Drug delivery by inhalation offers several advantages compared to other dosage forms, including rapid clinical onset, high bioavailability, and minimal systemic side effects. Drug delivery to the lung can be achieved as liquid suspensions or solutions in nebulizers and pressurized metered-dose inhalers (pMDI), or as dry powders in dry powder inhalers (DPIs). Compared to other delivery systems, DPIs are, in many cases, considered the most convenient as they are breath actuated and do not require the use of propellants. Currently, the delivery of low drug doses for the treatment of lung conditions such as asthma and chronic obstructive pulmonary disease are well established, with numerous commercial products available on the market. The delivery of low doses can be achieved from either standard carrier- or aggregate-based formulations, which are unsuitable in the delivery of high doses due to particle segregation associated with carrier active site saturation and the cohesiveness of micronized aggregates which have poor flow and de-agglomeration properties. High-dose delivery is required for the treatment of lung infection (i.e. antibiotics) and in the emerging application of drug delivery for the management of systemic conditions (i.e. diabetes). Therefore, there is a demand for new methods for production of high-dose dry powder formulations. This paper presents a review of co-mill processing, for the production of high-efficiency inhalation therapies, including the jet mill, mechanofusion, or ball mill methodologies. We investigate the different techniques, additives, and drugs studied, and impact on performance in DPI systems.

Introduction: Cystic fibrosis (CF) is a congenital life-limiting, orphan disease affecting 1/2500 – 1/3000 people worldwide with the greatest prevalence in Europe, North America and Australia. The primary reason underpinning the cause of morbidity and mortality of CF patients is associated with recurrent pulmonary inflammation and infection that leads to chronic, progressive lung deterioration and ultimately death of CF patients.

Areas covered: This review aims to explore the potential role for inhaled anti-inflammatory drugs as a more successful treatment option for CF, in comparison with current oral delivery. Specifically, the focus is on ibuprofen, the only nonsteroidal anti-inflammatory drug approved for chronic use in CF. The need for inhalation therapy has also been highlighted with an insight on the reasons and challenges associated with developing an inhalation therapy of nonsteroidal anti-inflammatory drugs (NSAIDs).

Expert opinion: There is a fundamental need to direct research towards development of anti-inflammatory drugs to control inflammation rather than just targeting infection. Development of an inhalable preparation of ibuprofen alone or in combination with an antibiotic holds the potential to be the most effective treatment option among the existing array of therapies available for CF.

Aim: Current inhaled treatments are not adequate to treat lung diseases. In this study, a promising nanotechnology has been developed to deliver a potential anti- inflammatory and muco-inhibitory compound, simvastatin, for treatment of inflammatory lung diseases via inhalation.

Material & methods: Simvastatin nanoparticles (SV-NPs) encapsulated with poly (Lactic-Co-Glycolic) acid were fabricated using the solvent and anti-solvernt precipitation method.

Results: SV-NPs were found to be stable up to 9 months at 4°C in a freeze-dried form prior to reconsititution. The amount of mucus produced was significantly reduced after SV-NPs treatment on inflamed epithelial cell model and were effective in suppressing the pro-inflammatory markers expression.

Conclusion: This study suggests that SV-NPs nebulisation could potentially be used for the treatment of chronic pulmonary diseases.

In this study, the development and validation of a novel modified version of the medium-sized Virginia Commonwealth University (VCU) mouth-throat (MT) and tracheal-bronchial (TB) realistic upper airway model, intended to evaluate total airway deposition and drug permeation behaviour for orally inhaled products (OIPs) in vitro, is presented. The VCU MT-TB model was modified to accommodate two Snapwell® permeable membrane inserts above the first TB airway bifurcation region to primarily collect deposited nebulised ciprofloxacinhydrochloride (CIP-HCL) droplets as a model drug aerosol system. Permeation characteristics were assessed by adapting the established Transwell® ‘fluid-capacity-limited’ dissolution test system. Firstly, the novel modified TB airway model resulted in significantly higher TB aerosol deposition compared with the original TB model. Secondly, the adapted Transwell permeation test system demonstrated reproducible and discriminatory permeation profiles for already-dissolved and nebulised CIP-HCL drug through a range of permeable membranes. Fundamentally, the rate and extent of CIP-HCL permeation depended on the permeable membrane material used, presence of a stirrer in the receptor compartment and, most importantly, the aerosol particle collection method. This novel hybrid in vitro approach, which incorporates a modified realistic airway model coupled with an adapted Transwell system holds great potential to evaluate other post-deposition characteristics, such as particle dissolution and cellular uptake of OIPs.

Purpose: Thickening polymers have been used as excipients in nasal formulations to avoid nasal run-off (nasal drip) post administration. However, increasing the viscosity of the formulation can have a negative impact on the quality of the aerosols generated. Therefore, the study aims to investigate the use of a novel smart nano-cellulose excipient to generate suitable droplets for nasal drug delivery that simultaneously has only marginally increased viscosity while still reducing nasal drips. 

Methods: Nasal sprays containing the nano-cellulose at different concentrations were investigated for the additive’s potential as an excipient. The formulations were characterised for their rheological and aerosol properties. This was then compared to the conventional nasal spray formulation containing the single-component hydroxyl-propyl cellulose (HPMC) viscosity enhancing excipient.

Results: The HPMC-containing nasal formulations behave in a Newtonian manner while the nano-cellulose formulations have a yield stress and shear-thinning properties. At higher excipient concentrations and shear rates, the nano-cellulose solutions have significantly lower viscosities compared to the HPMC solution, resulting in improved droplet formation when actuated through conventional nasal spray. 

Conclusions: Nano-cellulose materials could potentially be used as a suitable excipient for nasal drug delivery, producing consistent aerosol droplet size and enhanced residence time within the nasal cavity with reduced run-offs compared to conventional polymer thickeners. 

Background: Analysis of patterns of breathing over time may provide novel information on respiratory function and dysfunction. Devices which continuously record and analyse breathing rates may provide new options for the management of respiratory diseases. However, there is a paucity of information about design characteristics that would make such devices user-friendly and suitable for this purpose.

Objective: To determine key device attributes and user requirements for a wearable device to be used for long term monitoring of breathing.

Methods: An online survey was conducted between June 2016 and July 2016. Participants were predominantly recruited via the Woolcock Institute of Medical Research database of volunteers, as well as staff and students. Information regarding the survey, consent form and a link to a web-based questionnaire was sent to participants via email. All participants received an identical survey; those with doctor diagnosed asthma completed an extra questionnaire on asthma control (Asthma Control Test (ACT)). Survey responses were examined as a group using descriptive statistics. Responses were compared between those with and without asthma using the Chi-square test.

Results: The survey was completed by 134 participants (males: 39%, median age group: 50-59 years, asthma: 57%). Of those who completed the ACT, 61% (n=47 out of 77) had sub-optimal asthma control. Of the 134 participants, 62% would be willing to wear a device to monitor their breathing, in contrast to 7% who would not. The remaining 31% stated that their willingness depended on specific factors. Participants with asthma most commonly cited their asthma as motivation for using a wearable; the most common motivation for use in those without asthma was curiosity. More than 90% of total participants would use the device during the day, night or both day and night. Design preferences among all users included: a wrist watch (nominated by >90% for both day and night use, out of four body sites), the ability to synchronise breathing data with a mobile phone or tablet (80%), overnight power charging (34%), and a cost of AUD100 (54%). 

Conclusions: We have explored the motivations and likelihood for adopting wearable technologies for the purpose of breathing monitoring and identified user preferences for key design features. We found participants were motivated to adopt a wearable breathing monitor irrespective of health status, though rationale for use differed between those with and without asthma. These findings will help inform the design of a user-acceptable wearable device which will facilitate its eventual uptake in both healthy and asthma populations.

OBJECTIVE:
The aim of this work was to develop an amorphous solid dispersions/solutions (ASD) of a poorly soluble drug, budesonide (BUD) with a novel polymer Soluplus® (BASF, Germany) using a freeze-drying technique, in order to improve dissolution and absorption through the nasal route.
SIGNIFICANCE:
The small volume of fluid present in the nasal cavity limits the absorption of a poorly soluble drug. Budesonide is a corticosteroid, practically insoluble and normally administered as a suspension-based nasal spray.
METHODS:
The formulation was prepared through freeze-drying of polymer-drug solution. The formulation was assessed for its physicochemical (specific surface area, calorimetric analysis and X-ray powder diffraction), release properties and aerodynamic properties as well as transport in vitro using RPMI 2650 nasal cells, in order to elucidate the efficacy of the Soluplus-BUD formulation.
RESULTS:
The freeze-dried Soluplus-BUD formulation (LYO) showed a porous structure with a specific surface area of 1.4334 ± 0.0178 m2/g. The calorimetric analysis confirmed an interaction between BUD and Soluplus and X-ray powder diffraction the amorphous status of the drug. The freeze-dried formulation (LYO) showed faster release compared to both water-based suspension and dry powder commercial products. Furthermore, a LYO formulation, bulked with calcium carbonate (LYO-Ca), showed suitable aerodynamic characteristics for nasal drug delivery. The permeation across RPMI 2650 nasal cell model was higher compared to a commercial water-based BUD suspension.
CONCLUSIONS:
Soluplus has been shown to be a promising polymer for the formulation of BUD amorphous solid suspension/solution. This opens up opportunities to develop new formulations of poorly soluble drug for nasal delivery.

Context: Particle micronization for inhalation can impart surface disorder (amorphism) of crystalline structures. This can lead to stability issues upon storage at elevated humidity from recrystallization of the amorphous state, which can subsequently affect the aerosol performance of the dry powder formulation.
Objective: The aim of this study was to investigate the impact of an additive, magnesium stearate (MGST), on the stability and aerosol performance of co-milled active pharmaceutical ingredient (API) with lactose. 
Methods: Blends of API-Lactose with/without MGST were prepared and co-milled by the jet-mill apparatus. Samples were stored at 50% relative humidity (RH) and 75% RH for 1, 5, 15 days, respectively. Analysis of changes in particle size, agglomerate structure/strength, moisture sorption and aerosol performance were analyzed by laser diffraction, scanning electron microscopy (SEM), dynamic vapor sorption (DVS) and in-vitro aerodynamic size assessment by impaction respectively. 
Results: Co-milled formulation with MGST (5% w/w) led to a reduction in agglomerate size and strength after storage at elevated humidity compared to co-milled formulation without MGST, as observed from SEM and laser diffraction. Hysteresis in the sorption/desorption isotherm was observed in the co-milled sample without MGST, which was likely due to the recrystallization of the amorphous regions of micronized lactose. Deterioration in aerosol performance after storage at elevated humidity was greater for the co-milled samples without MGST, compared to co-milled with MGST.
Conclusion: MGST has been shown to have a significant impact on co-milled dry powder stability after storage at elevated humidity in terms of physico-chemical properties and aerosol performance.

Airway epithelial cells (AEC) exhibit a pro-inflammatory phenotype in patients with allergic asthma. We examined the effect of an allergic cytokine environment on the response of AEC to rhinovirus, the most common trigger of acute exacerbations of asthma. Calu-3 cells, a well-differentiated human AEC line, were cultured with or without the T-helper type 2 cytokines IL-4 and IL-13, then stimulated with a toll-like receptor (TLR) 3 agonist (poly I:C, dsRNA) or a TLR7 agonist (imiquimod), or infected with rhinovirus 16. Expression of pro-inflammatory and anti-viral mediators, and of viral pattern-recognition molecules, was assessed using nCounter assays, quantitative real-time PCR, and protein immunoassays. Both dsRNA and imiquimod stimulated expression of mRNA for IL6 and IL8, while expression of several chemokines and anti-viral response genes was induced only by dsRNA. Conversely, expression of other cytokines and growth factors was induced only by imiquimod. Rhinovirus infection not only stimulated expression of the inflammation-related genes induced by dsRNA, but also the complement pathway gene CFB and the novel pro- inflammatory cytokine IL32. In the Th2 cytokine environment, several mediators exhibited significantly enhanced expression, while expression of interferons was either unchanged or enhanced. The allergic environment also increased expression of pattern recognition receptors and of ICAM1, the cell surface receptor for rhinovirus. We conclude that Th2 cytokines promote increased production of pro- inflammatory mediators by AEC following infection with rhinovirus. Increased viral entry or enhanced signaling via pattern recognition receptors could also contribute to the exaggerated inflammatory response to rhinovirus observed in allergic asthmatics.

PURPOSE: Sprays from pressurised metered-dose inhalers are produced by a transient discharge of a multiphase mixture. Small length and short time scales have made the investigation of the governing processes difficult. Consequently, a deep understanding of the physical processes that govern atomisation and drug particle formation has been elusive.
METHODS: X-ray phase contrast imaging and quantitative radiography were used to reveal the internal flow structure and measure the time-variant nozzle exit mass density of 50 microL metered sprays of HFA134a, with and without ethanol cosolvent. Internal flow patterns were imaged at a magnification of 194 pixels/mm and 7759 frames per second with 150 ps temporal resolution. Spray projected mass was measured with temporal resolution of 1 ms and spatial resolution 6 microm x 5 microm.
RESULTS: The flow upstream of the nozzle comprised large volumes of vapour at all times throughout the injection. The inclusion of ethanol prevented bubble coalescence, altering the internal flow structure and discharge. Radiography measurements confirmed that the nozzle exit area is dominantly occupied by vapour, with a peak liquid volume fraction of 13%.
CONCLUSION: Vapour generation in pMDIs occurs upstream of the sump, and the dominant volume component in the nozzle exit orifice is vapour at all times in the injection. The flow in ethanol-containing pMDIs has a bubbly structure resulting in a comparatively stable discharge, whereas the binary structure of propellant-only flows results in unsteady discharge and the production of unrespirable liquid masses.

The aim of the study was to understand the impact of different concentrations of the additive material, magnesium stearate (MGST), and the active pharmaceutical ingredient (API), respectively, on the physico-chemical properties and aerosol performance of co-milled formulations for high dose delivery. Initially, blends of API- Lactose with different concentrations of MGST (1 - 7.5% w/w) were prepared and co- milled by the jet-mill apparatus. The optimal concentration of MGST in co-milled formulations was investigated, specifically for agglomerate structure and strength, particle size, uniformity of content, surface coverage and aerosol performance. Secondly, co-milled formulations with different API (1 - 40% w/w) concentrations were prepared and similarly analyzed. Co-milled 5% MGST (w/w) formulation resulted in a significant improvement in in-vitro aerosol performance due to the reduction in agglomerate size and strength compared to the formulation co-milled without MGST. Higher concentrations of MGST (7.5% w/w) led to reduction in aerosol performance likely due to excessive surface coverage of the micronized particles by MGST, which led to failure in uniformity of content and an increase in agglomerate strength and size. Generally, co-milled formulations with higher concentrations of API increased the agglomerate strength and size, which subsequently caused a reduction in aerosol performance. High dose delivery was achieved at API concentration of > 20% (w/w). The study provided a platform for the investigation of aerosol performance and physico-chemical properties of other API and additive materials in co-milled formulations for the emerging field of high dose delivery by dry powder inhalation.

This study focuses on development and in vitro characterization of a nasal delivery system based on uncoated or chitosan-coated solid lipid microparticles (SLMs) containing resveratrol, a natural anti-inflammatory molecule, as an effective alternative to the conventional steroidal drugs. The physico-chemical characteristics of the SLMs loaded with resveratrol were evaluated in terms of morphology, size, thermal behaviour and moisture sorption. The SLMs appeared as aggregates larger than 20 µm. In vitro nasal deposition was evaluated using a USP specification Apparatus E 7-stage cascade impactor equipped with a standard or a modified nasal deposition apparatus. More than 95% of resveratrol was recovered onto the nasal deposition chamber and stage 1 of impactor, suggesting that the SLMs mostly deposited in the nasal cavity. Additionally, the SLMs were not toxic on RPMI 2650 nasal cell line up to a concentration of approximately 40 µM of resveratrol.

The epithelial barrier in the respiratory system is a major obstacle for drug delivery to the systemic circulation both locally and systemically in the lung. Epithelial barrier hinders the transport of large macromolecules or polar drugs. Essential components of this epithelial fence are physical intercellular structures termed tight junctions. Therefore, modulating tight junctions can enhance paracellular transport across epithelial barrier. In this study, the effect of some of non-specific tight junction modulators (TJMs); (Sodium (Na) decanoate, oleic acid and ethyleneglycol-bis-(β-aminoethyl ether)-N, N'-tetraacetic acid (EGTA)) with established effect on intestinal  tight junctions was evaluated for its effects on bronchial epithelial cells (Calu-3 cells).  It was demonstrated that the effect of TJMs especially Na decanoate resulted in a reversible opening of tight junctions evidenced by the decrease in the transepithelial resistance. It was also demonstrated that this reduction of TEER upon exposing the epithelial cells to the TJMs resulted in a significant increase in Flu-Na (Paracellular marker) and PXS25 (anti-fibrotic compound) transepithelial transport through this barrier. In conclusion, among the investigated non-specific TJMs, Na decanoate fulfilled the requirements of an effective, non-toxic and reversible tight junction modulator for Calu-3 lung epithelial cells. 

Introduction: The effectiveness of conventional cancer chemotherapy is hampered by the occurrence of multidrug resistance (MDR) in tumor cells. Although many studies have reported the development of novel MDR chemotherapeutic agents, clinical success is lacking owing to the high associated toxicity. Nanoparticle-based delivery of chemotherapeutic drugs has emerged as alternative approach to treat MDR cancers via exploitation of leaky vasculature in the tumor microenvironment. Accordingly, func- tionalization of nanoparticles with target specific ligands can be employed to achieve significant improvements in the treatment of MDR cancer.
Areas covered: This review focuses on the recent advances in the functionalization of nanocarriers with specific ligands, including antibodies, transferrin, folate, and peptides to overcome MDR cancer. The limitations of effective ligand-functionalized nanoparticles as well as therapeutic successes in ligand targeting are covered in the review.
Expert opinion: Targeting MDR tumors with ligand-functionalized nanoparticles is a promising approach to improve the treatment of cancer. With this approach, higher drug concentrations at targeted sites would be achieved with lower dosage frequencies and reduced side effects in compar- ison to existing formulations of chemotherapeutic drugs. However, potential toxicities and immunolo- gical responses to ligands should be carefully reviewed for viable options in for future MDR cancer treatment.

The choices of inhaler therapies have been driven by technologists. However, the voice of patients and clinicians is now getting louder. This will lead to a change in inhaler technology and patient experience. This review looks at the current state-of-the-art and what the future holds for devices used in the treatment of asthma and COPD.

The pulmonary route is gaining increasing popularity as a fast and effective way of delivering drugs to the lungs, both locally and systemically. Although the lung is naturally permeable to small-molecule drugs, the epithelial barrier and the presence of tight junctions (TJ) strictly regulate the absorption of large and polar molecules. It has been shown that polyunsaturated fatty acids (PUFAs) may integrate into membrane lipids and modify their physical properties by altering membrane fluidity and thus barrier function. In this study, the in vitro effect of PUFAs, specifically docosahexaenoic acid (DHA), linoleic acid (LA), arachidonic acid (AA), gamma- linoleic acid (GLA) and palmitoleic acid (PA), on airway epithelial cells (Calu-3 cells) with regards to their tight junction modulatory effect was investigated. Moreover, the effect of PUFAs on mucus production and inflammatory response, and the viscoelastic behaviour of airway mucus were also investigated. Calu-3 cells were treated with 100 μM of each PUFA and the transepithelial resistance (TEER) of Calu-3 cells, which is an in vitro measure of epithelial cell integrity, and paracellular epithelial permeability of Na fluorescein (paracellular marker) were measured. It was shown that the resistance dropped significantly after Calu-3 cells were incubated with PUFAs, compared to non-treated control cells. In general, the permeability increased following the rank order: GLA≥PA >DHA>AA>LA. Specifically, GLA and PA treatments enhanced paracellular transport of Na fluorescein 1.5 times over control. This increase in paracellular transport mirrored the concurrent drop in TEER values. PUFAs resulted in reduced mucus production in Calu-3 cells (except DHA) and did not result in cytotoxicity or inflammation (except AA) with the experiment concentration. It was concluded that PUFAs have the potential to modulate TJ and thus enhance the permeation of drugs through the lung epithelial cell barrier via the paracellular route.

Pressurised metered dose inhalers (pMDI) are still the most heavily prescribed medicines for the treatment of asthma. Various add-on devices are made available through pharmacies either on prescription, over-the-counter or off-the-shelf. These include actuation aids, spacers and alternative actuators. The Sports-Haler™ is a replacement actuator for the conventional Ventolin™ actuator and offers a compact and colourful alternative to the conventional design. This article evaluates the performance of this replacement device and compares it to the standard product using Pharmacopeia methodology. In general, there were no differences in the aerosol performance and thus projected lung deposition of salbutamol sulphate. We discuss the pros and cons of such add-on devices from a pharmacy perspective and highlight potential issues that may be encountered when patients choose to modify the standard regulated pharmaceutical product. There are several considerations, which need to be reviewed when making decisions about the use of substitute and/or add-on devices.

Introduction: Gene therapy is a potential alternative to treat a number of diseases. Different hurdles are associated with aerosol gene delivery due to the susceptibility of pDNA structure to be degraded during the aerosolization process. Different strategies have been investigated in order to protect and efficiently deliver pDNA to the lungs using non-viral vectors. To date, no successful therapy involving non-viral vectors has been marketed, highlighting the need for further investigation in this field.

Areas covered: This review is focused on the formulation and delivery of DNA to the lungs, using non-viral vectors. Aerosol gene formulations are divided according to the current delivery systems for the lung: nebulizers, dry powder inhalers and pressurized metered dose inhalers; highlighting its benefits, challenges and potential application.

Expert Opinion: Successful aerosol delivery is achieved when DNA supercoiled structure is protected during aerosolization. A formulation strategy or compounds that can protect, stabilize and efficiently transfect DNA into the cells is desired in order to produce an effective, low-cost and safe formulation. Nebulizers and dry powder inhalers are the most promising approaches to be used for aerosol delivery, due to the lower shear forces involved. In this context it is also important to highlight the importance of considering the ‘pDNA-formulation-device system’ as an integral part of the formulation development for a successful nucleic acid delivery.

The aim of this study was to incorporate an optimized RPMI2650 nasal cell model into a 3D printed model of the nose to test deposition and permeation of drugs intended for use in the nose. The nasal cell model was optimized for barrier properties in terms of permeation marker and mucus production. RT-PCR was used to determine the xenobiotic transporter gene expression of RPMI 2650 cells in comparison with primary nasal cells. After 14 days in culture, the cells were shown to produce mucus, and to express trans-epithelial electrical resistance (TEER) values and sodium fluorescein permeability consistent with values reported for excised human nasal mucosa. In addition, good correlation was found between RPMI 2650 and primary nasal cells transporters expression values.

The purpose built 3D printed model of the nose takes the form of an expansion chamber with inserts for cells and an orifice for insertion of a spray drug delivery device. This model was validated against the FDA glass chamber with cascade impactors that is currently approved for studies of nasal products. No differences were found between the two apparatus.
The apparatus including the nasal cell model was used to test a commercial nasal product containing budesonide (Rhinocort, AstraZeneca, Australia). Drug deposition and transport studies on RPMI 2650 were successfully performed.

The new 3D printed apparatus that incorporate cells can be used as valid in vitro model to test nasal products in conditions that mimic the delivery from nasal devices in real life conditions.

Purpose: To investigate aerosol plume geometries of pressurised metered dose inhalers  (pMDIs) using a high-speed laser image system with different actuator nozzle materials and designs.

Method: Actuators made from aluminium, PET and PTFE were manufactured with four different nozzle designs: cone, flat, curved cone and curved flat. Plume angles and spans generated using the designed actuator nozzles with four solution-based pMDI formulations were imaged using Oxford Lasers EnVision system and analysed using EnVision Patternate software. 

Result: Reduced plume angles for all actuator materials and nozzle designs were observed with pMDIs formulations containing drug with high co-solvent concentration (ethanol) due to the reduced vapor pressure. Significantly higher plume angles were observed with the PTFE flat nozzle across all formulations, which could be a result of the nozzle geometry and material’s hydrophobicity. 

Conclusion: The plume geometry of pMDI aerosols can be influenced by the vapor pressure of the formulation, nozzle geometries and actuator material physiochemical properties.