Dual Endothelin Receptor Antagonist Bosentan Research Articles

Survival with first-line bosentan in patients with primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a progressive disease with high mortality. Administration of i.v. epoprostenol has demonstrated improved exercise tolerance, haemodynamics, and survival. The orally active, dual endothelin receptor antagonist bosentan improves exercise endurance, haemodynamics, and functional class over the short term. To determine the effect of first-line bosentan therapy on survival, this study followed 169 patients with PPH treated with bosentan in two placebo-controlled trials and their extensions. Data on survival and alternative treatments were collected from September 1999 (start of the first placebo-controlled study) to December 31, 2002. Observed survival up to 36 months was reported as Kaplan-Meier estimates and compared with predicted survival as determined for each patient by the National Institutes of Health Registry formula. Kaplan-Meier survival estimates were 96% at 12 months and 89% at 24 months. In contrast, predicted survival was 69% and 57%, respectively. In addition, at the end of 12 and 24 months, 85% and 70% of patients, respectively, remained alive and on bosentan monotherapy. Factors that predicted a worse outcome included World Health Organization Functional Class IV and 6-min walk distance below the median (358 m) at baseline. First-line bosentan therapy was found to improve survival in patients with advanced primary pulmonary hypertension.

Use of a mixed endothelin receptor antagonist in portopulmonary hypertension: A safe and effective therapy?

Portopulmonary hypertension (PPHTN), a severe complication of portal hypertension is observed in 3%-6% of patients evaluated for liver transplantation. Endothelin-1, a potent vasoconstrictor, is likely to play a role in the pathogenesis of primary pulmonary hypertension, and, in 2 recent trials, the dual endothelin receptor antagonist bosentan has shown beneficial effects in this disease. A role for endothelins in the development of both pulmonary hypertension and cirrhosis has been suggested. We therefore hypothesized that endothelin receptor blockade may be beneficial in the treatment of PPHTN. We report a case of a 42-year-old patient with PPHTN and alcoholic cirrhosis treated with the mixed endothelin receptor antagonist bosentan. The patient rapidly improved from NYHA IV to stage II, experienced a remarkable improvement of 6-minute walking distance from 0 to 590 m within 6 months, and resumed working full-time as a locksmith after 7 months of treatment. Improvement of cardiovascular parameters included a reduction of pulmonary vascular resistance by 60%, a decrease of mean pulmonary artery pressure (mPAP) from 55 to 44 mm Hg at 9 months, and a decline of plasma B-type natriuretic peptide (BNP) from 339 pg/mL to 19 pg/mL after 1 year. There were no adverse events except for a transient decrease in systemic blood pressure. To our knowledge, this is the first report of a patient with PPHTN treated with an endothelin receptor antagonist. The marked and sustained improvement supports the undertaking of controlled studies of the safety and efficacy of bosentan in PPHTN.

New Therapeutic Strategies for Systemic Sclerosis—a Critical Analysis of the Literature

Systemic sclerosis (SSc) is a multi-system disease characterized by skin fibrosis and visceral disease. Therapy is organ and pathogenesis targeted. In this review, we describe novel strategies in the treatment of SSc. Utilizing the MEDLINE and the COCHRANE REGISTRY, we identified open trials, controlled trials, for treatment of SSc from 1999 to April 2005. We used the terms scleroderma, systemic sclerosis, Raynaud's phenomenon, pulmonary hypertension, methotrexate, cyclosporin, tacrolimus, relaxin, low-dose penicillamine, IVIg, calcium channel blockers, losartan, prazocin, iloprost, N-acetylcysteine, bosentan, cyclophosphamide, lung transplantation, ACE inhibitors, anti-thymocyte globulin, and stem cell transplantation. Anecdotal reports were omitted. Methotrexate, cyclosporin, tacrolimus, relaxin, low-dose penicillamine, and IVIg may be beneficial in improving the skin tightness in SSc. Calcium channel blockers, the angiotensin II receptor type 1 antagonist losartan, prazocin, the prostacyclin analogue iloprost, N-acetylcysteine and the dual endothelin-receptor antagonist bosentan may be beneficial for Raynaud's phenomenon. Epoprostenol and bosentan are approved for therapy of pulmonary hypertension (PAH). Other options under investigation include intravenous or aerolized iloprost. Cyclophosphamide (CYC) pulse therapy is effective in suppressing active alveolitis. Stem cell and lung transplantation is a viable option for carefully selected patients. Renal crisis can be effectively managed when hypertension is aggressively controlled with angiotensin converting enzyme (ACE) inhibitors. Patients should continue taking ACE inhibitors even after beginning dialysis in hope of discontinuing dialysis. Anti-thymocyte globulin and mycophenolate mofetil appear safe in SSc. The improvement in skin score and the apparent stability of systemic disease during the treatment period suggest that controlled studies of these agents are justified. Stem cell transplantation is under investigation for severe disease. Novel therapies are currently being tested in the treatment of SSc and have the potential of modifying the disease process and overall clinical outcome. The evaluation of these studies is still a difficult process.

Actelion's dual endothelin receptor antagonist bosentan [Tracleer] has made further progress towards markets in Australia and Taiwan.

Actelion's dual endothelin receptor antagonist bosentan [Tracleer] has made further progress towards markets in Australia and Taiwan.

Effects of the Dual Endothelin Receptor Antagonist Bosentan in Patients With Pulmonary Arterial Hypertension: A 1-Year Follow-up Study

We report on the long-term safety and efficacy of bosentan treatment in patients with pulmonary arterial hypertension (PAH). In a preceding study, bosentan was well tolerated and significantly improved the exercise capacity and hemodynamics of patients with PAH after 12 weeks of treatment. The present study was an open-label extension to the preceding double-blind, placebo-controlled study of 32 patients with PAH (primary or associated with scleroderma) who received bosentan or placebo at 125 mg bid for 3 to 7 months. Twenty-nine of the original 32 patients received bosentan for an additional year (62.5 mg bid for 4 weeks and then 125 mg bid). Study end points included long-term safety, 6-min walk distance at week 4, modified New York Heart Association (NYHA) functional class of PAH at month 12, and the occurrence of withdrawal due to clinical worsening. Additional exploratory analyses included a walk test at month 6 for 19 patients and hemodynamic assessment at month 12 for 11 patients. At month 6, assessed patients continuing bosentan treatment maintained the improvement in walk distance observed at the end of the previous study (mean +/- SEM, 60 +/- 11 m), and patients starting bosentan treatment improved their walk distance by 45 +/- 13 m. Long-term treatment with bosentan for > 1 year was associated with an improvement in hemodynamic parameters and modified NYHA functional class. Overall, bosentan treatment was well tolerated. No patient underwent transplantation or died. Long-term treatment with bosentan is safe and has sustained benefits on exercise capacity and hemodynamics in patients with PAH.

Bosentan for the prevention of overcirculation-induced experimental pulmonary arterial hypertension.

The dual endothelin-receptor antagonist bosentan has been reported to improve pulmonary arterial hypertension, but the role of endothelins in the pathogenesis of the condition remains uncertain. We investigated the roles of endothelin-1 (ET-1), nitric oxide (NO), vascular endothelial growth factor (VEGF), and tenascin in overcirculation-induced pulmonary hypertension in piglets, as a model of early pulmonary arterial hypertension, with or without bosentan therapy. Thirty 3-week-old piglets were randomized to placebo or to bosentan 15 mg/kg BID after the anastomosis of the left subclavian artery to the pulmonary arterial trunk or after a sham operation. Three months later, the animals underwent a hemodynamic evaluation followed by cardiac and pulmonary tissue sampling for morphometry, immunohistochemistry, and real-time quantitative PCR. Chronic systemic-to-pulmonary shunting increased circulating plasma ET-1, pulmonary mRNA for ET-1, ET(B) receptor, inducible NO synthase, VEGF, and pulmonary ET-1 and VEGF proteins. There were increases in myocardial mRNA for ET(A) receptor and VEGF and in myocardial VEGF protein. Pulmonary and myocardial tissue mRNA for tenascin did not change. Normalized-flow pulmonary artery pressure increased from 20 (2) to 33 (1) mm Hg [mean (SEM)], arteriolar medial thickness increased on average by 83%, and these changes were completely prevented by bosentan therapy. Right ventricular end-systolic elastance increased in proportion to pulmonary arterial elastance with or without bosentan. Experimental overcirculation-induced pulmonary arterial hypertension appears to be causally related to an activation of the pulmonary ET-1 system and as such is completely prevented by the dual endothelin receptor antagonist bosentan.

Differential activation of NF-kappa B and AP-1 in increased fibronectin synthesis in target organs of diabetic complications.

Increased extracellular matrix protein production leading to structural abnormalities is a characteristic feature of chronic diabetic complications. We previously showed that high glucose in endothelial cell culture leads to the upregulation of basement membrane protein fibronectin (FN) via an endothelin (ET)-dependent pathway involving activation of NF-kappaB and activating protein-1 (AP-1). To delineate the mechanisms of basement membrane thickening, we used an animal model of chronic diabetes and evaluated ET-dependent activation of NF-kappaB and AP-1 and subsequent upregulation of FN in three target organs of chronic diabetic complications. After 3 mo of diabetes, retina, renal cortex, and myocardium demonstrated increased FN mRNA and increased ET-1 mRNA expression. Increased FN expression was shown to be dependent on ET receptor-mediated signaling, as the increase was prevented by the dual ET receptor antagonist bosentan. NF-kappaB activation was most pronounced in the retina, followed by kidney and heart. AP-1 activation was also most pronounced in the retina but was similar in both kidney and heart. Bosentan treatment prevented NF-kappaB activation in the retina and heart and AP-1 activation in the retina and kidney. These data indicate that, although ETs are important in increased FN production due to diabetes, the mechanisms with respect to transcription factor activation may vary depending on the microenvironment of the organ.

Effects of the dual endothelin-receptor antagonist bosentan in patients with pulmonary hypertension: a randomized placebo-controlled study

Effects of the dual endothelin-receptor antagonist bosentan in patients with pulmonary hypertension: a randomized placebo-controlled study

Effects of the dual endothelin-receptor antagonist bosentan in patients with pulmonary hypertension: a randomised placebocontrolled study

Endothelin 1, a powerful endogenous vasoconstrictor and mitogen, might be a cause of pulmonary hypertension. We describe the efficacy and safety of bosentan, a dual endothelin-receptor antagonist that can be taken orally, in patients with severe pulmonary hypertension. In this double-blind, placebo-controlled study, 32 patients with pulmonary hypertension (primary or associated with scleroderma) were randomly assigned to bosentan (62.5mg taken twice daily for 4 weeks then 125 mg twice daily) or placebo for a minimum of 12 weeks. The primary endpoint was change in exercise capacity. Secondary endpoints included changes in cardiopulmonary haemodynamics, Borg dyspnoea index, WHO functional class, and withdrawal due to clinical worsening. Analysis was by intention to treat. In patients given bosentan, the distance walked in 6 min improved by 70 m at 12 weeks compared with baseline, whereas it worsened by 6 m in those on placebo (difference 76 m [95% CI 12-139], p=0.021). The improvement was maintained for at least 20 weeks. The cardiac index was 1.0 L min(-1) m(-2) (95% CI 0.6-1.4, p<0.0001) greater in patients given bosentan than in those given placebo. Pulmonary vascular resistance decreased by 223 dyn s cm(-)(5) with bosentan, but increased by 191 dyn s cm(-5) with placebo (difference -415 [-608 to -221], p=0.0002). Patients given bosentan had a reduced Borg dyspnoea index and an improved WHO functional class. All three withdrawals from clinical worsening were in the placebo group (p=0.033). The number and nature of adverse events did not differ between the two groups. Bosentan increases exercise capacity and improves haemodynamics in patients with pulmonary hypertension, suggesting that endothelin has an important role in pulmonary hypertension.

Effects of the dual endothelin receptor antagonist bosentan in patients with pulmonary hypertension: a placebo-controlled study

Effects of the dual endothelin receptor antagonist bosentan in patients with pulmonary hypertension: a placebo-controlled study