BACKGROUND:

Palliative treatment with the Fontan procedure has greatly improved survival for children with functionally univentricular heart. Since Fontan performed the first successful operation, the procedure has evolved and is now performed as Total Cavo-Pulmonary Connection (TCPC).An increasing prevalence and longer life expectancy of TCPC patients have raised new challenges. The survivors are often suffering complications such as arrhythmias, myocardial dysfunction, thromboembolic events, neuropsychological deficit, protein-losing enteropathy and reduced exercise capacity. Several causes for the reduced exercise capacity may be present e.g. impaired function of the single ventricle, valve dysfunction and chronotropic impairment, and perhaps also increased pulmonary vascular resistance. Thus, plasma endothelin-1 has been shown to correlate with increased pulmonary vascular resistance and the risk of failing Fontan circulation. This has raised the question of the role for pulmonary vasodilation therapy, especially endothelin receptor antagonist in the management of TCPC patients.

METHODS:

The TEMPO trial aims to investigate whether Bosentan, an endothelin receptor antagonist, can be administered safely and improve exercise capacity in TCPC patients. The trial design is randomized, double-blind and placebo-controlled. Bosentan/placebo is administered for 14 weeks with control visits every four weeks. The primary endpoint is change in maximal oxygen consumption as assessed on bicycle ergometer test. Secondary endpoints include changes in pulmonary blood flow during exercise test, pro brain natriuretic peptide and quality of life.

DISCUSSION:

We hypothesize that treatment with Bosentan, an endothelin receptor antagonist, can be administered safely and improve exercise capacity in TCPC patients.Trial registrationclinicaltrials.gov NCT01292551.

Digital ulcers are a well-known problem in patients with systemic sclerosis. Lower extremity ulcers are less prevalent but are also a challenging and underestimated complication of the disease causing important pain and morbidity. Bosentan, an oral dual endothelin receptor antagonist, has been shown to be effective in preventing digital ulcers in patients with systemic sclerosis. A few recent observations showed the efficacy of bosentan for accelerating the healing of nondigital ulcers in scleroderma patients. This report deals with a 48-year-old patient with systemic sclerosis who developed painful ulcers on the left ankle and hallux. The ulcers were refractory to a combination of vasodilator therapy with a calcium antagonist and several courses of intravenous prostanoids, low molecular weight heparin, aspirin, simvastatin, and intensive local treatment. Bosentan treatment showed spectacular healing of the ulcers already after 4 months of therapy. This case supports the previous few observations of accelerating wound healing of lower extremity ulcers in systemic sclerosis patients with bosentan treatment.

The most effective approaches to escalating advanced therapies in pulmonary arterial hypertension (PAH) are controversial.To compare outcomes before and after introducing a target 6 min walk distance (6MWD) treatment strategy in PAH using registry data.From 2001 to 2005, WHO class II to IV patients were treated with bosentan or prostanoids. In July 2005, a target 6MWD strategy was adopted. Monotherapy continued if 6MWD remained >350 m. For patients in whom 6MWD was ≤350 m, sildenafil was added. If 6MWD remained <350 m, prostanoids were considered. Changes in 6MWD, WHO class and survival rate were compared between periods.Before using the 6MWD strategy, there was a statistically significant improvement in mean WHO class at six, nine and 12 months (2.5±0.8 [P<0.015]; 2.5±0.8 [P<0.005]; and 2.5±0.9 [P<0.03], respectively) compared with baseline (2.9±0.9). There was a statistically significant increase in mean 6MWD at three, six, nine and 12 months (383±113 m [P<0.005]; 401±102 m [P<0.006]; 400±109 m [P<0.001]; and 399±110 m [P<0.004], respectively) compared with baseline (321±119 m). The survival rate was 95% at one and two years. From 2005 to 2009, there was a statistically significant improvement in mean WHO class at three, six, nine and 12 months (2.6±0.8 [P<0.05]; 2.3±0.9 [P<0.0001]; 2.3±0.9 [P<0.0001]; and 2.3±1.0 [P<0.0005], respectively) compared with baseline (2.8±0.7). There was statistically significant improvement in 6MWD at six months (381±126 m [P<0.05]), followed by a decline toward baseline (354±117 m). One- and two-year survival rates in the 6MWD target era were 95% and 80%, respectively.Based on registry data, adoption of this strategy did not affect survival rates, nor cause a sustained improvement in 6MWD by 12 months. WHO class improved similarly in both treatment groups.

Background:

 The surgical indication for chronic thromboembolic pulmonary hypertension (CTEPH) has been modified due to recognition of peripheral type CTEPH and changes in surgical methods and skill. Bosentan and sildenafil are used as modern oral therapy (mod Tx) in patients with inoperable CTEPH, although it remains unknown whether they have positive effects on survival.

Methods and Results:

 A total of 202 patients were diagnosed with CTEPH at Chiba University Hospital between 1986 and 2010, 100 of whom underwent pulmonary endarterectomy. Seven medically treated patients with pulmonary vascular resistance (PVR) ≤300dyn·s·cm(-5) were regarded as having mild disease. Survival rate was stratified by date of diagnosis (group 1, 1986-1998; group 2, 1999-2004; group 3, 2005-2010), and prognostic factors in the remaining 95 medically treated patients were investigated. Group 3 included the most patients treated with mod Tx (group 1, 9.1%; group 2, 24.2%; group 3, 65.0%) and had significantly better survival than either group 1 or 2 (5-year survival: group 1, 54.6%; group 2, 69.7%; group 3, 87.3%). Patients receiving mod Tx had significantly better survival than those not on mod Tx (5-year survival: 88.9% vs. 60.2%). Multivariate analysis showed that mod Tx, lower PVR, and lack of comorbidity were significant predictors of better outcome.

Conclusions:

 Medically treated patients with CTEPH had a better survival rate, and the use of mod Tx contributed to improved survival.

What is known: Bosentan is a dual endothelin receptor antagonist approved for the treatment of pulmonary arterial hypertension (PAH). Since bosentan is frequently used to treat pediatric PAH patients, a pediatric formulation was developed.

Aim:

To evaluate the pharmacokinetic properties of bosentan and its active metabolite, Ro 48-5033, of the quadrisected, dispersible pediatric vs. the adult tablet after single-dose administration to healthy subjects. Secondary objectives of the study were to compare the pharmacokinetics of two inactive metabolites and the safety of both formulations. Materials and methods: In this open-label, two-way crossover study, subjects (20 - 43 years) were randomized to receive single oral doses of 62.5 mg of bosentan as 1 adult tablet and 64 mg as 2 pediatric tablets of 32 mg. Blood samples were drawn over a 48-hour period to measure bosentan and its metabolites.

Results:

16 subjects were enrolled and completed the study. Following treatment with the pediatric formulation, values for Cmax and AUC0-∞ of bosentan were lower than with the adult formulation with geometric mean ratios (90% confidence interval) of 0.82 (0.65, 1.04) and 0.87 (0.78, 0.97), respectively. Similar results were obtained for the primary active metabolite Ro 48-5033. Both treatments were well tolerated. What is new and conclusion: Although the 90% confidence intervals of the geometric mean ratios of Cmax and AUC0-∞ were not entirely within the conventional bioequivalence range (0.80 - 1.25), no clinically relevant effect of formulation on the pharmacokinetics of bosentan and Ro 48-5033 was detected. Both formulations were well tolerated.

Pulmonary arterial hypertension (PAH) is a progressive disease without a cure, which can lead to right heart failure and death. Over the past decades, several therapeutic advances have been developed for the management of PAH. Although these agents have demonstrated clinical safety and efficacy, some patients may require additional drug therapy due to a lack of response or disease progression.The purpose of this review was to evaluate the safety and efficacy of various combination PAH therapies.A systematic search was conducted using the MEDLINE database (1966 and June 2012) for relevant clinical studies. Searches were limited to English, human and clinical trial using the terms sildenafil, tadalafil, vardenafil, phosphodiesterase inhibitor, prostacyclin, prostaglandin, epoprostenol, treprostinil, iloprost, beraprost, endothelin receptor antagonist, bosentan, ambrisentan, sitaxsentan and pulmonary hypertension.Overall, 22 studies met inclusion criteria. Overall, the majority of trials demonstrated clinical efficacy in improving functional class, reducing pulmonary pressure, or increasing exercise capacity. Most trials were uncontrolled with small sample sizes investigating the acute effects of combination therapy and lacking long-term clinical outcomes. Adjunctive therapy was well tolerated by most patients.Overall, combination therapy is relatively safe and well tolerated. Published guidelines provide evidence-based recommendations for monotherapy. However, suggestions for combination therapy in refractory PAH patients are lacking. Several studies evaluating several combination therapies have been published. The preferred combination treatment among several PAH drug therapies remain controversial. Therefore, clinicians should consider ease of administration, cost, and tolerability when choosing specific combination therapies.Combination therapy appears promising for patients who are refractory to treatment or whose disease progression is not well controlled with monotherapy. An optimal combination drug therapy regimen remains debatable and should be customized for individual PAH patients. Further studies are needed to determine the optimal combination therapy in PAH based upon efficacy, safety and cost.

Endothelin receptor antagonists (ETRAs), authorized for pulmonary hypertension, have failed to prove their utility in chronic lung diseases with corticosteroid-resistant airway inflammation when applied at late disease stages with emphysema/fibrosis. Earlier administration might prove effective by targeting the interaction between airway inflammation and tissue remodeling. Hypothesis: human airway smooth muscle cells (HASMCs) participate in linking inflammation with remodeling; associated genes become differentially suppressed by ambrisentan (A-receptor selective ETRA) and bosentan (non-selective/dual ETRA). Inflammatory responses of ex-vivo-cultivated HASMCs to TNFα were investigated by whole-genome-microarray analyses. qRT-PCR and ELISA were used to test inflammatory and remodeling genes for sensitivity to bosentan and ambrisentan and to investigate differential sensitivities mechanistically. ETRA and corticosteroid effects were compared in HASMCs from patients with COPD. TNFα induced the expression of 18 cytokines/chemokines and five tissue remodeling genes involved in (severe/corticosteroid-insensitive) asthma, COPD, IPF and/or pulmonary hypertension. 13 cytokines/chemokines, MMP13 and WISP1 were suppressed by ETRAs. Eight genes had differential sensitivity to bosentan and ambrisentan depending on the endothelin-B-receptor impact on transcriptional regulation and mRNA stabilization. CCL2, CCL5, GM-CSF and MMP13 had increased sensitivity to bosentan or bosentan/dexamethasone combination versus dexamethasone alone. Suppression of cytokine and remodeling gene expression by ETRAs was confirmed in TNFα-activated human bronchial epithelial cells (HBECs). HASMCs and HBECs participate in the interaction of inflammation and tissue remodeling. This interaction is targeted differentially by selective and non-selective ETRAs, which could be utilized in therapies of chronic lung diseases with corticosteroid-resistant airway inflammation at early disease stages in order to attenuate inflammation-induced airway remodeling.

Herein we report a 21 year-old woman with a previously documented patent ductus arteriosus and Eisenmenger physiology. She presented with increasing cyanosis and exercise intolerance which could be explained by a new finding of right to left shunting through an interatrial communication. She was started on Bosentan therapy aiming to reduce the pulmonary pressure with consideration for heart-lung transplantation should any further deterioration occur.

Intravenous (IV) prostacyclin (epoprostanol) and its analogs (iloprost and treprostinil) are effective in treating pulmonary artery hypertension (PAH). Although prostacyclins are available for inhaled and subcutaneous delivery, IV administration of prostacyclins, sometimes in combination with other agents, such as bosentan or sildenafil, is considered the most aggressive method to manage PAH. This report attempts to help clinicians determine when to initiate IV treatment of PAH and when to refer a patient with PAH to a center for treatment. IV prostacyclin therapy initiation is suggested when patients exhibit World Health Organization functional class IV symptoms. The Registry to EValuate Early And Long-term Pulmonary Arterial Hypertension disease management (REVEAL) risk calculator can help determine a patient's 1-year mortality with PAH and characterize the clinical course, treatment, and predictors of outcomes in patients with PAH. Referring physicians can screen their patients for PAH and refer even before the diagnosis has been confirmed so that the center can facilitate the diagnostic process and provide suggestions for initial therapy selection and provide other collaborative and supportive services. Alternatively, the physician can diagnose and initiate early therapy with a plan to involve the pulmonary hypertension center at the need for IV therapy or consideration for transplantation, working closely with the patient to ensure stability. Physicians and pulmonary centers must develop good methods of communication to ensure effective diagnosis and management.