Inhaled Prostanoids in the Therapy of Pulmonary Hypertension

Acute Respiratory Distress Syndrome and the Use of Inhaled Pulmonary Vasodilators in the COVID-19 Era: A Narrative Review

The Coronavirus disease (COVID-19) pandemic of 2019 has resulted in significant morbidity and mortality, especially from severe acute respiratory distress syndrome (ARDS). As of September 2022, more than 6.5 million patients have died globally, and up to 5% required intensive care unit treatment. COVID-19-associated ARDS (CARDS) differs from the typical ARDS due to distinct pathology involving the pulmonary vasculature endothelium, resulting in diffuse thrombi in the pulmonary circulation and impaired gas exchange. The National Institute of Health and the Society of Critical Care Medicine recommend lung-protective ventilation, prone ventilation, and neuromuscular blockade as needed. Further, a trial of pulmonary vasodilators is suggested for those who develop refractory hypoxemia. A review of the prior literature on inhaled pulmonary vasodilators in ARDS suggests only a transient improvement in oxygenation, with no mortality benefit. This narrative review aims to highlight the fundamental principles in ARDS management, delineate the fundamental differences between CARDS and ARDS, and describe the comprehensive use of inhaled pulmonary vasodilators. In addition, with the differing pathophysiology of CARDS from the typical ARDS, we sought to evaluate the current evidence regarding the use of inhaled pulmonary vasodilators in CARDS.

Comprehensive Review on Novel Targets and Emerging Therapeutic Modalities for Pulmonary Arterial Hypertension

Pulmonary Arterial Hypertension (PAH) is the progressive increase in mean pulmonary arterial pressure (mPAP) (≥ 20 mmHg at rest). Current treatment strategies include the drugs targeting at nitric oxide pathway, endothelin receptors, prostaglandin receptors, thromboxane receptors and phosphodiesterase inhibitors, which provides the symptomatic relief. Despite of these treatments, the mortality amongst the PAH patients remains high due to non-reversal of the condition. This review primarily covers the introduction of PAH and the current treatments of the disease. This is followed by the newer disease targets expressed in the pathobiology of the disease like Rho Kinase Pathway, Vasoactive Intestinal Peptide Pathway, Receptor Tyrosine Kinases, Serotonin signalling pathway, Voltage-gated potassium (Kv) channel pathway. Newer formulation strategies for targeting at these specific receptors were covered and includes nano formulations like liposomes, Micelles, Polymeric Nanoparticles, Solid Lipid Nanoparticles (SLN), Bioresorbable stents, NONOates, Cell-Based Therapies, miRNA therapy for PAH. Novel targets were identified for their role in the pathogenesis of the PAH and needs to be targeted with new molecules or existing molecules effectively. Nanosystems have shown their potential as alternative carriers on the virtue of their better performance than traditional drug delivery systems.

Theranostic Nanomedicines for the Treatment of Cardiovascular and Related Diseases: Current Strategies and Future Perspectives

Cardiovascular and related diseases (CVRDs) are among the most prevalent chronic diseases in the 21st century, with a high mortality rate. This review summarizes the various nanomedicines for diagnostic and therapeutic applications in CVRDs, including nanomedicine for angina pectoris, myocarditis, myocardial infarction, pericardial disorder, thrombosis, atherosclerosis, hyperlipidemia, hypertension, pulmonary arterial hypertension and stroke. Theranostic nanomedicines can prolong systemic circulation, escape from the host defense system, and deliver theranostic agents to the targeted site for imaging and therapy at a cellular and molecular level. Presently, discrete non-invasive and non-surgical theranostic methodologies are such an advancement modality capable of targeted diagnosis and therapy and have better efficacy with fewer side effects than conventional medicine. Additionally, we have presented the recent updates on nanomedicine in clinical trials, targeted nanomedicine and its translational challenges for CVRDs. Theranostic nanomedicine acts as a bridge towards CVRDs amelioration and its management.

Inhaled antibiotic-loaded polymeric nanoparticles for the management of lower respiratory tract infections

Lower respiratory tract infections (LRTIs) are one of the leading causes of deaths in the world. Currently available treatment for this disease is with high doses of antibiotics which need to be administered frequently. Instead, pulmonary delivery of drugs has been considered as one of the most efficient routes of drug delivery to the targeted areas as it provides rapid onset of action, direct deposition of drugs into the lungs, and better therapeutic effects at low doses and is self-administrable by the patients. Thus, there is a need for scientists to design more convenient pulmonary drug delivery systems towards the innovation of a novel treatment system for LRTIs. Drug-encapsulating polymer nanoparticles have been investigated for lung delivery which could significantly reduce the limitations of the currently available treatment system for LRTIs. However, the selection of an appropriate polymer carrier for the drugs is a critical issue for the successful formulations of inhalable nanoparticles. In this review, the current understanding of LRTIs, management systems for this disease and their limitations, pulmonary drug delivery systems and the challenges of drug delivery through the pulmonary route are discussed. Drug-encapsulating polymer nanoparticles for lung delivery, antibiotics used in pulmonary delivery and drug encapsulation techniques have also been reviewed. A strong emphasis is placed on the impact of drug delivery into the infected lungs.

Design and Comprehensive Characterization of Tetramethylpyrazine (TMP) for Targeted Lung Delivery as Inhalation Aerosols in Pulmonary Hypertension (PH): In Vitro Human Lung Cell Culture and In Vivo Efficacy

This is the first study reporting on the design and development innovative inhaled formulations of the novel natural product antioxidant therapeutic, tetramethylpyrazine (TMP), also known as ligustrazine. TMP is obtained from Chinese herbs belonging to the class of Ligusticum. It is known to have antioxidant properties. It can act as a Nrf2/ARE activator and a Rho/ROCK inhibitor. The present study reports for the first time on the comprehensive characterization of raw TMP (non-spray dried) and spray dried TMP in a systematic manner using thermal analysis, electron microscopy, optical microscopy, and Raman spectroscopy. The in vitro aerosol dispersion performance of spray dried TMP was tested using three different FDA-approved unit-dose capsule-based human dry powder inhaler devices. In vitro human cellular studies were conducted on pulmonary cells from different regions of the human lung to examine the biocompatibility and non-cytotoxicity of TMP. Furthermore, the efficacy of inhaled TMP as both liquid and dry powder inhalation aerosols was tested in vivo using the monocrotaline (MCT)-induced PH rat model.

The ZAR1 protein in cancer; from epigenetic silencing to functional characterisation and epigenetic therapy of tumour suppressors

ZAR1, zygote arrest 1, is a zinc finger protein (C-terminus), which was initially identified in mouse oocytes. Later it was found that its expression is present in various human tissues e.g. lung and kidney. Interestingly, it was observed that in various tumour types the ZAR1 transcript is missing due to hypermethylation of its CpG island promoter, but not ZAR2. Since methylation of the ZAR1 promoter is described as a frequent event in tumourigenesis, ZAR1 could serve as a useful diagnostic marker in cancer screens. ZAR1 was described as a useful prognostic/diagnostic cancer marker for lung cancer, kidney cancer, melanoma and possibly liver carcinoma. Furthermore, ZAR1 was reactivated as a tumour suppressor by epigenetic therapy using CRISPR-dCas9 method. This method holds the potential to precisely target not only ZAR1 and reactivate tumour suppressors in a tailored cancer therapy. ZAR1 is highly conserved amongst vertebrates, especially its zinc finger, which is the relevant domain for its protein and RNA binding ability. ZAR1 is implicated in various cellular mechanisms including regulation of oocyte/embryo development, cell cycle control and mRNA binding, though little was known about the underlying mechanisms. ZAR1 was reported to regulate and activate translation through the binding to TCS translation control sequences in the 3'UTRs of its target mRNA the kinase WEE1. ZAR1 has a tumour suppressing function by inhibiting cell cycle progression. Here we review the current literature on ZAR1 focusing on structural, functional and epigenetic aspects. Characterising the cellular mechanisms that regulate the signalling pathways ZAR1 is involved in, could lead to a deeper understanding of tumour development and, furthermore, to new strategies in cancer treatment.

Hemodynamic and clinical effects of selexipag in children with pulmonary hypertension

Selexipag is an oral prostacyclin receptor agonist; it was recently approved for use in adults with pulmonary arterial hypertension. The safety and efficacy of selexipag has not yet been determined in the pediatric population. We describe short-term hemodynamic and clinical data with selexipag therapy in four pediatric patients with pulmonary hypertension. We reviewed clinical, echocardiographic, and hemodynamic data. One patient was transitioned from subcutaneous treprostinil to selexipag, and in three patients, selexipag was added as a third agent. Drug dosing was attained empirically based on patient body size. A follow-up catheterization was performed 12-18 months after initiation of selexipag therapy. All four patients tolerated selexipag well, without significant side effects. One patient transitioned successfully from subcutaneous treprostinil to selexipag. None of the four patients had clinical deterioration. In three patients who were able to perform a 6-minute walk test, pre and post selexipag distances were 350 and 400, 409 and 390, and 300 and 360 m, respectively. Echocardiograms showed no significant changes. Catheterization showed a variable change in pulmonary vascular resistance (small decrease in three patients and increase in one patient). Brain natriuretic peptide levels before and after selexipag in the four patients were 38 and 49, 33 and 54, 29 and 25, and 12 and 14 pg/mL, respectively. Selexipag use for 16-28 months was safe in four pediatric patients; none of them had clinical deterioration. Larger number of patients and longer follow-up intervals are necessary before further recommendations can be made.

lloprost delivered via the BREELIBTM nebulizer: a review of the clinical evidence for efficacy and safety

Inhaled iloprost is a well-established medication to treat pulmonary arterial hypertension (PAH), a serious and potentially fatal disease of the pulmonary resistance vessels. The therapeutic administration of iloprost requires six to nine inhalations per day, due to the short biological half-life of this prostacyclin analogue. The I-Neb^TM AAD^TM, introduced in 2006, is the most commonly used nebulizer for delivering iloprost, requiring at least 6.5 min for an inhaled dose of 5 µg. In order to reduce inhalation time, a portable nebulizer based on modern-device technology was developed. The acute safety and tolerability of rapid iloprost inhalation via the BREELIB^TM nebulizer was assessed in a four-part clinical trial. In this review, I describe the rationale and features of the new nebulizer, with particular emphasis on the safety and tolerability profile of iloprost inhalation via BREELIB^TM observed in the first clinical studies. Meanwhile, the BREELIB^TM nebulizer is approved and available for inhaled iloprost therapy combining significantly reduced inhalation time with good tolerability. This new approach will certainly improve patient convenience and compliance, possibly resulting in broader acceptance and improved efficacy of iloprost aerosol therapy in PAH.

Targeted Gene Delivery through the Respiratory System: Rationale for Intratracheal Gene Transfer

Advances in DNA- and RNA-based technologies have made gene therapy suitable for many lung diseases, especially those that are hereditary. The main objective of gene therapy is to deliver an adequate amount of gene construct to the intended target cell, achieve stable transduction in target cells, and to produce a clinically therapeutic effect. This review focuses on the cellular organization in the normal lung and how gene therapy targets the specific cell types that are affected by pulmonary disorders caused by genetic mutations. Furthermore, it examines the pulmonary barriers that can compromise the absorption and transduction of viral vectors and genetic agents by the lung. Finally, it discusses the advantages and limitations of direct intra-tracheal gene delivery with different viral vectors in small and large animal models and in clinical trials.

Inhalation of repurposed drugs to treat pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a rare, but severe and life-threatening disease characterized by vasoconstriction and remodeling of the pulmonary arterioles, leading to progressive increase in pulmonary vascular resistance and ultimately to right-heart failure. In the last two decades, significant progress in treatment of PAH has been made, with currently 12 drugs approved for targeted therapy. Among these, the stable prostacyclin analogues iloprost and treprostinil have been repurposed for inhalation. The paper highlights the development of the two drugs emphasizing the rationale and advantages of the inhalative approach. Despite substantial advances in the specific, mainly vasodilatory PAH therapy, disease progression is mostly inevitable and mortality remains unacceptably high. Thus, introduction of new drugs targeting the cancer-like remodeling of the diseased pulmonary arteries is urgently needed. Inhalation offers pulmonary selectivity and will hopefully pioneer the repurposing of novel highly potent drugs for effective aerosol therapy of PAH.

Delivering drugs to the lungs: The history of repurposing in the treatment of respiratory diseases

The repurposing of drug delivery by the pulmonary route has been applied to treatment and prophylaxis of an increasingly wide range of respiratory diseases. Repurposing has been most successful for the delivery of inhaled bronchodilators and corticosteroids in patients with asthma and chronic obstructive pulmonary disease (COPD). Repurposing utilizes the advantages that the pulmonary route offers in terms of more targeted delivery to the site of action, the use of smaller doses, and a lower incidence of side-effects. Success has been more variable for other drugs and treatment indications. Pulmonary delivery is now well established for delivery of inhaled antibiotics in cystic fibrosis (CF), and in the treatment of pulmonary arterial hypertension (PAH). Other inhaled treatments such as those for idiopathic pulmonary fibrosis (IPF), lung transplant rejection or tuberculosis may also become routine. Repurposing has progressed in parallel with the development of new drugs, inhaler devices and formulations.

Recent advances in targeting the prostacyclin pathway in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe disease characterised by increased pulmonary vascular resistance, which leads to restricted pulmonary arterial blood flow and elevated pulmonary arterial pressure. In patients with PAH, pulmonary concentrations of prostacyclin, a prostanoid that targets several receptors including the IP prostacyclin receptor, are reduced. To redress this balance, epoprostenol, a synthetic prostacyclin, or analogues of prostacyclin have been given therapeutically. These therapies improve exercise capacity, functional class and haemodynamic parameters. In addition, epoprostenol improves survival among patients with PAH. Despite their therapeutic benefits, treatments that target the prostacyclin pathway are underused. One key factor is their requirement for parenteral administration: continuous intravenous administration can lead to embolism and thrombosis; subcutaneous administration is associated with infusion-site pain; and inhalation is time consuming, requiring multiple daily administrations. Nevertheless, targeting the prostacyclin pathway is an important strategy for the management of PAH. The development of oral therapies for this pathway, as well as more user-friendly delivery devices, may alleviate some of the inconveniences. Continued improvements in therapeutic options will enable more patients with PAH to receive medication targeting the prostacyclin pathway.

Prolonged vasodilatory response to nanoencapsulated sildenafil in pulmonary hypertension

Direct vasodilator delivery to the airways enables a selective therapy of pulmonary hypertension (PH). However, short-term effects of the applied medication require multiple daily inhalations. Controlled release formulations (polymeric nanomedicines) offer the potential of prolonging drug effects within the respiratory tract, thereby reducing the number of necessary inhalations. In the model of U46619-elicited PH, sildenafil and two sildenafil-loaded polymeric submicron particle formulations were evaluated for their pharmacodynamic and pharmacokinetic characteristics and acute tolerability. Lung-delivered sildenafil caused a selective dose-dependent decline of the pulmonary arterial pressure and vascular resistance. Compared to the transient pharmacodynamic effect observed for sildenafil, the same dose of nanoencapsulated sildenafil resulted in prolongation, but not augmentation, of the pulmonary vasodilatation. An extended pharmacokinetic profile was observed for nanoencapsulated sildenafil, and nanomedicines revealed no acute toxicity. The amplification of pulmonary vasodilatory response caused by nanoencapsulation of sildenafil offers an intriguing approach to ameliorate the therapy of PH. From the Clinical Editor: Pulmonary hypertension usually results in right heart failure long term. Current medical therapy includes the use of potent vasodilators such as sildenafil. In this article, the authors investigated the use of nanoencapsulated formulation for sustained delivery via inhalation route. An extended pharmacokinetic profile was seen for this nanoformulation with little side effects. It is hoped that clinical application of this would come to fruition soon.

Pulmonary delivered polymeric micelles--pharmacokinetic evaluation and biodistribution studies

Polymeric micelles represent interesting delivery systems for pulmonary sustained release. However, little is known about their in vivo release and translocation profile after delivery to the lungs. In the present study, curcumin acetate (CA), which is an ester prodrug of curcumin, or the mixture of CA and Nile red was encapsulated into PEG–PLGA micelles by a solvent evaporation method. The micellar formulation increased the stability of CA in water and physiologically relevant fluids and led to a sustained drug release in vitro. Following intratracheal (IT) administration to rats, CA loaded micelles achieved not only prolonged pulmonary retention with AUC values almost 400-fold higher than by IV route, but also local sustained release up to 24 h. In addition, IT delivery of micelles appeared to facilitate the uptake into the pulmonary vascular endothelium and efficiently translocate across the air–blood barrier and penetrate into the brain. Co-localization of CA and Nile red confirmed that micelles in lung and brain tissue were still intact. This study is the first to demonstrate that aerosolized PEG–PLGA micelles are a promising carrier for both pulmonary and non-invasive systemic sustained release of labile drugs.

Systematic aging of degradable nanosuspension ameliorates vibrating-mesh nebulizer performance

CONTEXT

The process of vibrating-mesh nebulization is affected by sample physicochemical properties. Exemplary, electrolyte supplementation of diverse formulations facilitated the delivery of adequate aerosols for deep lung deposition.

OBJECTIVE

This study addressed the impact of storage conditions of poly(lactide-co-glycolide) nanosuspension on aerosol properties when nebulized by the eFlow®rapid.

MATERIALS AND METHODS

First, purified nanosuspensions were supplemented with electrolytes (i.e. sodium chloride, lactic and glycolic acid). Second, the degradable nanoparticles (NP) were incubated at different temperatures (i.e. 4, 22 and 36 °C) for up to two weeks. The effect of formulation supplementation and storage on aerosol characteristics was studied by laser diffraction and correlated with the sample conductivity.

RESULTS AND DISCUSSION

Nebulization of purified nanosuspensions resulted in droplet diameters of >7.0 µm. However, electrolyte supplementation and storage, which led to an increase in sample conductivity (>10-20 µS/cm), were capable of providing smaller droplet diameters during vibrating-mesh nebulization (≤5.0 µm). No relevant change of NP properties (i.e. size, morphology, remaining mass and molecular weight of the employed polymer) was observed when incubated at 22 °C for two weeks.

CONCLUSION

Sample aging is an alternative to electrolyte supplementation in order to ameliorate the aerosol characteristics of degradable NP formulations when nebulized by vibrating-mesh technology.

Oral sildenafil and inhaled iloprost in the treatment of pulmonary hypertension of the newborn

OBJECTIVE

This study was performed to examine the effectiveness and safety of oral sildenafil and inhaled iloprost in term newborns with persistent pulmonary hypertension of the newborn (PPHN).

PATIENTS AND METHODS

Oral sildenafil and inhaled iloprost were administered to 27 and 20 neonates, respectively, for treatment of persistent pulmonary hypertension. All patients were term infants at 37 gestational weeks or older. In the sildenafil group, 14 patients had meconium aspiration syndrome, 8 had asphyxia (hypoxic ischemic encephalopathy stages II and III), 3 had congenital pneumonia, 1 had transient tachypnea, and 1 had idiopathic PPHN. In the iloprost group, 9 patients had meconium aspiration syndrome, 7 had asphyxia (hypoxic ischemic encephalopathy stages II and III), 3 had congenital pneumonia, and 1 had transient tachypnea. Sildenafil citrate was administered via an oral feeding tube. Iloprost was administered endotracheally to patients on mechanical ventilation using a jet nebulizer.

RESULTS

Iloprost appeared to be more effective than sildenafil in the treatment of PPHN with regard to time to adequate clinical response, ventilatory parameters, duration of drug administration, duration of mechanical ventilation, duration of return to normal values of respiratory failure indices, use of MgSO4 as a second vasodilator and requirement for support with inotropic agents. We observed no side effects on blood pressure or homeostasis in any of the patients in the iloprost group. Systemic hypotension was significantly elevated in the sildenafil group. Four and three infants died of PPHN in the sildenafil and iloprost groups, respectively. Pulmonary systolic arterial pressure decreased to normal levels in the remaining 40 patients, and they were discharged from hospital.

CONCLUSION

We suggested that inhaled iloprost may be a safe and effective treatment choice in newborn infants with persistent pulmonary hypertension. In cases where treatment with inhaled iloprost, ECMO or INO is not possible, oral sildenafil can be an alternative therapy option in the treatment of PPHN.

Developing ways to evaluate in the laboratory how inhalation devices will be used by patients and care-givers: the need for clinically appropriate testing

The design of methods in the pharmaceutical compendia for the laboratory-based evaluation of orally inhaled product (OIP) performance is intentionally aimed for simplicity and robustness in order to achieve the high degree of accuracy and precision required for the assurance of product quality in a regulated environment. Consequently, performance of the inhaler when used or even misused by the patient or care-giver has often not been assessed. Indeed, patient-use-based methodology has been developed in a somewhat piecemeal basis when a need has been perceived by the developing organization. There is, therefore, a lack of in-use test standardization across OIP platforms, and often important details have remained undisclosed beyond the sponsoring organization. The advent of international standards, such as ISO 20072:2009, that focus specifically on the OIP development process, together with the need to make these drug delivery devices more patient-friendly as an aid to improving compliance, is necessitating that clinically appropriate test procedures be standardized at the OIP class level. It is also important that their capabilities and limitations are well understood by stakeholders involved in the process. This article outlines how this process might take place, drawing on current examples in which significant advances in methodology have been achieved. Ideally, it is hoped that such procedures, once appropriately validated, might eventually become incorporated into the pharmacopeial literature as a resource for future inhaler developers, regulatory agencies, and clinicians seeking to understand how these devices will perform in use to augment ongoing product quality testing which is adequately served by existing methods.

Targeting inhaled therapy beyond the lungs

Pulmonary disease has been the primary target of inhaled therapeutics for over 50 years. During that period, increasing interest has arisen in the use of this route of administration to gain access to the systemic circulation for the treatment of a number of diseases beyond the airways. In order to effectively employ this route, the barriers to transport from the lungs following deposition of aerosols must be considered, including the nature of the disease (whether proximal, as in pulmonary hypertension, or distal, as in diabetes). Delivery to the systemic circulation begins with the efficiency of aerosol generation and subsequent deposition in the airways and proceeds to the influence of mechanisms of clearance, including absorption, metabolism, and mucociliary and cell-mediated transport, on the residence time of the drugs in the lungs. The nature of the drug (small or large molecules/low or high molecular weight), susceptibility to degradation and general physicochemical properties play a role in the chemistry of its formulation, physics of aerosol delivery and biology of disposition.

Improved laboratory test methods for orally inhaled products

Existing pharmacopeial methods for the in vitro testing of orally inhaled products (OIPs) are simplified representations of clinical reality, as their objective is to provide metrics that are discriminating of product quality. Attempts to correlate measures such as fine particle fraction <5 µm aerodynamic diameter with in vivo measures of lung deposition have therefore been notoriously difficult to achieve. Although particle imaging-based techniques may be helpful to link in vitro to in vivo data as surrogates for clinical responses, a reappraisal of the purposes for laboratory-based testing of OIPs is required. This article provides guidance on approaches that may be helpful to develop clinically appropriate methods to assess OIP performance in the laboratory, with the ultimate goal of developing robust in vitro–in vivo relationships for the major inhaled drug classes.

Good Cascade Impactor Practice (GCIP) and considerations for "in-use" specifications

The multi-stage cascade impactor (CI) is widely used to determine aerodynamic particle size distributions (APSDs) of orally inhaled products. Its size-fractionating capability depends primarily on the size of nozzles of each stage. Good Cascade Impactor Practice (GCIP) requires that these critical dimensions are linked to the accuracy of the APSD measurement based on the aerodynamic diameter size scale. Effective diameter (Deff) is the critical dimension describing any nozzle array, as it is directly related to stage cut-point size (d50). d50 can in turn be determined by calibration using particles of known aerodynamic diameter, providing traceability to the international length standard. Movements in Deff within manufacturer tolerances for compendial CIs result in the worst case in shifts in d50 of <±10%. Stage mensuration therefore provides satisfactory control of measurement accuracy. The accurate relationship of Deff to d50 requires the CI system to be leak-free, which can be checked by sealing the apparatus at the entry to the induction port and isolating it from the vacuum source and measuring the rate of pressure rise before each use. Mensuration takes place on an infrequent basis compared with the typical interval between individual APSD determinations. Measurement of stage flow resistance (pressure drop; ΔPstage) could enable the user to know that the CI stages are fit for use before every APSD measurement, by yielding an accurate measure of Deff. However, more data are needed to assess the effects of wear and blockage before this approach can be advocated as part of GCIP.

Validation of a general in vitro approach for prediction of total lung deposition in healthy adults for pharmaceutical inhalation products

BACKGROUND

A validated method to predict lung deposition for inhaled medication from in vitro data is lacking in spite of many attempts to correlate in vitro and in vivo outcomes. By using an in vivo-like in vitro setup and analyzing inhalers from the same batches, both in vitro and in vivo, we wanted to create a situation where information from the in vitro and in vivo outcomes could be analyzed at the same time.

METHOD

Nine inhalation products containing either budesonide or AZD4818 were evaluated. These comprised two pressurized metered dose inhalers (pMDIs), a pMDI plus a spacer, four dry powder inhalers, and two dosimetric nebulizers. In vitro, an in vivo-like setup consisting of anatomically correct inlet throats were linked to a flow system that could replay actual inhalation flow profiles through the throat to a filter or to an impactor. In vivo, total lung deposition was measured in healthy adults by pharmacokinetic methods.

RESULTS AND CONCLUSION

We could show that the amount of drug escaping filtration in a realistic throat model under realistic delivery conditions predicts the typical total lung deposition in trained healthy adult subjects in the absence of significant exhaled mass. We could further show that by using combinations of throat models and flow profiles that represent realistic deviations from the typical case, variations in ex-cast deposition reflect between-subject variation in lung deposition. Further, we have demonstrated that ex-cast deposition collected either by a simple filter or by a cascade impactor operated at a fixed flow rate using a mixing inlet, to accommodate a variable flow profile through the inhaler, predicts equally well the lung deposited dose. Additionally, the ex-cast particle size distribution measured by this method may be relevant for predicting exhaled fraction and regional lung deposition by computational models.

Defective alterations in the collagen network to prostacyclin in COPD lung fibroblasts

BACKGROUND

Prostacyclin analogs are potent vasodilators and possess anti-inflammatory properties. However, the effect of prostacyclin on extracellular matrix (ECM) in COPD is not well known. Collagen fibrils and proteoglycans are essential ECM components in the lung and fibroblasts are key players in regulating the homeostasis of ECM proteins. The aim was to study the synthesis of prostacyclin and its effect on fibroblast activity and ECM production, and in particular collagen I and the collagen-associated proteoglycans biglycan and decorin.

METHODS

Parenchymal lung fibroblasts were isolated from lungs from COPD patients (GOLD stage IV) and from lungs and transbronchial biopsies from control subjects. The prostacyclin analog iloprost was used to study the effect of prostacyclin on ECM protein synthesis, migration, proliferation and contractile capacity of fibroblasts.

RESULTS

TGF-β1 stimulation significantly increased prostacyclin synthesis in fibroblasts from COPD patients (p < 0.01), but showed no effect on fibroblasts from control subjects. Collagen I synthesis was decreased by iloprost in both control and COPD fibroblasts (p < 0.05). Conversely, iloprost significantly altered biglycan and decorin synthesis in control fibroblasts, but iloprost displayed no effect on these proteoglycans in COPD fibroblasts. Proliferation rate was reduced (p < 0.05) and contractile capacity was increased in COPD fibroblasts (p < 0.05) compared to control fibroblasts. Iloprost decreased proliferative rate in control fibroblasts (p < 0.05), whereas iloprost attenuated contraction capacity in both COPD (p < 0.01) and control fibroblasts (p < 0.05).

CONCLUSIONS

Iloprost reduced collagen I synthesis and fibroblast contractility but did not affect the collagen-associated proteoglycans or proliferation rate in fibroblasts from COPD patients. Enhanced prostacyclin production could lead to improper collagen network fibrillogenesis and a more emphysematous lung structure in severe COPD patients.

Adapting the Abbreviated Impactor Measurement (AIM) concept to make appropriate inhaler aerosol measurements to compare with clinical data: a scoping study with the "Alberta" idealized throat (AIT) inlet

BACKGROUND

The Abbreviated Impactor Measurement (AIM) concept simplifies determination of aerodynamic size metrics for inhaler quality control testing. A similar approach is needed to compare in vitro particle size distribution metrics with human respiratory tract (HRT) deposition.

METHODS

An abbreviated impactor based on the Andersen eight-stage cascade impactor (ACI) was developed having two size-fractionating stages with cut-points at 4.7 and 1.1 μm aerodynamic diameter at 28.3 L/min, to distinguish between coarse (CPM), fine (FPM), and extra-fine (EPM) mass fractions likely to deposit in the oropharynx, airways of the lungs, or be exhaled, respectively. In vitro data were determined for pressurized metered dose inhaler (pMDI)-delivered salbutamol (100 μg/actuation ex valve) with an "Alberta" idealized adult upper airway (throat) inlet (AIM-pHRT). Corresponding benchmark data for a full resolution Andersen eight-stage cascade impactor with "Alberta" idealized throat (ACI-AIT) and ACI-Ph.Eur./USP inlet were obtained with the same product.

RESULTS

Mass recoveries (μg/actuation; mean ± SD) were equivalent at 100.5 ± 0.7; 97.2 ± 4.9 and 101.5 ± 9.5 for the AIM-pHRT, ACI-AIT, and ACI-Ph.Eur./USP induction port, respectively [one-way analysis of variance (ANOVA), p=0.64]. Corresponding values of CPM were 59.2 ± 4.2; 58.4 ± 2.4, and 65.6 ± 5.8; the AIT captured larger particles more efficiently than the Ph.Eur./USP induction port, so that less large particle mass was apparent in the upper stages of the ACI-AIT (p ≤ 0.037). Equivalent values of FPM were similar regardless of inlet/abbreviation at 41.3 ± 4.2; 38.7 ± 3.0, and 35.9 ± 3.8 (p=0.054), and EPM measures (1.7 ± 0.3; 2.0 ± 0.5; 2.1 ± 0.3) were also comparable (p=0.32).

CONCLUSIONS

The AIT inlet significantly increased the capture of the coarse fraction compared with that collected by the Ph.Eur./USP induction port. Measures obtained using the AIM-pHRT apparatus were comparable with those obtained with the ACI-AIT.

Passive lung-targeted drug delivery systems via intravenous administration

The treatment of lung diseases including lung cancer and tuberculosis is one of the most challenging problems in clinical practice, because the conventional drug delivery systems cannot deliver drug effectively to the lung, which result in low therapeutic effect. Therefore, lung-targeted drug delivery systems (LTDDS) that can deliver drug to the lung in an effective way to increase drug concentration in lung tissue and reduce drug distribution in other organs and tissues become an ideal strategy to treat lung diseases. The LTDDS mainly include microparticles (microspheres and microencapsules), liposomes and nanoparticles via intravenous administration, and dry powder carriers and nebulized suspensions via pulmonary inhalation. As lungs possess the large absorptive surface area, the low thickness of the epithelial barrier and good blood supply, pulmonary inhalation has received great attention. Intravenous route is the commonly practiced method for administration of larger doses of drugs into the body. Numerous drugs can be delivered directly into general circulation by avoiding their first-pass metabolism and have potential to transport drugs to the lung via intravenous administration. This present article reviews the development, evaluation and application of LTDDS via intravenous administration for the treatment of lung diseases reported in the past decades.

Long-term effects of inhaled treprostinil in patients with pulmonary arterial hypertension: the Treprostinil Sodium Inhalation Used in the Management of Pulmonary Arterial Hypertension (TRIUMPH) study open-label extension

BACKGROUND

Inhaled treprostinil improved functional capacity as add-on therapy in the short-term management of patients with pulmonary arterial hypertension (PAH). This study investigated the long-term effects of inhaled treprostinil in patients concurrently receiving oral background therapy.

METHODS

A total of 206 patients (81% women) completing the 12-week double-blind phase of the Treprostinil Sodium Inhalation Used in the Management of Pulmonary Arterial Hypertension (TRIUMPH) study transitioned into an open-label extension. Patients were assessed every 3 months for changes in 6-minute walk distance (6MWD), Borg dyspnea score, New York Heart Association (NYHA) functional class, quality of life (QOL) scores, and signs and symptoms of PAH.

RESULTS

Patients were primarily NYHA class III (86%), with a mean baseline 6MWD of 349 ± 81 meters. A median change in 6MWD of 28, 31, 32, and 18 meters in patients continuing therapy was observed at 6, 12, 18, and 24 months, respectively. This effect was more prominent in those patients originally allocated to active therapy in the double-blind phase. Survival rates for patients remaining on therapy were 97%, 94%, and 91% at 12, 18, and 24 months, respectively. In addition, 82%, 74%, and 69% of patients maintained treatment benefit as evidenced by lack of clinical worsening at 12, 18, and 24 months. The most common adverse events were known effects of prostanoid therapy (headache [34%], nausea [21%], and vomiting [10%]) or were due to the route of administration (cough [53%], pharyngolaryngeal pain [13%], and chest pain [13%]).

CONCLUSIONS

Long-term therapy with inhaled treprostinil demonstrated persistent benefit for PAH patients who remained on therapy for up to 24 months.

Pulmonary drug delivery strategies: A concise, systematic review

Because of limitations associated with the conventional treatment of various chronic diseases a growing attention has been given to the development of targeted drug delivery systems. Pulmonary route of drug delivery gaining much importance in the present day research field as it enables to target the drug delivery directly to lung both for local and systemic treatment. Over the last 2 decades, the systemic absorption of a broad range of therapeutics after pulmonary application has been demonstrated in animals as well as in humans. This review was prepared with an aim to discuss the technical, physiological, and efficacy aspects of the novel pulmonary route of drug targeting. The review also focuses on the mechanisms of pulmonary drug administration along with compatibility of the excipients employed, devices used, and techniques of particulate dosage production. This review was prepared based on the method of extensive literature survey on the topics covering all the aspects discussed in the present subject. Hence, the better understanding of complexes and challenges facing the development of pulmonary drug delivery system offer an opportunity to the pharmaceutical scientist in minimizing the clinical and technical gaps.

Controlled pulmonary drug and gene delivery using polymeric nano-carriers

Pulmonary drug and gene delivery to the lung represents a non-invasive avenue for local and systemic therapies. However, the respiratory tract provides substantial barriers that need to be overcome for successful pulmonary application. In this regard, micro- and nano-sized particles offer novel concepts for the development of optimized therapeutic tools in pulmonary research. Polymeric nano-carriers are generally preferred as controlled pulmonary delivery systems due to prolonged retention in the lung. Specific manipulation of nano-carrier characteristics enables the design of "intelligent" carriers specific for modulation of the duration and intensity of pharmacological effects. New formulations should be tested for pulmonary absorption and distribution using more advanced ex vivo and in vivo models. The delivery of nano-carriers to the air-space enables a detailed characterization of the interaction between the carrier vehicle and the natural pulmonary environment. In summary, polymeric nanoparticles seem to be especially promising as controlled delivery systems and represent a solid basis for future advancement for pulmonary delivery applications.

Pulmonary delivery of therapeutic compounds for treating CNS disorders

Delivering therapeutic compounds via the lungs presents potential advantages relative to other routes of administration. Depending on the compound and the disease state, these advantages may include: non-invasive medication delivery, ease of administration, higher bioavailability leading to dose sparing and lower systemic toxicity, potentially greater blood–brain barrier penetration and rapid pharmacodynamic effect. The practice of inhaling drugs has been around for centuries, including both medical and recreational usage. It is only more recently that formal clinical development programs have been undertaken specifically to use medication delivery via the lung to achieve systemic blood levels for the treatment of CNS disorders. At present, there are several CNS therapies being developed for pulmonary administration, with some of those programs at or near the marketing authorization stage. While there are still regulatory hurdles before these therapies can be put into practice, the success of these programs thus far demonstrates the scientific viability of inhalation therapies for treating CNS disorders.

Prostacyclins in pulmonary arterial hypertension: the need for earlier therapy

Pulmonary arterial hypertension (PAH) is a rare but serious condition, which if untreated, is associated with a 2-3-year median survival time. A number of treatment options are available for PAH, leading to improvements in exercise capacity, symptoms, and hemodynamics. However, the disease remains incurable and most patients will ultimately progress to right heart failure and death. Three classes of drugs are currently available to improve PAH outcomes, although this review will focus solely on a class of potent vasodilators known as prostacyclins. Currently, four prostacyclin analogs are licensed for the treatment of PAH: epoprostenol, treprostinil, and iloprost in the USA and some European countries, and beraprost in Japan and Korea. Prostacyclins have become the treatment of choice in patients with severe PAH, but there is also evidence to suggest that their earlier use may also benefit patients with mild-to-moderate disease. This review discusses the advantages of prostacyclins in terms of their usefulness in patients whose condition has deteriorated following monotherapy with other agents, and their integral role in combination therapy. The latter appears to offer the potential for pulmonary vasculature remodeling and could be regarded as an emerging paradigm to treat and prevent the progression of PAH.

Product lifecycle approach to cascade impaction measurements

Over the lifecycle of an orally inhaled product (OIP), multi-stage cascade impactor (CI) measurements are used for different purposes and to address different questions. Full-resolution CIs can provide important information during product development and are widely used but are time- and resource-intensive, highly variable, and suboptimal for OIP quality control (QC) testing. By contrast, Efficient Data Analysis (EDA) combined with Abbreviated Impactor Measurement (AIM) systems pertinent either for QC and-possibly-for adult Human Respiratory Tract (pHRT) has been introduced for OIP performance assessment during and post-development. This article summarizes available evidence and discusses a strategy for using either abbreviated or full-resolution CI systems depending on the purpose of the measurement, such that adequate, accurate, and efficient testing of aerodynamic particle size distribution (APSD) of OIPs can be achieved throughout the lifecycle of a product. Under these proposals, a comprehensive testing program should initially be conducted by full-resolution CI in OIP development to ascertain the product's APSD. Subsequently, correlations should be established from the selected AIM CIs to the corresponding full-resolution system, ideally developing specifications common to both techniques. In the commercial phase, it should be possible to release product using AIM/EDA, keeping the full-resolution CI for investigations, change control, and trouble-shooting, thus optimizing resources for APSD characterization throughout the product lifecycle. If an in vitro-in vivo relationship is established and clinically relevant sizes are known, an AIM-pHRT could serve as a quick indicator that clinically relevant fractions have not changed and also, in the management of post-approval changes.

The potential for inhaled treprostinil in the treatment of pulmonary arterial hypertension

Inhaled treprostinil is a safe and well-tolerated approved pharmaceutical for the treatment of pulmonary arterial hypertension. In a series of open-label studies and in the pivotal trial with 253 patients, this long-acting prostacyclin analogue demonstrated pronounced pulmonary selectivity of vasodilatory effects, improved physical capacity and excellent tolerability and safety following aerosol administration. For efficient treatment, only four daily inhalations of treprostinil are necessary compared with six to nine in iloprost aerosol therapy. This review describes in detail the development of inhaled treprostinil, starting with intravenous epoprostenol followed by inhaled iloprost and subcutaneous treprostinil, all three representing well-established and widely approved prostanoid therapies for pulmonary hypertension.

In order to circumvent the drawbacks of intravenous epoprostenol, stable prostacyclin analogues with similar pharmacological properties have been investigated. In addition, alternative routes of administration have been proposed and evaluated, mainly inhaled and subcutaneous delivery. The concept of inhaled treprostinil was to combine the pulmonary selectivity of an aerosolized vasodilator with the long-acting effects of a stable prostacyclin analogue.

Pulmonary arterial hypertension remains, however, a severe, life-threatening disease, in spite of the enormous progress in specific drug therapy over the last decade. Therefore, further improvement of drug therapy will be essential, with clear potential for inhaled treprostinil: a reduction of inhalation frequency and duration would markedly improve quality of life and compliance, and a longer-lasting local prostanoid effect might further enhance the efficacy of inhaled treprostinil. The advantageous pharmacological properties of treprostinil offer the opportunity to establish a convenient metered dose inhaler as a delivery system, to combine inhaled treprostinil with available or future drugs for pulmonary arterial hypertension, or to develop sustained release formulations of treprostinil suitable for inhalation based on liposomes or biodegradable nanoparticles.

Inhalation of an ethanol-based zileuton formulation provides a reduction of pulmonary adenomas in the A/J mouse model

Potential efficacy of zileuton, a 5-LOX inhibitor, was evaluated for the reduction of pulmonary adenomas in the A/J murine model when administered via nose-only inhalation. Development of pulmonary adenomas was induced with benzo(a)pyrene. Animals were treated with a zileuton solution (5 mg/mL in 85:15 ethanol/water) either twice weekly or five times a week via nose-only inhalation; The placebo solution (85:15 EtOH/H2O, no active) was also evaluated. Dose delivered was calculated to be 1.2 mg/kg per exposure for each zileuton group. After 20 weeks of treatment, surface tumors were enumerated and histologically assessed. A significant reduction in tumor count was noted for both the twice weekly administration (40%) and the five times a week administration (59%). The data also showed a significant reduction for the group, which received the placebo (approximately 58%). The treatment groups were also found to have an impact on the histological stages of adenoma development.

Potential health impact of ultrafine particles under clean and polluted urban atmospheric conditions: a model-based study

The main goal of this study was to improve the knowledge of ultrafine particle number distributions in large urban areas and also to call the attention to the importance of these particles on assessing health risks. Measurements of aerosol size distributions were performed during 2 weeks, with distinct pollutant concentrations (polluted and clean periods), on the rooftop of a building located in downtown of the megacity of São Paulo, Brazil. CO, NO(2), PM(10), SO(2), and O(3) concentrations and meteorological variables were also used. Aerosol size distribution measurements showed that geometric mean diameters of the size spectra in the polluted period are on average considerably larger than those in the clean one. Besides the fact that total number of ultrafine particles did not show significant differences, during the polluted period, geometric mean diameter was larger than during the clean one. The results of a mathematical model of particle deposition on human respiratory tract indicated a more significant effect of smaller particles fraction of the spectra, which predominate under clean atmospheric conditions. The results also indicated that urban environmental conditions usually considered good for air quality, under the criteria of low mass concentration, do not properly serve as air quality standard to very small particles. In the size range of ultrafine particles, this traditional clean atmospheric condition can offer a strong risk to pulmonary hazards, since the cleansing of the atmosphere creates good conditions to increase the concentration of nucleation mode particles.