A review of prostaglandin analogs in the management of patients with pulmonary arterial hypertension

Successful Weaning From Veno-Venous Extracorporeal Membrane Oxygenation (VV-ECMO) After Initiation of Inhaled Epoprostenol in a Neonate With Refractory Persistent Pulmonary Hypertension of the Newborn (PPHN)

Despite improvements in the medical management of persistent pulmonary hypertension of the newborn (PPHN), a significant number of patients persist with inadequate gas exchange and are treated with extracorporeal membrane oxygenation (ECMO). Prolonged time to weaning ECMO can increase mortality risk. Therefore, multiple therapies are utilized for pulmonary hypertension treatment, including pharmacotherapy with pulmonary vasodilators, to improve the prognosis of these critical patients. We report a case of a 37 2/7-week neonate with severe PPHN refractory to triple pulmonary vasodilator therapy (inhaled nitric oxide (iNO), sildenafil, and milrinone) and required veno-venous (VV)-ECMO support to improve oxygenation. Our patient was successfully weaned from ECMO after the addition of inhaled epoprostenol (iEPO) therapy. This report indicates that inhaled prostacyclin therapy effectively helps refractory PPHN patients off extracorporeal life support (ECLS) and should be considered a valuable treatment.

Pharmacotherapy for Pulmonary Hypertension in Infants with Bronchopulmonary Dysplasia: Past, Present, and Future

Approximately 8-42% of premature infants with chronic lung disease of prematurity, bronchopulmonary dysplasia (BPD), develop pulmonary hypertension (PH). Infants with BPD-PH carry alarmingly high mortality rates of up to 47%. Effective PH-targeted pharmacotherapies are desperately needed for these infants. Although many PH-targeted pharmacotherapies are commonly used to treat BPD-PH, all current use is off-label. Moreover, all current recommendations for the use of any PH-targeted therapy in infants with BPD-PH are based on expert opinion and consensus statements. Randomized Control Trials (RCTs) are needed to determine the efficacy of PH-targeted treatments in premature infants with or at risk of BPD-PH. Prior to performing efficacy RCTs, studies need to be conducted to obtain pharmacokinetic, pharmacodynamic, and safety data for any pharmacotherapy used in this understudied and fragile patient population. This review will discuss current and needed treatment strategies, identify knowledge deficits, and delineate both challenges to be overcome and approaches to be taken to develop effective PH-targeted pharmacotherapies that will improve outcomes for premature infants with or at risk of developing BPD-PH.

Use of Aerosolized Prostacyclins in Critically Ill Patients and Association With Clinical Outcomes

Aerosolized prostacyclins are frequently used in patients with severe acute respiratory distress syndrome and refractory hypoxia. Previous studies have shown improvement in oxygenation with use of pulmonary vasodilators such as iloprost and epoprostenol; however, there is no head-to-head comparison between these agents.

OBJECTIVES

To compare the effects of inhaled epoprostenol and inhaled iloprost in critically ill patients with refractory hypoxia.

DESIGN SETTING AND PARTICIPANTS

We performed a retrospective cohort analysis of patients admitted to the ICUs at the University of Oklahoma Health Sciences Center between 2015 and 2018. Adult patients who received aerosolized epoprostenol or iloprost for more than 4 hours were included in the analysis.

MAIN OUTCOMES AND MEASURES

The primary endpoint measured was to compare the change in Pao₂/Fio₂ ratio between patients treated with iloprost compared with epoprostenol. Secondary outcomes measured were 90-day in-hospital mortality and improvement in vasopressor requirements.

RESULTS

A total of 126 patients were included in the study, 95 of whom received iloprost (75%) and 31 patients (25%) received epoprostenol. There were significant improvements in Pao₂/Fio₂ ratio in both the iloprost and epoprostenol group. Patients in the epoprostenol group appeared to have a higher 90-day mortality compared with the iloprost group. However, our study was not powered to detect a mortality difference and this finding likely represents a sicker population in the epoprostenol group and prescription bias. The use of iloprost was associated with higher vasopressor requirements in the first 12 hours of administration, an association was not observed in the epoprostenol group.

CONCLUSIONS AND RELEVANCE

In this retrospective cohort analysis, use of both pulmonary vasodilators was associated with similar improvement in gas exchange. The mortality difference observed likely represents difference in severity of illness. Further studies are needed to corroborate these findings.

Targeted metabolomics combined with network pharmacology to reveal the protective role of luteolin in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease that significantly endangers human health, where metabolism may drive pathogenesis: a shift from mitochondrial oxidation to glycolysis occurs in diseased pulmonary vessels and the right ventricle. An increase in pulmonary vascular resistance in patients with heart failure with a preserved ejection fraction portends a poor prognosis. Luteolin exists in numerous foods and is marketed as a dietary supplement assisting in many disease treatments. However, little is known about the protective effect of luteolin on metabolism disorders in diseased pulmonary vessels. In this study, we found that luteolin apparently reversed the pulmonary vascular remodeling of PAH rats by inhibiting the abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs). Moreover, network pharmacology and metabolomics results revealed that the arachidonic acid pathway, amino acid pathway and TCA cycle were dysregulated in PAH. A total of 14 differential metabolites were significantly changed during the PAH, including DHA, PGE2, PGD2, LTB4, 12-HETE, 15-HETE, PGF2α, and 8-iso-PGF2α metabolites in the arachidonic acid pathway, and L-asparagine, oxaloacetate, N-acetyl-L-ornithine, butane diacid, ornithine, glutamic acid metabolites in amino acid and TCA pathways. However, treatment with luteolin recovered the LTB4, PGE2, PGD2, 12-HETE, 15-HETE, PGF2α and 8-iso-PGF2α levels close to normal. Meanwhile, we showed that luteolin also downregulated the gene and protein levels of COX 1, 5-LOX, 12-LOX, and 15-LOX in the arachidonic acid pathway. Collectively, this work highlighted the metabolic mechanism of luteolin-protected PAH and showed that luteolin would hold great potential in PAH prevention.

A Comparison of Inhaled Epoprostenol in Patients With Acute Respiratory Distress Syndrome and COVID-19-Associated Acute Respiratory Distress Syndrome

Introduction

Acute respiratory distress syndrome (ARDS) and coronavirus disease 2019 (COVID-19)-associated acute respiratory distress syndrome (CARDS) are both characterized by non-cardiogenic pulmonary edema and severe hypoxemia that leads to a high percentage of patients suffering in-hospital mortality. Mechanistically, inhaled epoprostenol (iEPO) has shown a role in the treatment of ARDS and CARDS but little data are available directly comparing the two disease processes. Due to the lack of evidence of iEPO in ARDS and CARDS, the authors sought to compare the pulmonary effects of iEPO for mechanically ventilated patients with CARDS against a case match control of those with ARDS.

Methods

A retrospective cohort of all patients receiving iEPO between January 1, 2020, and February 22, 2022, was reviewed. Patients with ARDS were case-matched in a 2:1 allocation ratio of CARDS to ARDS by the number of medical comorbidities and age +/- 5 years. Clinical data collected included patient demographics, laboratory values, ventilator settings, length of hospitalization, and 28-day mortality. Comparisons of the effectiveness of iEPO between ARDS and CARDS were conducted using the chi-squared statistic for categorical variables and the Mann-Whitney statistic for continuous variables.

Results

A total of 72 patients were included in the final analysis, with 24 having ARDS and 48 CARDS. The number of medical comorbidities was no different for patients with ARDS or CARDs (p = 0.18), though the frequency of patients diagnosed with coronary artery disease (p=0.007), congestive heart failure (p=0.003), chronic obstructive pulmonary disease (p=0.004), and pulmonary hypertension (p=0.004) did vary between the two groups. A moderate but non-significant difference in pre-iEPO partial pressure of oxygen (PaO₂)/fraction of inspired oxygen (FiO₂) ratio was noted between the groups (0.74 vs 0.65; p=0.33). Following iEPO treatment, patients with ARDS showed a greater PaO₂/FiO₂ ratio than those with CARDS (0.87 vs 0.70; p=0.02). CARDS patients who received iEPO had a longer length of stay as compared to those with ARDS (17.5 vs 12.5 days; p=0.01). However, no difference was noted in 28-day mortality between the two groups (14 vs 34; p=0.29).

Conclusion

In this small sample from a single community hospital, a statistically significant improvement in the PaO₂/FiO₂ ratio was noted for both those with ARDS and CARDS. However, those with CARDS who were given iEPO had a longer length of stay without a significant difference in mortality as compared to those with traditional ARDS.

Genome-wide Meta-analysis Reveals New Gene Signatures and Potential Drug Targets of Hypertension

The prevalence of hypertension reported around the world is increasing and is an important public health challenge. This study was designed to explore the disease's genetic variations and to identify new hypertension-related genes and target proteins. We analyzed 22 publicly available Affymetrix cDNA datasets of hypertension using an integrated system-level framework involving differential expression genetic (DEG) analysis, data mining, gene enrichment, protein-protein interaction, microRNA analysis, toxicogenomics, gene regulation, molecular docking, and simulation studies. We found potential DEGs after screening out the extracellular proteins. We studied the functional role of seven shortlisted DEGs (ADM, EDN1, ANGPTL4, NFIL3, MSR1, CEBPD, and USP8) in hypertension after disease gene curation analysis. The expression profiling and cluster analysis showed significant variations and enriched GO terms. hsa-miR-365a-3p, hsa-miR-2052, hsa-miR-3065-3p, hsa-miR-603, hsa-miR-7113-3p, hsa-miR-3923, and hsa-miR-524-5p were identified as hypertension-associated miRNA targets for each gene using computational algorithms. We found functional interactions of source DEGs with target and important gene signatures including EGFR, AGT, AVP, APOE, RHOA, SRC, APOB, STAT3, UBC, LPL, APOA1, and AKT1 associated with the disease. These DEGs are mainly involved in fatty acid metabolism, myometrial pathways, MAPK, and G-alpha signaling pathways linked with hypertension pathogenesis. We predicted significantly disordered regions of 71.2, 48.8, and 45.4% representing the mutation in the sequence of NFIL3, USP8, and ADM, respectively. Regulation of gene expression was performed to find upregulated genes. Molecular docking analysis was used to evaluate Food and Drug Administration-approved medicines against the four DEGs that were overexpressed. For each elevated target protein, the three best drug candidates were chosen. Furthermore, molecular dynamics (MD) simulation using the target's active sites for 100 ns was used to validate these 12 complexes after docking. This investigation establishes the worth of systems genetics for finding four possible genes as potential drug targets for hypertension. These network-based approaches are significant for finding genetic variant data, which will advance the understanding of how to hasten the identification of drug targets and improve the understanding regarding the treatment of hypertension.

The impact of nebulized epoprostenol and iloprost on hemoglobin oxygen affinity: an ex vivo experiment

Inhalational prostacyclins act as strong vasodilators, potentially improving oxygenation by reducing shunt fraction and ventilation-perfusion mismatch. As prostacyclin receptors are known to be present on human erythrocytes, possible direct effects on hemoglobin oxygen transport were further explored by examining the sole in vitro influence of prostacyclins on hemoglobin oxygen (Hb-O2) affinity. Venous blood samples from 20 healthy volunteers were exposed in vitro to supramaximal doses of epoprostenol, iloprost, and compared with control. By high-throughput measurements, hemoglobin oxygen dissociation curves (ODCs) were derived. Hb-O2 affinity, expressed by P50 and Hill coefficient, was determined and analyzed for three subgroups: males (n = 10), females not taking oral contraceptives (n = 4), and females taking oral contraceptives (n = 6). Epoprostenol significantly decreased P50 in all (males, females without contraceptives, and females taking oral contraceptives) [27.5 (26.4-28.6) mmHg (control) vs. 24.2 (22.7-25.3) mmHg; P < 0.001. median (interquartile range, IQR)] thereby increasing Hb-O2 affinity. Inversely, iloprost only showed significant effects in females taking oral contraceptives where P50 was markedly increased and therefore Hb-O2 affinity decreased [28.4 (27.9-28.9) mmHg (control) vs. 34.4 (32.2-36.0) mmHg; P < 0.001]. Prostacyclin-receptor stimulation and subsequent cAMP-mediated ATP release from erythrocytes are discussed as a possible underlying mechanism for the effect of epoprostenol on Hb-O2 affinity. The reason for the sex hormone-modified iloprost effect remains unclear. Being aware of potentially differing effects on Hb-O2 affinity might help select the right prostacyclin (epoprostenol vs. iloprost) depending on the patient and the underlying disease (e.g., acute respiratory distress syndrome vs. peripheral arterial disease).

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.

Survival and drug persistence in patients receiving inhaled treprostinil at doses greater than 54 µg (nine breaths) four times daily

Treprostinil is a prostacyclin approved for the treatment of pulmonary arterial hypertension. Commercial data sets indicate that approximately 20-25% of patients are prescribed a higher dose than the maximum recommended dosage of nine breaths per treatment session (bps) (54 μg), four times a day (QID) and numerous studies have demonstrated the safety of doses >9 bps QID. This phase 4, retrospective analysis of specialty pharmacy records assessed the effects of inhaled treprostinil at doses >9 bps QID. Patients receiving inhaled treprostinil between September 2009 and June 2018 were included, and a random sampling of 5000 patients was selected for further analysis. Subjects were grouped based on the highest dose reached for ≥2 months within a rolling six-month window and were followed for up to three years. Of the total of 5000 patients analyzed, 28.5% received >9 bps QID. Survival rates were significantly higher in the >9 bps QID dosing group for years one, two, and three (P < 0.001). The time to transition to parenteral therapy was significantly longer for those at doses >9 bps (17.5 months) compared to doses ≤9 bps (9.5 moths; P < 0.0001). Drug persistence was also significantly higher for those taking >9 bps at years 1, 2, and 3 (P < 0.0001). Patients receiving inhaled treprostinil at doses >9 bps QID had a higher rate of survival and drug persistence over a three-year period, suggesting that higher doses may provide clinically relevant benefits while remaining tolerable.

Endothelial cells in the pathogenesis of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a devastating disease that involves pulmonary vasoconstriction, small vessel obliteration, large vessel thickening and obstruction, and development of plexiform lesions. PAH vasculopathy leads to progressive increases in pulmonary vascular resistance, right heart failure and, ultimately, premature death. Besides other cell types that are known to be involved in PAH pathogenesis (e.g. smooth muscle cells, fibroblasts and leukocytes), recent studies have demonstrated that endothelial cells (ECs) have a crucial role in the initiation and progression of PAH. The EC-specific role in PAH is multi-faceted and affects numerous pathophysiological processes, including vasoconstriction, inflammation, coagulation, metabolism and oxidative/nitrative stress, as well as cell viability, growth and differentiation. In this review, we describe how EC dysfunction and cell signalling regulate the pathogenesis of PAH. We also highlight areas of research that warrant attention in future studies, and discuss potential molecular signalling pathways in ECs that could be targeted therapeutically in the prevention and treatment of PAH.

Eicosanoid receptors as therapeutic targets for asthma

Eicosanoids comprise a group of oxidation products of arachidonic and 5,8,11,14,17-eicosapentaenoic acids formed by oxygenases and downstream enzymes. The two major pathways for eicosanoid formation are initiated by the actions of 5-lipoxygenase (5-LO), leading to leukotrienes (LTs) and 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE), and cyclooxygenase (COX), leading to prostaglandins (PGs) and thromboxane (TX). A third group (specialized pro-resolving mediators; SPMs), including lipoxin A4 (LXA4) and resolvins (Rvs), are formed by the combined actions of different oxygenases. The actions of the above eicosanoids are mediated by approximately 20 G protein-coupled receptors, resulting in a variety of both detrimental and beneficial effects on airway smooth muscle and inflammatory cells that are strongly implicated in asthma pathophysiology. Drugs targeting proinflammatory eicosanoid receptors, including CysLT1, the receptor for LTD4 (montelukast) and TP, the receptor for TXA2 (seratrodast) are currently in use, whereas antagonists of a number of other receptors, including DP2 (PGD2), BLT1 (LTB4), and OXE (5-oxo-ETE) are under investigation. Agonists targeting anti-inflammatory/pro-resolving eicosanoid receptors such as EP2/4 (PGE2), IP (PGI2), ALX/FPR2 (LXA4), and Chemerin1 (RvE1/2) are also being examined. This review summarizes the contributions of eicosanoid receptors to the pathophysiology of asthma and the potential therapeutic benefits of drugs that target these receptors. Because of the multifactorial nature of asthma and the diverse pathways affected by eicosanoid receptors, it will be important to identify subgroups of asthmatics that are likely to respond to any given therapy.

Intravenous Delivery of Lung-Targeted Nanofibers for Pulmonary Hypertension in Mice

Pulmonary hypertension is a highly morbid disease with no cure. Available treatments are limited by systemic adverse effects due to non-specific biodistribution. Self-assembled peptide amphiphile (PA) nanofibers are biocompatible nanomaterials that can be modified to recognize specific biological markers to provide targeted drug delivery and reduce off-target toxicity. Here, PA nanofibers that target the angiotensin I-converting enzyme and the receptor for advanced glycation end-products (RAGE) are developed, as both proteins are overexpressed in the lung with pulmonary hypertension. It is demonstrated that intravenous delivery of RAGE-targeted nanofibers containing the targeting epitope LVFFAED (LVFF) significantly accumulated within the lung in a chronic hypoxia-induced pulmonary hypertension mouse model. Using 3D light sheet fluorescence microscopy, it is shown that LVFF nanofiber localization is specific to the diseased pulmonary tissue with immunofluorescence analysis demonstrating colocalization of the targeted nanofiber to RAGE in the hypoxic lung. Furthermore, biodistribution studies show that significantly more LVFF nanofibers localized to the lung compared to major off-target organs. Targeted nanofibers are retained within the pulmonary tissue for 24 h after injection. Collectively, these data demonstrate the potential of a RAGE-targeted nanomaterial as a drug delivery platform to treat pulmonary hypertension.

Nanoscale Drug Delivery Systems for Glaucoma: Experimental and In Silico Advances

In this review, nanoscale-based drug delivery systems, particularly in relevance to the antiglaucoma drugs, have been discussed. In addition to that, the latest computational/in silico advances in this field are examined in brief. Using nanoscale materials for drug delivery is an ideal option to target tumours, and the drug can be released in areas of the body where traditional drugs may fail to act. Nanoparticles, polymeric nanomaterials, single-wall carbon nanotubes (SWCNTs), quantum dots (QDs), liposomes and graphene are the most important nanomaterials used for drug delivery. Ocular drug delivery is one of the most common and difficult tasks faced by pharmaceutical scientists because of many challenges like circumventing the blood-retinal barrier, corneal epithelium and the blood-aqueous barrier. Authors found compelling empirical evidence of scientists relying on in-silico approaches to develop novel drugs and drug delivery systems for treating glaucoma. This review in nanoscale drug delivery systems will help us understand the existing queries and evidence gaps and will pave the way for the effective design of novel ocular drug delivery systems.

The Efficacy and Safety of Pulmonary Vasodilators in Pediatric Pulmonary Hypertension (PH): A Systematic Review and Meta-analysis

Background: We performed a meta-analysis to evaluate the efficacy and safety of pulmonary vasodilators in pediatric pulmonary hypertension (PH) patients. Methods: We searched electronic databases including PubMed, EMBASE, and the Cochrane Library up to May 2020, and conducted a subgroup analysis for pulmonary vasodilators or underlying disease. Results: Fifteen studies with 719 pediatric PH patients were included in the meta-analysis. Adverse events did not differ (p = 0.11, I ² = 15%) between the pulmonary vasodilators group and the control group, neither in the subgroups. In total, compared with the control group treatment, pulmonary vasodilators significantly decreased the mortality (p = 0.002), mean pulmonary artery pressure (mPAP, p = 0.02), and mechanical ventilation duration (p = 0.03), also improved the oxygenation index (OI, p = 0.01). In the persistent pulmonary hypertension of the newborn (PPHN) subgroup, phosphodiesterase type 5 inhibitors (PDE5i) significantly reduced mortality (p = 0.03), OI (p = 0.007) and mechanical ventilation duration (p = 0.004). Administration of endothelin receptor antagonists (ERAs) improved OI (p = 0.04) and mechanical ventilation duration (p < 0.00001) in PPHN. We also found that in the pediatric pulmonary arterial hypertension (PPAH) subgroup, mPAP was pronouncedly declined with ERAs (p = 0.006). Systolic pulmonary artery pressure (sPAP, p < 0.0001) and pulmonary arterial/aortic pressure (PA/AO, p < 0.00001) were significantly relieved with PDE5i, partial pressure of arterial oxygen (PaO₂) was improved with prostacyclin in postoperative PH (POPH) subgroup (p = 0.001). Compared with the control group, pulmonary vasodilators could significantly decrease PA/AO pressure (p < 0.00001) and OI (p < 0.00001) in the short-term (duration <7 days) follow-up subgroup, improve mPAP (p = 0.03) and PaO₂ (p = 0.01) in the mid-term (7-30 days) follow-up subgroup, also decrease mortality, mPAP (p = 0.0001), PA/AO pressure (p = 0.0007), duration of mechanical ventilation (p = 0.004), and ICU stay (p < 0.00001) in the long-term follow subgroup (>30 days). Conclusion: Pulmonary vasodilators decrease the mortality in pediatric PH patients, improve the respiratory and hemodynamic parameters, reduce the mechanical ventilation duration.

Combination Therapy in Pulmonary Arterial Hypertension-Targeting the Nitric Oxide and Prostacyclin Pathways

Pulmonary arterial hypertension (PAH) is a chronic and progressive disorder characterized by vascular remodeling of the small pulmonary arteries, resulting in elevated pulmonary vascular resistance and ultimately, right ventricular failure. Expanded understanding of PAH pathophysiology as it pertains to the nitric oxide (NO), prostacyclin (prostaglandin I₂) (PGI₂) and endothelin-1 pathways has led to recent advancements in targeted drug development and substantial improvements in morbidity and mortality. There are currently several classes of drugs available to target these pathways including phosphodiesterase-5 inhibitors (PDE5i), soluble guanylate cyclase (sGC) stimulators, prostacyclin class agents and endothelin receptor antagonists (ERAs). Combination therapy in PAH, either upfront or sequentially, has become a widely adopted treatment strategy, allowing for simultaneous targeting of more than one of these signaling pathways implicated in disease progression. Much of the current treatment landscape has focused on initial combination therapy with ambrisentan and tadalafil, an ERA and PDE5I respectively, following results of the AMBITION study demonstrating combination to be superior to either agent alone as upfront therapy. Consequently, clinicians often consider combination therapy with other drugs and drug classes, as deemed clinically appropriate, for patients with PAH. An alternative regimen that targets the NO and PGI₂ pathways has been adopted by some clinicians as an effective and sometimes preferred therapeutic combination for PAH. Although there is a paucity of prospective data, preclinical data and results from secondary data analysis of clinical studies targeting these pathways may provide novel insights into this alternative combination as a reasonable, and sometimes preferred, alternative approach to combination therapy in PAH. This review of preclinical and clinical data will discuss the current understanding of combination therapy that simultaneously targets the NO and PGI₂ signaling pathways, highlighting the clinical advantages and theoretical biochemical interplay of these agents.

Potassium (K+) channels in the pulmonary vasculature: Implications in pulmonary hypertension Physiological, pathophysiological and pharmacological regulation

The large K⁺ channel functional diversity in the pulmonary vasculature results from the multitude of genes expressed encoding K⁺ channels, alternative RNA splicing, the post-transcriptional modifications, the presence of homomeric or heteromeric assemblies of the pore-forming α-subunits and the existence of accessory β-subunits modulating the functional properties of the channel. K⁺ channels can also be regulated at multiple levels by different factors controlling channel activity, trafficking, recycling and degradation. The activity of these channels is the primary determinant of membrane potential (Em) in pulmonary artery smooth muscle cells (PASMC), providing an essential regulatory mechanism to dilate or contract pulmonary arteries (PA). K⁺ channels are also expressed in pulmonary artery endothelial cells (PAEC) where they control resting Em, Ca²⁺ entry and the production of different vasoactive factors. The activity of K⁺ channels is also important in regulating the population and phenotype of PASMC in the pulmonary vasculature, since they are involved in cell apoptosis, survival and proliferation. Notably, K⁺ channels play a major role in the development of pulmonary hypertension (PH). Impaired K⁺ channel activity in PH results from: 1) loss of function mutations, 2) downregulation of its expression, which involves transcription factors and microRNAs, or 3) decreased channel current as a result of increased vasoactive factors (e.g., hypoxia, 5-HT, endothelin-1 or thromboxane), exposure to drugs with channel-blocking properties, or by a reduction in factors that positively regulate K⁺ channel activity (e.g., NO and prostacyclin). Restoring K⁺ channel expression, its intracellular trafficking and the channel activity is an attractive therapeutic strategy in PH.

Phosphodiesterase inhibitors and prostaglandin analogues in dermatology: A comprehensive review

Due to immune-mediated nature, medicines with immunomodulatory and anti-inflammatory effects can used to treat many dermatologic diseases. Phosphodiesterase and prostaglandins are involved in many inflammatory pathways that cause cutaneous disorders. Phosphodiesterase inhibitors (PDEIs) and prostaglandin analogues are currently employed to treat several dermatologic disorders. Given the few comprehensive reviews in this context, focusing on the dermatologic applications and efficacy of these medicines appears valuable. The present comprehensive review was, therefore, performed on the applications of PDEIs and prostaglandin analogues in different cutaneous disorders. All the relevant articles were selected to perform this review by searching databases such as Medline, Google Scholar, Scopus, and Web of Science. Oral PDEIs, especially apremilast, is an effective medicine in psoriasis and a number of other cutaneous disorders such as vitiligo. Topical PDEIs, including crisaborole ointment 2%, is a safe and effective treatment in atopic dermatitis. Prostaglandin analogues, especially their topical forms such as latanoprost and bimatoprost, have different applications in cutaneous disorders, including pigmentary disorders, especially vitiligo and hair repigmentation; for instance, bimatoprost is used for eyelash repigmentation. Prostaglandin analogues are also used in alopecia, including androgenetic alopecia and alopecia areata. Oral (apremilast) and topical (crisaborole) PDEIs and topical prostaglandin analogues, including latanoprost and bimatoprost, were found safe and effective in different skin diseases. In terms of efficiency and safety, these medicines compete with other medications of similar use even with higher efficacy and fewer side effects that necessitate further studies.

Pharmacokinetics and tolerability of LIQ861, a novel dry-powder formulation of treprostinil

A dry-powder inhaled formulation of treprostinil (LIQ861) produced using PRINT® technology offers a substantial advantage over current nebulized therapy. Treprostinil is a synthetic prostacyclin analogue that is currently approved for inhalation administration to patients with pulmonary arterial hypertension via nebulized Tyvaso® inhalation solution. LTI-101 was a phase 1, placebo-controlled, double-blind, randomized, single-center study that evaluated the ascending single-dose pharmacokinetics of LIQ861 in healthy subjects. Six sequential, escalating doses (25, 50, 75, 100, 125, and 150 mcg) were studied to investigate treprostinil exposure from LIQ861 inhalation. Subjects (n = 57) were randomly assigned in a 3:1 ratio to receive a single dose of either LIQ861 (n = 43) or placebo (n = 14); 56 subjects completed all protocol-defined assessments. Following single-dose administration, treprostinil exposure from LIQ861 increased proportionally across the dose range studied, and the pharmacokinetics profile of treprostinil administered as LIQ861 was similar to prior reports of inhaled treprostinil. All doses of LIQ861 were generally well-tolerated with no deaths, serious adverse events, or dose-limiting toxicities. The most frequently reported treatment-emergent adverse events related to study drug administration were coughing and throat irritation, which are common to dry-powder formulations. Treatment-related treatment-emergent adverse events were reported more frequently at higher dose levels; however, all were assessed as mild in severity. We conclude that the pharmacokinetics profile of treprostinil using a dry-powder inhaled formulation increased in proportion to dose as anticipated and was similar to earlier reports of inhaled, nebulized treprostinil (Tyvaso®). Based on these results, a phase 3 study (INSPIRE; Clinicaltrials.gov Identifier NCT03399604) evaluating the long-term safety and tolerability of LIQ861 in patients with pulmonary arterial hypertension was initiated.

Use of selexipag in a teenage patient with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic, progressive, multifactorial disease. Currently, combination therapy is an attractive option for PAH management because three pathways (endothelin, nitric oxide, and prostacyclin) are involved in this disease. Selexipag is a novel oral prostacyclin pathway drug and is a highly selective IP prostacyclin receptor agonist with vasodilatory and antiproliferative effects. We report the case of a teenage patient with idiopathic PAH who presented in World Health Organization functional Class IV and showed no clinical improvement with dual therapy. We added oral selexipag to the treatment regimen and observed substantial improvement in her quality of life at the short-time follow-up. Despite the lack of childhood data regarding the use of selexipag in pediatric patients with PAH, the use of this drug in the current teenage patient improved her quality of life and exercise capacity.

The influence of topical non-steroidal anti-inflammatory drugs on the intraocular pressure lowering effect of topical prostaglandin analogues-A systemic review and meta-analysis

PURPOSE

This study aimed to review previous articles and evaluate the influence of topical non-steroidal anti-inflammatory drugs (NSAIDs) on intraocular pressure (IOP) in glaucoma patients who were treated with prostaglandin analogues (PGs).

METHOD

The presenting study was designed as a meta-analysis of previous research. Databases include PubMed, Web of science, Cochrane library, and Embase were searched with keywords of "intraocular pressure, prostaglandin analogues, NSAIDs, latanoprost, travoprost, bimatoprost, tafluprost, unoprostone, latanoprostene bunod, ketorolac, diclofenac, nepafenac, bromfenac, flurbiprofen". Inclusion criteria were: 1. Study population were glaucoma patients; 2. Comparison between PGs monotherapy and PGs in combination with topical NSAIDs; 3. Changes of IOP as final outcomes. Studies with non-randomized design, treatments combining other anti-glaucomatous drugs, or unavailable absolute IOP were excluded from the analysis. Estimated difference in IOP were calculated using STATA 14.0.

RESULT

Seven studies were retrieved for this meta-analysis. Since there is a significant heterogeneity (I2 = 94%) in these studies, random-effect model was used to calculate pooled standardized mean differences (SMD). Our results showed a significantly favorable IOP lowering effect in glaucoma patients treated with combination of topical NSAIDs and PGEs (SMD: 1.3 and -0.03, 95% CI: 0.29 to 2.38 and -0.32 to 0.26, Z = 2.50 and 0.23, p = 0.013 and 0.820, respectively).

CONCLUSION

Results of our meta-analysis suggested that topical NSAIDs may enhance the IOP lowering effect of topical PGs in glaucoma patients.

[Experience with Selexipag to Treat Pulmonary Arterial Hypertension]

Aim To present an own experience in using a medication selexipag in patients with pulmonary arterial hypertension (PAH) included into the V. A. Almazov National Medical Research Center registry and participating in the GRIPHON and GRIPHON OL clinical studies.Material and methods 26 patients with PAH were included into this study since 2010: 20 patients with idiopathic PAH, 4 patients with PAH associated with systemic scleroderma, and 2 patients with corrected congenital heart defects. At the time of randomization, 19 patients had been receiving therapy with phosphodiesterase type 5 inhibitors for at least one month. Among the patients treated with selexipag (n=14), 4 patients reached a high individual maintenance dose (1200-1600 µg b.i.d.), 4 patients reached a medium dose (600-1000 µg b.i.d.), and 6 patients reached a low dose (200-400 µg b.i.d.).Results The selexipag therapy exerted a positive effect on secondary endpoints, specifically, on changes in the functional class of pulmonary hypertension, serum concentration of NT-proBNP, and physical working capacity of patients. Adverse events associated with the selexipag treatment, which resulted in termination of study participation, were observed in one patient.Conclusion To achieve the main goal of drug therapy, low risk of death with selexipag it is critical to observe the titration schedule and to aim at reaching the highest individual maintenance dose.

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.

The prostacyclin analogue treprostinil in the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare but life-threatening disease that progresses rapidly and is currently without a cure. Pharmacological treatments aim to slow down disease progression and to reduce symptoms by targeting the prostacyclin, the endothelin or the nitric oxide pathway. Drugs targeting the prostacyclin pathway have been shown to be favourable for PAH patients by causing vasodilatative, anti-proliferative as well as anti-inflammatory effects, but tend to be underused, partially due to adverse effects and difficulties associated with their intravenous administration. Treprostinil, a stable prostacyclin analogue, was FDA-approved in 2002 to improve exercise capacity in PAH patients and is available in intravenous, subcutaneous, inhaled and oral form. The four different possible ways of administration, a long half-life and its stability at room temperature give treprostinil an advantage over epoprostenol, iloprost and selexipag, the three other FDA-approved drugs targeting the prostacyclin pathway. In clinical trials, treprostinil improved exercise capacity, quality of life (QOL), functional class and clinical status. While the different forms of treprostinil lead to specific complications, its general adverse effects are dizziness, nausea, pain in the jaw and extremities, diarrhoea, flushing and headache. This MiniReview will assess the benefits and drawbacks of treprostinil in the treatment of PAH by examining its specific mechanism of action and pharmacological properties, such as pharmacokinetics, pharmacodynamics, adverse effects and interactions. In addition, we will analyse and discuss results from different clinical trials, comparing treprostinil's four different forms to each other as well as to other drugs targeting the prostacyclin pathway.

Selenium and selenoproteins in prostanoid metabolism and immunity

Selenium (Se) is an essential trace element that functions in the form of the 21st amino acid, selenocysteine (Sec) in a defined set of proteins. Se deficiency is associated with pathological conditions in humans and animals, where incorporation of Sec into selenoproteins is reduced along with their expression and catalytic activity. Supplementation of Se-deficient population with Se has shown health benefits suggesting the importance of Se in physiology. An interesting paradigm to explain, in part, the health benefits of Se stems from the observations that selenoprotein-dependent modulation of inflammation and efficient resolution of inflammation relies on mechanisms involving a group of bioactive lipid mediators, prostanoids, which orchestrate a concerted action toward maintenance and restoration of homeostatic immune responses. Such an effect involves the interaction of various immune cells with these lipid mediators where cellular redox gatekeeper functions of selenoproteins further aid in not only dampening inflammation, but also initiating an effective and active resolution process. Here we have summarized the current literature on the multifaceted roles of Se/selenoproteins in the regulation of these bioactive lipid mediators and their immunomodulatory effects.

Lipids - two sides of the same coin in lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive extracellular matrix deposition in the lung parenchyma leading to the destruction of lung structure, respiratory failure and premature death. Recent studies revealed that the pathogenesis of IPF is associated with alterations in the synthesis and the activity of lipids, lipid regulating proteins and cell membrane lipid transporters and receptors in different lung cells. Furthermore, deregulated lipid metabolism was found to contribute to the profibrotic phenotypes of lung fibroblasts and alveolar epithelial cells. Consequently, several pharmacological agents, targeting lipids, lipid mediators, and lipoprotein receptors, was successfully tested in the animal models of lung fibrosis and entered early phase clinical trials. In this review, we highlight new therapeutic options to counteract disturbed lipid hemostasis in the maladaptive lung remodeling.

Mechanism of Beraprost Effects on Pulmonary Hypertension: Contribution of Cross-Binding to PGE2 Receptor 4 and Modulation of O2 Sensitive Voltage-Gated K+ Channels

Background: The purpose of this study is to elucidate mechanism(s) by which the orally active PGI2 analog, Beraprost (BPS), ameliorates pulmonary hypertension (PH). Prostaglandins are an important treatment for PH. Mechanisms of their action are not fully elucidated in relation to receptor subtype and effects on O2 sensitive Kv channels. Methods: Distal (3rd order and beyond) pulmonary arteries from chronically hypoxic rats and from humans with established PH were studied. Measurements included pulmonary haemodynamics and histology, vascular reactivity, prostanoid receptor expression and activity of the O2 sensitive Kv channels. Results: Prostacyclin receptor (IP), prostaglandin receptor E3 (EP3) and prostaglandin receptor E4 (EP4) are the main pulmonary artery receptor subtypes in both rat and human pulmonary arteries. Circulating levels of PGI2 and PGE2 were reduced in PH. PH was also associated with reduced receptor expression of IP but not of EP4. The effects on IP expression were overcome with BPS. Dilatory responses in PH to BPS were reduced in the presence of EP4 blockade. Expression and activity of oxygen sensitive Kv channels were reduced in pulmonary artery smooth muscle cell from rats with PH and humans with PAH and were also overcome by administration of BPS. Effects of BPS on oxygen sensitive Kv channels were reduced in the presence of EP4 blockade implicating the EP4 receptor, as well as the IP receptor, in mediating BPS effects. Conclusion: Reduced expression of pulmonary IP receptors and reduced activity of O2 sensitive Kv channels are found in PH in both humans and rats. The orally active prostacyclin analogue, BPS, is able to reverse these changes, partly through binding to the EP4 receptor.

Synthetic approaches to isocarbacyclin and analogues as potential neuroprotective agents against ischemic stroke

Isocarbacyclin is a valuable synthetic analogue of prostacyclin with potential neuroprotective effects for the treatment of ischemic stroke. Herein, we describe the synthesis of isocarbacyclin and bicyclic analogues in only 7-10 steps, with the ω-side chain diversified at a late stage. A combination of new reaction design, function-oriented synthesis, and late-stage diversification led to a series of compounds that were tested for their neuroprotective activities. Efforts toward the synthesis of tricyclic analogues of isocarbacyclin, using the same combination of metal-catalyzed reactions, is also described.

Phosphine-catalyzed dearomative (3 + 2) annulation of 2-nitrobenzofurans and nitrobenzothiophenes with allenoates

An efficient Ph₂PMe-catalyzed dearomative (3 + 2) annulation of 2-nitrobenzofurans, 2-nitrobenzothiophenes, and 3-nitrobenzothiophenes with allenoates is reported.

The Role of G Protein-Coupled Receptors in the Right Ventricle in Pulmonary Hypertension

Pressure overload of the right ventricle (RV) in pulmonary arterial hypertension (PAH) leads to RV remodeling and failure, an important determinant of outcome in patients with PAH. Several G protein-coupled receptors (GPCRs) are differentially regulated in the RV myocardium, contributing to the pathogenesis of RV adverse remodeling and dysfunction. Many pharmacological agents that target GPCRs have been demonstrated to result in beneficial effects on left ventricular (LV) failure, such as beta-adrenergic receptor and angiotensin receptor antagonists. However, the role of such drugs on RV remodeling and performance is not known at this time. Moreover, many of these same receptors are also expressed in the pulmonary vasculature, which could result in complex effects in PAH. This manuscript reviews the role of GPCRs in the RV remodeling and dysfunction and discusses activating and blocking GPCR signaling to potentially attenuate remodeling while promoting improvements of RV function in PAH.

Titration of pulmonary arterial hypertension therapeutics: Experience-based recommendations

The availability of new medications has improved exercise capacity, enhanced quality of life, and extended time to clinical worsening in patients with pulmonary arterial hypertension (PAH). For many of these medications, careful individualized dose titration is required to maximize therapeutic effectiveness while minimizing side effects. In addition, specific routes of administration, including intravenous (IV), subcutaneous (SC), and inhaled administration may present additional challenges for patients and healthcare providers. These challenges include the possibility of catheter-related infections (IV), infusion site pain (SC), and adherence to frequent dosing schedules (inhaled). Temporary discontinuations may require re-titration and, in some cases, may even be life threatening. Here, based on our clinical experience, we provide our recommendations for dose titration schemes for PAH medications that require individualized dosing in adult patients, including agents acting on the endothelin-1 pathway (bosentan and ambrisentan), the prostacyclin pathway (epoprostenol, treprostinil, and selexipag), and the nitric oxide pathway (tadalafil and the soluble guanylate cyclase stimulator riociguat). A case study that illustrates the application of best practices for PAH medication dose titration in a real-world setting is presented. Good two-way communication between specialty pharmacies and other healthcare providers promotes optimal medication usage and patient health. Experience has shown that slow, cautious up-titration is generally associated with better long-term outcomes. In all cases, patient education, frequent monitoring and careful management of side effects, and treatment adherence are critical.

Nanotherapeutics for Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a devastating and fatal chronic lung disease. While current pharmacotherapies have improved patient quality of life, PAH drugs suffer from limitations in the form of short-term pharmacokinetics, instability, and poor organ specificity. Traditionally, nanotechnology-based delivery strategies have proven advantageous at increasing both circulation lifetimes of chemotherapeutics and accumulation in tumors due to enhanced permeability through fenestrated vasculature. Importantly, increased nanoparticle (NP) accumulation in diseased tissues has been observed pre-clinically in pathologies characterized by endothelial dysfunction and remodeled vasculature, including myocardial infarction and heart failure. Recently, this phenomenon has also been observed in preclinical models of PAH, leading to the exploration of NP-based drug delivery as a therapeutic modality in PAH. Herein, we discussed the advantages of NPs for efficacious treatment of PAH, including heightened therapeutic delivery to diseased lungs for increased drug bioavailability, as well as highlighted innovative nanotherapeutic approaches for PAH.

EP4 Agonist L-902,688 Suppresses EndMT and Attenuates Right Ventricular Cardiac Fibrosis in Experimental Pulmonary Arterial Hypertension

Right ventricular (RV) hypertrophy is characterized by cardiac fibrosis due to endothelial–mesenchymal transition (EndMT) and increased collagen production in pulmonary arterial hypertension (PAH) patients, but the mechanisms for restoring RV function are unclear. Prostanoid agonists are effective vasodilators for PAH treatment that bind selective prostanoid receptors to modulate vascular dilation. The importance of prostanoid signaling in the RV is not clear. We investigated the effects of the EP4-specific agonist L-902,688 on cardiac fibrosis and TGF-β-induced EndMT. EP4-specific agonist treatment reduced right ventricle fibrosis in the monocrotaline (MCT)-induced PAH rat model. L-902,688 (1 µM) attenuated TGF-β-induced Twist and α-smooth muscle actin (α-SMA) expression, but these effects were reversed by AH23848 (an EP4 antagonist), highlighting the crucial role of EP4 in suppressing TGF-β-induced EndMT. These data indicate that the selective EP4 agonist L-902,688 attenuates RV fibrosis and suggest a potential approach to reducing RV fibrosis in patients with PAH.

Evidence for increase in finger blood flow, evaluated by laser Doppler flowmetry, following iloprost infusion in patients with systemic sclerosis: a week-long observational longitudinal study

OBJECTIVES

Iloprost plays an important role in the treatment of Raynaud's phenomenon (RP), but has transient vasodilatory effects owing to its very short half-time. We aimed to evaluate short- and medium-term haemodynamic effects of iloprost by measuring dorsal finger microvessel blood flow using laser Doppler flowmetry (LDF), in patients with RP associated with systemic sclerosis (SSc).

METHOD

In 24 consecutive SSc patients with RP (disease duration 10.5 ± 1.3 years), LDF with heating probes was used to measure blood flow in four fingers by occlusive and heating tests, at baseline, after 3 consecutive days of iloprost infusion, and at 24 h and 7 days after last iloprost infusion. Nailfold videocapillaroscopy (NVC) patterns of microvascular damage were investigated. Sixteen healthy controls were studied to compare baseline flows.

RESULTS

Compared to controls, SSc patients showed significantly impaired axon reflex vasoregulation and nitric oxide responses at baseline (p = 0.001 and p = 0.03, respectively). After iloprost, a prompt but transient significant improvement in endothelial-dependent vasodilation (occlusive test) was seen only in SSc patients with an 'active' NVC pattern (p ≤ 0.05). The iloprost effects vanished within 7 days after the last infusion. No significant differences were found, in the whole study, between patients with and without digital ulcers.

CONCLUSIONS

Microcirculatory blood flow increases following 3 days of iloprost infusion but fades shortly after treatment. Although iloprost is effective in reducing the severity of RP in SSc, the most suitable regimen and timing to obtain longer lasting vasodilatory benefits remain to be established.

Diastereo- and Enantioselective Dearomative [3 + 2] Cycloaddition Reaction of 2-Nitrobenzofurans with 3-Isothiocyanato Oxindoles

Enantioselective dearomative [3 + 2] cycloaddition reaction of 2-nitrobenzofurans with 3-isothiocyanato oxindoles was developed. The reaction employs a chiral bis(oxazoline)/Zn(OTf)₂ catalyst, allowing a practical, straightforward access to structurally diverse spirooxindoles containing a 2,3-dihydrobenzofuran motif and three contiguous stereocenters with excellent diastereo- and enantioselectivities. The synthetic potentials of the method have been demonstrated by the scale-up experiment and transformations of the products. The preliminary mechanism was investigated with experimental observations, nonlinear effects studies, and MS experiments.

Pulmonary vascular development in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a rare congenital anomaly characterised by a diaphragmatic defect, persistent pulmonary hypertension (PH) and lung hypoplasia. The relative contribution of these three elements can vary considerably in individual patients. Most affected children suffer primarily from the associated PH, for which the therapeutic modalities are limited and frequently not evidence based. The vascular defects associated with PH, which is characterised by increased muscularisation of arterioles and capillaries, start to develop early in gestation. Pulmonary vascular development is integrated with the development of the airway epithelium. Although our knowledge is still incomplete, the processes involved in the growth and expansion of the vasculature are beginning to be unravelled. It is clear that early disturbances of this process lead to major pulmonary growth abnormalities, resulting in serious clinical challenges and in many cases death in the newborn. Here we provide an overview of the current molecular pathways involved in pulmonary vascular development. Moreover, we describe the abnormalities associated with CDH and the potential therapeutic approaches for this severe abnormality.

Elicitation of health state utilities associated with the mode of administration of drugs acting on the prostacyclin pathway in pulmonary arterial hypertension

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a rare, incurable disease associated with decreased life expectancy and a marked impact on quality of life (QoL). There are three classes of drugs available for treatment: endothelin receptor antagonists (ERA), drugs acting on nitric oxide pathway (riociguat and phosphodiesterase type 5 inhibitors [PDE5i]), and drugs acting on prostacyclin pathway. The latter have widely different modes of administration - continuous intravenous infusion, continuous subcutaneous infusion, inhaled, and oral - each associated with variable treatment burden, and implications for health economic assessment. This study aimed to establish utility values associated with different modes of administration of drugs acting on the prostacyclin pathway for use in economic evaluations of PAH treatments.

METHODS

A UK general public sample completed the EQ-5D-5L and valued four health states in time trade-off interviews. The health states drafted from literature and interviews with PAH experts (n=3) contained identical descriptions of PAH and ERA/PDE5i treatment, but differed in description of administration including oral (tablets), inhaled (nebulizer), continuous subcutaneous infusion, and continuous intravenous infusion.

RESULTS

A total of 150 participants (63% female; mean age 37 years) completed interviews. Utilities are presented as values between 0 and 1, with 0 representing the state of being dead and 1 representing being in full health. The mean (SD) utility for oral health state was 0.85 (0.16), while all other health states were significantly lower at 0.74 (0.27) for inhaled (p=0.001), 0.59 (0.31) for subcutaneous (p<0.001) and 0.54 (0.32) for intravenous (p<0.001), indicating that there are disutilities (negative differences) associated with non-oral health states. Disutilities were -0.11 for inhaled, -0.26 for subcutaneous, and -0.31 for intravenous administration.

CONCLUSION

The results demonstrate quantifiable QoL differences between modes of administration of drugs acting on the prostacyclin pathway. QoL burden should be considered for economic evaluation of drugs for PAH treatment.

Enantioselective synthesis of cyclopenta[b]benzofurans via an organocatalytic intramolecular double cyclization

An enantioselective organocatalytic strategy, combining Brønsted base and N-heterocyclic carbene catalysis in a unique manner, is demonstrated for a concise construction of the privileged cyclopenta[b]benzofuran scaffold, present in many bioactive compounds having both academic and commercial interests. The reaction concept relies on an intramolecular one-pot double cyclization involving a cycle-specific enantioselective Michael addition followed by a benzoin condensation of ortho-substituted cinnamaldehydes. Cyclopenta[b]benzofurans were achieved in moderate to good yields, with excellent stereoselectivities. A proof of principle for a diastereodivergent variation is demonstrated through the synthesis of cyclopenta[b]benzofurans containing two contiguous aromatic substituents in a substitution pattern present in commercial and natural compounds. Furthermore, several transformations have been performed, demonstrating the synthetic utility of the products. Finally, insights into the activation mode and stereoindution models are presented for this new synthetic strategy.

Prostanoid EP4 agonist L-902,688 activates PPARγ and attenuates pulmonary arterial hypertension

Prostacyclin agonists that bind the prostacyclin receptor (IP) to stimulate cAMP synthesis are effective vasodilators for the treatment of idiopathic pulmonary arterial hypertension (IPAH), but this signaling may occur through nuclear peroxisome proliferator-activated receptor-γ (PPARγ). There is evidence of scant IP and PPARγ expression but stable prostanoid EP₄ receptor (EP₄) expression in IPAH patients. Both IP and EP₄ functionally couple with stimulatory G protein (G_s), which activates signal transduction. We investigated the effect of an EP₄-specific agonist on pulmonary arterial remodeling and its regulatory mechanisms in pulmonary arterial smooth muscle cells (PASMCs). Immunoblotting evealed IP, EP₄, and PPARγ expression in human pulmonary arterial hypertension (PAH) and monocrotaline (MCT)-induced PAH rat lung tissue. Isolated PASMCs from MCT-induced PAH rats (MCT-PASMCs) were treated with L-902,688, a selective EP₄ agonist, to investigate the anti-vascular remodeling effect. Scant expression of IP and PPARγ but stable expression of EP₄ was observed in IPAH patient lung tissues and MCT-PASMCs. L-902,688 inhibited IP-insufficient MCT-PASMC proliferation and migration by activating PPARγ in a time- and dose-dependent manner, but these effects were reversed by AH-23848 (an EP₄ antagonist) and H-89 [a protein kinase A (PKA) inhibitor], highlighting the crucial role of PPARγ in the activity of this EP₄ agonist. L-902,688 attenuated pulmonary arterial remodeling in hypoxic PAH mice and MCT-induced PAH rats; therefore, we conclude that the selective EP₄ agonist L-902,688 reverses vascular remodeling by activating PPARγ. This study identified a novel EP₄-PKA-PPARγ pathway, and we propose EP₄ as a potential therapeutic target for PAH.

What Is the Role of Oral Prostacyclin Pathway Medications in Pulmonary Arterial Hypertension Management?

PURPOSE OF REVIEW

Prostacyclin pathway medications have been shown to be highly efficacious in the treatment of pulmonary arterial hypertension (PAH) through multiple prospective clinical trials and more than two decades of clinical experience. The strongest support for prostacyclin use in PAH management is with parenteral administration. Numerous risks and limitations of parenteral delivery systems as well as significant patient burdens restrict widespread parenteral use. Highly effective and tolerable oral prostacyclin preparations to manage PAH have long been sought. We review the development of the oral prostacyclin agents beraprost, treprostinil, and selexipag and including current indications and limitations. Research into new approaches to the management of PAH, expanding indications for existing agents, and development of novel agents are also discussed.

RECENT FINDINGS

Two oral prostacyclin pathway medications, oral treprostinil and selexipag, were FDA approved in December 2013 and 2015, respectively. Current guidelines recommend use of selexipag in WHO-FC II and III (class 1, level B recommendation) and oral treprostinil in WHO-FC III (class 2b, level B recommendation). The use of these medications is challenging due to complexity in dosing and their side effect profiles which limit patient tolerability and acceptance. There is a promising role for oral prostacyclin pathway medications in patients with PAH. Future investigations are underway of alternative dose regimens and transitioning from parenteral therapies in order to improve efficacy and tolerability.

Pulmonary Arterial Hypertension in Women

Pulmonary arterial hypertension (PAH) is characterized by pathological hemodynamic elevation in pulmonary artery pressure. Development of international registries over the last decade has raised awareness about the disease, leading to the development of new and improved therapies. Paradigm shifts such as these warrant review of existing literature regarding PAH, especially in females, as the disease continues to affect women more than males. The aim of this review is to provide an update on the classification, pathophysiology, diagnosis, and treatment of PAH while focusing specifically on its impact on women.