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Introduction: Historically, patients recently (≤ 6 months) diagnosed with pulmonary arterial hypertension (PAH; incident) have had poorer survival than those with a longer (> 6 months) time from PAH diagnosis (prevalent). Despite guideline recommendations for initial combination therapy for most patients with PAH, many are initiated and maintained on monotherapy. Real-world evidence to evaluate the benefit of early combination treatment in newly-diagnosed patients is lacking., Methods: Patients with PAH initiating combination therapy with the endothelin receptor antagonist macitentan and the phosphodiesterase-5 inhibitor tadalafil (M+T) were identified from the combined dataset of the US, multicenter OPUS (prospective, observational drug registry; NCT02126943) and OrPHeUS (retrospective, medical chart review; NCT03197688) studies (2013-2020). Descriptive analyses were performed for the incident and prevalent cohorts, as well as the subcohort of incident patients who received M+T as first-line combination therapy (incident initial combination)., Results: In OPUS/OrPHeUS, 1336 patients with PAH received M+T during the observation period. For the incident [n = 453 (33.9%)], incident initial combination [n = 272 (20.4%)], and prevalent [n = 837 (62.6%)] cohorts: median (Q1, Q3) M+T exposure was 14.2 (4.2, 27.5), 12.2 (3.2, 25.5), and 14.7 (4.5, 28.0) months. 12-month Kaplan-Meier estimates (95% confidence limits) for survival were 91.2% (87.7, 93.7), 88.5% (83.2, 92.2), and 92.9% (90.6, 94.6), for patients free from hospitalization were 59.4% (54.1, 64.4), 56.3% (49.1, 62.9), and 62.3% (58.5, 65.9), and for patients persisting on combination therapy were 68.6% (63.9, 72.8), 65.0% (58.8, 70.6) and 66.9% (63.5, 70.0). Adverse events (OPUS only) were reported in 77.8%, 80.2%, and 80.3% of patients, respectively, with no unexpected adverse events observed., Conclusions: Despite a historically worse prognosis, incident patients receiving M+T, including as initial combination therapy, had similar survival and hospitalization as prevalent patients. Safety profiles were similar across cohorts. Together, these data support the use of early combination therapy with macitentan and tadalafil., (© 2024. The Author(s).)

Pulmonary arterial hypertension (PAH) is a severe pulmonary vascular disorder marked by vascular remodeling, which is linked to the malignant phenotypes of pulmonary vascular cells. The prevailing therapeutic approaches for PAH tend to neglect the potential role of vascular remodeling, leading to the clinical prognosis remains poor. Previously, we first demonstrated that heat shock protein (Hsp110) was significantly activated to boost Hsp110-STAT3 interaction, which resulted in abnormal proliferation and migration of human pulmonary arterial endothelial cells (HPAECs) under hypoxia. In the present study, we initially postulated the allosteric site of Hsp110, performed a virtual screening and biological evaluation studies to discover novel Hsp110-STAT3 interaction inhibitors. Here, we identified compound 29 (AN-329/43448068) as the effective inhibitor of HPAECs proliferation and the Hsp110-STAT3 association with good druggability. In vitro, 29 significantly impeded the chaperone function of Hsp110 and the malignant phenotypes of HPAECs. In vivo, 29 remarkably attenuated pulmonary vascular remodeling and right ventricular hypertrophy in hypoxia-induced PAH rats (i.g). Altogether, our data support the conclusion that it not only provides a novel lead compound but also presents a promising approach for subsequent inhibitor development targeting Hsp110-STAT3 interaction., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

A 51-year-old Thai woman diagnosed with β-thalassemia underwent regular blood transfusion and iron-chelating therapy. However, after voluntarily discontinuing treatment, the patient developed progressive dyspnea and was diagnosed with pulmonary hypertension following right heart catheterization. Despite resuming blood transfusions, her condition did not improve. Because the patient had a history of multiple organ failure, curative treatment for β-thalassemia was not feasible, and macitentan was administered. Despite experiencing hypotension as an adverse event, her condition remained stable during macitentan treatment. Thus, macitentan may be well tolerated in patients with pulmonary hypertension caused by β-thalassemia with multiple organ dysfunction.

Aim: Bosentan, ambrisentan, and macitentan are endothelin receptor antagonists (ERAs), currently available in Australia for treatment of pulmonary arterial hypertension (PAH). This study assessed the comparative adherence of these ERAs for PAH in Australian patients., Methods: This retrospective, observational study used data for adults with PAH from the Services Australia 10% Pharmaceuticals Benefits Scheme (PBS) dataset (01/2006-10/2020). The primary outcome was treatment adherence (i.e. receiving ≥80% of ERA doses over 12 months). Secondary outcomes were time to treatment change (add-on or switch) and overall survival., Results: The study included 436 patients who took bosentan ( n  = 200), ambrisentan ( n  = 69), or macitentan ( n  = 167). Treatment adherence was significantly greater in patients who received macitentan (65.3%) versus ambrisentan (56.5%) and bosentan (58.0%), with odds ratios (ORs; 95% CI) of 0.51 (0.30-0.88; p  = 0.016) for bosentan versus macitentan and 0.48 (0.24-0.96; p  = 0.037) for ambrisentan versus macitentan. The median time to treatment change was 47.2 and 43.4 months for bosentan and ambrisentan, respectively (not calculated for macitentan because of insufficient duration of data)., Limitations and Conclusions: Real-world data for Australian patients with PAH showed that treatment adherence for ERAs was suboptimal. Adherence was higher for macitentan compared with ambrisentan and bosentan.

Background: Pulmonary hypertension (PH) is a severe hemodynamic condition with high morbidity and mortality. Approved targeted therapies are limited for pediatric subjects, and treatments are widely adopted from adult algorithms. Macitentan is a safe and effective drug used for adult PH, but data on pediatric patients are limited. In this prospective single-center study, we investigated mid- and long-term effects of macitentan in children with advanced pulmonary hypertensive vascular disease., Methods: Twenty-four patients were enrolled in the study for treatment with macitentan. Efficacy was determined by echo parameters and brain natriuretic peptide levels (BNP) at 3 months and 1 year. For detailed analysis, the entire cohort was subgrouped into patients with congenital heart disease-related PH (CHD-PH) and non-CHD-PH patients, respectively., Results: Mean age of the patients was 10.7 ± 7.6 years; median observation period was 36 months. Twenty of 24 patients were on additional sildenafil and/or prostacyclins. Two of 24 patients discontinued because of peripheral edema. Within the entire cohort, BNP levels and all echo measures such as right ventricular systolic pressure (RVSP), right ventricular end-diastolic diameter (RVED), tricuspid annular plane systolic excursion (TAPSE), pulmonary velocity time integral (VTI), and pulmonary artery acceleration time (PAAT) improved significantly after 3 months (p ≤ 0.01), whereas in the long term significant improvement persisted for BNP levels (-16%), VTI (+14%) and PAAT (+11%) (p < 0.05). By subgroup analysis, non-CHD PH patients showed significant improvements in BNP levels (-57%) and all echo measures (TAPSE +21%, VTI +13%, PAAT +37%, RVSP -24%, RVED -12%) at 3 months (p ≤ 0.01), whereas at 12 months, improvements persisted (p < 0.05) except for RVSP and RVED (nonsignificant). In CHD-PH patients, none of the measures changed (nonsignificant). 6-MWD (distance walked in 6 minutes) slightly increased but was not statistically evaluated., Conclusion: Data presented herein account for the largest cohort of severely affected pediatric patients receiving macitentan. Overall, macitentan was safe and associated with significant beneficial effects and sustained positive signals after 1 year, albeit in the long term disease progression remains a major concern. Our data suggest limited efficacy in CHD-related PH, whereas favorable outcomes were mainly driven by improvements in patients with PH not related to CHD. Larger studies are needed to verify these preliminary results and to prove efficacy of this drug in different pediatric PH entities., (© 2023. The Author(s).)

Pulmonary hypertension (PH) associated with congenital heart disease is a progressive hemodynamic disease that can lead to increased pulmonary vascular resistance, vascular remodeling, and even right heart failure and death. LF3 is a novel inhibitor of the reporter gene activity of β-catenin/TCF4 interaction in the Wnt/β-catenin signal pathway. However, whether this action of LF3 can prevent PH development remains unclear. In this study, we investigated the therapeutic effect of LF3 in rat primary pulmonary artery smooth muscle cells (PASMCs) of the PH model. We found that LF3 inhibited the decrease in pulmonary artery acceleration time and ejection time by ultra-high-resolution ultrasound imaging and blocked the increase of pulmonary artery systolic pressure by using the BL420 biological function experimental system and right ventricular hypertrophy index by the electronic scales. Simultaneously, it prevented the increase of α-smooth muscle actin and fibronectin and the decrease of elastin in pulmonary arteries of rats in the PH group, as revealed by an immunohistochemical analysis. Moreover, cell proliferation and migration assays showed that LF3 significantly reduced the proliferation and migration of PASMCs. Western blotting and quantitative real-time polymerase chain reaction analyses revealed that LF3 suppressed the expression of proliferating cell nuclear antigens and Bcl-2 and increased the expression of Bax but did not alter the expressions of β-catenin and TCF4. Taken together, LF3 can reduce the migration and proliferation of PASMCs and induce their apoptosis to prevent the development of PH. It would be worthwhile to explore the potential use of LF3 in the treatment of PH., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Macitentan treatment for chronic thromboembolic pulmonary hypertension (CTEPH) in the routine clinical setting is increasing. However, 'real world' macitentan experience is scarce and is needed to differentiate from controlled clinical trial settings., Objective: We describe our outcomes and clinical 'real world' experience of macitentan mono- and combination therapy with riociguat or sildenafil in CTEPH., Methods: We included all consecutive CTEPH patients, either non-operated or with residual PH after pulmonary endarterectomy (PEA), treated with macitentan in the St. Antonius hospital in Nieuwegein, the Netherlands, between 01-2014 and 11-2019. We describe clinical outcomes and adverse events (AEs) until 2 years after macitentan initiation., Results: In total 73 CTEPH patients on macitentan were included, of which 18 patients were clinically inoperable (n = 7 declined PEA, n = 11 nonacceptable risk-benefit) and 55 had technically inoperable CTEPH (n = 48)/residual PH (n = 7). Clinically inoperable patients (mean age 72.4 ± 10.2 years, 61% female, 28% macitentan monotherapy, observation period 2.0 (1.9-2.0) years) had a survival of 100% and clinical worsening (CW)-free survival of 88% at 2-year follow-up respectively, with a significant increased 6-min walking distance (6MWD). Technically inoperable/residual PH patients (mean age 62.1 ± 14.1 years, 60% female, 27% macitentan monotherapy, observation period 2.0 (1.0-2.0) years) had a 2-year survival and CW-free survival of 86% and 68% respectively, with significant improved 6MWD and NT-proBNP. Nonsevere AEs were reported in 30% of all patients., Conclusion: Macitentan mono- and combination therapy in non-operated CTEPH and residual PH is safe and improves clinical outcomes till 2-year follow-up., Competing Interests: Declaration of competing interest M. van Thor, J. Mager and M. Post report grants from Actelion Pharmaceuticals. L ten Klooster has nothing to disclose. R. Snijder reports grants from Pfizer and Actelion Pharmaceuticals., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Pulmonary hypertension (PH) is a known complication of pulmonary sarcoidosis and is associated with higher morbidity and mortality. Currently, there are no approved PH-targeted therapies for sarcoidosis-associated pulmonary hypertension (SAPH). Macitentan is frequently used as treatment for pulmonary arterial hypertension, but no results are known in the SAPH population., Objective: We investigated the safety and effect of macitentan as treatment for SAPH., Methods: We retrospectively reviewed our patient database for all SAPH patients receiving macitentan as treatment, with a minimum follow-up of twelve months for monitoring safety. Safety outcomes included reported side-effects, hospitalisations and mortality. Furthermore, six-minutes walking distance, New York Heart Association functional class and NT-proBNP levels were collected., Results: Six cases (three men) with a median age of 64 years (range 52-74 years) were identified. During macitentan treatment, one patient experienced side effects and aborted therapy after five days of treatment and died 16 months later. Three patients were hospitalised during treatment for congestive heart failure. Four patients showed improvement of their functional class and three patients in exercise capacity after 12 months of therapy., Conclusion: Macitentan was well tolerated in five out of six cases with severe pulmonary sarcoidosis and PH. Functional capacity improved in four cases. Prospective controlled trials are warranted before therapeutic recommendations can be made. (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (1): 74-78) ., (Copyright: © 2020 SARCOIDOSIS VASCULITIS AND DIFFUSE LUNG DISEASES.)

Objective: Research comparing bosentan and macitentan in chronic thromboembolic pulmonary hypertension (CTEPH) is scarce, although macitentan might have superior pharmacologic properties. We present the first real-world, 2-year follow-up results and compare clinical outcomes of both drugs in CTEPH., Methods: All consecutive, technical inoperable or residual CTEPH patients receiving bosentan or macitentan, diagnosed in our multidisciplinary team between January 2003 and January 2019, were included. We report and compare survival, clinical worsening (CW), adverse events, WHO FC, NT-proBNP and 6-min walking test (6MWT) until 2 years after medication initiation., Results: In total, 112 patients receiving bosentan or macitentan (58% female, mean age 62 ± 14 years, 68% WHO FC III/IV, 51% bosentan) could be included. Mean treatment duration was 1.9 ± 0.4 years for bosentan and 1.2 ± 0.6 years for macitentan. Two-year survival rate was 91% for bosentan and 80% for macitentan (HR mortality macitentan 1.85 [0.56-6.10], p = 0.31). Two-year CW-free survival was 81% and 58%, respectively (HR CW macitentan 2.16 [0.962-4.87], p = 0.06). Right atrial pressure, cardiac output (for mortality alone) and 6MWT lowest saturation were multivariate predictors at baseline. Overall adverse event rates were comparable and WHO FC, NT-proBNP and 6MWT distance improved similar for both drugs till 2-year follow-up., Conclusion: CTEPH patients receiving bosentan or macitentan have improved clinical outcomes till 2-year follow-up, without significant differences in outcomes between both therapies.

Objectives: To assess whether switching patients with suboptimally controlled pulmonary arterial hypertension from bosentan or ambrisentan to macitentan would improve six-minute walk test (6MWT) distance and World Health Organization functional class., Methods: This was a retrospective cohort analysis of 37 patients from a single center. Patients were separated into three heterogeneous treatment groups and followed for 18 months: switch group (n = 14): patients switched to macitentan from bosentan/ambrisentan; added group (n = 11): patients who began macitentan as de novo therapy (n = 5) or who added macitentan to an existing sildenafil regimen (n = 6); and control group (n = 12): patients for whom sildenafil and/or bosentan/ambrisentan therapy was unchanged., Results: Mortality was observed in two patients (one each, switch and added groups). Patients in the control group had one hospital admission and 100% survival. There was significant improvement in functional class for the switch and added groups. Statistically significant improvement was observed in 6MWT distance in the added group alone. Overall, 92% of patients continued macitentan throughout the study., Conclusion: Macitentan was well tolerated. For bosentan/ambrisentan-treated patients with suboptimally controlled pulmonary arterial hypertension, switching to macitentan may facilitate an improvement in functional class.

Macitentan is an endothelin receptor antagonist commonly used in the treatment of pulmonary arterial hypertension (PAH). A novel, rapid, simple and sensitive UPLC-MS/MS method was developed and validated for pharmacokinetic study and the determination of macitentan in PAH patients. Macitentan and bosentan, which are used as internal standards, were detected using atmospheric pressure chemical ionization in positive ion and multiple reaction monitoring mode by monitoring the mass transitions m/z 589.1 → 203.3 and 552.6 → 311.5, respectively. Chromatographic separation was performed on a reverse-phase C18 column (5 μm, 4.6 × 150 mm) with an isocratic mobile phase, which consisted of water containing 0.2% acetic acid-acetonitrile (90:10, v/v) at a flow rate of 1 mL/min. Retention times were 1.97 and 1.72 min for macitentan and IS, respectively. The calibration curve with high correlation coefficient (0.9996) was linear in the range 1-500 ng/mL. The lower limit of quantitation and average recovery values were determined as 1 ng/mL and 89.8%, respectively. This method is the first UPLC-MS/MS method developed and validated for the determination of macitentan from human plasma. The developed analytical method was fully validated for linearity, selectivity, specificity, accuracy, precision, sensitivity, stability, matrix effect and recovery according to US Food and Drug Administration guidelines. The developed method was applied successfully for pharmacokinetic study and the determination of macitentan in PAH patients., (© 2019 John Wiley & Sons, Ltd.)

Background: Eisenmenger syndrome describes congenital heart disease-associated severe pulmonary hypertension accompanied by right-to-left shunting. The multicenter, double-blind, randomized, placebo-controlled, 16-week, phase III MAESTRO study (Macitentan in Eisenmenger Syndrome to Restore Exercise Capacity) evaluated the efficacy and safety of the endothelin receptor antagonist macitentan in patients with Eisenmenger syndrome., Methods: Patients with Eisenmenger syndrome aged ≥12 years and in World Health Organization functional class II-III were randomized 1:1 to placebo or macitentan 10 mg once daily for 16 weeks. Patients with complex cardiac defects, Down syndrome and background PAH therapy were eligible. The primary end point was change from baseline to week 16 in 6-minute walk distance. Secondary end points included change from baseline to week 16 in World Health Organization functional class. Exploratory end points included NT-proBNP (N-terminal pro-B-type natriuretic peptide) at end of treatment expressed as a percentage of baseline. In a hemodynamic substudy, exploratory end points included pulmonary vascular resistance index (PVRi) at week 16 as a percentage of baseline., Results: Two hundred twenty six patients (macitentan n=114; placebo n=112) were randomized. At baseline, 60% of patients were in World Health Organization functional class II and 27% were receiving phosphodiesterase type-5 inhibitors. At week 16, the mean change from baseline in 6-minute walk distance was 18.3 m and 19.7 m in the macitentan and placebo groups (least-squares mean difference, -4.7 m; 95% confidence limit (CL), -22.8, 13.5; P=0.612). World Health Organization functional class improved from baseline to week 16 in 8.8% and 14.3% of patients in the macitentan and placebo groups (odds ratio, 0.53; 95% CL, 0.23, 1.24). NT-proBNP levels decreased with macitentan versus placebo (ratio of geometric means, 0.80; 95% CL, 0.68, 0.94). In the hemodynamic substudy (n=39 patients), macitentan decreased PVRi compared with placebo (ratio of geometric means, 0.87; 95% CL, 0.73, 1.03). The most common adverse events with macitentan versus placebo were headache (11.4 versus 4.5%) and upper respiratory tract infection (9.6 versus 6.3%); a hemoglobin decrease from baseline of ≥2 g/dL occurred in 36.0% versus 8.9% of patients. Five patients (3 macitentan; 2 placebo) prematurely discontinued treatment and 1 patient died (macitentan group)., Conclusions: Macitentan did not show superiority over placebo on the primary end point of change from baseline to week 16 in exercise capacity in patients with Eisenmenger syndrome., Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01743001.

Macitentan (10 mg once daily orally), a dual endothelin receptor antagonist (ERA) developed by modifying the structure of bosentan to increase the efficacity and safety, is approved for the treatment of pulmonary arterial hypertension (PAH). The pivotal SERAPHIN trial, (a landmark trial in the history of PAH trials because of the large number of included patients, the long-term follow up and the first trial with morbidity/mortality as the primary endpoint) showed a reduction of the risk of a morbidity or mortality event by 45% over the treatment time compared with placebo. The positive effect on the primary endpoint was observed whether or not the patient was already on PAH therapy. There has been no direct comparison between macitentan and other ERAs, which were approved based on improved exercise capacity, but preclinical and clinical data suggest better pharmacological and safety profiles. Further analyses of the SERAPHIN trial investigated the predictive value of different indices and events on long-term outcome and mortality. The efficacy in children, the long-term effects and safety of macitentan and its place in combination therapy compared with other ERAs are still under investigation. This review presents the preclinical evidence of superiority of macitentan compared with other ERAs, and the available clinical trial data. The place of macitentan in the therapeutic algorithm for PAH treatment, post-marketing experience and future perspectives are discussed.

Background: Newer endothelin receptor antagonists (ERAs) used to treat patients with pulmonary arterial hypertension (PAH) are associated with fewer drug-drug interactions than bosentan and require less monitoring. This, combined with a pharmacokinetic basis for improved efficacy, means there may be a clinical rationale for changing therapies. However, this can be challenging and few data on its safety in patients with PAH are available., Aims: At the Royal Free Hospital in London, UK, home-based medication transitioning has been standard practice since 2009 to avoid unnecessary hospital visits for patients, unless there is a clinical imperative. In this audit of standard practice we evaluated the consequences of adopting such a strategy when transitioning PAH patients between ERA therapies., Methods and Results: Using a Clinical Nurse Specialist-led, home-based transitioning strategy, 92 patients with PAH were transitioned from bosentan to macitentan or ambrisentan. Observational data were analysed retrospectively. The majority of patients were female with PAH associated with connective tissue disease and their ERA was changed in the hope of improving efficacy. The process was well tolerated with no adverse events associated with the process. Seventeen patients died during the study (macitentan, n = 5; ambrisentan, n = 12). None of the deaths was considered related to ERA treatment. The majority of patients remained clinically stable, based on WHO functional class and exercise capacity., Conclusion: An established home-based transitioning strategy can be adopted safely for patients with PAH changing ERA therapies. Most patients remained stable and the therapy change was well tolerated.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with an unknown cause. Two drugs, nintedanib and pirfenidone, have been shown to slow, but not stop, disease progression. Pulmonary hypertension (PH) is a frequent complication in IPF patients and is associated with poor prognosis. Macitentan is a dual endothelin receptor antagonist that is approved for pulmonary arterial hypertension treatment. We hypothesised that using macitentan to treat animals with pulmonary fibrosis induced by adenoviral vector encoding biologically active transforming growth factor-β1 (AdTGF-β1) would improve the PH caused by chronic lung disease and would limit the progression of fibrosis.Rats (Sprague Dawley) which received AdTGF-β1 were treated by daily gavage of macitentan (100 mg·kg -1 ·day -1 ), pirfenidone (0.5% food admix) or a combination from day 14 to day 28. Pulmonary artery pressure (PAP) was measured before the rats were killed, and fibrosis was subsequently evaluated by morphometric measurements and hydroxyproline analysis.AdTGF-β1 induced pulmonary fibrosis associated with significant PH. Macitentan reduced the increase in PAP and both macitentan and pirfenidone stopped fibrosis progression from day 14 to day 28. Macitentan protected endothelial cells from myofibroblast differentiation and apoptosis whereas pirfenidone only protected against fibroblast-to-myofibroblast differentiation. Both drugs induced apoptosis of differentiated myofibroblasts in vitro and in vivo Our results demonstrate that dual endothelin receptor antagonism was effective in both PH and lung fibrosis whereas pirfenidone only affected fibrosis., Competing Interests: Conflict of interest: M. Iglarz is an employee of Actelion Pharmaceuticals Ltd, the manufacturer of macitentan. Conflict of interest: M. Kolb reports grants and personal fees from Roche, Boehringer Ingelheim, GSK, Gilead, Prometic and Alkermes, grants from Actelion, Respivert and Synairgen, and personal fees from AstraZeneca and Genoa, outside the submitted work., (Copyright ©ERS 2018.)

The approval of macitentan has increased the number of pharmacological treatments of pulmonary arterial hypertension (PAH). Here, we review the effect on PAH of macitentan compared to other endothelin receptor antagonists. Drugs targeting the endothelin (ET) pathway include the selective ET A receptor antagonist ambrisentan, the ET A /ET B receptor antagonists, bosentan and macitentan, which were recently approved for PAH treatment. Macitentan exhibits higher antagonistic potency than bosentan and ambrisentan in pulmonary smooth muscle cells. Compared to ambrisentan and bosentan, macitentan has a longer duration of action, reflected by the longer half-life, as well as pharmacodynamics attributed to its active metabolite, ACT-132577. The efficacy of macitentan on PAH was investigated in the phase III SERAPHIN trial (NCT00660179). Macitentan significantly reduced morbidity and mortality. It improved the 6-min. walk distance (6MWD) among PAH patients. In the AMB-320/321-E (NCT00578786) study, ambrisentan improved exercise capacity. In the EARLY study (NCT00091715), bosentan showed improvements in 6MWD which were not statistically significant. Bosentan had an effect on PAH in patients with Eisenmenger syndrome (ES) in the BREATHE-5 study (NCT00367770), while macitentan did not improve 6MWD in these patients, but there are differences regarding study size and functional class, and that 30% of the patients treated with macitentan were already in treatment with a phosphodiesterase type 5 inhibitor. Macitentan revealed a lower risk of developing peripheral oedema and hepatotoxicity in the SERAPHIN study. In summary, macitentan has an efficiency comparable to bosentan and ambrisentan in the treatment of PAH. Patients treated with macitentan exhibited less adverse effects compared to bosentan and ambrisentan. In patients with PAH associated with ES, the trials with bosentan and macitentan do not seem comparable, and it needs to be clarified whether these drugs are effective when administered as part of a combination treatment in this condition., (© 2018 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

Background and Objective: Bosentan therapy has been recommended for pulmonary arterial hypertension (PAH) and might be beneficial for chronic thromboembolic pulmonary hypertension (CTEPH). We aimed to evaluate the specific effects of bosentan for PAH and CTEPH., Materials and Methods: We performed a systemic review and meta-analysis of randomized controlled trials (RCTs), comparing efficacy and safety of bosentan treatment for PAH and CTEPH through major biomedical database., Results: A total of 10 RCTs including 1185 patients were enrolled. For PAH patients, bosentan prolonged 6-minute walk distance with a weighted mean difference of 35.7 m, reduced mean pulmonary arterial pressure by 5.7 mm Hg, increased cardiac index by 0.4 L/min/m 2 , reduced pulmonary vascular resistance by 305.1 dyn·s/cm 5 , prevented functional class from deterioration and reduced clinical worsening as compared with placebo. For CTEPH patients, bosentan improved cardiac index by 0.3 L/min/m 2 and reduced pulmonary vascular resistance by 176.0 dyn·s/cm 5 . Other efficacy outcomes regarding CTEPH did not attain statistical difference. For both PAH and CTEPH, there was no significant difference in mortality or adverse event between bosentan and placebo group. However, bosentan raised the risk of abnormal liver function in both PAH and CTEPH patients., Conclusions: Bosentan is effective in treating PAH, whereas it improves only certain hemodynamic parameters of CTEPH. Incidence of liver function abnormality is higher in bosentan treatment., (© 2018 John Wiley & Sons Ltd.)

Pulmonary arterial hypertension (PAH), a condition that is defined by pulmonary vasculature constriction and remodeling, involves dysfunctional signaling of the serotonin (5-HT) receptors, 5-HT 2A/2B/7 . In a rat model of monocrotaline (MCT)-induced PAH, the effectiveness of RP5063 (RP), a dopamine and 5-HT receptor modulator, was evaluated as monotherapy and as an adjunct to standard PAH treatments. After a single 60 mg/kg dose of MCT, rats received vehicle (MCT+Veh; gavage twice-daily [b.i.d.]), RP (10 mg/kg; gavage b.i.d.), bosentan (B; 100 mg/kg; gavage BID), sildenafil (S; 50 mg/kg; gavage, BID), treprostinil (T; 100 ng/kg/min over 24 h intravenous), RP+B, RP+S, and RP+T for 28 days. Single-agent RP limited the functional and structural effects of PAH seen in the MCT+Veh group, with significant improvements in pulmonary hemodynamics, right ventricular (RV) hypertrophy, SO 2 , and pulmonary blood vessel structural changes. These effects appeared comparable with those associated with B, S, and T. Adjunctive RP treatment resulted in significantly lower mean pulmonary arterial pressures, RV systolic pressure. It also improved SO 2 measurements, as compared with MCT+Veh (P < 0.05), and diastolic pulmonary artery pressure (P < 0.05), as compared with single-agent B and S therapy (Bonferroni method adjusting for multiplicity). RP+S appeared to show the most consistent and extensive effects on pulmonary hemodynamics, respiratory parameters, and histopathologic changes. These results corroborate earlier preclinical findings supporting the efficacy of single-agent RP in PAH. RP, as mono and adjunctive therapy compared with induced-control, mitigated the functional and structural effects of MCT-induced PAH., (Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.)

Since 2015, macitentan, the new oral dual endothelin receptors antagonist (ERA), has been successfully introduced into clinical practice in the Russian Federation for the treatment of pulmonary arterial hypertension (PAH) patients. It has improved physicochemical properties, which provides tissue specificity. Among ERA and other drugs of specific therapy, macitentan is the only one with indication-prevention of PAH progression. In the randomized, placebo-controlled study SERAPHIN in 742 PAH patients aged >12 years, macitentan 10 mg compared with placebo reduced the risk of morbidity and mortality by 45%. By month 6, macitentan with favorable tolerability profile provided a significant increase in the 6-minute walk test distance, the improvement of the functional class (FC) and hemodynamic parameters - pulmonary vascular resistance (PVR) and cardiac index. Macitentan significantly reduced the need for hospitalization for all reasons, including associated with PAH worsening. This review presents a modern view on the possibility of using macitentan in the clinical practice. It is shown that the drug is an important choice among ERA for the treatment of PAH patients. In the study MERIT-1 macitentan significantly improved PVR (geometric mean ratio 0.84, 95% CI 0.70-0,99, p=0.041) in inoperable CTEPH patients. The evidence base for the macitantan use in various PAH subgroups, including portopulmonary hypertension, in children as well as beyond group 1 - CTEPH, left heart diseases - is supplementing with the new data, which will expand the possibilities of its clinical use.

Background: Macitentan is the first endothelin receptor antagonist with demonstrated efficacy on morbidity and mortality in pulmonary arterial hypertension (PAH) in the pivotal study SERAPHIN., Methods: The pharmacokinetics (PK) of macitentan and its active metabolite, ACT-132577, were characterized in a population model. Efficacy and hemodynamics (pharmacodynamics, PD) were related to PK based on PK/PD modeling., Results: Sex, age, and body weight influenced the PK to a statistically significant extent. Model-based simulations showed that these variables are clinically not relevant. Concomitant use of PAH medication (PDE-5 inhibitors) did not influence macitentan trough concentration to a relevant extent. Efficacy and hemodynamics showed clear differences from placebo for macitentan concentrations on 3 and 10 mg with consistent superior effects for 10 mg. After 6 months, PAH patients showed model-predicted 6-min walk distance (6-MWD) improvements of 1.0 m on placebo compared to 29.8 and 34.1 m on 3 and 10 mg of macitentan, respectively. Higher macitentan concentrations were associated with reductions in pulmonary vascular resistance (PVR), mean right atrial and pulmonary arterial pressure, and total pulmonary resistance (TPR) and increases in cardiac index (CI) and mixed venous oxygen saturation. Statistical significance was determined for PVR, TPR, and CI but not for 6-MWD. In addition, PVR showed more pronounced differences between active treatment and placebo than 6-MWD., Conclusions: Modeling identified statistically significant inter-patient differences; simulations to assess the magnitude of the effects permitted clinical judgment. The same approach will allow for extrapolation to children. Hemodynamic markers might be better markers of treatment effects than 6-MWD., Trial Registration: The SERAPHIN study and its open-label extension are registered with ClinicalTrials.gov with identifiers NCT00660179 (https://www.clinicaltrials.gov/ct2/show/NCT00660179) and NCT00667823 (https://clinicaltrials.gov/ct2/show/NCT00667823) and with EudraCT with identifiers 2007-002440-14 (https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-002440-14) and 2007-003694-27 (https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-003694-27)., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term event-driven study. Aim Few studies compared the clinical efficacy and safety of switch from bosentan to macitentan only in adult patients with pulmonary arterial hypertension. We aimed to evaluate the clinical efficacy and safety of switch from bosentan to macitentan in children and young adults., Methods: This is a single-institution, 24-week prospective study. Patients ⩾12 years of age with idiopathic/heritable pulmonary arterial hypertension or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan therapy were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors and inhaled prostanoids was allowed. Outcome measures included change from baseline to week 24, in the 6-minute walk distance, functional class, oxygen saturation at rest/after 6-minute walk distance test, systolic pulmonary artery pressure estimated by echocardiography, and brain natriuretic peptide levels. Safety end points included adverse events laboratory abnormalities., Results: A total of 13 patients - 5 male and 8 female - completed the study. The mean age was 20.3±6.5 years (12-35) and weight was 54.0±14.5 kg (27-75). Five patients were ⩽18 years of age. Macitentan improved 6-minute walk distance from baseline (mean: 466±35 m (300-590)), at 12 weeks (mean: 494±78 m (325-590), +28 m) (p0.05). None of the patients had anaemia, hepatotoxicity, and peripheral oedema., Conclusions: Our study is the first study that showed that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension and is well tolerated without any adverse events.

The MELODY-1 study evaluated macitentan for pulmonary hypertension because of left heart disease (PH-LHD) in patients with combined post- and pre-capillary PH.63 patients with PH-LHD and diastolic pressure gradient ≥7 mmHg and pulmonary vascular resistance (PVR) >3WU were randomised to macitentan 10 mg (n=31) or placebo (n=32) for 12 weeks. The main end-point assessed a composite of significant fluid retention (weight gain ≥5% or ≥5 kg because of fluid overload or parenteral diuretic administration) or worsening in New York Heart Association functional class from baseline to end of treatment. Exploratory end-points included changes in N-terminal pro-brain natriuretic peptide (NT-proBNP) and haemodynamics at week 12.Seven macitentan-treated and four placebo-treated patients experienced significant fluid retention/worsening functional class; treatment difference, 10.08% (95% CI -15.07-33.26; p=0.34). The difference, driven by the fluid retention component, was apparent within the first month. At week 12, versus placebo, the macitentan group showed no change in PVR, mean right atrial pressure or pulmonary arterial wedge pressure; a non-significant increase in cardiac index (treatment effect 0.4 (95% CI 0.1-0.7) L·min -1 ·m -2 ) and decrease in NT-proBNP (0.77 (0.55-1.08)) was observed. Adverse events and serious adverse events were numerically more frequent with macitentan versus placebo.Macitentan-treated patients were quantitatively more likely to experience significant fluid retention versus placebo. Macitentan resulted in no significant changes in any exploratory end-points., Competing Interests: Conflict of interest: Disclosures can be found alongside this article at erj.ersjournals.com, (Copyright ©ERS 2018.)

SERAPHIN was a double-blind, placebo-controlled, event-driven phase III trial that evaluated the effects of long-term treatment with macitentan, an oral endothelin receptor antagonist, in patients with pulmonary arterial hypertension (PAH). The majority of patients were receiving PAH therapy at enrollment, providing the opportunity to evaluate the efficacy and safety of macitentan in combination with other PAH therapies (predominantly phosphodiesterase type 5 inhibitors [PDE-5i]). In patients receiving background therapy, macitentan reduced the risk of morbidity/mortality by 38% compared with placebo (hazard ratio [HR] 0.62; 95% confidence level [CL] 0.43-0.89; p = 0.009). Furthermore, patients receiving macitentan and background therapy had a 37% reduction in the risk of being hospitalized for PAH (HR 0.63; 95% CL 0.41-0.96) compared with patients receiving background therapy only (placebo arm). Macitentan treatment in combination with background therapy was also associated with improvements in exercise capacity, functional class, cardiopulmonary hemodynamics, and health-related quality of life compared with background therapy alone. The safety profile of macitentan as part of a combination therapy regimen was consistent with that of macitentan in the overall SERAPHIN population. The SERAPHIN study has provided evidence that combination therapy with macitentan and a PDE-5i is effective and well tolerated in the management of PAH. Based on these data, and those from subsequent long-term trials, combination therapy is increasingly recognized as an important treatment option for improving long-term outcomes in PAH., Clinical Trial Registration Number: NCT00660179.

Background: No drugs have been approved for the treatment of patients with pulmonary hypertension (PH) secondary to idiopathic pulmonary fibrosis (IPF), particularly those with idiopathic honeycomb lung. This study was conducted to investigate the long-term efficacy and safety of bosentan for PH based on changes in prognosis and respiratory failure., Methods: IPF patients with borderline or less severe PH and completely organized honeycomb lung were randomized (1:1) to bosentan or no treatment for PH for 2 years and assessed at baseline and every 6 months for respiratory failure, activities of daily living (ADL), lung and heart functions by right cardiac catheterization, and other parameters. An interim analysis was performed, however, following detection of a significant survival benefit favoring bosentan therapy., Results: Significant differences were noted for the bosentan-treated (n = 12) vs. untreated (n = 12) groups in hospital-free survival (603.44 ± 50.074 days vs. 358.87 ± 68.65 days; hazard ratio [HR], 0.19; P = 0.017) and overall survival (671 days vs. 433.78 ± 66.98 days; HR, 0.10; P = 0.0082). Again, significant improvements were noted for the bosentan-treated group from baseline to month 6 or 12 in several indices in ADL, pulmonary circulation, and %DLCO. Without requiring O 2 inhalation, bosentan was associated with no increase but a trend toward a decrease in adverse events and an improvement in respiratory status., Conclusions: Bosentan tended to improve prognosis and ADL without worsening respiratory failure in IPF patients with borderline or less severe PH and completely organized honeycomb lung alone., Trial Registration: This study was registered on December 18, 2010 with UMIN-CTR Clinical Trial as UMIN000004749 to investigate the long-term influence of bosentan on cardiac function, as well as its cardioprotective efficacy and safety, in patients with pulmonary hypertension secondary to concurrent COPD and IPF, respectively.

Background: Altered myocardial energy metabolism has been linked to worsening of RV function in pulmonary arterial hypertension (PAH). The aim of this study was to evaluate RV glucose and fatty acid metabolism in vivo in a rat model of PAH using positron emission tomography (PET) and investigate the effects of Macitentan on RV substrate utilization., Methods: PAH was induced in male Sprague-Dawley rats by a single subcutaneous injection of Sugen 5416 (20 mg/kg) followed by 3 weeks of hypoxia (10% oxygen). At week 5 post-injection, the PAH rats were randomized to Macitentan (30 mg/kg daily) treatment or no treatment. Substrate utilization was serially assessed 5 and 8 weeks post-injection with 2-[ 18 F]fluoro-2-deoxyglucose (FDG) and 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid (FTHA) PET for glucose and fatty acid metabolism respectively and correlated with in vivo functional measurements., Results: PAH induction resulted in a 2.5-fold increase in RV FDG uptake (standardized uptake value (SUV) of normal control: 1.6 ± 0.4, week 5: 4.1 ± 1.9, week 8: 4.0 ± 1.6, P < 0.05 for all groups vs. control). RV FTHA showed twofold increased uptake at week 5 (SUV control: 1.50 ± 0.39, week 5: 3.06 ± 1.10, P = 0.03). Macitentan significantly decreased RV FDG uptake at 8 weeks (SUV: 2.5 ± 0.9, P = 0.04), associated with improved RV ejection fraction and reduced RV systolic pressure, while FTHA uptake was maintained., Conclusion: PAH is associated with metabolic changes in the RV, characterized by a marked increase in FDG and FTHA uptake. Macitentan treatment reduced PAH severity and was associated with a decrease in RV FDG uptake and improved RV function.

Objective: To evaluate the antifibrotic effects of the pan-peroxisome proliferator-activated receptor (PPAR) agonist IVA337 in preclinical mouse models of pulmonary fibrosis and related pulmonary hypertension (PH)., Methods: IVA337 has been evaluated in the mouse model of bleomycin-induced pulmonary fibrosis and in Fra-2 transgenic mice, this latter being characterised by non-specific interstitial pneumonia and severe vascular remodelling of pulmonary arteries leading to PH. Mice received two doses of IVA337 (30 mg/kg or 100 mg/kg) or vehicle administered by daily oral gavage up to 4 weeks., Results: IVA337 demonstrated at a dose of 100 mg/kg a marked protection from the development of lung fibrosis in both mouse models compared with mice receiving 30 mg/kg of IVA337 or vehicle. Histological score was markedly reduced by 61% in the bleomycin model and by 50% in Fra-2 transgenic mice, and total lung hydroxyproline concentrations decreased by 28% and 48%, respectively, as compared with vehicle-treated mice. IVA337 at 100 mg/kg also significantly decreased levels of fibrogenic markers in lesional lungs of both mouse models. In addition, IVA337 substantially alleviated PH in Fra-2 transgenic mice by improving haemodynamic measurements and vascular remodelling. In primary human lung fibroblasts, IVA337 inhibited in a dose-dependent manner fibroblast to myofibroblasts transition induced by TGF-β and fibroblast proliferation mediated by PDGF., Conclusion: We demonstrate that treatment with 100 mg/kg IVA337 prevents lung fibrosis in two complementary animal models and substantially attenuates PH in the Fra-2 mouse model. These findings confirm that the pan-PPAR agonist IVA337 is an appealing therapeutic candidate for these cardiopulmonary involvements., Competing Interests: Competing interests: JA has/had consultancy relationship and/or has received research funding in relationship with the treatment of systemic sclerosis from Actelion, Roche, Pfizer and Bristol-Myers Squibb. YA has/had consultancy relationship and/or has received research funding in relationship with the treatment of systemic sclerosis from Actelion, Bayer, Biogen Idec, Bristol-Myers Squibb, Genentech/Roche, Inventiva, Medac, Pfizer, Sanofi/Genzyme, Servier and UCB. IK, J-ML and PB are employed by Inventiva. J-LJ has consultancy relationship with Inventiva., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

We present the use of pulmonary vasodilators in three adult patients with unrepaired tetralogy of Fallot, pulmonary atresia, aortopulmonary collaterals, and segmental pulmonary arterial hypertension. Patients improved by 1-2 NYHA classes with modest exercise-tolerance increase, and remained stable without side effects during 2.5, 10, and 14 years. Literature review revealed five studies with pulmonary vasodilators in heterogeneous, mostly repaired patient populations.

Background: Macitentan is beneficial for long-term treatment of pulmonary arterial hypertension. The microvasculopathy of chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension are similar., Methods: The phase 2, double-blind, randomised, placebo-controlled MERIT-1 trial assessed macitentan in 80 patients with CTEPH adjudicated as inoperable. Patients identified as WHO functional class II-IV with a pulmonary vascular resistance (PVR) of at least 400 dyn·s/cm 5 and a walk distance of 150-450 m in 6 min were randomly assigned (1:1), via an interactive voice/web response system, to receive oral macitentan (10 mg once a day) or placebo. Treatment with phosphodiesterase type-5 inhibitors and oral or inhaled prostanoids was permitted for WHO functional class III/IV patients. The primary endpoint was resting PVR at week 16, expressed as percentage of PVR measured at baseline. Analyses were done in all patients who were randomly assigned to treatment; safety analyses were done in all patients who received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT02021292., Findings: Between April 3, 2014, and March 17, 2016, we screened 186 patients for eligibility at 48 hospitals across 20 countries. Of these, 80 patients in 36 hospitals were randomly assigned to treatment (40 patients to macitentan, 40 patients to placebo). At week 16, geometric mean PVR decreased to 73·0% of baseline in the macitentan group and to 87·2% in the placebo group (geometric means ratio 0·84, 95% CI 0·70-0·99, p=0·041). The most common adverse events in the macitentan group were peripheral oedema (9 [23%] of 40 patients) and decreased haemoglobin (6 [15%])., Interpretation: In MERIT-1, macitentan significantly improved PVR in patients with inoperable CTEPH and was well tolerated., Funding: Actelion Pharmaceuticals Ltd., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Few controlled clinical trials exist to support oral combination therapy in pulmonary arterial hypertension (PAH)., Methods: Patients with PAH (idiopathic [IPAH] or associated with connective tissue disease [APAH-CTD]) taking bosentan (62.5 or 125 mg twice daily at a stable dose for ≥3 months) were randomized (1:1) to sildenafil (20 mg, 3 times daily; n = 50) or placebo (n = 53). The primary endpoint was change from baseline in 6-min walk distance (6MWD) at week 12, assessed using analysis of covariance. Patients could continue in a 52-week extension study. An analysis of covariance main-effects model was used, which included categorical terms for treatment, baseline 6MWD (<325 m; ≥325 m), and baseline aetiology; sensitivity analyses were subsequently performed., Results: In sildenafil versus placebo arms, week-12 6MWD increases were similar (least squares mean difference [sildenafil-placebo], -2.4 m [90% CI: -21.8 to 17.1 m]; P = 0.6); mean ± SD changes from baseline were 26.4 ± 45.7 versus 11.8 ± 57.4 m, respectively, in IPAH (65% of population) and -18.3 ± 82.0 versus 17.5 ± 59.1 m in APAH-CTD (35% of population). One-year survival was 96%; patients maintained modest 6MWD improvements. Changes in WHO functional class and Borg dyspnoea score and incidence of clinical worsening did not differ. Headache, diarrhoea, and flushing were more common with sildenafil., Conclusions: Sildenafil, in addition to stable (≥3 months) bosentan therapy, had no benefit over placebo for 12-week change from baseline in 6MWD. The influence of PAH aetiology warrants future study., Trial Registration: ClinicalTrials.gov NCT00323297 (registration date: May 5, 2006).

Aim: The aim of the present study was to investigate whether increasing the bosentan dosing frequency from 2 mg kg -1 twice daily (b.i.d.) to 2 mg kg -1 three times daily (t.i.d.) in children with pulmonary arterial hypertension (PAH) (from ≥3 months to <12 years of age) would increase exposure., Methods: An open-label, prospective, randomized, multicentre, multiple-dose, phase III study was conducted. Patients (n = 64) were randomized 1:1 to receive oral doses of bosentan of 2 mg kg -1 b.i.d. or t.i.d. The main pharmacokinetic endpoint was the daily exposure to bosentan over 24 h corrected to the 2 mg kg -1 dose (AUC 0-24C ). The maximum plasma concentration corrected to the 2 mg kg -1 dose (C maxC ), the time to reach the maximum plasma concentration (t max ) and safety endpoints were also assessed., Results: The geometric mean [95% confidence interval (CI)] for AUC 0-24C was 8535 h.ng ml -1 (6936, 10 504) and 7275 h.ng ml -1 (5468, 9679) for 2 mg kg -1 b.i.d. and t.i.d., respectively [geometric mean ratio (95% CI) 0.85 (0.61, 1.20)]. The geometric mean (95% CI) for C maxC was 743 ng ml -1 (573, 963) and 528 ng ml -1 (386, 722) for 2 mg kg -1 b.i.d. and t.i.d., respectively [geometric mean ratio (95% CI) 0.71 (0.48, 1.05)]. The median (range) for t max was 3.0 h (0.0-7.5) and 3.0 h (1.0-8.0) for 2 mg kg -1 b.i.d. and t.i.d., respectively. The proportions of patients who experienced ≥1 adverse event were similar in the b.i.d. (66.7%) and t.i.d. (67.7%) groups., Conclusions: There appeared to be no clinically relevant difference in exposure to bosentan, or in safety, when increasing the frequency of bosentan dosing from b.i.d. to t.i.d. Therefore, the present study provides no indication that the dosing recommendation should be changed, and 2 mg kg -1 b.i.d. remains the recommended dosing regimen for bosentan in paediatric PAH patients., (© 2017 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Background: The Fontan circulation, a result of a palliative procedure in patients with single systemic ventricles, is defined by chronically elevated pulmonary vascular resistance. When traditional heart failure therapies fail, pharmacological agents that reduce pulmonary artery pressures may be used. These include endothelial-receptor antagonists, prostanoids and phosphodiesterase type 5 inhibitors. We report the first use of macitentan, an endothelin-receptor antagonist, in a patient with a Fontan circulation., Case Presentation: We describe the case of a 50 year old female with tricuspid atresia and transposition of the great arteries. Following complex surgery as a child, she subsequently underwent a fenestrated modified atrial pulmonary Fontan operation which was later converted to a total cavopulmonary anastomosis Fontan circulation. Due to failure of various medications to relieve her worsening symptoms, she was commenced on macitentan in April 2016. Few months later, she demonstrated a significant symptomatic improvement and associated increase in her incremental shuttle walking test distance., Conclusions: Macitentan has slower receptor dissociation kinetics compared to other endothelin-receptor antagonists, leading to enhanced pharmacological activity with promising effects in patients with pulmonary arterial hypertension. The patient we report has shown considerable improvement in exercise capacity following introduction of this medication and thus we suggest further randomised trials to establish the role of different endothelin-receptor antagonists in the management of the Fontan circulation.

The study provides the physicochemical characteristic of bosentan (BOS) in comparison to tadalafil (TA) and sildenafil citrate (SIL). Despite some reports dealing with thermal characteristic of SIL and TA, physicochemical properties of BOS have not been investigated so far. Recent clinical reports have indicated that the combination of bosentan and PDE-5 inhibitor can improve the effectiveness of pharmacotherapy of pulmonary arterial hypertension (PAH). However, in order to design personalized medicines for therapy of chronic rare diseases, detailed information on the thermal behaviour and solubility of each drug is indispensable. Thus, XRD, DSC and TGA-QMS analyses were applied to compare the properties of the drugs, their thermal stability as well as to identify the products of thermal degradation. The dehydration of BOS started at 70°C and was followed by the chemical degradation with the onset at 290°C. The highest thermal stability was stated for TA, which decomposed at ca. 320°C, whereas the lowest onset of the thermal decomposition process was stated for SIL, i.e. 190°C. The products of the drug decomposition were identified. FT-FIR was applied to study intra- and intermolecular interactions between the drug molecules. FT-MIR and Raman spectroscopy were used to examine the chemical structure of the drugs. Chemoinformatic tools were used to predict the polar surface area, pKa, or logP of the drugs. Their results were in line with solubility and dissolution studies.

Background: In this multi-centre, randomised, placebo-controlled pilot trial, we investigated the clinical and haemodynamic effects of the endothelin-receptor blocker Bosentan in patients with heart failure, preserved ejection fraction and pulmonary hypertension (PH-HFpEF)., Materials and Methods: Eligible patients received either 12 weeks of Bosentan therapy, or a placebo drug. Patients were thereafter followed for a further period of 12 weeks without the study medication. At three points during the study (study Commencement, Week 12 and Week 24), a six-minute walk test (6MWT), echocardiographic and laboratory assessments were performed, as well as a quality of life survey. Right heart catheterisation (RHC) was undertaken at commencement only. The study was aborted early, after an interim analysis favoured the placebo., Results: Six-minute walk distance (6MWD) did not change in the Bosentan group (309.7±96.3m (Commencement), 317.0±126.1m (Week 12), 307.0±84.4m (Week 24); p=0.86), but almost reached statistical significance in the placebo group from 328.8±79.6m, to 361.6±98.2m and 384.0±74.9m (Week 24); p=0.075. In the placebo group, estimated systolic pulmonary artery pressure (measured via echocardiography) significantly decreased (from 62.3±16.7mmHg [Commencement], 45.3±13.9mmHg [Week 12], to 44.6±14.5mmHg [Week 24]; p=0.014) as did right atrial pressure (13.1±5.3 [Commencement], 10.0±3.8 [Week 12], to 9.4±3.2 [Week 24]; p=0.046)., Conclusion: Despite this study's limited sample size and premature cessation, it nevertheless suggests that endothelin receptor blockade in patients with PH-HFpEF may have no beneficial effects and could even be detrimental in comparison to a placebo., (Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.)

Aims: The effect of macitentan on haemodynamic parameters and NT-proBNP levels was evaluated in pulmonary arterial hypertension (PAH) patients in the SERAPHIN study. Association between these parameters and disease progression, assessed by the primary endpoint (time to first morbidity/mortality event), was explored., Methods and Results: Of the 742 randomized patients, 187 with right heart catheterization at baseline and month 6 participated in a haemodynamic sub-study. Prespecified endpoints included change from baseline to month 6 in cardiac index (CI), right atrial pressure (RAP), mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), mixed-venous oxygen saturation, and NT-proBNP. Exploratory analyses examined associations between CI, RAP, and NT-proBNP and disease progression using the Kaplan-Meier method and Cox regression models. Macitentan improved CI, RAP, mPAP, PVR and NT-proBNP vs. placebo at month 6. Absolute levels of CI, RAP and NT-proBNP at baseline and month 6, but not their changes, were associated with morbidity/mortality events. Patients with CI > 2.5 L/min/m2, RAP < 8 mmHg, or NT-proBNP < 750 fmol/ml at month 6 had a lower risk of morbidity/mortality than those not meeting these thresholds (HR 0.49, 95% CL 0.28-0.86; HR 0.72, 95% CL 0.42-1.22; and HR 0.22, 95% CL 0.15-0.33, respectively)., Conclusions: For all treatment groups, baseline and month 6 values of CI, RAP, and NT-proBNP, but not their changes, were associated with morbidity/mortality events, confirming their relevance in predicting disease progression in patients with PAH. By improving those parameters, macitentan increased the likelihood of reaching threshold values associated with lower risk of morbidity/mortality., (© The Author 2017. Published on behalf of the European Society of Cardiology)

Background: Bosentan is approved for use in adult patients with pulmonary arterial hypertension. The primary aim of the pharmacokinetic modeling was the provision of a systematic guidance for study design and enhanced understanding of pharmacokinetics across the entire pediatric age range., Methods: A physiologically based pharmacokinetic model was developed for the pediatric population; starting from an adult model, the effects of body weight, age, and maturation of relevant metabolizing enzymes were incorporated to extrapolate the pharmacokinetics to children. A pediatric population pharmacokinetic model was developed to identify relevant covariates., Results: Based on model predictions, a dose of 0.5 mg/kg led to an exposure distinguishable from a dose of 2 mg/kg, and an additional blood sampling time point at 2 h (the predicted time of maximum concentration) allowed more precise estimation of bosentan exposure in children. The lower exposure observed in children compared with adults could be explained by maturation-related changes in clearance. Clinical data confirmed the model predictions., Conclusions: Maturational changes in drug clearance and developmental changes in body weight were identified as key elements of bosentan pharmacokinetics in pediatric patients. Estimating bosentan exposure using physiologically based and population pharmacokinetic modeling and simulation supported dose selection in pediatric patients. Model-based exposure estimates helped in reducing the number of the youngest pediatric patients to be studied. Pharmacokinetic models can provide a systematic guidance for study design and enhanced understanding of pharmacokinetics across the entire pediatric age range.

Background: Monotherapy and sequential combination therapy have been widely used in the treatment of pulmonary arterial hypertension (PAH). There is limited evidence for initial combination therapy in patients with PAH, particularly those with World Health Organization (WHO) functional class III or IV., Methods: Twenty-seven consecutive treatment-naive PAH subjects with WHO functional class III or IV PAH were randomized into 3 groups with a 1:1:1 ratio: a combination therapy group with 125 mg of bosentan twice daily plus 10 μg of iloprost 4-6 times/d; a bosentan monotherapy group with 125 mg of bosentan twice daily; and a iloprost monotherapy group with 10 μg of iloprost 4-6 times/d. Clinical and hemodynamic data were collected at baseline, 6 weeks, and 3 months. The primary end point was the change in the 6-min walk distance (6MWD) from baseline values., Results: At baseline, there were no differences in demographics, WHO classification, hemodynamics, classification of PAH, or 6MWD among the 3 groups. The 6MWD significantly improved in the combination therapy group compared with the bosentan monotherapy and iloprost monotherapy groups at week 6 ( P = .001) and after 3 months ( P < .001), respectively. Secondary end points significantly improved in the combination therapy group for mean pulmonary artery pressure, cardiac index, and WHO functional classification after 3 months of treatment and for N-terminal pro-brain natriuretic peptide, Minnesota Living with Heart Failure questionnaire scores, and P aO2 after 6 weeks and 3 months of treatment, compared with the monotherapy groups., Conclusions: Initial combination therapy in treatment-naive PAH subjects with WHO functional class III or IV can significantly improve 6MWD, hemodynamics, and quality of life compared with monotherapy. Further studies with large samples and placebo controls are required to assess the tolerability and efficacy of initial combination therapy in patients with PAH. (ClinicalTrials.gov registration NCT01712997)., (Copyright © 2017 by Daedalus Enterprises.)

Objectives: Pulmonary arterial hypertension (PAH) is a progressive disease that can be treated with several medications. Macitentan, an endothelin receptor antagonist (ERA), has received approval as a PAH therapy. We report our data regarding the tolerability in patients with PAH who were switched from bosentan to macitentan., Methods: At the Baylor Pulmonary Hypertension Program, 24 patients with PAH who had been taking bosentan and were switched to macitentan were identified in this retrospective study. Data from these patients who switched from bosentan 125 mg orally twice per day to macitentan 10 mg orally daily (between October 2013 and February 2015) when macitentan became commercially available were collected. Patients were advised to take their last evening dose of bosentan and then take the first dose of macitentan the following morning within 12 to 24 hours of the last bosentan dose. Baseline data and postswitch data, including 6-minute walk distance, brain naturietic peptide, alanine transaminase (ALT) and aspartate transaminase (AST) levels, World Health Organization Functional Class (WHO FC), Borg dyspnea score, presence of peripheral edema., Results: At the time of the switch, the mean age was 58 ± 13 (mean ± standard deviation) years, the duration of disease was 6.6 ± 4.4 years, 21 patients were women, 54% were white, and 25% had idiopathic PAH. The mean duration of follow-up after the switch was 5.7 ± 1.5 months. The 6-minute walk distance was 344 ± 106 m preswitch and 319 ± 85 m postswitch ( P = 0.18). Brain naturietic peptide levels were 91 ± 170 pg/mL preswitch and 90 ± 137 pg/mL postswitch ( P = 0.93). At the time of the switch, 42% were WHO FC II and 50% had edema, and 55% had edema. AST and ALT remained unchanged postswitch. Two patients did not tolerate the switch to macitentan and had to be returned to bosentan: one patient with portopulmonary hypertension developed elevated AST and ALT and the second patient's macitentan was stopped because of malaise and tachyarrhythmia. One patient who underwent a successful liver transplant had macitentan stopped following the transplant., Conclusions: A rapid switch from bosentan to macitentan was well tolerated and safe with maintained WHO FC, with no significant change in edema and liver enzyme levels. The switch from bosentan to macitentan eliminates the need for monthly liver function test monitoring and removes the potential for bosentan treatment interruption.

Aim: The aim of this study was to evaluate N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with systemic sclerosis (SSc)-associated pulmonary arterial hypertension (PAH) and changes after therapy with bosentan., Method: Twenty-one patients with SSc-PAH on bosentan therapy were enrolled. PAH was diagnosed by right heart catheterization. NT-proBNP levels, 6-min walking test (6MWT), Doppler echocardiography to estimated systolic pulmonary arterial pressure (sPAP), New York Heart Association (NYHA) functional class for dyspnea and carbon monoxide lung diffusion capacity (DLco) were recorded at baseline, and after 1 and 2 years. Fifty-two SSc patients without PAH were also evaluated as controls., Results: NT-proBNP plasma levels were significantly higher in SSc-PAH at 385 pg/mL (SD ± 427) than in SSc without PAH and 72 pg/mL (SD ± 52, P < 0.001) at baseline, but did not significantly change following bosentan therapy at 1 year (330 pg/mL [SD ± 291] and 2 years (374 pg/mL [SD ± 291]). However, NYHA class significantly improved at 2 years (P = 0.01) as well as 6MWT (P = 0.04). NT-proBNP levels were positively correlated only with sPAP but not with DLco, NYHA class or 6MWT., Conclusions: NT-proBNP levels were found to be significantly higher in SSc-PAH at baseline. Serial assessment of NT-proBNP in SSc-PAH patients on bosentan therapy showed no relation to the clinical improvement. This suggests that NT-proBNP may lack 'sensitivity to change', but further studies are warranted to assess the role of NT-proBNP as a biomarker of the therapeutic response in larger cohorts of SSc patients., (© 2015 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.)

Purpose: Bosentan reduces pulmonary arterial pressure and improves exercise capacity in patients with pulmonary arterial hypertension (PAH). However, there are limited data regarding the extent to which the changes in echocardiographic variables reflect improvements in exercise capacity. We aimed to assess the improvement of echocardiographic variables and exercise capacity after 6 months of bosentan treatment for PAH., Methods: We performed a prospective study from June 2012 to June 2015 in seven participating medical centers. Echocardiography, including tissue Doppler imaging (TDI) and the 6-minute walk test distance (6MWD), was performed at baseline and after 6 months of bosentan treatment., Results: We analyzed 19 patients with PAH: seven with congenital shunt, six with collagen vascular disease, and six with idiopathic PAH. After bosentan treatment, mean 6MWD increased by 50 meters. Right ventricle (RV) systolic pressure, tricuspid annular plane systolic excursion, myocardial performance index (MPI) derived from TDI (MPI-TDI) of RV and left ventricle (LV), RV fractional area change, and RV ejection fraction were significantly improved. In particular, the magnitude of RV and LV MPI-TDI showed good correlation with changes in the 6MWD., Conclusions: The magnitude of RV and LV MPI-TDI was strongly associated with improvements in exercise capacity. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:28-34, 2017., (© 2016 Wiley Periodicals, Inc.)

Purpose: To report a case of transient, bilateral cotton spots after initiation of macitentan, an endothelin receptor antagonist used for the treatment of pulmonary arterial hypertension., Methods: Case report., Results: A 76-year-old woman with WHO Class IIIb pulmonary arterial hypertension was referred for evaluation of bilateral cotton-wool spots 1 week after starting macitentan therapy. The patient was asymptomatic and visual acuity was 20/25 in each eye. Fluorescein angiography and optical coherence tomography were completed. Given lack of symptoms and alternative treatment options, the patient was observed closely. The cotton-wool spots resolved 8 weeks after presentation and visual acuity remained stable at 20/25. Throughout the observation period, average mean arterial pressure was within normal limits at 84.8., Conclusion: In patients using endothelin receptor antagonists, medication side effect should be considered in the differential diagnosis of cotton-wool spots.

Objective: When bronchopulmonary dysplasia (BPD) is complicated by pulmonary hypertension (PH), morbidity and mortality are significantly increased. BPD-associated PH is not included in the current indications for PH medications. However, limited data demonstrate hemodynamic improvement and decreased mortality with PH-specific treatment. This report describes our 6-year experience treating BPD-associated PH with PH medications, mainly sildenafil., Study Design: The medical records of 20 infants diagnosed with BPD-associated PH at a tertiary pediatric pulmonary hypertension clinic in 2008-2014 were reviewed. Clinical improvement was defined as a decrease in Ross functional class by at least one degree. PH severity was classified by echocardiography as mild, moderate, or severe. Hemodynamic improvement was defined as a decrease in PH severity by at least one level., Results: Eighteen out of 20 patients were treated with PH medications: 12 sildenafil, 5 sildenafil and bosentan, and 1 bosentan. Median follow-up time was 2 years. Mean functional class significantly decreased from 3.2 ± 0.9 at diagnosis to 1.7 ± 0.9 at the last follow-up. Improvement in functional class was observed in 15/16 children (94%). Moderate or severe PH was found in 13/18 children (72%) at diagnosis, and in three (17%, all moderate PH) at the last follow-up. Improvement in PH class by echocardiography was demonstrated in 14/18 children (78%). The survival rate was 95%., Conclusion: Treatment of BPD complicated by PH with PH-specific medications, mainly sildenafil, is associated with improvement in both clinical and hemodynamic parameters and a low mortality rate. Pediatr Pulmonol. 2017;52:77-83. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Background: Pulmonary arterial hypertension (PAH) leads to reduced health-related quality of life (HRQoL). The objectives of this analysis were to evaluate the effect of macitentan on HRQoL in patients with PAH in the Study with an Endothelin Receptor Antagonist in Pulmonary Arterial Hypertension to Improve Clinical Outcome (SERAPHIN) study. The association between baseline HRQoL and long-term outcomes was also investigated., Methods: Patients were randomized to placebo, macitentan 3 mg, or macitentan 10 mg once daily. Patients aged 14 years or older completed the 36-Item Short Form Survey (SF-36) at baseline, at month 6 and month 12, and at the end of treatment (EOT). The absolute change from baseline to month 6 in SF-36 scores was calculated. The time to a clinically meaningful deterioration in the SF-36 physical component summary and mental component summary (PCS and MCS) scores and associations between baseline PCS/MCS scores and time to morbidity/mortality events were also assessed., Results: At month 6, macitentan 10 mg significantly improved seven of eight SF-36 domains and the PCS and MCS scores vs placebo. Macitentan 10 mg significantly reduced the risk of a three-point or greater deterioration in PCS (hazard ratio [HR], 0.60; 95% CI, 0.47-0.76; P < .0001) and MCS scores (HR, 0.76; 95% CI, 0.61-0.95; P = .0173) until EOT vs placebo. Patients with a baseline PCS score greater than the median baseline value had a significantly reduced risk of morbidity/mortality compared with patients with a PCS score less than the median; a similar result was observed for the MCS score., Conclusions: Macitentan significantly improved HRQoL in patients with PAH compared with placebo and significantly reduced the risk of a clinically meaningful HRQoL deterioration. An association between better baseline HRQoL and improved long-term outcomes was shown., Trial Registry: ClinicalTrials.gov; No.: NCT00660179; URL: clinicaltrials.gov., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Aim: To provide a pharmacoeconomic estimate of macitentan versus bosentan in therapy for pulmonary arterial hypertension (PAH)., Subject and Methods: An analysis was carried out on the basis of a social perspective for patients, whose mean age was 50 years. A budget impact analysis was performed without discounting; with the time horizon of the study being 5 years. Assessing the cost- effectiveness of endothelin receptor antagonists used a Markov model based on the meta-analysis of clinical trials. The cost of bosentan was calculated from the 2016 registered prices with VAT. That of macitentan was estimated from the expected price of 170,000 rubles per 10-mg dose pack #28 if the drug is included in the List of Essential Medicines with VAT. The cost of sildenafil and iloprost was consistent with the January-to-November 2016 auctio., Results: At cost-effectiveness assessment costs and outcomes were both discounted at an annual rate of 3,5%., Results: After 5 years of therapy with macitentan in patients with baseline Functional Class (FC) II PAH, the proportion of patients with FC I-II was shown to be 2.6% more than that during therapy with bosentan (20.1 and 17.5%, respectively), and that of the died patients was 1.5% lower (69.5 and 71%, respectively). In baseline FC III PAH following 5 years, the proportion of patients with FC III PAH on initial macitentan treatment was 1% more than that on bosentan therapy (8.1 and 7.1%, respectively), and that of the died patients was 0.5% lower (87.2, and 87.7%, respectively). The cost-effectiveness analysis shows that therapy with macitentan versus bosentan not only causes some increase in life expectancy in terms of quality of life (by 0.414 and 0.230 QALYs in FC II and III PAH, respectively), but also results in a small cost decrease in FC II and III PAH (by 11,000 and 16,000 rubles per patient, respectively). Thus, macitentan is a dominant alternative versus bosentan. The budget impact analysis indicates that when bosentan is replaced with macitentan, the reduction in health care costs in the Russian Federation will amount to 1.9 million rubles over 5 years, and in all budgetary costs will be 14.7 million rubles., Conclusion: Treatment with macitentan in patients with FC II-III PAH is more cost-effective than that with bosentan and does not require an increase in budget costs.

The results of evaluating the efficacy and safety of bosentan in patients with pulmonary arterial hypertension (PAH), as shown by the data of foreign randomized controlled trials and the authors' own experience, convincingly demonstrate that the introduction of the drug into clinical practice has led to a significant improvement of the possibilities of drug therapy in patients with this serious illness. Bosentan substantially improves physical activity in patients, reduces the severity of clinical symptoms, slows down the rates of disease progression, and prolongs survival in patients with different forms of PAH.