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Effects of a dual endothelin receptor antagonist, bosentan on peripheral circulatioin and skin lesions as well as pulmonary arterial hypertension (PAH) were investigated in Japanese patients with connective tissue diseases (CTD). Fifteen patients with PAH associated with CTD [systemic sclerosis (SSc) 13, mixed connective tissue disease (MCTD) 2] were treated with bosentan for 40–96 weeks, and changes of exercise capacity (6-min walk distance and Borg’s dyspnea scale), cardio-pulmonary hemodynamics (right ventricular pressure, specific activity scale and cardiac index), Raynaud’s phenomenon, digital ulcers and dermal sclerosis were observed. Bosentan improved exercise capacity, had a positive effect on hemodynamic parameters, and was well tolerated as previously reported. After a median 8 weeks of treatment, 13 out of 15 patients had improved Raynaud’s phenomenon. Digital ulcers also improved after a median 12 weeks’ treatment in all of 8 patients. Modified Rodnan total skin score decreased from 21.0 ± 5.9 to 11.5 ± 3.9 in diffuse cutaneous SSc and from 17.0 ± 6.5 to 9.5 ± 4.5 in limited cutaneous SSc after 24 months’ treatment, reaching significance after 6 months in both groups. These data suggest that bosentan is effective for both PAH and peripheral vascular diseases in Japanese patients with CTD. The pathological background to the improvement in dermal sclerosis observed in this study should be further investigated. [ABSTRACT FROM AUTHOR]

Bosentan, an endothelin receptor antagonist, has been widely used as a first-line medication for the treatment of pulmonary arterial hypertension (PAH). It has been shown to improve symptoms of hypertension, exercise capacity, and hemodynamics and prolong time to clinical worsening. However, liver dysfunction is a major side effect of bosentan treatment that could hamper the optimal management of patients with PAH. Previously, we demonstrated, using drug metabolism enzymes and transporters analysis, that the carbohydrate sulfotransferase 3 ( CHST3 ) and CHST13 alleles are significantly more frequent in patients with elevated aminotransferases during therapy with bosentan than they are in patients without liver toxicity. In addition, we constructed a pharmacogenomics model to predict bosentan-induced liver injury in patients with PAH using two single-nucleotide polymorphisms and two nongenetic factors. The purpose of the present study was to externally validate the predictive model of bosentan-induced liver toxicity in Japanese patients. We evaluated five cases of patients treated with bosentan, and one presented with liver dysfunction. We applied mutation alleles of CHST3 and CHST13 , serum creatinine, and age to our model to predict liver dysfunction. The sensitivity and specificity were calculated as 100% and 50%, respectively. Considering that PAH is a rare disease, multicenter collaboration would be necessary to validate our model.

Therapeutic strategies for pulmonary arterial hypertension (PAH) have made remarkable progress over the last two decades. Currently, 3 types of drugs can be used to treat PAH; prostacyclins, phosphodiesterase 5 inhibitors, and endothelin receptor antagonists (ERA). In Japan, the first generation ERA bosentan was reimbursed in 2005, following which the 2nd generation ERAs ambrisentan and macitentan were reimbursed in 2009 and 2015, respectively. The efficacy of each ERA on hemodynamics in PAH patients remains to be elucidated. The aims of this study were to evaluate the hemodynamic effects of ERAs and compare these effects among each generation of ERAs.We retrospectively examined the clinical parameters of 42 PAH patients who were prescribed an ERA (15 bosentan, 12 ambrisentan, and 15 macitentan) and who underwent a hemodynamic examination before and after ERA introduction at our institution from January 2007 to July 2019.In a total of 42 patients, mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) were significantly decreased and cardiac index was significantly increased after ERA introduction (P < 0.001) and the World Health Organization-Functional class (WHO-Fc) was significantly improved after ERA introduction (P = 0.005). Next, in a comparison between 1st and 2nd generation ERAs, 2nd generation ERAs were found to have brought about greater improvements in hemodynamic parameters (mPAP and PVR. P < 0.01), heart rate, brain natriuretic peptide, arterial oxygen saturation, and mixed venous oxygen saturation than the 1st generation ERA bosentan.We conclude that all ERAs could successfully improve the hemodynamics of PAH patients and that the newer generation ERAs, ambrisentan and macitentan, seemed to be preferable to bosentan.

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.)