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The purpose of this study was to prepare and evaluate multiple unit mini tablets (MTs) of prolonged released (PR) bosentan (BSN) and fast release (FR) sildenafil citrate (SDC) on the basis of encapsulation method for the effective management of pulmonary artery hypertension. The system consists of MTs are in the form of uncoated tablets containing the superdisintegrating agents where as the PRMTs contains the polymer with film coating. All the units are prepared by direct compression method and encapsulated using size 1 hard gelatin capsule shells. The formulations were evaluated for differential scanning calorimetry, dissolution test and post compression studies for their quality attributes and it was found that all the parameters were in the acceptable limits. The optimized formulation for BSN PRMTs i.e BS3 which contains 5 % HPMC K15M shows a promising sustained release profile of 82.31 % in 24 h similarly FRMTs of SDC of formulation SD6 that having 3 % of magnesium aluminium silicate shows about 90 % of drug release within 15 min. The in-vivo pharmacokinetic characterization of the system was carried out using wister rats where the AUC value for SDC FRMTs and BSN PRMTs was found to be 94256.88625 ± 123.65 ng h/mL and 142438.084 ± 324.11 ng h/mL respectively. The other pharmacokinetics are also determined and found to be satisfactory. The six months stability samples showed no significant change in the drug content, hardness and uniformity of the content of the optimized formulations.

Bosentan is choice of drug for pulmonary arterial hypertension. It belongs to BCS class-II category. Due to poor solubility in aqueous media, treatment leads to frequent dosing & increasing cost of therapy subsequently. One cannot unseen the shortcomings of commonly existing solubility enhancement techniques such as physical and chemical modifications of the drug, salt formation, solid dispersion, complexation because of the need for sophisticated equipment, decreased yield, incomplete removal of organic solvents, etc. The novel hybridization technique is a fusion of complexation and liquisolid technique. In this research work, Bosentan was complexed with captisol in the first step. In the second step, the complex was dispersed in non-volatile solvent & mixed with the carrier using mortar-pestle followed by the addition of coating material to form a free-flowing powder. It was then compressed into tablets by mixing with other excipients. The formulation was characterized by phase solubility study, DSC, FTIR, and XRD to confirm drug-excipients compatibility, crystallinity etc. The phase solubility study showed ∼28.85 fold increase in solubility. From screening, Avicel PH101 & Parteck SLC 500 as carrier and coating material respectively & PEG-600 as non-volatile solvent were selected. Explotab as super-disintegrant and Pearlitol 100SD as direct compressible excipient were used. Optimization by 32 factorial design gave Bosentan tablet with disintegrate in time of 7–8 min and showed 87.264±0.823% drug release in 30 min higher than marketed tablet i.e. 61.750±1.226%. From the stability study, the Novel hybridization technique was proved as a choice for solubility enhancement.

Background: Persistent Pulmonary Hypertension of the newborn (PPHN) is characterized by sustained elevated Pulmonary Artery Pressure (PAP). Drug resistance and the adverse effects of current therapeutic agents warrant investigation of other targeted therapies. Bosentan has shown benefits in affected neonates. However, trials reported the association with unwanted effects. Thus, in this study, we assess another agent in the same family, Macitentan. However, its efficacy in the treatment of PPHN is not yet reported. Hence, this study evaluated the effect of Macitentan compared to Bosentan in terms of efficacy and safety in the treatment of PPHN., Methods: This randomized, double-blinded non-inferiority clinical trial was conducted in Shahid Akbar Abadi hospital, Tehran, Iran. Sixty clinically stable neonates with signs suggestive of PPHN were randomly allocated into two groups (n = 30 in each group) and they received either Bosentan 1 mg/kg/dose BD (twice daily) or Macitentan 1 mg/kg/dose BD simultaneously with sildenafil. The echocardiographic and laboratory indices of efficacy and safety were compared between groups. SPAP (systolic pulmonary artery pressure) was used to assess the non-inferiority of the Macitentan compared to the Bosentan in their respective doses used in the study., Results: Participants' mean (SD) age was 3.53 (1.21) days, and 55% were female. No mortality case occurred. SPAP was reduced in both Bosentan and Macitenan groups with the mean difference in SPAP of 9 (95% CI: 7.34-10.65) in Bosentan and SPAP mean difference of 14 (95% CI: 12.12-15.86) in Macitentan group. Categorical comparison of primary outcome improvement showed that Macitentan was superior to Bosentan with a 10% non-inferiority margin. Similar results were obtained in other echocardiographic indices. Also, no significant alterations were observed in laboratory safety parameters., Conclusion: Macitentan 1 mg/kg/dose BD (twice daily) is non-inferior to Bosentan 1 mg/kg/dose BD in improving echo outcomes of PPHN and it was even more effective in improving some of these. Also, it is non-inferior to Bosentan in terms of safety. TRIAL REGISTRY NUMBER: (IRCT20160120026115N9)., Competing Interests: Declaration of competing interest The authors have no competing interests., (Copyright © 2024 Taiwan Pediatric Association. Published by Elsevier B.V. All rights reserved.)

Background: Persistent pulmonary hypertension of the newborn (PPHN) contributes to neonatal hypoxemia and is associated with a high mortality. Some PPHN patients are unresponsive to inhaled nitric oxide (iNO). Bosentan, an oral endothelin-1 receptor antagonist, reduces pulmonary vascular resistance and hence may play a role in the treatment of PPHN. Methods: A retrospective medical records review was performed in newborns who received oral bosentan as an adjunctive therapy for treatment of PPHN between January 2013 and February 2016 at the neonatal intensive care unit of Songklanagarind Hospital. The main outcomes were the effect of bosentan on oxygenation and hemodynamic status after commencement of treatment and the safety of bosentan. Results: Forty neonates at a median (IQR) gestation of 38 (36.8–40) weeks and an initial median (IQR) oxygen index (OI) of 29.2 (13.4–40.1) received bosentan therapy. Oral bosentan was commenced at a median (IQR) age of 27 (14.5–40.2) hours and the mean (SD) duration of treatment was 6.2 (3.1) days. The OI, alveolar-arterial oxygen difference (AaDO2) and oxygen saturation (SpO2) improved significantly at 2 h after treatment (p = 0.002, p = 0.01 and p

A 72-year-old woman was admitted to our hospital and was diagnosed with interstitial pneumonia (IP) associated with amyopathic dermatomyositis (ADM). The patient experienced three acute IP exacerbations in the 7 years that followed, which were each treated and resolved with steroid pulse therapy. The patient was closely examined for respiratory failure with right heart catheterization (RHC), which demonstrated that she had a mean pulmonary artery pressure (mPAP) of 34 mmHg. The patient was thus diagnosed as having pulmonary hypertension (PH) associated with anti-synthetase syndrome (ASS) and was started on bosentan therapy, which led to improvements in mPAP as well as in subjective symptoms over time. Indeed, she had had no acute exacerbations with serum markers of IP remaining low over 6 years following initiation of bosentan therapy, suggesting that bosentan may have a role in controlling IP. In addition, she was confirmed to be anti-ARS antibody-positive after 5 years of bosentan therapy, when anti-aminoacyl tRNA synthetase (anti-ARS) antibody testing became available.

Pulmonary hypertension is a poor prognostic factor in patients with interstitial lung disease. No established treatment exists for pulmonary hypertension secondary to interstitial pneumonia. We describe the case of an 81-year-old woman with idiopathic pulmonary fibrosis (IPF), who was admitted to our hospital due to aggravation of dyspnea and decreased oxygen saturation, as well as onset of orthopnea and rapidly progressing edema. The transthoracic echocardiography and right heart catheterization showed the mean pulmonary artery pressure was 39 mmHg and the mean pulmonary capillary wedge pressure was 9 mmHg. After various examinations, the diagnoses of pulmonary hypertension (PH) due to IPF and of congestive heart failure secondary to PH were established. Diuretic therapy was started, but the patient's condition showed poor improvement. Subsequent initiation of oral bosentan therapy led to improvement in symptoms and findings. At the follow-up assessment one year later her pulmonary function showed no significant changes and no apparent worsening of arterial blood gases, with evident improvement of PH, WHO functional class, maximum exercise tolerance on treadmill exercise testing, right heart catheterization, and transthoracic echocardiography. This report describes a case of successful treatment with bosentan for severe pulmonary hypertension in a patient with idiopathic pulmonary fibrosis. We also present a review of the literature on treatment of pulmonary hypertension in patients with chronic lung disease. Bosentan appears to be efficacious in some patients with pulmonary hypertension secondary to idiopathic interstitial pneumonitis.

Objectives: Pulmonary arterial hypertension (PAH) is a chronic and progressive disease that, if left untreated, shortens the life expectancy of patients. Endothelin receptor antagonists, such as macitentan and bosentan, play an essential role in improving the patient's symptoms, quality of life, and life expectancy. This study aimed to evaluate the cost-utility of macitentan compared with bosentan in treating PAH from the health system perspective in Iran., Methods: For evaluating the cost-effectiveness of macitentan, a Markov model consisting of 5 states, functional class (FC) I, FC II, FC III, FC IV, and death, was designed using the TreeAge software. The lifetime time horizon and a 3-month cycle length were set. Patients entered the model from FC II or FC III states based on the initial probabilities. Costs were measured in US dollars (USD), and outcomes were measured in terms of quality quality-adjusted life-years (QALYs). Consequently, the incremental cost-effectiveness ratio (ICER) was calculated. In addition, sensitivity analysis was performed to determine the robustness of the model by examining the possible effects of uncertainties on the final result., Results: The costs of treatment with macitentan and bosentan in PAH in Iran were calculated at 19 429 and 17 246 USD, and the outcomes were 4.02 and 3.04 QALYs, respectively. Therefore, ICER was calculated at 2233.46 USD/QALY. One-way sensitivity analysis demonstrates that the model is robust; nevertheless, it is most sensitive to the price of macitentan and bosentan., Conclusion: Treatment with macitentan was associated with both higher costs and QALYs than bosentan. Nevertheless, it is considered the cost-effective treatment strategy in Iran given that the calculated ICER falls below the willingness to pay threshold., (Copyright © 2022 International Society for Health Economics and Outcomes Research. Published by Elsevier Inc. All rights reserved.)

Quantifying drug-protein interactions has a pivotal role in both early phase drug development and clinical processes. Diverse affinity chromatographic methods like nonlinear chromatography can realize such quantification, however, their throughputs are challenged due to the loading of a single ligand during each run. This work derivatized a new equation for simultaneously determining the bindings of two ligands to a protein relying on assumption that the retention factors of the ligands are dependent on their injection amounts. Experimental validation of the derivatization was performed on an immobilized endothelin A receptor (ET A R) column taking ambrisentan, bosentan, and macitentan as injecting solutes. All three ligands presented a decrease in retention times along with increasing moles of injection when they were singly injected into the column. Likewise, negative relationships between the retentions and the injection amounts were observed when co-injection of ambrisentan/bosentan or bosentan/macitentan was performed, thus confirming the assumption of the derivatization. The association constants of ambrisentan, bosentan, and macitentan binding to ET A R were (1.42 ± 0.78)×10 4 , (1.81 ± 0.22)×10 4 , and (1.71 ± 0.41)×10 4  L/mol when each of them was singly loaded on the column. Such data displayed insignificant changes in four weeks thereby providing a proof of good stability of the column during the period. Co-injections of the two ligand pairs resulted in the association constants of (2.97 ± 0.13)×10 4 for ambrisentan, (2.51 ± 0.87)×10 4 for bosentan, and (2.88 ± 0.34)×10 4  L/mol for macitentan. These results were in good agreement with the calculation when each of the ligands was injected alone into the column and demonstrated little differences from the data by nonlinear chromatography. Owning to the simultaneous analysis of two ligands, the throughput of the proposed method was twofold higher than the typical assays including frontal analysis, zonal elution, and nonlinear chromatography. It is possible to become an alternative for rapid analysis of drug-protein 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 © 2022 Elsevier B.V. All rights reserved.)

There is cumulating evidence that endothelin-1 (ET-1) may play a role in migraine, however controversial findings still impede a conclusion to be drawn. Herein we tested the hypothesis that endothelin ETB receptors are major contributors to migraine-like responses. ET-1, IRL-1620 (selective ETB receptor agonist) or CGRP were injected into the trigeminal ganglion (TG) of female Wistar rats, and the development of periorbital mechanical allodynia was assessed hourly with von Frey hairs. Twenty-four hours later, rats were exposed to an aversive light for 1 h, after which the reactivation of periorbital mechanical allodynia (indicating photic sensitivity) was assessed up to 4 h. Moreover, the effect of systemic Bosentan (ETA/ETB receptors antagonist) or the selective antagonists of ETA (BQ-123) and ETB (BQ-788) receptors injected into the TG were evaluated against CGRP-induced responses. ET-1 and IRL-1620 injection into the TG induced periorbital mechanical allodynia and photic sensitivity. Bosentan attenuated periorbital mechanical allodynia but failed to affect photic sensitivity induced by CGRP. Selective blockade of ETB receptors in the TG fully prevented the development of periorbital mechanical allodynia and photic sensitivity induced by CGRP, but ETA receptor blockade caused only a slight reduction of periorbital mechanical allodynia without affecting photic sensitivity. ETB receptor-operated mechanisms in the TG may contribute to migraine-like responses in female rats., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The management of acute hypoxemic respiratory failure (AHRF) in newborns continues to be a clinical challenge with elevated risk for significant morbidities and mortality, especially when accompanied with persistent pulmonary hypertension of the newborn (PPHN). PPHN is a syndrome characterized by marked hypoxemia secondary to extrapulmonary right-to-left shunting across the ductus arteriosus and/or foramen ovale with high pulmonary artery pressure and increased pulmonary vascular resistance (PVR). After optimizing respiratory support, cardiac performance and systemic hemodynamics, targeting persistent elevations in PVR with inhaled nitric oxide (iNO) therapy has improved outcomes of neonates with PPHN physiology. Despite aggressive cardiopulmonary management, a significant proportion of patients have an inadequate response to iNO therapy, prompting consideration for additional pulmonary vasodilator therapy. This article reviews the pathophysiology and management of PPHN in term newborns with AHRF while highlighting both animal and human data to inform a physiologic approach to the use of PH-targeted therapies., (Copyright © 2022. Published by Elsevier Ltd.)

OBJETIVO: Estabelecer uma revisão acerca do manejo diagnóstico e terapêutico da hipertensão pulmonar na população pediátrica, com ênfase nos aspectos farmacológicos. FONTES DOS DADOS: Busca eletrônica de publicações nas bases de dados MEDLINE/PubMed, LILACS e Cochrane Collaboration. Estabeleceu-se uma estratégia de busca priorizando a identificação de ensaios clínicos (controlados ou não controlados), revisões sistemáticas e diretrizes publicados nos últimos 10 anos. SÍNTESE DOS DADOS: Muitos avanços têm sido incorporados ao conhecimento da hipertensão pulmonar nos últimos anos. Aspectos relativos a diferenças nos mecanismos fisiopatológicos da doença entre as diferentes faixas etárias têm modificado o tratamento e o prognóstico dos pacientes. Uma ação combinada de propriedades vasodilatadoras mais seletivas e ação antiproliferativa e o emprego de novas drogas representam princípios fundamentais das novas propostas terapêuticas. Para considerar benefícios associados à utilização dessas novas terapêuticas, é fundamental que cada paciente tenha a sua doença adequadamente diagnosticada, classificado o grau de comprometimento da doença e a sua capacidade de reatividade vascular estabelecida, o que é mais difícil na população pediátrica. CONCLUSÃO: Até o momento, não existe um tratamento que possa ser considerado ideal para o manejo da hipertensão pulmonar. Considerando a possibilidade do emprego de novas drogas, a maioria dos estudos existentes foi conduzida em populações adultas. Poucos dados são disponíveis para crianças, sendo a maioria ensaios clínicos não controlados e séries de casos. Considerando diferenças já estabelecidas entre os mecanismos da doença e aspectos prognósticos entre as diferentes faixas etárias, é difícil afirmar que tais drogas possam ser incorporadas, com as mesmas indicações e os mesmos resultados, ao tratamento da hipertensão pulmonar infantil.OBJECTIVE: To perform a review of the diagnostic and therapeutic management of pulmonary hypertension in the pediatric population, with emphasis on pharmacological factors. SOURCES: Electronic search of publications on the MEDLINE/PubMed, LILACS and Cochrane Collaboration databases. The search strategy adopted gave priority to the identification of clinical trials (controlled or uncontrolled), systematic reviews and directives published during the last 10 years. SUMMARY OF THE FINDINGS: Many advances have been incorporated into our understanding of pulmonary hypertension during recent years. Issues related to differences in the pathophysiological mechanism of the disease between different age groups have altered both the treatment and prognosis of patients. The combined effect of more selective vasodilatory properties and antiproliferative action and the employment of new drugs are the basic principles of new treatment proposals. In order to be able to gauge the benefits associated with the use of these new therapies, it is of fundamental importance that all patients have their disease correctly diagnosed, the degree of functional compromise classified and their vascular reactivity capacity established, which is more difficult with pediatric patients. CONCLUSIONS: To date there is no treatment that can be considered ideal for the management of pulmonary hypertension. With reference to the possibility of employing new drugs, the majority of studies that have been published were undertaken with adult populations. Few data are available on children, and the majority of studies are uncontrolled trials or case series. Taking into account differences that have already been established between different age groups in terms of disease mechanisms and prognostic aspects, it is difficult to claim that these drugs can be incorporated into the treatment of childhood pulmonary hypertension with the same indications and results.

5-fluorouracil (5-FU) is a widely used chemotherapeutic agent but cardiotoxicity challenges its clinical usefulness. Thus, searching for more cardioprotective drugs is highly required to prevent the accompanied cardiac hazards. Up to date, the different mechanisms involved in 5-FU cardiotoxicity are still unclear and there is no evaluation of bosentan's role in controlling these cardiac complications. This forced us to deeply study and evaluate the possible cardiopreserving properties of bosentan and different mechanisms involved in mediating it. 32 Wistar albino rats were included in our experiment and induction of cardiotoxicity was performed via administration of 5-FU (150 mg/kg) on 5th day of the experiment by intraperitoneal (i.p.) injection with or without co-administration of bosentan (50 mg/kg/day) orally for 7days. Our data revealed that 5-FU could induce cardiotoxicity which was detected as significant increases of troponin I, lactate dehydrogenase (LDH), creatine kinase- MB (CK-MB), endothelin receptors, malondialdehyde (MDA), toll like receptor4 (TLR4), myeloid differentiation primary response 88 (MyD88), nuclear factor kappa B (NFκB), and caspase 3 levels. However, there is marked decrease in endothelial nitric oxide synthase (eNOS), reduced glutathione (GSH) and total antioxidant capacity (TAC). In addition, the histopathological examination showed severe toxic features of cardiac injury. Interestingly, co-administration of bosentan could ameliorate 5-FU-induced cardiotoxicity via improving the detected biochemical and histopathological changes besides modulation of TLR4/MyD88/NFκB signaling pathway, eNOS, and endothelin receptors. Bosentan had a significant cardioprotective effect against 5-FU induced cardiac damage. This effect may be attributed to its ability to inhibit endothelin receptors, stimulates eNOS, anti-oxidant, anti-inflammatory, anti-apoptotic properties with modulation of TLR4/MyD88/NFκB signaling pathway., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background/aims: Sex dependent differences in coronary artery vasoregulation may be due to variations in responses to endogenous vasoactive compounds including endothelin (ET-1) and nitric oxide (NO)., Methods: Septal coronary arteries (<200 μm) from healthy, sexually mature male, female and ovariectomized (i.e. surgical menopause) Sprague-Dawley rats were used. Myogenic tone, measured by pressure myography, was initially determined for all vessel segments studied before and after exposure to the nonselective ET A /ET B receptor blocker, bosentan (1 μM). Vasoconstrictor responses (vascular endothelium intact) to cumulative ET-1 (10 -12 - 10 -9  M) were assessed in a separate set of septal coronary vessels. Additional studies, examined the vasoconstrictor effects of ET-1 after NO blockade with L-NAME (200 μM)., Results: Myogenic tone was 26 ± 7% in male, 20 ± 7% in female (p = 0.04 versus male) and 24 ± 3% in ovariectomized (p = NS versus male/female) vessels. Antagonism of ET-1 receptors produced a greater reduction in myogenic tone in male, compared to female rats over a similar range of intraluminal pressure (20-80 mmHg). Robust constrictor responses to cumulative concentrations of ET-1 were observed in all vessels; however, male rats exhibited greater sensitivity to vasoconstrictor effects of ET-1. After exposure to L-NAME vessel responses to ET-1 were normalized in male and female (not studied in ovariectomized) groups., Conclusions: These findings confirm marked sex differences for myogenic tone and vessel constrictor responses to ET-1 in coronary resistance vessels. Results also suggest greater sensitivity to vasoconstrictor effects of ET-1 in male coronary resistance vessels., Competing Interests: Declaration of conflicting interests The authors declare no conflict of interest regarding research, authorship or publication of the present paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Pancreatic adenocarcinoma is currently one of the leading causes of cancer-related death worldwide. The high rate of mortality in pancreatic cancer patients is due to the inability to detect early-stage disease and the disease being highly refractory to therapy. Gemcitabine has been the standard chemotherapy for advanced pancreatic cancer patients for the last two decades. However, gemcitabine resistance develops within a few weeks of treatment, and the associated mechanism remains poorly understood. Therefore, a novel therapeutic strategy is needed to overcome the limited clinical efficacy of gemcitabine in pancreatic adenocarcinoma. In this study, we demonstrated that ET-1/ETAR axis gene expression was upregulated in pancreatic cancer cells after treatment with gemcitabine. Additionally, ETAR expression was significantly higher in tumor tissues than in normal tissues, and patients with high ETAR expression had a notably worse overall survival rate than those with low ETAR expression. Furthermore, our results revealed that bosentan, an ETAR antagonist, enhanced the growth-inhibiting and proapoptotic effects of gemcitabine on pancreatic cancer cells. Thus, our findings indicate that blockade of the ET-1/ETAR axis signaling pathway promotes the antiproliferative effect of gemcitabine on pancreatic cancer. Therefore, combination of ETAR blockade and gemcitabine serves as an effective therapeutic approach to achieve clinical benefits in pancreatic adenocarcinoma patients., 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 © 2020 Elsevier Inc. All rights reserved.)

Organic anion transporting polypeptide 1B1 (OATP1B1), a liver-specific uptake transporter, was associated with drug induced liver injury (DILI). Screening and identifying potent OATP1B1 inhibitors with little toxicity is of great value in reducing OATP1B1-mediated DILI. Flavonoids are a group of polyphenols ubiquitously present in vegetables, fruits and herbal products, some of them were reported to produce transporter-mediated DDI. Our objective was to investigate potential inhibitors of OATP1B1 from 99 flavonoids, and to assess the hepatoprotective effects on bosentan induced liver injury. Eight flavonoids, including biochanin A, hispidulin, isoliquiritigenin, isosinensetin, kaempferol, licochalcone A, luteolin and sinensetin exhibited significant inhibition (>50 %) on OATP1B1 in OATP1B1-HEK293 cells, which reduced the OATP1B1-mediated influx of methotrexate, accordingly decreased its cytotoxicity in OATP1B1-HEK293 cells and increased its AUC 0-t in different extents in rats, from 28.27%-82.71 %. In bosentan-induced rat liver injury models, 8 flavonoids reduced the levels of serum total bile acid (TBA) and the liver concentration of bosentan in different degrees. Among them, kaempferol decreased the concentration most significantly, by 54.17 %, which indicated that flavonoids may alleviate bosentan-induced liver injury by inhibiting OATP1B1-mediated bosentan uptake. Furthermore, the pharmacophore model indicated the hydrogen bond acceptors and hydrogen bond donors may play critical role in the potency of flavonoids inhibition on OATP1B1. Taken together, our findings would provide helpful information for predicting the potential risks of flavonoid-containing food/herb-drug interactions in humans and alleviating bosentan -induced liver injury by OATP1B1 regulation., 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 © 2020 Elsevier B.V. All rights reserved.)

Bosentan, an endothelin receptor antagonist, has been widely used as a first-line drug for the treatment of pulmonary arterial hypertension (PAH). In addition, bosentan is approved for patients with digital ulcers related to systemic sclerosis. Liver dysfunction is a major adverse effect of bosentan and may lead to discontinuation of therapy. The purpose of this study was to identify genomic biomarkers to predict bosentan-induced liver injury. A total of 69 PAH patients were recruited into the study. An exploratory analysis of 1936 single-nucleotide polymorphisms (SNPs) in 231 genes involved in absorption, distribution, metabolism, and elimination of multiple medications using Affimetrix DMET™ (Drug Metabolism Enzymes and Transporters) chips was performed. We extracted 16 SNPs (P <  0.05) using the Jonckheere-Terpstra trend test and multiplex logistic analysis; we identified two SNPs in two genes, CHST3 and CHST13, which are responsible for proteoglycan sulfation and were significantly associated with bosentan-induced liver injury. We constructed a predictive model for bosentan-induced liver injury (area under the curve [AUC]: 0.89, sensitivity: 82.61%, specificity: 86.05%) via receiver operating curve (ROC) analysis using 2 SNPs and 2 non-genetic factors. Two SNPs were identified as potential predictive markers for bosentan-induced liver injury in Japanese patients with pulmonary arterial hypertension. This is the first pharmacogenomics study linking proteoglycan sulfating genes to drug-induced liver dysfunction, a frequently observed clinical adverse effect of bosentan therapy. These results may provide a way to personalize PAH medicine as well as provide novel mechanistic insights to drug-induced liver dysfunction., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Persistent pulmonary hypertension of the newborn (PPHN) contributes to neonatal hypoxemia and is associated with a high mortality. Some PPHN patients are unresponsive to inhaled nitric oxide (iNO). Bosentan, an oral endothelin-1 receptor antagonist, reduces pulmonary vascular resistance and hence may play a role in the treatment of PPHN., Methods: A retrospective medical records review was performed in newborns who received oral bosentan as an adjunctive therapy for treatment of PPHN between January 2013 and February 2016 at the neonatal intensive care unit of Songklanagarind Hospital. The main outcomes were the effect of bosentan on oxygenation and hemodynamic status after commencement of treatment and the safety of bosentan., Results: Forty neonates at a median (IQR) gestation of 38 (36.8-40) weeks and an initial median (IQR) oxygen index (OI) of 29.2 (13.4-40.1) received bosentan therapy. Oral bosentan was commenced at a median (IQR) age of 27 (14.5-40.2) hours and the mean (SD) duration of treatment was 6.2 (3.1) days. The OI, alveolar-arterial oxygen difference (AaDO 2 ) and oxygen saturation (SpO 2 ) improved significantly at 2 h after treatment (p = 0.002, p = 0.01 and p < 0.001, respectively). In 21 (52.5%) neonates who received iNO and bosentan, the median OI (IQR) was 34.2 (29.0-42.6) with a significant decrease of OI at 6 h (p = 0.005) after treatment. In 19 (47.5%) neonates who received bosentan alone, the median OI (IQR) was 13.0 (9.8-30.9) with a significant decrease of OI in 2 h (p = 0.01) after treatment. The blood pressures before and after bosentan treatment were not statistically significantly different. The mortality rate was 12.5% (5/40)., Conclusion: Oral bosentan may be a safe and effective treatment to improve oxygenation in neonates with PPHN. Bosentan can be used as an adjuvant therapy with iNO and can be an alternative therapy option in mild-to-moderate PPHN., (Copyright © 2017. Published by Elsevier B.V.)

Physiologically based pharmacokinetic models were constructed for hepatic organic anion-transporting polypeptides (OATPs) and cytochrome P450 3A (CYP3A) substrates (bosentan, repaglinide, clarithromycin, and simeprevir), a CYP3A probe substrate (midazolam), and selective inhibitors for OATPs (rifampicin) and CYP3A (itraconazole), although the role of OATPs in the hepatic uptake of clarithromycin is unclear. The pharmacokinetic data were obtained from our previous clinical drug-drug interaction (DDI) study. Parameters optimized from clinical PK data were confirmed to reproduce their blood concentrations in control phase. DDIs with rifampicin and itraconazole were simulated using in vivo R dif (ratio of diffusional uptake to active uptake) and β (the fraction of the sum of intrinsic clearances for metabolism and biliary excretion in all possible itineraries of intracellular drugs including basolateral efflux) estimated by static analyses based on the extended clearance concept, in vivo inhibition constant (K i ) for hepatic OATPs reported previously, and in vivo K i for CYP3A determined from DDI data with midazolam and itraconazole. Sensitivity analyses showed the magnitudes of DDIs largely depended on R dif and β. In conclusion, our approach using physiologically based pharmacokinetic modeling showed that the rational estimation of parameters governing rate-determining process of hepatic elimination is critical to accurately predict DDI magnitudes involving OATPs/CYP3A inhibition., (Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Failure of the normal circulatory adaptation to extrauterine life results in persistent pulmonary hypertension of the newborn (PPHN). Although this condition is most often secondary to parenchymal lung disease or lung hypoplasia, it may also be idiopathic. PPHN is characterized by elevated pulmonary vascular resistance with resultant right-to-left shunting of blood and hypoxemia. Although the preliminary diagnosis of PPHN is often based on differential cyanosis and labile hypoxemia, the diagnosis is confirmed by echocardiography. Management strategies include optimal lung recruitment and use of surfactant in patients with parenchymal lung disease, maintaining optimal oxygenation and stable blood pressures, avoidance of respiratory and metabolic acidosis and alkalosis, and pulmonary vasodilator therapy. Extracorporeal membrane oxygenation is considered when medical management fails. Although mortality associated with PPHN has decreased significantly with improvements in medical care, there remains the potential risk for neurodevelopmental disability which warrants close follow-up of affected infants after discharge., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: The objective of this clinical trial was to evaluate the long-term effect of endothelin receptor antagonism with bosentan on the morbidity and mortality of patients with severe chronic heart failure., Background: Endothelin may play a role in heart failure, but short-term clinical trials with endothelin receptor antagonists have reported disappointing results. Long-term trials are lacking., Methods: In 2 identical double-blind trials, we randomly assigned 1,613 patients with New York Heart Association functional class IIIb to IV heart failure and an ejection fraction <35% to receive placebo or bosentan (target dose 125 mg twice daily) for a median of 1.5 years. The primary outcome for each trial was clinical status at 9 months (assessed by the hierarchical clinical composite); the primary outcome across the 2 trials was death from any cause or hospitalization for heart failure., Results: Bosentan did not influence clinical status at 9 months in either trial (p = 0.928 and p = 0.263). In addition, 321 patients in the placebo group and 312 patients in the bosentan group died or were hospitalized for heart failure (hazard ratio [HR]: 1.01; 95% confidence interval [CI]: 0.86 to 1.18; p = 0.90). The bosentan group experienced fluid retention within the first 2 to 4 weeks, as evidenced by increased peripheral edema, weight gain, decreases in hemoglobin, and an increased risk of hospitalization for heart failure, despite intensification of background diuretics. During follow-up, 173 patients died in the placebo group and 160 patients died in the bosentan group (HR: 0.94; 95% CI: 0.75 to 1.16). About 10% of the bosentan group showed meaningful increases in hepatic transaminases, but none had acute or chronic liver failure., Conclusions: Bosentan did not improve the clinical course or natural history of patients with severe chronic heart failure and but caused early and important fluid retention., (Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Biased ligands represent a new strategy for the development of more effective and better tolerated drugs. To date there has been a paucity of research exploring the potential of ligands that exhibit either G protein or β-arrestin pathway selectivity at the endothelin receptors. Re-analysis of data may allow researchers to determine whether there is existing evidence that the endogenous ET peptides or currently available agonists and antagonists exhibit pathway bias in a particular physiological or disease setting and this is explored in the review. An alternative to molecules that bind at the orthosteric site of the ET receptors are cell penetrating peptides that interact with a segment of an intracellular loop of the receptor to modify signalling behaviour. One such peptide IC2B has been shown to have efficacy in a model of pulmonary arterial hypertension. Finally, understanding the molecular pathways that contribute to disease is critical to determining whether biased ligands will provide clinical benefit. The role of ETA signalling in ovarian cancer has been delineated in some detail and this has led to the suggestion that the development of ETA G protein biased agonists or β-arrestin biased antagonists should be explored., (Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.)

Aims: Pulmonary hypertension (PH) is a common complication of chronic hypoxic lung diseases. Bone morphogenetic protein (BMP) and endothelin-1 signaling pathways have been shown to be altered in hypoxic PH and to play crucial roles in the associated pulmonary artery remodeling. We, therefore, aimed to study the potential link between hypoxia and the alteration of BMP and endothelin-1 signaling observed in pulmonary artery smooth muscle cells (PA-SMCs) in hypoxic PH., Materials and Methods: Human PA-SMCs were treated with hypoxia-mimetic agent cobalt chloride (CoCl2; 100μM), with or without pretreatment with a dual endothelin receptor antagonist bosentan (10μM). Expressions of preproendothelin-1 (PPET1), BMP type 2 receptor (BMPR-2), and one BMP signaling target gene, the inhibitor of DNA binding 1 (ID1) were evaluated by real time quantitative polymerase chain reaction. BMP2-treated PA-SMCs were assessed for Smad1/5/8 signaling activation by Western Blotting., Key Findings: Treatment of PA-SMCs with CoCl2 increased PPET1 gene expression, while it did not alter expressions of endothelin converting enzyme, endothelin receptor type A or type B. Hypoxia-mimetic agent CoCl2 decreased the expressions of BMPR-2 and ID1 maximally after 3- and 6-hour treatment respectively, while CoCl2 treatment progressively increased noggin expression. Bosentan pretreatment restored expressions of BMPR-2 and ID1, as well as the activation (by phosphorylation) of Smad1/5/8 signaling induced by BMP2., Significance: Hypoxia induces the downregulation of the BMP signaling in PA-SMCs, at least, partly through the endothelin system. In hypoxic PH, increased endothelin-1 production might therefore contribute to the altered BMP signaling and subsequent PA-SMC hyperplasia., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Cytochrome P450 2C9 (CYP2C9) is an important member of the cytochrome P450 enzyme superfamily, with 57 CYP2C9 allelic variants being previously reported. Recently, we identified 22 novel alleles (*36 -*56 and N418T) in the Han Chinese population. This study aims to assess the catalytic activities of wild-type (CYP2C9*1) and 36 CYP2C9 allelic variants found in the Chinese population toward phenytoin (PHT) in vitro. Insect microsomes expressing CYP2C9*1 and 36 CYP2C9 variants were incubated with 1-200 μM phenytoin for 30 min at 37 °C. Then, these products were extracted and the signal detection was performed by HPLC-MS/MS. The intrinsic clearance (Vmax/Km) values of all variants, with the exception of CYP2C9*2, CYP2C9*11, CYP2C9*23, CYP2C9*29, CYP2C9*34, CYP2C9*38, CYP2C9*44, CYP2C9*46 and CYP2C9*48, were significantly different from CYP2C9*1. CYP2C9*27, *40, *41, *47, *49, *51, *53, *54, *56 and N418T variant exhibited markedly larger values than CYP2C9*1 (>152.8%), whereas 17 variants exhibited smaller values (from 48.6% to 99.9%) due to larger Km and/or smaller Vmax values than CYP2C9*1. The findings suggest that more attention should be paid on subjects carrying these infrequent CYP2C9 alleles when administering phenytoin in clinic., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

The objective of the present study was to develop an optimal equation for the pediatric dose-response relationship of warfarin using a size parameter with an exponent of body weight (SIZE) which has been proposed for scaling drug clearance. Twenty patients with stable anticoagulation by warfarin were enrolled in the present study. During a mean follow-up period of 7.36 years, 857 data points were obtained. The average patient age and body weight were 8.49 years and 24.5 kg, respectively. The relative response index to warfarin with PT-INR values normalized by daily-dose per SIZE showed fewer systematic changes than those per body weight. The anticoagulant effect of warfarin in patients with the VKORC1 1173CT or 1173CC genotype was 47.3% of that with the 1173TT genotype. Concomitant use of bosentan attenuated the anticoagulant effect of warfarin to 84.1%. In conclusion, the SIZE parameter appeared to be an effective way to describe the pediatric dose-response relationship of warfarin, and consequently, a longitudinal follow-up study design with multiple measurements was useful to detect changes within individual subjects., (Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

Background: Idiopathic pulmonary fibrosis (IPF) is a form of chronic progressive fibrosing interstitial lung disease of unknown origin. Recently, nintedanib and pirfenidone demonstrated efficacy in slowing disease progression and were approved by the US Food and Drug Administration. Although numerous treatments have been evaluated in IPF, none have shown significant decreases in mortality. The objective of this study was to identify all pharmacologic treatments evaluated for IPF and analyze their efficacy via Bayesian network meta-analysis and pairwise indirect treatment comparisons. This review did not evaluate the effect of steroid therapy., Methods: We searched MEDLINE, Embase, and the Cochrane Library for studies published on or before August 2014. Studies were required to contain a randomized evaluation of nonsteroidal drug therapy for treatment of IPF and be published in English. Key outcomes of interest for this analysis were pulmonary function as measured by FVC as well as all-cause and respiratory-specific death. All outcomes were analyzed via a Bayesian framework., Results: Our review identified 30 eligible studies that evaluated 16 unique treatments. Under both the fixed-effect and random-effect models for respiratory-specific mortality, no treatments performed better than placebo. For all-cause mortality, pirfenidone and nintedanib had effects approaching significance with credible intervals slightly crossing the null under a fixed-effect model. Notably, for respiratory-specific mortality, all-cause mortality, and decline in percent predicted FVC, nintedanib and pirfenidone were virtually indistinguishable and no clear advantage was detected., Conclusions: Although two treatments have been approved for IPF on the basis of reduced decline in pulmonary function, neither one has a clear advantage on mortality outcomes., (Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Background: A novel formulation of bosentan was evaluated in children with pulmonary arterial hypertension (PAH) in FUTURE-1, which characterized its pharmacokinetic and clinical profile. The subsequent phase III, open-label, long-term extension study, FUTURE-2, aimed to provide long-term tolerability, safety and exploratory efficacy data., Methods: Children (≥2 and <12 years) with idiopathic or heritable PAH, who completed 12-week treatment in FUTURE-1 and for whom bosentan was considered beneficial were enrolled, and continued to receive bosentan 4 mg/kg twice-daily, which could be down-titrated to 2mg/kg if not tolerated. Safety and tolerability were evaluated via treatment-emergent adverse events (AEs), serious AEs, growth, and laboratory measurements. Exploratory efficacy endpoints included time to PAH worsening and long-term survival. All analyses were conducted on pooled data of both studies., Results: 36 patients were enrolled in FUTURE-1 and 33 continued in FUTURE-2. The overall median duration of exposure to bosentan was 27.7 (range 1.9-59.6) months. Treatment-emergent AEs occurred in 32 (88.9%) patients; AEs considered treatment-related in 15 (41.7%) patients. Of 51 serious AEs, three were considered treatment-related: two incidences of reported PAH worsening and one of autoimmune hepatitis. Six deaths occurred; none were considered treatment-related. Kaplan-Meier event-free estimates of PAH worsening were 78.9% and 73.6% at 2 and 4 years, respectively., Conclusions: The pediatric bosentan formulation was generally well tolerated, its safety profile comparable to that of the adult formulation when used in children. The results are in line with the efficacy profile of bosentan in previous pediatric and adult PAH studies of shorter duration., (Copyright © 2015. Published by Elsevier Ireland Ltd.)

Thyroid development and formation vary among species, but in most species the thyroid morphogenesis consists of five stages: specification, budding, descent, bilobation and folliculogenesis. The detailed mechanisms of these stages have not been fully clarified. During early development, the cranial neural crest (CNC) contributes to the thyroid gland. The removal of the postotic CNC (corresponding to rhombomeres 6, 7 and 8, also known as the cardiac neural crest) results in abnormalities of the cardiovascular system, thymus, parathyroid glands, and thyroid gland. To investigate the influence of the CNC on thyroid bilobation process, we divided the CNC into two regions, the postotic CNC and the preotic CNC (from the mesencephalon to rhombomere 5) regions and examined. We found that preotic CNC-ablated embryos had a unilateral thyroid lobe, and confirmed the presence of a single lobe or the absence of lobes in postotic CNC-ablated chick embryos. The thyroid anlage in each region-ablated embryos was of a normal size at the descent stage, but at a later stage, the thyroid in preotic CNC-ablated embryos was of a normal size, conflicting with a previous report in which the thyroid was reduced in size in the postotic CNC-ablated embryos. The postotic CNC cells differentiated into connective tissues of the thyroid in quail-to-chick chimeras. In contrast, the preotic CNC cells did not differentiate into connective tissues of the thyroid. We found that preotic CNC cells encompassed the thyroid anlage from the specification stage to the descent stage. Finally, we found that endothelin-1 and endothelin type A receptor-knockout mice and bosentan (endothelin receptor antagonist)-treated chick embryos showed bilobation anomalies that included single-lobe formation. Therefore, not only the postotic CNC, but also the preotic CNC plays an important role in thyroid morphogenesis., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Systemic sclerosis (SSc) is a multisystem connective tissue disease featured by immune abnormalities, vasculopathy and tissue fibrosis with unknown etiology. A series of studies on disease-susceptibility genes and twins have demonstrated the association of genetic factors with autoimmunity and disease severity and the contribution of environmental factors to the induction of clinical features in this disease. Friend leukemia virus integration 1 (Fli1), a member of Ets transcription factor family, is epigenetically suppressed in the lesional skin of SSc patients, suggesting that Fli1 is a potential predisposing factor of SSc reflecting the influence of environmental factors. Consistent with this idea, Fli1 deficiency induces SSc-like phenotypes in dermal fibroblasts and dermal microvascular endothelial cells in vivo and in vitro at molecular levels. Furthermore, Fli1 haploinsufficiency recapitulates tissue fibrosis, vascular activation and inflammation characteristic of SSc to a greater extent in bleomycin-treated mice. Importantly, bosentan, a dual endothelin receptor antagonist with a potential disease-modifying effect on SSc vasculopathy, reverses the expression of Fli1 protein by increasing its protein stability. Therefore, Fli1 may serve as a predisposing factor of SSc and can be a promising therapeutic target of this incurable and devastating disease. This article is part of a Directed Issue entitled: Epigenetics dynamics in development and disease., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Aims: Chronic thromboembolic pulmonary hypertension (CTEPH) is a devastating disease, and treating patients with CTEPH who are not eligible for pulmonary endarterectomy is particularly challenging. Short-term bosentan or phosphodiesterase type-5-inhibitor treatment can greatly improve symptoms and hemodynamics in these patients; however, the long-term benefits of advanced pulmonary vasodilators are not known. We retrospectively investigated the long-term effects of advanced pharmacological therapy in Japanese patients with inoperable CTEPH., Main Methods: Seven consecutive patients with inoperable CTEPH (five women; mean age, 62.6±6.9 years) treated with bosentan were included. World Health Organization functional class (WHO-FC), hemodynamics, exercise capacity, and plasma B-type natriuretic peptide (BNP) concentration were evaluated at baseline and for more than 2 years. Time to clinical worsening was also examined during long-term follow-up., Key Findings: WHO-FC improved significantly, from 3.1±0.4 to 2.1±0.4 (p=0.005). Significant improvement was also seen in pulmonary vascular resistance, which decreased from 786.9±300.0 to 352.2±210.7 dynes s cm(-5) (p<0.05). Plasma BNP concentration decreased significantly from 1160.0±971.4 to 305.1±285.9 pg/mL (p<0.05). No patient required hospitalization during the follow-up period (mean, 896±564 days)., Significance: Long-term advanced therapy with bosentan significantly improves symptoms, pulmonary vascular resistance, plasma BNP concentration, and time to clinical worsening in Japanese patients with inoperable CTEPH. We consider bosentan to be an essential treatment for these patients., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Aims: We have shown that diabetes causes cerebrovascular remodeling in part by the activation of the endothelin (ET-1) system in a glucose-dependent manner. We also reported increased yet dysfunctional cerebral angiogenesis in diabetes. Here, we tested the hypothesis that dual ET-1 receptor antagonism or glycemic control can reverse already established diabetes-induced vascular remodeling and neovascularization., Main Methods: 18-week non-obese type-2 diabetic Goto-Kakizaki (GK) were treated with vehicle, metformin (300 mg/kg/day) or bosentan (100 mg/kg/day) for 4 weeks by oral gavage and compared to 10 and 18-weeks GK rats. Isolated middle cerebral artery (MCA) lumen diameter (LD), media thickness (MT), media:lumen (M:L) ratio, and cross-sectional area (CSA) were measured using pressurized arteriograph. Assessment of remodeling and angiogenesis in the brain parenchyma was achieved by three-dimensional reconstruction of fluorescently labeled images of the vasculature acquired by confocal microscopy, and measurement of neovascularization indices including vascular volume and surface area, branch density and tortuosity., Key Findings: MCA remodeling (increased M:L ratio and CSA, but decreased LD) occurred by 18 weeks and did not progress by 22 weeks in diabetic GK rats. Metformin and bosentan partially corrected large artery remodeling. Both treatments significantly reduced all indices of neovascularization compared to untreated diabetic rats., Significance: Glycemic control or ET-1 antagonism can partially reverse diabetes-induced cerebrovascular remodeling and neovascularization. These results strongly suggest that either approach offers a therapeutic benefit and combination treatments need to be tested., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Aims: The 6-min walking distance is often used for assessing the exercise capacity under the treatment with an endothelin receptor antagonist (ERA) in patients with chronic thromboembolic pulmonary hypertension (CTEPH). The cardiopulmonary exercise testing (CPX) was reported to be more useful for the patients with pulmonary arterial hypertension (PAH), however, few reports exist in patients with inoperable CTEPH. The aim of this study was to investigate the effects of an oral dual ERA, bosentan, on exercise capacity using CPX in patients with PAH and inoperable CTEPH., Main Methods: This study included all patients diagnosed with 17 PAH and 12 CTEPH in the World Health Organization functional classes II-IV who started treatment with bosentan therapy. They underwent CPX, which was performed before bosentan therapy and at 3 to 6 months of the treatment., Key Findings: In PAH patients, peak VO2 significantly increased after the bosentan treatment (p=0.009). On the other hand, in CTEPH patients, there were no significant differences in the peak VO2. However, the peak PETCO2 was significantly increased from 23.9±5.2 mm Hg at baseline to 29.3±10.7 mm Hg after the bosentan treatment (p=0.040). In addition, peak heart rate during exercise tended to decrease after the bosentan therapy (p=0.089)., Significance: Bosentan therapy improved peak PETCO2 but not peak VO2 in patients with inoperable CTEPH. These findings demonstrated that CPX is useful for assessing the exercise capacity of patients with PAH and inoperable CTEPH under the treatment with an ERA., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Aims: The endothelin (ET) system is a tissular system, as the production of ET isoforms is mostly autocrine or paracrine. Macitentan is a novel dual ETA/ETB receptor antagonist with enhanced tissue distribution and sustained receptor binding properties designed to achieve a more efficacious ET receptor blockade. To determine if these features translate into improved efficacy in vivo, a study was designed in which rats with either systemic or pulmonary hypertension and equipped with telemetry were given macitentan on top of maximally effective doses of another dual ETA/ETB receptor antagonist, bosentan, which does not display sustained receptor occupancy and shows less tissue distribution., Main Methods: After establishing dose-response curves of both compounds in conscious, hypertensive Dahl salt-sensitive and pulmonary hypertensive bleomycin-treated rats, macitentan was administered on top of the maximal effective dose of bosentan., Key Findings: In hypertensive rats, macitentan 30 mg/kg further decreased mean arterial blood pressure (MAP) by 19 mm Hg when given on top of bosentan 100 mg/kg (n=9, p<0.01 vs. vehicle). Conversely, bosentan given on top of macitentan failed to induce an additional MAP decrease. In pulmonary hypertensive rats, macitentan 30 mg/kg further decreased mean pulmonary artery pressure (MPAP) by 4 mm Hg on top of bosentan (n=8, p<0.01 vs. vehicle), whereas a maximal effective dose of bosentan given on top of macitentan did not cause any additional MPAP decrease., Significance: The add-on effect of macitentan on top of bosentan in two pathological models confirms that this novel compound can achieve a superior blockade of ET receptors and provides evidence for greater maximal efficacy., (Copyright © 2014. Published by Elsevier Inc.)

Aims: Up-regulation of the endothelin (ET) system in type-2 diabetes increases contraction and decreases relaxation in basilar artery. We showed that 1) ET-receptor antagonism prevents diabetes-mediated cerebrovascular dysfunction; and 2) glycemic control prevents activation of the ET-system in diabetes. Here, our goal is to determine whether and to what extent glycemic control or ET-receptor antagonism reverses established cerebrovascular dysfunction in diabetes., Main Methods: Non-obese type-2 diabetic Goto-Kakizaki rats were administered either vehicle, metformin (300 mg/kg/day) or dual ET-receptor antagonist bosentan (100mg/kg) for 4-weeks starting at 18-weeks after established cerebrovascular dysfunction (n=5-6/group). Control group included vehicle-treated aged-matched Wistar rats. Blood glucose and pressure were monitored weekly. At termination, basilar arteries were collected and cumulative dose-response curves to ET-1 (0.1-500 nM), 5-HT (1-1000 nM) and acetylcholine (Ach, 0.1 nM-5 μM) were studied by wire myograph. Middle cerebral artery (MCA) myogenic reactivity and tone were measured using pressurized arteriograph., Key Findings: There was no difference in ET-1 and 5-HT-mediated constrictions. Endothelium-dependent relaxation was impaired in diabetes. Bosentan improved sensitivity to Ach as well as the maximum relaxation. Myogenic-tone is decreased over the course of the disease. Both treatments improved the ability of MCAs to develop tone at 80 mm Hg and only bosentan improved the tone at higher pressures., Significance: These results suggest that contractile response is not affected by glycemic control or ET-receptor antagonism. Meanwhile, dual ET-receptor blockade is effective in partially improving endothelium-dependent relaxation and myogenic response in a blood pressure-independent manner even after established cerebrovascular dysfunction and offers therapeutic potential., (Published by Elsevier Inc.)

Aims: To report a case of unexpected pulmonary hypertensive crisis caused by endothelin release from melanoma cells after surgery for choroidal melanoma., Main Methods: A 56-year-old man suddenly developed dyspnea after resection of choroidal melanoma. Worsening hypoxia required intensive treatment, including percutaneous cardiopulmonary support, after which a series of tests were immediately performed. The tentative diagnosis was idiopathic pulmonary arterial hypertension., Key Findings: Previous studies noted a significant association between melanoma and endothelin (ET)-1. We hypothesized that a substantial amount of ET-1 had been released from malignant melanoma cells during resection, thus triggering the pulmonary hypertensive crisis in our patient. The patient fully recovered after intensive treatment and administration of the endothelin receptor antagonist bosentan., Significance: The success of bosentan treatment, along with the extremely high level of ET-1 on pathologic analysis, confirmed our hypothesis regarding the increase in plasma ET-1 level., (Copyright © 2014 Elsevier Inc. All rights reserved.)