. PCL nanoparticles showed spherical shapes with particle sizes around 143-489 nm. Encapsulation efficiency was found to be very low because of water-solubility properties of CIP. However, the surface modification of nanoparticles with chitosan caused an increase in the encapsulation efficiency of nanoparticles. At drug release study, CIP-loaded PCL nanoparticles showed initial burst effect for 4 h and then continuously released for 72 h. Nanocomposite microparticles containing CIP-loaded PCL nanoparticles were prepared freeze-drying method and mannitol was used as carrier material. Tapped density and MMADt results show that nanocomposite microparticles have suitable aerodynamic properties for pulmonary administration. Antimicrobial efficacy investigations showed that CIP-encapsulated PCL nanoparticles and nanocomposite microparticles inhibited the growth of bacteria. Also, when the antimicrobial activity of the nanoparticles at the beginning and at the sixth month was examined, it was found that the structure of the particulate system was still preserved. These results indicated that nanocomposite microparticles containing CIP-loaded PCL nanoparticles can be used for pulmonary delivery.

Polymeric nanoparticles in development for treatment of pulmonary infectious diseases

Serious lung infections, such as pneumonia, tuberculosis, and chronic obstructive cystic fibrosis-related bacterial diseases, are increasingly difficult to treat and can be life-threatening. Over the last decades, an array of therapeutics and/or diagnostics have been exploited for management of pulmonary infections, but the advent of drug-resistant bacteria and the adverse conditions experienced upon reaching the lung environment urge the development of more effective delivery vehicles. Nanotechnology is revolutionizing the approach to circumventing these barriers, enabling better management of pulmonary infectious diseases. In particular, polymeric nanoparticle-based therapeutics have emerged as promising candidates, allowing for programmed design of multi-functional nanodevices and, subsequently, improved pharmacokinetics and therapeutic efficiency, as compared to conventional routes of delivery. Direct delivery to the lungs of such nanoparticles, loaded with appropriate antimicrobials and equipped with 'smart' features to overcome various mucosal and cellular barriers, is a promising approach to localize and concentrate therapeutics at the site of infection while minimizing systemic exposure to the therapeutic agents. The present review focuses on recent progress (2005-2015) important for the rational design of nanostructures, particularly polymeric nanoparticles, for the treatment of pulmonary infections with highlights on the influences of size, shape, composition, and surface characteristics of antimicrobial-bearing polymeric nanoparticles on their biodistribution, therapeutic efficacy, and toxicity. WIREs Nanomed Nanobiotechnol 2016, 8:842-871. doi: 10.1002/wnan.1401 For further resources related to this article, please visit the WIREs website.

The function and performance of aqueous aerosol devices for inhalation therapy

OBJECTIVES

In this review paper, we explore the interaction between the functioning mechanism of different nebulizers and the physicochemical properties of the formulations for several types of devices, namely jet, ultrasonic and vibrating-mesh nebulizers; colliding and extruded jets; electrohydrodynamic mechanism; surface acoustic wave microfluidic atomization; and capillary aerosol generation.

KEY FINDINGS

Nebulization is the transformation of bulk liquids into droplets. For inhalation therapy, nebulizers are widely used to aerosolize aqueous systems, such as solutions and suspensions. The interaction between the functioning mechanism of different nebulizers and the physicochemical properties of the formulations plays a significant role in the performance of aerosol generation appropriate for pulmonary delivery. Certain types of nebulizers have consistently presented temperature increase during the nebulization event. Therefore, careful consideration should be given when evaluating thermo-labile drugs, such as protein therapeutics. We also present the general approaches for characterization of nebulizer formulations.

SUMMARY

In conclusion, the interplay between the dosage form (i.e. aqueous systems) and the specific type of device for aerosol generation determines the effectiveness of drug delivery in nebulization therapies, thus requiring extensive understanding and characterization.

Salicylic acid derivatives as potential anti asthmatic agents using disease responsive drug delivery system for prophylactic therapy of allergic asthma

Asthma is a multi-factorial and complicated lung disorder of the immune system which has expanded to a wider ambit unveiling its etiology to be omnipresent at both ends of the spectrum involving basic pharmacology and in-depth immunology. As asthma occurs through triggered activation of various immune cells due to different stimuli, it poses a great challenge to uncover specific targets for therapeutic interventions. Recent pharmacotherapeutic approaches for asthma have been focused on molecular targeting of transcription factors and their signaling pathways; mainly nucleus factor kappa B (NFκB) and its associated pathways which orchestrate the synthesis of pro-inflammatory cytokines (IL-1β, TNF-α, GM-CSF), chemokines (RANTES, MIP-1a, eotaxin), adhesion molecules (ICAM-1, VCAM-1) and inflammatory enzymes (cyclooxygenase-2 and iNOS). 5-aminosalicylic acid (5-ASA) and sodium salicylate are known to suppress NFκB activation by inhibiting inhibitor of kappa B kinase (IKκB). In order to target the transcription factor, a suitable carrier system for delivering the drug to the intracellular space is essential. 5-ASA and sodium salicylate loaded liposomes incorporated into PEG-4-acrylate and CCRGGC microgels (a polymer formed by crosslinking of trypsin sensitive peptide and PEG-4-acrylate) could probably suit the needs for developing a disease responsive drug delivery system which will serve as a prophylactic therapy for asthmatic patients.

Multivariate Analysis of Effects of Asthmatic Patient Respiratory Profiles on the In Vitro Performance of a Reservoir Multidose and a Capsule-Based Dry Powder Inhaler

PURPOSE

The aim of this work was to evaluate the effect of two different dry powder inhalers, of the NGI induction port and Alberta throat and of the actual inspiratory profiles of asthmatic patients on in-vitro drug inhalation performances.

METHODS

The two devices considered were a reservoir multidose and a capsule-based inhaler. The formulation used to test the inhalers was a combination of formoterol fumarate and beclomethasone dipropionate. A breath simulator was used to mimic inhalatory patterns previously determined in vivo. A multivariate approach was adopted to estimate the significance of the effect of the investigated variables in the explored domain.

RESULTS

Breath simulator was a useful tool to mimic in vitro the in vivo inspiratory profiles of asthmatic patients. The type of throat coupled with the impactor did not affect the aerodynamic distribution of the investigated formulation. However, the type of inhaler and inspiratory profiles affected the respirable dose of drugs.

CONCLUSIONS

The multivariate statistical approach demonstrated that the multidose inhaler, released efficiently a high fine particle mass independently from the inspiratory profiles adopted. Differently, the single dose capsule inhaler, showed a significant decrease of fine particle mass of both drugs when the device was activated using the minimum inspiratory volume (592 mL).

Devices for dry powder drug delivery to the lung

Dry powder inhalers (DPIs) are an important and increasingly investigated method of modern therapy for a growing number of respiratory diseases. DPIs are a promising option for certain patient populations, and may help to overcome several limitations that are associated with other types of inhalation delivery systems (e.g., accuracy and reproducibility of the dose delivered, compliance and adherence issues, or environmental aspects). Today, more than 20 different dry powder inhalers are on the market to deliver active pharmaceutical ingredients (APIs) for local and/or systemic therapy. Depending on the mechanism of deagglomeration, aerosolization, dose metering accuracy, and the interpatient variability, dry powder inhalers demonstrate varying performance levels. During development, manufacturers focus on improving aspects characteristic of their specific DPI devices, depending on the intended type of application and any particular requirements associated with it. With the wide variety of applications related to specific APIs, there exists a range of different devices with distinct features. In addition to the routinely used multi-use DPIs, several single-use disposable devices are under development or already approved. The recent introduction of disposable devices will expand the range of possible applications for use by including agents such as vaccines, analgesics, or even rescue medications. This review article discusses the performance and advantages of recently approved dry powder inhalers as well as disposable single-use inhalers that are currently under development.

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.

Formulation of inhalable lipid-based salbutamol sulfate microparticles by spray drying technique

Background

The aim of this work was to develop dry powder inhaler (DPI) formulations of salbutamol sulfate (SS) by the aid of solid lipid microparticles (SLmPs), composed of biocompatible phospholipids or cholesterol.

Methods

The SLmPs were prepared by using two different solvent systems (ethanol and water-ethanol) and lipid carriers (dipalmitoylphosphatidylcholine (DPPC) and cholesterol) with/without L-leucine in the spray drying process. The spray-dried microparticles were physically-mixed with coarse lactose monohydrate in order to make our final DPI formulations and were investigated in terms of physical characteristics as well as in vitro drug release profile and aerosolization behavior.

Results

We observed significant differences in the sizes, morphologies, and in vitro pulmonary depositions between the formulations. In particular, the SS-containing SLmPs prepared with water-ethanol (30:70 v/v) solution of DPPC and L-leucine which had then been blended with coarse lactose (1:9 w/w) exhibited the highest emitted dose (87.9%) and fine particle fraction (42.7%) among the formulations. In vitro drug release study indicated that despite of having a significant initial burst release for both cholesterol and DPPC-based microparticles, the remained drug released more slowly than the pure drug.

Conclusion

This study demonstrated the potential of using lipid carriers as well as L-leucine in DPI formulations of SS to improve its aerosolization behavior and retard the release profile of the drug.

Formulation considerations for dry powder inhalers

The market for inhalable dry powder medication has consistently grown over past years. Targeting the lungs has been recognized to offer several advantages compared with oral application of drugs. The successive development of inhalation products has led to advances in local treatment of different respiratory diseases, but has also demonstrated the possibility to utilize the lungs for systemic drug delivery. Since a dry powder inhalation product is always a combination of drug formulation and inhalation device, the requirements for the development of such a system may be particularly complex. Therefore, this review aims to give an overview of the necessary considerations for a successful dry powder inhaler development.

Hydrogels for controlled pulmonary delivery

A significant number of research articles have focused on pulmonary delivery as an alternative administration route owing to no first-pass metabolism, low protease activity, thin epithelium barrier and large surface area in the lung system. Controlled release in the pulmonary delivery system further reduces loading dose, frequency of dosing and systemic side effects, and also increases duration of action and patient compliance. Compared with other microparticles used in controlled-release pulmonary administration, hydrogels (3D polymeric matrix networks) have recently been investigated due to their swelling and mucoadhesive properties that could help bypass pulmonary delivery barriers. This review introduces controlled-release drug delivery to the lung, followed by a summary of currently available approaches for controlled-release pulmonary drug delivery. Lastly, the origin, advantages, detailed applications and concerns of hydrogels in pulmonary delivery are discussed.

How can we bring high drug doses to the lung?

In the last decades, dry powder inhalation has become a very attractive option for pulmonary drug delivery to treat lung diseases like cystic fibroses and lung infections. In contrast to the traditional pulmonary application of drugs for asthma and chronic obstructive pulmonary disease, these therapies require higher lung doses to be administered. The developments and improvements toward high dose powder pulmonary drug delivery are summarized and discussed in this chapter. These include the invention and improvement of novel inhaler devices as well as the further development of formulation principles and new powder engineering methods. The implementation of these strategies is subsequently described for some prototypes and formulations in research and development stage as well as for already marketed dry powder products. Finally, possible adverse effects that can occur after inhalation of high powder doses are shortly addressed.

Evaluation and modification of commercial dry powder inhalers for the aerosolization of a submicrometer excipient enhanced growth (EEG) formulation

The aim of this study was to evaluate and modify commercial dry powder inhalers (DPIs) for the aerosolization of a submicrometer excipient enhanced growth (EEG) formulation. The optimized device and formulation combination was then tested in a realistic in vitro mouth-throat - tracheobronchial (MT-TB) model. An optimized EEG submicrometer powder formulation, consisting of albuterol sulfate (drug), mannitol (hygroscopic excipient), l-leucine (dispersion enhancer) and poloxamer 188 (surfactant) in a ratio of 30:48:20:2 was prepared using a Büchi Nano spray dryer. The aerosolization performance of the EEG formulation was evaluated with five conventional DPIs: Aerolizer, Novolizer, HandiHaler, Exubera and Spiros. To improve powder dispersion, the HandiHaler was modified with novel mouth piece (MP) designs. The aerosol performance of each device was assessed using a next generation impactor (NGI) at airflow rates generating a pressure drop of 4 kPa across the DPI. In silico and in vitro deposition and hygroscopic growth of formulations was studied using a MT-TB airway geometry model. Both HandiHaler and Aerolizer produced high emitted doses (EDs) together with a significant submicrometer aerosol fraction. A modified HandiHaler with a MP including a three-dimensional (3D) array of rods (HH-3D) produced a submicrometer particle fraction of 38.8% with a conventional fine particle fraction (%<5 μm) of 97.3%. The mass median diameter (MMD) of the aerosol was reduced below 1 μm using this HH-3D DPI. The aerosol generated from the modified HandiHaler increased to micrometer size (2.8 μm) suitable for pulmonary deposition, when exposed to simulated respiratory conditions, with negligible mouth-throat (MT) deposition (2.6%).

Characterization and aerosol dispersion performance of advanced spray-dried chemotherapeutic PEGylated phospholipid particles for dry powder inhalation delivery in lung cancer

Pulmonary inhalation chemotherapeutic drug delivery offers many advantages for lung cancer patients in comparison to conventional systemic chemotherapy. Inhalable particles are advantageous in their ability to deliver drug deep in the lung by utilizing optimally sized particles and higher local drug dose delivery. In this work, spray-dried and co-spray dried inhalable lung surfactant-mimic PEGylated lipopolymers as microparticulate/nanoparticulate dry powders containing paclitaxel were rationally designed via organic solution advanced spray drying (no water) in closed-mode from dilute concentration feed solution. Dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine poly(ethylene glycol) (DPPE-PEG) with varying PEG chain length were mixed with varying amounts of paclitaxel in methanol to produce co-spray dried microparticles and nanoparticles. Scanning electron microscopy showed the spherical particle morphology of the inhalable particles. Thermal analysis and X-ray powder diffraction confirmed the retention of the phospholipid bilayer structure in the solid-state following spray drying, the degree of solid-state molecular order, and solid-state phase transition behavior. The residual water content of the particles was very low as quantified analytically Karl Fisher titration. The amount of paclitaxel loaded into the particles was quantified which indicated high encapsulation efficiencies (43-99%). Dry powder aerosol dispersion performance was measured in vitro using the Next Generation Impactor (NGI) coupled with the Handihaler dry powder inhaler device and showed mass median aerodynamic diameters in the range of 3.4-7 μm. These results demonstrate that this novel microparticulate/nanoparticulate chemotherapeutic PEGylated phospholipid dry powder inhalation aerosol platform has great potential in lung cancer drug delivery.

Design, physicochemical characterization, and optimization of organic solution advanced spray-dried inhalable dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine poly(ethylene glycol) (DPPE-PEG) microparticles and nanoparticles for targeted respiratory nanomedicine delivery as dry powder inhalation aerosols

Novel advanced spray-dried and co-spray-dried inhalable lung surfactant-mimic phospholipid and poly(ethylene glycol) (PEG)ylated lipopolymers as microparticulate/nanoparticulate dry powders of biodegradable biocompatible lipopolymers were rationally formulated via an organic solution advanced spray-drying process in closed mode using various phospholipid formulations and rationally chosen spray-drying pump rates. Ratios of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine PEG (DPPE-PEG) with varying PEG lengths were mixed in a dilute methanol solution. Scanning electron microscopy images showed the smooth, spherical particle morphology of the inhalable particles. The size of the particles was statistically analyzed using the scanning electron micrographs and SigmaScan^® software and were determined to be 600 nm to 1.2 μm in diameter, which is optimal for deep-lung alveolar penetration. Differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) were performed to analyze solid-state transitions and long-range molecular order, respectively, and allowed for the confirmation of the presence of phospholipid bilayers in the solid state of the particles. The residual water content of the particles was very low, as quantified analytically via Karl Fischer titration. The composition of the particles was confirmed using attenuated total-reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and confocal Raman microscopy (CRM), and chemical imaging confirmed the chemical homogeneity of the particles. The dry powder aerosol dispersion properties were evaluated using the Next Generation Impactor™ (NGI™) coupled with the HandiHaler^® dry powder inhaler device, where the mass median aerodynamic diameter from 2.6 to 4.3 μm with excellent aerosol dispersion performance, as exemplified by high values of emitted dose, fine particle fraction, and respirable fraction. Overall, it was determined that the pump rates defined in the spray-drying process had a significant effect on the solid-state particle properties and that a higher pump rate produced the most optimal system. Advanced dry powder inhalers of inhalable lipopolymers for targeted dry powder inhalation delivery were successfully achieved.

In vitro tests for aerosol deposition II: IVIVCs for different dry powder inhalers in normal adults

BACKGROUND

A new in vitro test method for dry powder inhalers (DPIs) was recently found to be predictive of the published in vivo results for Budelin Novolizer. The present study was intended to assess the method's robustness by evaluating correlations between average drug deposition in vitro and in vivo from five different DPIs.

METHODS

In vitro drug deposition from five marketed DPIs was assessed in a realistic physical airway model of a "medium" sized adult in an experimental setup that allowed deposition to be characterized regionally for carefully selected simulated air flow rate versus time profiles. The DPIs studied were Spiriva(®) HandiHaler(®), Relenza(®) Diskhaler(®), Salbutamol Easyhaler(®), Pulmicort(®) Turbuhaler(®), and Foradil(®) Aerolizer(®). In vitro regional deposition results were compared with those reported in the literature in order to create in vitro-in vivo correlations (IVIVCs) for each inhaler.

RESULTS

Mean percent total lung deposition (TLD ± SD) in vitro for Spiriva HandiHaler, Relenza Diskhaler, Salbutamol Easyhaler, Pulmicort Turbuhaler, and Foradil Aerolizer were 17.3 ± 1.2, 22.6 ± 1.1, 29.0 ± 1.1, 28.0 ± 3.0, and 21.7 ± 1.2, respectively. These results showed excellent agreement with reported in vivo values, with absolute prediction errors in TLD of ≤ 2% for all DPIs except Relenza Diskhaler. Similarly, in vitro mouth-throat and device deposition results were stoichiometrically comparable to those reported in vivo for all DPIs except Relenza Diskhaler and Turbuhaler. Inspection of the scintigraphy studies for Relenza Diskhaler and Turbohaler revealed possible problems with powder labeling and result interpretation in their in vivo clinical assessments.

CONCLUSIONS

A characteristic physical airway model representing a medium-sized adult, when coupled to carefully chosen characteristic inhalation maneuvers used in the clinic, produced results that correlated with regional drug deposition estimates from scintigraphy across a group of different DPIs.

The development of a novel dry powder inhaler

A novel active and multi-dose dry powder inhaler (DPI) was developed and evaluated to deliver a small quantity (100-500 μg) of pure drug without any excipient. This dry powder inhaler utilized two compressed air flows to dispense and deliver drug powder: the primary flow aerosolizes the drug powder from its pocket and the secondary flow further disperses the aerosol. In vitro tests by Anderson Cascade Impactor (ACI) indicated that the fine particle fraction (FPF) (<4.7 μm) of drug delivery could reach over a range of 50-70% (w/w). Emitted dose tests showed that delivery efficiency was above 85% and its relative standard deviation (RSD) was under 10%. Confocal microscopy was used to confirm the deposition of fluorescently labeled spray-dried powder in rabbit lungs. Also, a chromatographic method was used to quantify drug deposition. The results of animal tests showed that 57% of aerosol deposited in the rabbit lung and 24% deposited in its trachea. All the results implied that this novel active dry powder inhaler could efficiently deliver a small quantity of fine drug particles into the lung with quite high fine particle fraction.

Effect of carrier gas properties on aerosol distribution in a CT-based human airway numerical model

The effect of carrier gas properties on particle transport in the human lung is investigated numerically in an imaging based airway model. The airway model consists of multi-detector row computed tomography (MDCT)-based upper and intra-thoracic central airways. The large-eddy simulation technique is adopted for simulation of transitional and turbulent flows. The image-registration-derived boundary condition is employed to match regional ventilation of the whole lung. Four different carrier gases of helium (He), a helium-oxygen mixture (He-O(2)), air, and a xenon-oxygen mixture (Xe-O(2)) are considered. A steady inspiratory flow rate of 342 mL/s is imposed at the mouthpiece inlet to mimic aerosol delivery on inspiration, resulting in the Reynolds number at the trachea of Re( t ) ≈ 190, 460, 1300, and 2800 for the respective gases of He, He-O(2), air, and Xe-O(2). Thus, the flow for the He case is laminar, transitional for He-O(2), and turbulent for air and Xe-O(2). The instantaneous and time-averaged flow fields and the laminar/transitional/turbulent characteristics resulting from the four gases are discussed. With increasing Re( t ), the high-speed jet formed at the glottal constriction is more dispersed around the peripheral region of the jet and its length becomes shorter. In the laminar flow the distribution of 2.5-μm particles in the central airways depends on the particle release location at the mouthpiece inlet, whereas in the turbulent flow the particles are well mixed before reaching the first bifurcation and their distribution is strongly correlated with regional ventilation.

Novel dry powder inhaler particle-dispersion systems

Dry powder inhalers are a diverse family of devices that have emerged as a rapidly growing segment of the respiratory therapeutics area. The forces that these devices must impart into dry powder formulations for effective dispersion performance and reproducibility of delivery are relatively large, and multiple mechanisms have been developed in attempts to improve the efficiency of these systems. In this review, we address the reasons for the proliferation of dry powder inhalers, beginning with an abbreviated introduction on the basic inter-particulate forces that need to be disrupted to achieve successful powder dispersion and effective lung delivery. From this background, we survey the diversity of inhaler designs, starting from marketed devices, before introducing some of the novel device designs under development, both patient driven (passive) and device driven (active), as we attempt to link the themes of the device design features to the present understanding of the dynamics governing powder dispersion. Finally, we conclude by providing some assessment on the future of the wide range of device designs and mechanisms that have evolved by considering technical, regulatory and market forces.

Development of an inhalation chamber and a dry powder inhaler device for administration of pulmonary medication in animal model

CONTEXT

Pulmonary route of administration is becoming more popular for drug delivery in pulmonary tract and lungs for local and systemic actions.

OBJECTIVE

A dry powder inhaler (DPI) for delivery of dry powder and a nose-only inhalation chamber for small animals that can be used with nebuliser/DPI were designed.

MATERIALS AND METHODS

The inhalation chamber was made with a polypropylene-rectangular box and centrifuge tubes. DPI was made of a polypropylene tube. Micronized voriconazole and voriconazole solution were used for DPI and nebulizer, respectively, for both in vitro and in vivo studies.

RESULTS

In vitro drug deposition from nebulizer was found to be 11-26% w/w and that from DPI was 42 to 57% w/w depending on experimental set up. Uniform deposition across all the inhalation ports was observed irrespective of the methods. Respirable fraction (RF) varied from 34 to 73% in case of nebulizer and from 47 to 54% in case of DPI. In vivo deposition of voriconazole in lungs was found to be 80-130 µg/g of lung tissue in case of DPI and 40-68 µg/g of lung tissue in case of using nebulizer.

DISCUSSION

DPI designed was efficient in fluidizing powder bed and dispensing dry powder for inhalation. The inhalation chamber designed was efficient in uniformly distributing drug in various inhalation ports of the chamber.

CONCLUSIONS

The DPI and inhalation chamber designed can be successfully used for inhalation study with multiple animals especially mice.

Aerosol drug delivery: developments in device design and clinical use

Aerosolised drugs are prescribed for use in a range of inhaler devices and systems. Delivering drugs by inhalation requires a formulation that can be successfully aerosolised and a delivery system that produces a useful aerosol of the drug; the particles or droplets need to be of sufficient size and mass to be carried to the distal lung or deposited on proximal airways to give rise to a therapeutic effect. Patients and caregivers must use and maintain these aerosol drug delivery devices correctly. In recent years, several technical innovations have led to aerosol drug delivery devices with efficient drug delivery and with novel features that take into account factors such as dose tracking, portability, materials of manufacture, breath actuation, the interface with the patient, combination therapies, and systemic delivery. These changes have improved performance in all four categories of devices: metered dose inhalers, spacers and holding chambers, dry powder inhalers, and nebulisers. Additionally, several therapies usually given by injection are now prescribed as aerosols for use in a range of drug delivery devices. In this Review, we discuss recent developments in the design and clinical use of aerosol devices over the past 10-15 years with an emphasis on the treatment of respiratory disorders.

Challenges and advances in the development of inhalable drug formulations for cystic fibrosis lung disease

INTRODUCTION

Cystic fibrosis (CF) is a multisystem genetic disorder, which usually results in significant respiratory dysfunction. At present there is no cure for CF, but advances in pharmacotherapy have gradually increased the life expectancy of CF patients. As many drugs used in the therapy of CF are delivered by inhalation, the demand for effective and convenient inhalational CF drug formulations will grow as CF patients live longer. Knowledge of the current limitations in inhalational CF drug delivery is critical in identifying new opportunities and designing rational delivery strategies.

AREAS COVERED

This review discusses current and emerging therapeutic agents for CF therapy, selected physiological challenges to effective inhalational medication delivery, and various approaches to overcoming these challenges. The reader will find an integrated view of the known inhalational drug delivery challenges and the rationales for recent investigational inhalational drug formulations.

EXPERT OPINION

An ideal drug/gene delivery system to CF airways should overcome the tenacious sputum, which presents physical, chemical and biological barriers to effective transport of therapeutic agents to the targets and various cellular challenges.

Alternative routes of administration for systemic delivery of protein pharmaceuticals

Non-invasive and patient-friendly delivery of proteins are important targets for protein formulation development. Traditionally, a lyophilized cake for reconstitution followed by s.c. or i.v. administration has been used. At present, several protein pharmaceuticals delivered by alternative routes of administration are under investigation. The long-term effects of protein delivery by these alternative routes are not known. Nevertheless, these alternative administration routes can in the near future lead to new, successful protein pharmaceuticals on the market.: