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

Prostaglandin and prostaglandin receptors: present and future promising therapeutic targets for pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH), Group 1 pulmonary hypertension (PH), is a type of pulmonary vascular disease characterized by abnormal contraction and remodeling of the pulmonary arterioles, manifested by pulmonary vascular resistance (PVR) and increased pulmonary arterial pressure, eventually leading to right heart failure or even death. The mechanisms involved in this process include inflammation, vascular matrix remodeling, endothelial cell apoptosis and proliferation, vasoconstriction, vascular smooth muscle cell proliferation and hypertrophy. In this study, we review the mechanisms of action of prostaglandins and their receptors in PAH.

MAIN BODY

PAH-targeted therapies, such as endothelin receptor antagonists, phosphodiesterase type 5 inhibitors, activators of soluble guanylate cyclase, prostacyclin, and prostacyclin analogs, improve PVR, mean pulmonary arterial pressure, and the six-minute walk distance, cardiac output and exercise capacity and are licensed for patients with PAH; however, they have not been shown to reduce mortality. Current treatments for PAH primarily focus on inhibiting excessive pulmonary vasoconstriction, however, vascular remodeling is recalcitrant to currently available therapies. Lung transplantation remains the definitive treatment for patients with PAH. Therefore, it is imperative to identify novel targets for improving pulmonary vascular remodeling in PAH. Studies have confirmed that prostaglandins and their receptors play important roles in the occurrence and development of PAH through vasoconstriction, vascular smooth muscle cell proliferation and migration, inflammation, and extracellular matrix remodeling.

CONCLUSION

Prostacyclin and related drugs have been used in the clinical treatment of PAH. Other prostaglandins also have the potential to treat PAH. This review provides ideas for the treatment of PAH and the discovery of new drug targets.

Effects of sotatercept on haemodynamics and right heart function: analysis of the STELLAR trial

BACKGROUND

In the phase 3 STELLAR trial, sotatercept, an investigational first-in-class activin signalling inhibitor, demonstrated beneficial effects on 6-min walk distance and additional efficacy endpoints in pre-treated participants with pulmonary arterial hypertension (PAH).

METHODS

This post hoc analysis evaluated data from right heart catheterisation (RHC) and echocardiography (ECHO) obtained from the STELLAR trial. Changes from baseline in RHC and ECHO parameters were assessed at 24 weeks. An analysis of covariance (ANCOVA) model was used to estimate differences in least squares means with treatment and randomisation stratification (mono/double versus triple therapy; World Health Organization functional class II versus III) as fixed factors, and baseline value as covariate.

RESULTS

Relative to placebo, treatment with sotatercept led to significant (all p<0.0001 except where noted) improvements from baseline in mean pulmonary artery (PA) pressure (-13.9 mmHg), pulmonary vascular resistance (-254.8 dyn·s·cm-5), mean right atrial pressure (-2.7 mmHg), mixed venous oxygen saturation (3.84%), PA elastance (-0.42 mmHg·mL-1·beat-1), PA compliance (0.58 mL·mmHg-1), cardiac efficiency (0.48 mL·beat-1·mmHg-1), right ventricular (RV) work (-0.85 g·m) and RV power (-32.70 mmHg·L·min-1). ECHO showed improvements in tricuspid annular plane systolic excursion (TAPSE) to systolic pulmonary artery pressure ratio (0.12 mm·mmHg-1), end-systolic and end-diastolic RV areas (-4.39 cm2 and -5.31 cm2, respectively), tricuspid regurgitation and RV fractional area change (2.04% p<0.050). No significant between-group changes from baseline were seen for TAPSE, heart rate, cardiac output, stroke volume or their indices.

CONCLUSION

In pre-treated patients with PAH, sotatercept demonstrated substantial improvements in PA pressures, PA compliance, PA-RV coupling and right heart function.

Safety and efficacy of the endothelin receptor antagonist macitentan in pediatric pulmonary hypertension

Background

Macitentan, a dual endothelin receptor antagonist (ERA), was approved in 2014 for the treatment of adults with idiopathic pulmonary arterial hypertension (PAH). Once-per-day dosing and low potential hepatic toxicity make macitentan an appealing therapeutic option for children with PAH, but reports on its use in pediatric patients are still lacking.

Methods

Prospective observational study of 18 children [10 male; median age: 8.5, minimum (min.): 0.6, maximum (max.): 16.8 years] with pulmonary hypertension (PH). Four of these 18 patients were treatment-naïve and started on a de novo macitentan therapy. The remaining 14/18 children were already on a PH-targeted pharmacotherapy (sildenafil or bosentan as monotherapy or in combination). Nine children who were on bosentan were switched to macitentan. We analyzed the 6-minute walking distance (6MWD), NYHA functional class (FC)/modified ROSS score, invasive hemodynamics, echocardiographic variables and the biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP).

Results

The median follow up was 6 months (min.: 0.5, max.: 30). Macitentan treatment was associated with improvement of invasive hemodynamics, e.g., the ratio of mean pulmonary arterial pressure/mean systemic arterial pressure decreased from a median of 62% (min.: 30%, max.: 87%) to 49% (min.: 30%, max.: 69%), P<0.05; pulmonary vascular resistance index (PVRi) decreased from a median of 7.6 (min.: 3.3, max.: 11.5) to 4.8 Wood units × m² body surface area (min.: 2.5, max.: 10), P<0.05. The tricuspid annular plane systolic excursion (TAPSE) increased from a median of 1.4 (min.: 0.8, max.: 2.8) to 1.9 (min.: 0.8, max.: 2.7) cm, (P<0.05). NT-proBNP values decreased from a median of 272 (min.: 27, max.: 2,010) to 229 (min.: 23, max.: 814) pg/mL under macitentan therapy (P<0.05). The 6MWD and NYHA FC/modified ROSS score did not change significantly.

Conclusions

This is the first prospective study of macitentan pharmacotherapy in infants and children with PH <12 years of age. Except in one patient, macitentan treatment was well tolerated and was associated with improvements in invasive hemodynamics, longitudinal systolic RV function (TAPSE) and serum NT-proBNP values.

The right treatment for the right ventricle

PURPOSE OF REVIEW

Right ventricular (RV) function is an important determinant of morbidity and mortality in patients with pulmonary arterial hypertension (PAH). Although substantial progress has been made in understanding the development of RV failure in the last decennia, this has not yet resulted in the development of RV selective therapies. In this review, we will discuss the current status on the treatment of RV failure and potential novel therapeutic strategies that are currently being investigated in clinical trials.

RECENT FINDINGS

Increased afterload results in elevated wall tension. Consequences of increased wall tension include autonomic disbalance, metabolic shift and inflammation, negatively affecting RV contractility. Compromised RV systolic function and low cardiac output activate renin-angiotensin aldosterone system, which leads to fluid retention and further increase in RV wall tension. This vicious circle can be interrupted by directly targeting the determinants of RV wall tension; preload and afterload by PAH-medications and diuretics, but is also possibly by restoring neurohormonal and metabolic disbalance, and inhibiting maladaptive inflammation. A variety of RV selective drugs are currently being studied in clinical trials.

SUMMARY

Nowadays, afterload reduction is still the cornerstone in treatment of PAH. New treatments targeting important pathobiological determinants of RV failure directly are emerging.

Iron Deficiency as a Therapeutic Target in Cardiovascular Disease

Iron deficiency is the most common nutritional disorder in the world. It is prevalent amongst patients with cardiovascular disease, in whom it is associated with worse clinical outcomes. The benefits of iron supplementation have been established in chronic heart failure, but data on their effectiveness in other cardiovascular diseases are lacking or conflicting. Realising the potential of iron therapies in cardiovascular disease requires understanding of the mechanisms through which iron deficiency affects cardiovascular function, and the cell types in which such mechanisms operate. That understanding has been enhanced by recent insights into the roles of hepcidin and iron regulatory proteins (IRPs) in cellular iron homeostasis within cardiovascular cells. These studies identify intracellular iron deficiency within the cardiovascular tissue as an important contributor to the disease process, and present novel therapeutic strategies based on targeting the machinery of cellular iron homeostasis rather than direct iron supplementation. This review discusses these new insights and their wider implications for the treatment of cardiovascular diseases, focusing on two disease conditions: chronic heart failure and pulmonary arterial hypertension.

Intracellular iron deficiency in pulmonary arterial smooth muscle cells induces pulmonary arterial hypertension in mice

Pulmonary arterial hypertension (PAH) is a disease in which lung blood pressure is raised chronically, causing right heart failure. It has been shown that iron deficiency also raises lung blood pressure. However, we don’t know the mechanisms because we don’t understand precisely how cells of the lung blood vessels are affected by iron levels. The smooth muscle cells of the lung blood vessels are important for controlling lung blood pressure. Our study shows that iron deficiency specifically within these cells is sufficient to cause PAH, even against a background of normal iron levels in other tissues.

Iron deficiency augments hypoxic pulmonary arterial pressure in healthy individuals and exacerbates pulmonary arterial hypertension (PAH) in patients, even without anemia. Conversely, iron supplementation has been shown to be beneficial in both settings. The mechanisms underlying the effects of iron availability are not known, due to lack of understanding of how cells of the pulmonary vasculature respond to changes in iron levels. The iron export protein ferroportin (FPN) and its antagonist peptide hepcidin control systemic iron levels by regulating release from the gut and spleen, the sites of absorption and recycling, respectively. We found FPN to be present in pulmonary arterial smooth muscle cells (PASMCs) and regulated by hepcidin cell autonomously. To interrogate the importance of this regulation, we generated mice with smooth muscle-specific knock in of the hepcidin-resistant isoform fpn C326Y. While retaining normal systemic iron levels, this model developed PAH and right heart failure as a consequence of intracellular iron deficiency and increased expression of the vasoconstrictor endothelin-1 (ET-1) within PASMCs. PAH was prevented and reversed by i.v. iron and by the ET receptor antagonist BQ-123. The regulation of ET-1 by iron was also demonstrated in healthy humans exposed to hypoxia and in PASMCs from PAH patients with mutations in bone morphogenetic protein receptor type II. Such mutations were further associated with dysregulation of the HAMP/FPN axis in PASMCs. This study presents evidence that intracellular iron deficiency specifically within PASMCs alters pulmonary vascular function. It offers a mechanistic underpinning for the known effects of iron availability in humans.

Treatment of children with pulmonary hypertension. Expert consensus statement on the diagnosis and treatment of paediatric pulmonary hypertension. The European Paediatric Pulmonary Vascular Disease Network, endorsed by ISHLT and DGPK

Treatment of children and adults with pulmonary hypertension (PH) with or without cardiac dysfunction has improved in the last two decades. The so-called pulmonary arterial hypertension (PAH)-specific medications currently approved for therapy of adults with PAH target three major pathways (endothelin, nitric oxide, prostacyclin). Moreover, some PH centres may use off-label drugs for compassionate use. Pulmonary hypertensive vascular disease (PHVD) in children is complex, and selection of appropriate therapies remains difficult. In addition, paediatric PAH/PHVD therapy is vastly based on experience and trial data from adult rather than paediatric studies; however, the first randomised paediatric PAH trials have been conducted recently. We present consensus recommendations for the treatment of children with PH. Class of recommendation and level of evidence were assigned based on paediatric data only or on adult studies that included >10% children. After a systematic literature search and analysis of the published data, we developed treatment strategies and algorithms that can guide goal-oriented PH therapy. We discuss early combination therapy (double, triple) in patients with PAH in functional class II-IV and in those with inadequate response to the initial pharmacotherapy. In those children with progressive, severe PAH and inadequate response, advances in drug development, and interventional and surgical approaches provide promising new strategies to avoid, reverse or ameliorate right heart failure and left ventricular compression. In particular, first follow-up data indicate that Potts shunt (left pulmonary artery to descending aorta anastomosis) may be an alternative destination therapy, or bridge to bilateral lung transplantation, in end-stage paediatric PAH.

Where do we go from here? Reappraising the data on anticoagulation in pulmonary arterial hypertension

The use of anticoagulation as part of the treatment regimen in pulmonary arterial hypertension (PAH) remains a topic of debate. A recently published analysis of anticoagulation use in the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL) study offers conflicting conclusions regarding the benefit of this therapeutic strategy. There remains no robust randomized trial in PAH weighing the risks versus benefits of including anticoagulation in treatment regimens, leaving clinicians to surmise value in individual patients. Reexamination of available data may help to provide guidance on this controversial topic in the absence of future dedicated investigations.

Impact of Superoxide Dismutase Mimetic AEOL 10150 on the Endothelin System of Fischer 344 Rats

Endothelin-1 is a potent vasoconstrictor and mitogenic peptide involved in the regulation of vasomotor tone and maintenance of blood pressure. Oxidative stress activates the endothelin system, and is implicated in pulmonary and cardiovascular diseases including hypertension, congestive heart failure, and atherosclerosis. Superoxide dismutase mimetics designed with the aim of treating diseases that involve reactive oxygen species in their pathophysiology may exert a hypotensive effect, but effects on the endothelin system are unknown. Our objective was to determine the effect of the superoxide dismutase mimetic AEOL 10150 on the basal endothelin system in vivo. Male Fischer-344 rats were injected subcutaneously with 0, 2 or 5 mg/kg body weight of AEOL 10150 in saline. Plasma oxidative stress markers and endothelins (bigET-1, ET-1, ET-2, ET-3) as well as lung and heart endothelin/nitric oxide system gene expressions were measured using HPLC-Coularray, HPLC-Fluorescence and RT-PCR respectively. AEOL 10150 reduced (p<0.05) the circulating levels of isoprostane (-25%) and 3-nitrotyrosine (-50%) measured in plasma 2h and 24h after treatment, confirming delivery of a physiologically-relevant dose and the potent antioxidant activity of the drug. The reduction in markers of oxidative stress coincided with sustained 24h decrease (p<0.05) of plasma levels of ET-1 (-50%) and ET-3 (-10%). Expression of preproET-1 and endothelin converting enzyme-1 mRNA were not altered significantly in the lungs. However preproET-1 (not significant) and ECE-1 mRNA (p<0.05) were increased (10-25%) in the heart. Changes in the lungs included decrease (p<0.05) of mRNA for the ET-1 clearance receptor ETB and the vasoconstriction-signaling ETA receptor (-30%), and an early surge of inducible nitric oxide synthase expression followed by sustained decrease (-40% after 24 hours). The results indicate that interception of the endogenous physiological flux of reactive nitrogen species and reactive oxygen species in rats impacts the endothelin/nitric oxide system, supporting a homeostatic relationship between those systems.

The pathophysiology of pulmonary hypertension in left heart disease

Pulmonary hypertension (PH) is characterized by elevated pulmonary arterial pressure leading to right-sided heart failure and can arise from a wide range of etiologies. The most common cause of PH, termed Group 2 PH, is left-sided heart failure and is commonly known as pulmonary hypertension with left heart disease (PH-LHD). Importantly, while sharing many clinical features with pulmonary arterial hypertension (PAH), PH-LHD differs significantly at the cellular and physiological levels. These fundamental pathophysiological differences largely account for the poor response to PAH therapies experienced by PH-LHD patients. The relatively high prevalence of this disease, coupled with its unique features compared with PAH, signal the importance of an in-depth understanding of the mechanistic details of PH-LHD. The present review will focus on the current state of knowledge regarding the pathomechanisms of PH-LHD, highlighting work carried out both in human trials and in preclinical animal models. Adaptive processes at the alveolocapillary barrier and in the pulmonary circulation, including alterations in alveolar fluid transport, endothelial junctional integrity, and vasoactive mediator secretion will be discussed in detail, highlighting the aspects that impact the response to, and development of, novel therapeutics.

Bosentan, a mixed endothelin receptor antagonist, inhibits superoxide anion-induced pain and inflammation in mice

Bosentan is a mixed endothelin receptor antagonist widely used to treat patients with pulmonary arterial hypertension, and the emerging literature suggests bosentan as a potent anti-inflammatory drug. Superoxide anion is produced in large amounts during inflammation, stimulates cytokine production, and thus contributes to inflammation and pain. However, it remains to be determined whether endothelin contributes to the inflammatory response triggered by the superoxide anion. The present study investigated the effects of bosentan in a mouse model of inflammation and pain induced by potassium superoxide, a superoxide anion donor. Male Swiss mice were treated with bosentan (10-100 mg/kg) by oral gavage, 1 h before potassium superoxide injection, and the inflammatory response was evaluated locally and at spinal cord (L4-L6) levels. Bosentan (100 mg/kg) inhibited superoxide anion-induced mechanical and thermal hyperalgesia, overt pain-like behavior (abdominal writhings, paw flinching, and licking), paw edema, myeloperoxidase activity (neutrophil marker) in the paw skin, and leukocyte recruitment in the peritoneal cavity. Bosentan also inhibited superoxide anion-induced interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) production, while it enhanced IL-10 production in the paw skin and spinal cord. Bosentan inhibited the reduction of antioxidant capacity (reduced glutathione, ferric reducing antioxidant power, and ABTS radical scavenging ability) induced by the superoxide anion. Finally, we demonstrated that intraplantar injection of potassium superoxide induces the mRNA expression of prepro-endothelin-1 in the paw skin and spinal cord. In conclusion, our results demonstrated that superoxide anion-induced inflammation, pain, cytokine production, and oxidative stress depend on endothelin; therefore, these responses are amenable to bosentan treatment.

Effect of PAH specific therapy on pulmonary hemodynamics and six-minute walk distance in portopulmonary hypertension: a systematic review and meta-analysis

Background. Little is known about the effect of pulmonary arterial hypertension (PAH) specific therapy on pulmonary hemodynamics and exercise capacity in patients with portopulmonary hypertension (PoPH) because such patients are usually excluded from randomized clinical trials (RCT) of such therapy. Methods. We searched PUBMED using the terms “(Therapy/Broad (filter)) AND (portopulmonary hypertension).” We included studies that met the following criteria: ≥5 patients, AND PoPH confirmed by right heart catheterization (RHC), AND follow-up RHC data, AND/OR baseline and follow-up 6MWD available. Results. 12 studies met our inclusion criteria. None was a RCT. The baseline mPAP was 48.6 ± 4.4 mmHg, cardiac output (CO) 5.6 ± 0.9 L/min, and pulmonary vascular resistance (PVR) 668.6 ± 219.1 dynes.sec/cm⁵. The baseline 6MWD was 348.2 ± 35.6 meters. The use of PAH specific therapy improved mPAP by 7.54 mmHg (95% CI 10.2 to 4.9), CO by 1.77 L/min (95% CI 1.1 to 2.4), and PVR by 253 dynes.sec/cm⁵ (95% CI 291.4 to 214.6) (n = 135) and 6MWD by 61.8 meters (95% CI 47.5 to 76) (n = 122). Conclusions. The use of PAH specific therapy in PoPH results in significant improvement in both pulmonary hemodynamics and 6MWD.

[Treatment of pulmonary arterial hypertension]

Treatment of pulmonary arterial hypertension has achieved significant progress over the past 20 years. Currently, 3 groups of drugs have proven useful for the treatment of this disease: endothelin receptor antagonist, phosphodiesterase inhibitors and prostacyclin and its analogues. It is recommended to initiate treatment with one of these drugs, the choice depending on the initial severity of patient disease and the preferences of the treating physician. When the patient does not have a satisfactory response, new drugs acting at a different pathway are most commonly added. At this time, considering referral for lung transplantation could be an alternative. Most experts recommend grouping maximum experience in what is known as expert centers. Treatment has led to better survival in these patients, but there is still a long way to cure this life-threatening disease.

Pulmonary hypertension in patients with chronic and end-stage kidney disease

Pulmonary hypertension is defined as a mean pulmonary artery pressure ≥25 mm Hg and is a recently recognized complication of chronic kidney disease and end-stage renal disease. There is significant epidemiological overlap with kidney disease and the underlying causes of World Health Organization group 1-4 pulmonary hypertension (pulmonary arteriopathy, left heart disease, chronic pulmonary disease, and chronic thromboembolic disease, respectively). In addition, an entity of 'unexplained pulmonary hypertension,' group 5, in patients with chronic kidney disease and end-stage renal disease has emerged, with prevalence estimates of 30-50%. The pathogenesis of pulmonary hypertension in this population is due to alterations in endothelial function, increased cardiac output, and myocardial dysfunction leading to elevated left heart filling pressure, with recent data suggesting that left heart dysfunction may account for the vast majority of pulmonary hypertension in patients with kidney disease. Pulmonary hypertension is an independent predictor of increased mortality in patients on dialysis and those undergoing kidney transplantation. This review summarizes what is known about the epidemiology, pathogenesis, transplantation outcomes, mortality, and treatment of pulmonary hypertension in patients with chronic kidney disease and end-stage renal disease.

Prostanoids for Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a severe condition that markedly reduces exercise capacity and survival in the affected patient population. PAH includes primary pulmonary hypertension (PPH) and pulmonary hypertension associated with collagen vascular diseases, congenital systemic-to-pulmonary shunts, portal hypertension and HIV infection. All these conditions share virtually identical obstructive pathologic changes of the pulmonary microcirculation and probably similar pathobiologic processes. The pathophysiology is characterized by a progressive increase in pulmonary vascular resistance, leading to right ventricular failure and death. Prostacyclin is an endogenous substance that is produced by vascular endothelial cells and induces vasodilatation, inhibition of platelet activity, and antiproliferative effects. A dysregulation of prostacyclin metabolic pathways has been shown in patients with PAH and this represents the rationale for the exogenous therapeutic administration of this substance. The clinical use of prostacyclin in patients with PAH has been made possible by the synthesis of stable analogs that possess different pharmacokinetic properties but share similar pharmacodynamic effects. Experience in humans has been initially collected with epoprostenol, which is a synthetic salt of prostacyclin. Epoprostenol has a short half-life in the circulation and requires continuous administration by the intravenous route by means of infusion pumps and permanent tunnelized catheters. In addition, epoprostenol is unstable at room temperature, and the complex delivery system required is associated with several adverse effects and potentially serious complications. For these reasons, alternatives to intravenous epoprostenol have been sought and this has led to the development of analogs that can be administered subcutaneously (treprostinil), orally (beraprost sodium) or by inhalation (iloprost). Three unblinded clinical trials and several uncontrolled trials have shown that treatment with epoprostenol improved symptoms and exercise capacity in New York Heart Association (NYHA) class III and IV PAH patients and also survival in patients with PPH. Subcutaneous treprostinil improved symptoms, exercise, hemodynamics and clinical events in the largest clinical trial ever performed in PAH, but local infusion site reactions limited efficacy in a proportion of patients. Oral beraprost sodium improved exercise capacity only in patients with PPH and is the only prostacyclin analog that has also been tested in NYHA class II patients. Inhaled iloprost has improved symptoms, exercise capacity and clinical events in patients with PAH and inoperable chronic thromboembolic pulmonary hypertension. The favorable effects of prostanoids observed in all studies coupled with different profiles of adverse events and tolerability for each prostacyclin analog allow the unique opportunity to select the most appropriate compound for the individual patient with PAH.

Sildenafil and bosentan improve arterial oxygenation during acute hypoxic exercise: a controlled laboratory trial

OBJECTIVES

Sildenafil and, recently, bosentan have been reported to increase arterial saturation and exercise capacity at altitude. The mechanisms behind this are still poorly defined but may be related to attenuation of hypoxic pulmonary vasoconstriction (HPV) and improved gas exchange. This study was designed to examine and compare the effect of sildenafil and bosentan on pulmonary gas exchange during acute hypoxic exercise in a controlled laboratory setting.

METHODS

Sixteen athletic university students (8 males, 8 females) were examined during exercise in a hypoxic chamber (11% oxygen) before and after the administration of either sildenafil (n=10) or bosentan (n=6). Respiratory and metabolic measurements were taken at rest and during increasing exercise intensity (up to 90% of their individual maximal oxygen uptake [VO(2)max]) in concert with arterial blood gas sampling.

RESULTS

Both drugs resulted in small, but significant increases in arterial PO(2) (2-3 Torr) and O(2) saturation (3-4%) at rest and during hypoxic exercise, in both men and women. No significant changes in arterial PCO(2) or ventilation were seen at rest or during exercise in hypoxia; however, heart rate (both at rest and during exercise) was increased with both sildenafil and bosentan in both men and women.

CONCLUSIONS

These data demonstrate that sildenafil and bosentan equally improve arterial oxygenation in acute hypoxia in both men and women, which could account for improved physical performance at altitude.

Key role of the RhoA/Rho kinase system in pulmonary hypertension

Pulmonary hypertension (PH) is a general term comprising a spectrum of pulmonary hypertensive disorders which have in common an elevation of mean pulmonary arterial pressure (mPAP). The prototypical form of the disease, termed pulmonary arterial hypertension (PAH), is a rare but lethal syndrome with a complex aetiology characterised by increased pulmonary vascular resistance (PVR) and progressive elevation of mPAP; patients generally die from heart failure. Current therapies are inadequate and median survival is less than three years. PH due to chronic hypoxia (CH) is a condition separate from PAH and is strongly associated with chronic obstructive pulmonary disease (COPD). An early event in the pathogenesis of this form of PH is hypoxic pulmonary vasoconstriction (HPV), an acute homeostatic process that maintains the ventilation-perfusion ratio during alveolar hypoxia. The mechanisms underlying HPV remain controversial, but RhoA/Rho kinase (ROK)-mediated Ca²+-sensitisation is considered important. Increasing evidence also implicates RhoA/ROK in PASMC proliferation, inflammatory cell recruitment and the regulation of cell motility, all of which are involved in the pulmonary vascular remodelling occurring in all forms of PH. ROK is therefore a potential therapeutic target in treating PH of various aetiologies. Here, we examine current concepts regarding the aetiology of PAH and also PH due to CH, focusing on the contribution that RhoA/ROK-mediated processes may make to their development and on ROK inhibitors as potential therapies.

Effectiveness of transition from intravenous epoprostenol to oral/inhaled targeted pulmonary arterial hypertension therapy in pediatric idiopathic and familial pulmonary arterial hypertension

Before 2001, intravenous epoprostenol was the only approved drug for patients with idiopathic pulmonary arterial hypertension (IPAH) or familial pulmonary arterial hypertension (FPAH) who were nonresponsive to high-dose calcium channel blockade. The investigators report transitioning select pediatric patients with IPAH or FPAH from intravenous epoprostenol to oral and/or inhaled agents for pulmonary arterial hypertension. A retrospective review was performed on all pediatric patients with IPAH or FPAH treated at Columbia University (1987 to 2008) who transitioned off epoprostenol to oral or inhaled drugs. Criteria for transition included functional class I or II, mean pulmonary arterial pressure <35 mm Hg, normal cardiac index, and age >6 years. Hemodynamic and clinical data were obtained at baseline (before epoprostenol), at peak epoprostenol dose, and after epoprostenol discontinuation. Fourteen of 104 pediatric patients with IPAH or FPAH transitioned off epoprostenol to oral or inhaled drugs from April 2003 to July 2008. Of the 14 subjects, 13 transitioned off epoprostenol successfully to oral or inhaled drugs. No significant changes in functional class, hemodynamics, or exercise data were seen after epoprostenol (mean follow-up duration 7.0 +/- 5.8 months) compared to peak epoprostenol, but further improvement was reported in World Health Organization functional class (p <0.005) after epoprostenol discontinuation. After successful epoprostenol discontinuation, 77% of patients were treated with endothelin receptor antagonists, 69% with phosphodiesterase-5 inhibitors, 38% with calcium channel blockers, and 8% inhaled iloprost. At the cut-off date (May 2009), there was 100% survival and 93% transition success. In conclusion, in carefully selected children with IPAH or FPAH initiated on intravenous epoprostenol before the availability of nonparenteral therapy, transition to oral or inhaled therapy for pulmonary arterial hypertension appears safe, with efficacy maintained when performed with close follow-up at a pulmonary hypertension specialty center.

The emergence of oral tadalafil as a once-daily treatment for pulmonary arterial hypertension

Pulmonary hypertension (PH) is found in a vast array of diseases, with a minority representing pulmonary arterial hypertension (PAH). Idiopathic PAH or PAH in association with other disorders has been associated with poor survival, poor exercise tolerance, progressive symptoms of dyspnea, and decreased quality of life. Left untreated, patients with PAH typically have a progressive decline in function with high morbidity ultimately leading to death. Advances in medical therapy for PAH over the past decade have made significant inroads into improved function, quality of life, and even survival in this patient population. Three classes of pulmonary artery-specific vasodilators are currently available in the United States. They include prostanoids, endothelin receptor antagonists, and phosphodiesterase type 5 (PDE5) inhibitors. In May 2009, the FDA approved tadalafil, the first once-daily PDE5 inhibitor for PAH. This review will outline the currently available data on tadalafil and its effects in patients with PAH.

Outcome of pulmonary hypertension subjects transitioned from intravenous prostacyclin to oral bosentan

INTRODUCTION

Prostacyclin (PG) remains the gold standard therapy for severe pulmonary arterial hypertension (PAH). Previously, we reported the successful transitioning of PAH subjects from intravenous prostacyclin to oral bosentan (Suleman et al. Chest 2004;126:808-15). We report here the 5-year follow-up data.

METHODS

In the transition study, 11 PAH subjects were successfully transitioned to oral bosentan in 12 weeks. Two subjects who subsequently developed liver function test (LFT) abnormalities were taken off bosentan and switched to another endothelin receptor antagonist. Demographics, six-minute walk distance (6MWD), WHO functional class (FC), and survival data was collected.

RESULTS

10 Females and 1 male ranging in age from 35 to 79 were successfully transitioned. Mean duration of illness prior to transition was 50.55+/-26 months. Mean duration that these subjects remained on oral therapy was 34+/-24 months. Mean duration that patients remained off PG was 28+/-21 months. In 7 of the 11 subjects (64%), PG was resumed due to clinical deterioration. One patient remained on bosentan as monotherapy, five had phosphodiesterase 5-inhibitor added. 9 Of the 11 subjects were WHO FC II post-transition and 5 of the 7 subjects at follow-up were WHO FC II (82% vs 67%). Post-transition 6MWD was 386+/-85 in 10 subjects and at follow-up 6MWD was 396+/-99 in 9 subjects (p=0.81).

CONCLUSIONS

In this study, patients frequently required prostanoid resumption after transition from intravenous prostanoid to oral therapy. However, in these carefully selected patients, transition to oral therapy offered prolonged stable FC and 6MWD, cost savings and substantial quality of life benefits.

Inhibition of endothelin receptors in the treatment of pulmonary arterial hypertension: does selectivity matter?

Treatment options for pulmonary arterial hypertension (PAH) have considerably improved in the past few years. Endothelin (ET)-receptor antagonism has been established as a first-line option for the majority of PAH patients. Endothelin-receptor antagonists (ETRAs) comprise sulfonamide and non-sulfonamide agents with different affinities for ET-receptor subtypes (ET_A and ET_B), and the focus of development has shifted from drugs with less selectivity to those with high selectivity. There is ongoing debate as to whether selective or non-selective ET-receptor antagonism is more beneficial in the treatment of PAH. This paper reviews the current evidence from experimental and clinical studies obtained from a thorough literature search focusing on the three marketed drugs bosentan, sitaxentan, and ambrisentan. A clinically meaningful difference among the three approved ETRAs with respect to their ET-receptor selectivity could not be demonstrated to date. Therefore, in clinical practice, other features are likely to be of greater relevance when considering treatment, such as the potential for serious drug–drug interactions, convenience of dosing schedule, or rates of limiting side effects. These characteristics bear more relation to the chemical or pharmacological properties of the drugs than to receptor selectivity itself.

Pulmonary arterial hypertension

Significant advances in the treatment of pulmonary arterial hypertension (PAH) have occurred over the last 10 years, starting with the approval of epoprostenol in 1998. Subsequently, multiple additional medications have received approval, including a subcutaneous prostacyclin, an inhaled prostacyclin, and oral medications in 2 separate classes. Over this same period, the classification of pulmonary hypertension has been revised with changes including the substitution of the term idiopathic for primary PAH and an expanded list of conditions felt to be associated with the development of PAH. Long-term follow-up studies have provided better information on prognosis and expected outcomes with treatment, with particularly valuable data on reassessment of prognosis after treatment with epoprostenol. Combination therapy is more frequently being used, and limited data on novel therapies such as stem cell transplantation have been published. The purpose of this review is to describe the current state of evidence for the diagnosis, prognosis, and treatment of the patient with PAH.

Pulmonary arterial hypertension: current therapeutic strategies

The treatment of pulmonary arterial hypertension--once a lethal condition--has evolved considerably over the past few years as the number of therapeutic options available to treat this disease has increased. In this Review we attempt to summarize the current knowledge of the pathogenesis of pulmonary hypertension, in relation to the therapies presently available and those that could become available in the near future. The use of prostacyclin and its analogs, calcium-channel blockers, endothelin-receptor antagonists and phosphodiesterase type 5 inhibitors is reviewed. Newer concepts, such as the use of combination therapy, and the potential for long-term disease amelioration and improvement of outcomes, are also discussed. The role of supportive care and medications not specific to pulmonary hypertension is also examined. In addition, we review the novel emerging therapies, such as imatinib, fasudil, simvastatin, ghrelin and vasoactive intestinal peptide, which hold therapeutic potential for disease modification as well as treatment of symptoms.

Effect of sitaxsentan treatment on quality of life in pulmonary arterial hypertension

In recent years new therapeutic options have been developed for the management of pulmonary arterial hypertension (PAH). Sitaxsentan is an oral, once daily, highly selective endothelin A receptor antagonist that recently demonstrated a positive effect on functional capacity and haemodynamics of PAH patients. The aim of this study is to evaluate the effect of sitaxsentan in the quality of life (QOL) of PAH patients. Twenty-three patients with idiopathic PAH or PAH associated to collagen vascular diseases were evaluated at baseline and after 16 weeks of treatment with sitaxsentan 100 mg orally, once daily. 6-min walk test distance (6MWD) and QOL questionnaire (QOLQ) (SF-36) were obtained at baseline and at week 16. There was a significant improvement in functional capacity evaluated by 6MWD (472 m vs. 490 m, p = 0.03) and also in the physical component of the QOLQ (p < 0.01). Evaluating each of the domains of the SF-36 QOLQ, those more related to physical capacity presented a significant increase while the domains related to the mental component presented a trend of improvement, without reaching statistical significance. Sitaxsentan improves QOL in patients with PAH mainly through the domains related to functional capacity.

Successful treatment of portopulmonary hypertension with bosentan: case report

Pulmonary arterial hypertension (PAH) is found in 2-20% of cirrhosis patients who have portal hypertension (portopulmonary hypertension, PPHT). Endothelin (ET), a potent vasoconstrictor, is likely to play a role in the pathogenesis of portal hypertension. We describe the long-term successful use of the dual ET(A)/ET(B) receptor antagonist bosentan in a 43-year-old male with alcohol-related cirrhosis (Child-Pugh A), right ventricular enlargement and dysfunction, respectively, and moderate PAH. Elevated pulmonary arterial pressure was substantially reduced and exercise capacity increased. Improvement was maintained over 2 years, and bosentan treatment continues in this patient. Our report is in line with a series of current reports in PPHT that support the use of bosentan in this subset of PAH patients.

Bosentan treatment of portopulmonary hypertension related to liver cirrhosis owing to hepatitis C

Pulmonary arterial hypertension (PAH) with coexisting portal hypertension has been defined as portopulmonary hypertension (PPHTN). It is often related to liver cirrhosis of various aetiologies and is associated with a high mortality rate. Endothelin-1 (ET) is supposed to play an important role in the pathogenesis of PAH as well as portal hypertension. Therefore, therapy with an ET(A)/ET(B) receptor antagonist might be of use in the treatment of PPHTN. We report the case of a 76-year-old male with liver cirrhosis owing to chronic hepatitis C virus infection and PPHTN who was treated with the dual ET(A)/ET(B) receptor antagonist bosentan. The patient showed remarkable improvement of 6-min walking distance from 300 to 480 m after 2 weeks and to 540 m after 14 weeks, respectively. In addition, a significant decline of N-terminal pro B-type natriuretic peptide fraction (NT-proBNP) from 4928 ng mL(-1) to 640 ng mL(-1) was observed. Bosentan might be a promising new therapeutical option for patients suffering from PPHTN.

Sildenafil: from angina to erectile dysfunction to pulmonary hypertension and beyond

In less than 20 years, the first selective type 5 phosphodiesterase inhibitor, sildenafil, has evolved from a potential anti-angina drug to an on-demand oral treatment for erectile dysfunction (Viagra), and more recently to a new orally active treatment for pulmonary hypertension (Revatio). Here we describe the key milestones in the development of sildenafil for these diverse medical conditions, discuss the advances in science and clinical medicine that have accompanied this journey and consider possible future indications for this versatile drug.

Effect of bosentan treatment on surrogate markers in pulmonary arterial hypertension

OBJECTIVE

The aim of this study was to evaluate the effect of the oral dual ET(A)/ET(B) receptor antagonist bosentan on different surrogate markers in patients with pulmonary arterial hypertension (PAH).

DESIGN AND SETTING

Prospective, open label, uncontrolled study in a University Hospital in Brazil.

POPULATION

Fifteen PAH patients (11 females) with mean age of 40 +/- 11 years (5 in WHO functional class II, 10 in class III).

METHODS

All patients were investigated at baseline and after 16 weeks of bosentan treatment. We used the following surrogate markers for patients' evaluation: 6-min walk test, quality of life questionnaire (Short Form SF-36) and N-terminal proBNP (B type natriuretic peptide) fraction levels in blood.

RESULTS

Between the evaluation at baseline and week 16, the 6-min walk test distance changed from 396 +/- 135 to 434 +/- 137 m (p < 0.05). Each of the eight domains of the SF-36 was significantly improved. Mean NT-proBNP levels were decreased from a mean of 1670 pg/mL to 1010 pg/mL (p = 0.01).

CONCLUSION

The study suggests that bosentan treatment results in the improvement of different kinds of surrogate markers independently of their specificity to reflect functional capacity, quality of life and myocardial stress. It is concluded that the combined use of these different markers may be an alternative endpoint for future short duration clinical trials.

Medikament�se Therapie der pulmonalen Hypertonie

New drugs for pulmonary arterial hypertension have shown efficacy in randomized controlled trials. Endothelin receptor antagonists (ERA) and prostanoids are most important for clinical practice. Bosentan represents the first approved orally active therapy for PAH. Besides its hepatotoxicity it is mostly well tolerated. The first approved prostanoid, epoprostenol, is currently first choice only for decompensated right heart failure in PAH. It has to be delivered continuously intravenously and is prone to complications, side effects and very high costs. Alternatively, subcutaneous treprostinil can be applied. It is less risky and expensive but may cause local pain at the infusion site. Inhaled iloprost combines the features of a prostanoid with pulmonary and intrapulmonary selectivity. Alternatively, iloprost is being used as continuous intravenous infusion. The phosphodiesterase-5 inhibitor sildenafil was effective in two randomized controlled trials but has not been approved for PAH therapy.

Comparative analysis of clinical trials and evidence-based treatment algorithm in pulmonary arterial hypertension

The numerous controlled clinical trials performed recently in pulmonary arterial hypertension (PAH) can allow us to abandon a clinical-based treatment strategy and adopt an evidence-based therapy. Both uncontrolled and controlled clinical trials with different compounds and procedures are reviewed and compared in order to define the efficacy-to-side-effect ratio of each treatment. A grading system for the level of evidence of treatments based on the number of favorable controlled clinical trials performed with a given compound is adopted; a treatment algorithm based on the evidence derived by clinical trials is proposed. It includes drugs approved by regulatory agencies for the treatment of patients with PAH and/or drugs available on the market for other indications. The algorithm is restricted to patients in New York Heart Association (NYHA) functional class III or IV because they represent the largest population included in controlled clinical trials. In addition, the different treatments have been evaluated mainly in sporadic, idiopathic PAH and in PAH associated with scleroderma or to anorexigen use. Extrapolation of these recommendations to the other PAH subgroups should be done with caution. Oral anticoagulation is proposed for all patients, whereas diuretic treatment and supplemental oxygen are indicated in cases of fluid retention and hypoxemia, respectively. High doses of calcium channel blockers are indicated only in the minority of patients who are responders to acute vasoreactivity testing. Nonresponders to acute vasoreactivity testing, or responders who remain in NYHA functional class III, should be considered candidates for treatment with either an endothelin receptor antagonist or a prostanoid. Continuous intravenous administration of epoprostenol is proposed as rescue treatment in NYHA functional class IV patients. Phosphodiesterase-V inhibitors should be considered in patients who have failed or are not candidates to other therapies. Combination therapy can be attempted in selected cases. Both balloon atrial septostomy and lung transplantation are indicated for refractory patients or where medical treatment is unavailable.

ET-1 receptor gene expression and distribution in L1 and L2 cells from hypertensive sheep pulmonary artery

We examined gene and surface expression and activity of the endothelin (ET)-1 receptors (ETA and ETB) in subendothelial (L1) and inner medial (L2) cells from the main pulmonary artery of sheep with continuous air embolization (CAE)-induced chronic pulmonary hypertension (CPH). According to quantitative real-time RT-PCR, basal gene expression of both receptors was significantly higher in L2 than L1 cells, and hypertensive L2 cells showed significantly higher gene expression of ETB than controls. Expression of both genes in hypertensive L1 cells was similar to controls. Fluorescence-activated cell sorter analysis confirmed the increased distribution of ET(B) in hypertensive L2 cells. Although only the ETA receptors in control L2 cells showed significant binding of [125I]-labeled ET-1 at 1 h, both receptors bound ET-1 to hypertensive cells. Exposure to exogenous ET-1 for 18 h revealed that only the L2 cells internalized ET-1, and internalization by hypertensive L2 cells was significantly reduced when compared with controls. Treatment with ETA (BQ-610) and ETB (BQ-788) receptor antagonists demonstrated that both receptors contributed to internalization of ET-1 in control L2 cells, whereas in hypertensive cells only when both receptor antagonists were used in combination was significant suppression of ET-1 internalization found. We conclude that in sheep receiving CAE, alterations in ETB receptors in cells of the L2 layer may contribute to the maintenance of CPH via alterations in their expression, distribution, and activity.

Exaggerated hypoxic pulmonary hypertension in endothelin B receptor-deficient rats

Mechanisms by which endothelin (ET)-1 mediates chronic pulmonary hypertension remain incompletely understood. Although activation of the ET type A (ET(A)) receptor causes vasoconstriction, stimulation of ET type B (ET(B)) receptors can elicit vasodilation or vasoconstriction. We hypothesized that the ET(B) receptor attenuates the development of hypoxic pulmonary hypertension and studied a genetic rat model of ET(B) receptor deficiency (transgenic sl/sl). After 3 wk of severe hypoxia, the transgenic sl/sl pulmonary vasculature lacked expression of mRNA for the ET(B) receptor and developed exaggerated pulmonary hypertension that was characterized by elevated pulmonary arterial pressure, diminished cardiac output, and increased total pulmonary resistance. Plasma ET-1 was fivefold higher in transgenic sl/sl rats than in transgenic controls. Although mRNA for prepro-ET-1 was not different, mRNA for ET-converting enzyme-1 was higher in transgenic sl/sl than in transgenic control lungs. Hypertensive lungs of sl/sl rats also produced less nitric oxide metabolites and 6-ketoprostaglandin F(1alpha), a metabolite of prostacyclin, than transgenic controls. These findings suggest that the ET(B) receptor plays a protective role in the pulmonary hypertensive response to chronic hypoxia.

Influence of food intake and formulation on the pharmacokinetics and metabolism of bosentan, a dual endothelin receptor antagonist

The purpose of the study was to investigate the effect of food intake on the pharmacokinetics and metabolism as well as the relative bioavailability of bosentan. Sixteen healthy male subjects were treated in a randomized, four-way, crossover design with single oral doses of 125 mg bosentan, given as one tablet (with or without food), two tablets of 62.5 mg (with food), and a suspension (without food). The pharmacokinetic parameters of bosentan (and also three of its metabolites) were very similar after the four treatments: geometric means for Cmax and AUC0-infinity, ranged from 1.3 to 1.6 microg/ml and from 7.8 to 8.9 microg x h/ml, respectively, and median t(max) from 3.0 to 4.0 hours. The bioavailability of the 125 mg tablet relative to that of the suspension, both given fasted, was 102%. In the presence of food, Cmax and AUC0-max increased by 22% and 10%, respectively, whereas the two 62.5 mg tablets were bioequivalent to the 125mg tablet, both under fed conditions. The pharmacokinetics of the metabolites was independent of the treatment administered. In conclusion, bosentan bioavailability from the newly developed 125 mg tablet formulation is similar to that of the suspension, and food intake does not influence its pharmacokinetics to a clinically relevant extent.

Endothelin receptor antagonists and cardiovascular diseases of aging

Our understanding of the role of the endothelin system in human cardiovascular physiology and pathophysiology has evolved very rapidly since the initial description of its constituent parts in 1988. Endothelin-1 (ET-1) is the predominant endothelin isoform in the human cardiovascular system and has potent vasoconstrictor, mitogenic and antinatriuretic properties which have implicated it in the pathophysiology of a number of cardiovascular diseases. The effects of ET-1 have been shown to be mediated by 2 principal endothelin receptor subtypes: ET(A) and ET(B). The development of a range of peptidic and nonpeptidic endothelin receptor antagonists represents an exciting breakthrough in human cardiovascular therapeutics. Two main classes of endothelin receptor antagonist have been developed for possible human therapeutic use: ET(A)-selective and nonselective antagonists. Extensive laboratory and clinical research with these agents has highlighted their promise in various cardiovascular diseases. Randomised, placebo-controlled clinical trials have yielded very encouraging results in patients with hypertension and chronic heart failure with more preliminary data suggesting a possible role in the treatment and prevention of atherosclerosis and stroke. Much more research is needed, however, before endothelin receptor antagonists can be considered for clinical use.

Pediatric Primary Pulmonary Hypertension

Primary pulmonary hypertension is a disease for which there is no single best therapy. Rather, it is a process that progresses inexorably to disability and death, for which there are a variety of palliative therapies, all with significant side effects, and none curative. Nevertheless, it is clear that the available therapies improve the quality of life and prolong life; failure to offer therapy for patients with this disease in the current era is indefensible. As primary pulmonary hypertension progresses, one must chose from among the available therapies the regimen that provides the most benefit for the patient with the least associated morbidity. Organ replacement is appropriate only after all other available therapies have been exhausted. The recommended hierarchy of therapy is 1) anticongestive therapy, anticoagulation, and supplemental oxygen, 2) calcium channel blockade, 3) continuous intravenous prostacyclin, 4) beta-receptor agonists for cardiac support, and 5) lung transplantation. Newer therapies, described in this review, soon will be incorporated into this hierarchy.

Therapeutic potential for endothelin receptor antagonists in cardiovascular disorders

The endothelins are synthesized in vascular endothelial and smooth muscle cells, as well as in neural, renal, pulmonal, and inflammatory cells. These peptides are converted by endothelin-converting enzymes (ECE-1 and -2) from 'big endothelins' originating from large preproendothelin peptides cleaved by endopeptidases. Endothelin (ET)-1 has major influence on the function and structure of the vasculature as it favors vasoconstriction and cell proliferation through activation of specific ET(A) and ET(B) receptors on vascular smooth muscle cells. In contrast, ET(B )receptors on endothelial cells cause vasodilation via release of nitric oxide (NO) and prostacyclin. Additionally, ET(B) receptors in the lung are a major pathway for the clearance of ET-1 from plasma. Indeed, ET-1 contributes to the pathogenesis of important disorders as arterial hypertension, atherosclerosis, and heart failure. In patients with atherosclerotic vascular disease (as well as in many other disease states), ET-1 levels are elevated and correlate with the number of involved sites. In patients with acute myocardial infarction, they correlate with 1-year prognosis. ET receptor antagonists have been widely studied in experimental models of cardiovascular disease. In arterial hypertension, they prevent vascular and myocardial hypertrophy. Experimentally, ET receptor blockade also prevents endothelial dysfunction and structural vascular changes in atherosclerosis due to hypercholesterolemia. In experimental myocardial ischemia, treatment with an ET receptor antagonist reduced infarct size and prevented left ventricular remodeling after myocardial infarction. Most impressively, treatment with the selective ET(A) receptor antagonist BQ123 significantly improved survival in an experimental model of heart failure. In many clinical conditions, such as congestive heart failure, both mixed ET(A/B )as well as selective ET(A) receptor antagonism ameliorates the clinical status of patients, i.e. symptoms and hemodynamics. A randomized clinical trial showed that a mixed ET(A/B) receptor antagonist effectively lowered arterial blood pressure in patients with arterial hypertension. In patients with primary pulmonary hypertension or pulmonary hypertension related to scleroderma, treatment with a mixed ET(A/B) receptor antagonist resulted in an improvement in exercise capacity. ET receptor blockers thus hold the potential to improve the outcome in patients with various cardiovascular disorders. Randomized clinical trials are under way to evaluate the effects of ET receptor antagonism on morbidity and mortality.

Pulmonary hypertension associated with COPD

Pulmonary hypertension is a common complication of chronic obstructive pulmonary disease (COPD). The increase in pulmonary artery pressures is often mild to moderate, but some patients may suffer from severe pulmonary hypertension, and present with a progressively downhill clinical course because of right-sided heart failure added to ventilatory handicap. The cause of pulmonary hypertension in COPD is generally assumed to be hypoxic pulmonary vasoconstriction leading to permanent medial hypertrophy. However, recent pathological studies point, rather, to extensive remodeling of the pulmonary arterial walls, with prominent intimal changes. These aspects account for minimal reversibility with supplemental oxygen. There may be a case for pharmacological treatment of pulmonary hypertension in selected patients with advanced COPD and right-sided heart failure. Candidate drugs include prostacyclin derivatives, endothelin antagonists and inhaled nitric oxide, all of which have been reported of clinical benefit in primary pulmonary hypertension. However, it will be a challenge for randomized controlled trials to overcome the difficulties of the diagnosis of right ventricular failure and the definition of a relevant primary endpoint in pulmonary hypertensive COPD patients.