Efficacy and safety of sildenafil added to treprostinil in pulmonary hypertension

Medical Management of Pulmonary Arterial Hypertension: Current Approaches and Investigational Drugs

Pulmonary arterial hypertension (PAH) is a malignant pulmonary vascular syndrome characterized by a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure, which eventually leads to right heart failure and even death. Although the exact mechanism of PAH is not fully understood, pulmonary vasoconstriction, vascular remodeling, immune and inflammatory responses, and thrombosis are thought to be involved in the development and progression of PAH. In the era of non-targeted agents, PAH had a very dismal prognosis with a median survival time of only 2.8 years. With the deep understanding of the pathophysiological mechanism of PAH as well as advances in drug research, PAH-specific therapeutic drugs have developed rapidly in the past 30 years, but they primarily focus on the three classical signaling pathways, namely the endothelin pathway, nitric oxide pathway, and prostacyclin pathway. These drugs dramatically improved pulmonary hemodynamics, cardiac function, exercise tolerance, quality of life, and prognosis in PAH patients, but could only reduce pulmonary arterial pressure and right ventricular afterload to a limited extent. Current targeted agents delay the progression of PAH but cannot fundamentally reverse pulmonary vascular remodeling. Through unremitting efforts, new therapeutic drugs such as sotatercept have emerged, injecting new vitality into this field. This review comprehensively summarizes the general treatments for PAH, including inotropes and vasopressors, diuretics, anticoagulants, general vasodilators, and anemia management. Additionally, this review elaborates the pharmacological properties and recent research progress of twelve specific drugs targeting three classical signaling pathways, as well as dual-, sequential triple-, and initial triple-therapy strategies based on the aforementioned targeted agents. More crucially, the search for novel therapeutic targets for PAH has never stopped, with great progress in recent years, and this review outlines the potential PAH therapeutic agents currently in the exploratory stage to provide new directions for the treatment of PAH and improve the long-term prognosis of PAH patients.

2018 TSOC guideline focused update on diagnosis and treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized as a progressive and sustained increase in pulmonary vascular resistance, which may induce right ventricular failure. In 2014, the Working Group on Pulmonary Hypertension of the Taiwan Society of Cardiology (TSOC) conducted a review of data and developed a guideline for the management of PAH.⁴ In recent years, several advancements in diagnosis and treatment of PAH has occurred. Therefore, the Working Group on Pulmonary Hypertension of TSOC decided to come up with a focused update that addresses clinically important advances in PAH diagnosis and treatment. This 2018 focused update deals with: (1) the role of echocardiography in PAH; (2) new diagnostic algorithm for the evaluation of PAH; (3) comprehensive prognostic evaluation and risk assessment; (4) treatment goals and follow-up strategy; (5) updated PAH targeted therapy; (6) combination therapy and goal-orientated therapy; (7) updated treatment for PAH associated with congenital heart disease; (8) updated treatment for PAH associated with connective tissue disease; and (9) updated treatment for chronic thromboembolic pulmonary hypertension.

Regulation, signalling and functions of hormonal peptides in pulmonary vascular remodelling during hypoxia

Hypoxic state affects organism primarily by decreasing the amount of oxygen reaching the cells and tissues. To adjust with changing environment organism undergoes mechanisms which are necessary for acclimatization to hypoxic stress. Pulmonary vascular remodelling is one such mechanism controlled by hormonal peptides present in blood circulation for acclimatization. Activation of peptides regulates constriction and relaxation of blood vessels of pulmonary and systemic circulation. Thus, understanding of vascular tone maintenance and hypoxic pulmonary vasoconstriction like pathophysiological condition during hypoxia is of prime importance. Endothelin-1 (ET-1), atrial natriuretic peptide (ANP), and renin angiotensin system (RAS) function, their receptor functioning and signalling during hypoxia in different body parts point them as disease markers. In vivo and in vitro studies have helped understanding the mechanism of hormonal peptides for better acclimatization to hypoxic stress and interventions for better management of vascular remodelling in different models like cell, rat, and human is discussed in this review.

Present and future treatment strategies for pulmonary arterial hypertension : focus on phosphodiesterase-5 inhibitors

Idiopathic pulmonary arterial hypertension (IPAH) is a rare progressive disorder historically associated with mortality in <3 years post-diagnosis. The etiology of PAH is complex, multifactorial, and likely involves the interplay between genetic and environmental factors. These are reviewed with emphasis on the nitric oxide pathway. Use of treatment modalities including vasodilator therapy have resulted in improved symptoms, hemodynamics, and survival in these patients. Vasodilators, including the calcium channel antagonists, prostanoids, and endothelin receptor antagonists, have been used to counteract potential imbalances in vasoactive mediators in PAH patients; all have produced improved long-term symptomatology and hemodynamics. Only the prostanoid epoprostenol has improved survival in IPAH patients. Although these medications have worked well in many patients with PAH, each of them has limitations. The phosphodiesterase-5 (PDE-5) inhibitors are a relatively new form of treatment for PAH. They are designed to potentiate the effects of cyclic guanosine monophosphate, thereby mimicking endogenous nitric oxide within the vasculature. PDE-5 inhibitors are selective pulmonary vasodilators effective in animal models of pulmonary hypertension. The published clinical studies evaluating their use have been small in size to date but appear to demonstrate benefit. The recently completed 12-week randomized placebo-controlled Sildenafil Use in Pulmonary Hypertension (SUPER-1) trial demonstrated improvement in 6-minute walk distance and hemodynamics in patients receiving sildenafil. These data suggest that the PDE-5 inhibitors are effective in treating PAH and that it is likely that their usage will increase over time. The purpose of this review is to present a current view of the pathogenesis and treatment of PAH, with an emphasis on the use of PDE-5 inhibitors in these patients.

Safety and Tolerability of High-dose Inhaled Treprostinil in Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) has emerging therapeutic options including prostacyclin analogs. Inhaled therapy offers advantages compared with alternative routes of administration. We aimed to determine the safety and tolerability of inhaled treprostinil (iTRE) titrated to target maintenance dose higher than the labeled dose for PAH. Our study included 80 consecutive patients (69% female, 70% White) followed at the Duke University Medical Center prescribed iTRE at dose >9 breaths (54 μg). Etiology of pulmonary hypertension was most frequently PAH (51%) or secondary to lung disease (35%). Median follow-up was 20.3 months (interquartile range 14.2-33.2). Most patients (91%) had titrated iTRE dose to 12 breaths (72 μg) four times daily. Common side effects reported with drug initiation were cough (41%), headache (28%), and throat irritation (8%); most of the side effects improved at follow-up. Overall, 25% patients discontinued iTRE: 9 transitioned to parenteral therapy, 4 had untolerable side effects, 3 died, and 4 had other reasons. Overall, iTRE taken at a higher dose than approved for use in PAH was safe and well-tolerated in our cohort of pulmonary hypertension patients.

Survival with sildenafil and inhaled iloprost in a cohort with pulmonary hypertension: an observational study

Background

Combination therapy is frequently used to treat patients with pulmonary hypertension but few studies have compared treatment regimens. This study examined the long-term effect of different combination regimens of inhaled iloprost and oral sildenafil on survival and disease progression.

Methods

This was a retrospective study of patients in the Giessen Pulmonary Hypertension Registry who received iloprost monotherapy followed by addition of sildenafil (iloprost/sildenafil), sildenafil monotherapy followed by addition of iloprost (sildenafil/iloprost), or upfront combination therapy (iloprost + sildenafil). The primary outcome was transplant-free survival (Kaplan–Meier analysis). When available, haemodynamic parameters and 6-minute-walk distance were evaluated.

Results

Overall, 148 patients were included. Baseline characteristics were similar across treatment groups; however, the iloprost + sildenafil cohort had higher mean pulmonary vascular resistance and pulmonary arterial pressure than the others. Transplant-free survival differed significantly between groups (P = 0.007, log-rank test). Cumulative transplant-free survival was highest for patients who received iloprost/sildenafil (1 year survival: iloprost/sildenafil, 95.1 %; sildenafil/iloprost, 91.8 %; iloprost + sildenafil, 62.9 %); this group also remained on monotherapy significantly longer than the sildenafil/iloprost group (median 17.0 months vs 7.0 months, respectively; P = 0.004). Compared with pre-treatment values, mean 6-minute-walk distance increased significantly for all groups 3 months after beginning combination therapy.

Conclusions

In this observational study of patients with pulmonary hypertension receiving combination therapy with iloprost and sildenafil, cumulative transplant-free survival was highest in those who received iloprost monotherapy initially. However, owing to the size and retrospective design of this study, further research is needed before making firm treatment recommendations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0164-2) contains supplementary material, which is available to authorized users.

Use of outcome measures in pulmonary hypertension clinical trials

OBJECTIVES

To evaluate the use of surrogate measures in pulmonary hypertension (PH) clinical trials and how it relates to clinical practice.

BACKGROUND

Studies of pulmonary arterial hypertension (PAH) employ a variety of surrogate measures in addition to clinical events because of a small patient population, participant burden, and costs. The use of these measures in PH drug trials is poorly defined.

METHODS

We searched PubMed/MEDLINE/Embase for randomized or prospective cohort PAH clinical treatment trials from 1985 to 2013. Extracted data included intervention, trial duration, study design, patient characteristics, and primary and secondary outcome measures. To compare with clinical practice, we assessed the use of surrogate measures in a clinical sample of patients on PH medications at Duke University Medical Center between 2003 and 2014.

RESULTS

Between 1985 and 2013, 126 PAH trials were identified and analyzed. Surrogate measures served as primary endpoints in 119 trials (94.0%). Inclusion of invasive hemodynamics decreased over time (78.6%, 75.0%, 52.2%; P for trend = .02), while functional testing (7.1%, 60.0%, 81.5%; P for trend < .0001) and functional status or quality of life (0%, 47.6%, 62.8%; P for trend < .0001) increased in PAH trials over the same time periods. Echocardiography data were reported as a primary or secondary outcome in 32 trials (25.4%) with increased use from 1985-1994 to 1995-2004 (7.1% vs 35.0%, P = .04), but the trend did not continue to 2005-2013 (25.0%). In comparison, among 450 patients on PAH therapies at our institution between 2003 and 2013, clinical assessments regularly incorporated serial echocardiography and 6-minute walk distance tests (92% and 95% of patients, respectively) and repeat measurement of invasive hemodynamics (46% of patients).

CONCLUSIONS

The majority of PAH trials have utilized surrogate measures as primary endpoints. The use of these surrogate endpoints has evolved significantly over time with increasing use of patient-centered endpoints and decreasing or stable use of imaging and invasive measures. In contrast, imaging and invasive measures are commonly used in contemporary clinical practice. Further research is needed to validate and standardize currently used measures.

[Phosphodiesterase-5 inhibitors for the treatment of pulmonary arterial hypertension]

In experimental and clinical cardiology, phosphodiesterase type 5 (PDE-5) inhibitors have brought scientific interest as a therapeutic tool in pulmonary arterial hypertension (PAH) management in recent years. Phosphodiesterases are a superfamily of enzymes that inactivate cyclic adenosine monophosphate and cyclic guanosine monophosphate, the second messengers of prostacyclin and nitric oxide. The rationale for the use of PDE-5 inhibitors in PAH is based on their capacity to overexpresss the nitric oxide pathway pursued inhibition of cyclic guanosine monophosphate hydrolysis. By increasing cyclic guanosine monophosphate levels it promotes vasodilation, antiproliferative and pro-apoptotic effects that may reverse pulmonary vascular remodeling. There is also evidence that these drugs may directly enhance right ventricular contractility through an increase in cyclic adenosine monophosphate mediated by the inhibition of the cyclic guanosine monophosphate -sensitive PDE-3. Sildenafil, tadalafil and vardenafil are 3 specific PDE-5 inhibitors in current clinical use, which share similar mechanisms of action but present some significant differences regarding potency, selectivity for PDE-5 and pharmacokinetic properties. Sildenafil received approval in 2005 by the Food and Drug Administration and the European Medicines Agency and tadalafil in 2009 by the Food and Drug Administration and the European Medicines Agency for the treatment of PAH in patients classified as NYHA/WHO functional class II and III. In Mexico, sildenafil and tadalafil were approved by Comisión Federal de Protección contra Riesgos Sanitarios for this indication in 2010 and 2011, respectively.

The role of phosphodiesterase inhibitors in the management of pulmonary vascular diseases

Phosphodiesterase inhibitors (PDE) can be used as therapeutic agents for various diseases such as dementia, depression, schizophrenia and erectile dysfunction in men, as well as congestive heart failure, chronic obstructive pulmonary disease, rheumatoid arthritis, other inflammatory diseases, diabetes and various other conditions. In this review we will concentrate on one type of PDE, mainly PDE5 and its role in pulmonary vascular diseases.

Clinical utility of treprostinil in the treatment of pulmonary arterial hypertension: an evidence-based review

Pulmonary arterial hypertension (PAH) remains a progressive disease without a cure, despite the development of several treatment options over the past several decades. Its management strategy consists of the endothelin receptor antagonists (ambrisentan, bosentan, macitentan), phosphodiesterase-5 inhibitors (sildenafil, tadalafil, vardenafil), and prostacyclin analogs (epoprostenol, treprostinil, iloprost). Treprostinil, a stable prostacyclin analog, displays vasodilatory effects in the pulmonary vasculature, as well as antiplatelet aggregation properties. Clinical practice guidelines recommend oral endothelin receptor antagonist or phosphodiesterase inhibitor therapy in mild to moderate PAH. Epoprostenol is specifically suggested as first-line therapy in moderate to severe PAH patients (ie, World Health Organization/New York Heart Association functional class III-IV). However, treprostinil may be an alternative option in these severe PAH patients. The longer half-life and stability at room temperature with treprostinil may be associated with lower risk of pulmonary hemodynamic worsening as a result of abrupt infusion discontinuation and less frequent drug preparation. These characteristics make treprostinil an attractive alternative to continuous infusion of epoprostenol, due to convenience and patient safety. The purpose of this review is to evaluate the safety and efficacy of continuous infusion of treprostinil as well as the inhaled and oral routes of administration in PAH.

Pulmonary arterial hypertension in adults: novel drugs and catheter ablation techniques show promise? Systematic review on pharmacotherapy and interventional strategies

This systematic review aims to provide an update on pharmacological and interventional strategies for the treatment of pulmonary arterial hypertension in adults. Currently US Food and Drug Administration approved drugs including prostanoids, endothelin-receptor antagonists, phosphodiesterase type-5 inhibitors, and soluble guanylate-cyclase stimulators. These agents have transformed the prognosis for pulmonary arterial hypertension patients from symptomatic improvements in exercise tolerance ten years ago to delayed disease progression today. On the other hand, percutaneous balloon atrioseptostomy by using radiofrequency perforation, cutting balloon dilatation, or insertion of butterfly stents and pulmonary artery catheter-based denervation, both associated with very low rate of major complications and death, should be considered in combination with specific drugs at an earlier stage rather than late in the progression of pulmonary arterial hypertension and before the occurrence of overt right-sided heart failure.

Pulmonary arterial hypertension: pharmacologic therapies and potential pulmonary artery denervation treatment

Pulmonary arterial hypertension (PAH) is a group of diseases related to progressively increasing pulmonary vascular resistance, a high incidence of right ventricular failure and premature death. Only a limited number of pharmaceutical therapies have proven to be beneficial for PAH. These therapies improve symptoms, exercise capacity, and haemodynamics; however, the clinical relevance of these effects has been challenged. Therefore, the effect of currently approved treatment options remains inconclusive. Conversely, several new drugs for various aetiologies and clinical stages are expected to provide significant advances for the treatment of PAH. Moreover, percutaneous pulmonary artery denervation treatment may lead to a new therapeutic orientation in patients with PAH. The aim of this review is to present the new developments in PAH treatment, provide a brief overview of future directions in the field and discuss the potential future prospects of these innovative therapies.

Sildenafil, a PDE5 inhibitor, in the treatment of pulmonary hypertension

Pulmonary hypertension is a devastating disorder, characterized by vascular proliferation, intimal hypertrophy and vasoconstriction. In this disorder, alterations in the nitric oxide pathway have borne out to be important in not only vascular proliferation, but also in the maintenance of vascular tone. After synthesis by soluble guanylate cyclase, cGMP effects vasodilation via protein kinase G and other mediators, and is hydrolyzed by phosphodiesterases (PDEs). PDE5 is abundantly expressed in the mammalian lung and its inhibition by sildenafil has been demonstrated to improve pulmonary vascular physiology in vitro and in vivo animal models of pulmonary hypertension. Recent human data has confirmed the efficacy of sildenafil in therapy for humans with pulmonary arterial hypertension. The following review will discuss the underlying basic science supporting the use of sildenafil, as well as human evidence supporting the critical role of this drug in therapy of patients with pulmonary hypertension.

Combination therapy in pulmonary arterial hypertension

Despite major advances in understanding the mechanisms of disease and development of specific drug therapy, pulmonary arterial hypertension (PAH) remains a progressive, fatal disease. At present there are 3 classes of drug therapy for PAH: prostaglandins, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors. To maximize therapeutic benefit, and according to national and international guidelines, many patients are treated with combinations of these medications. This review presents a detailed account of the published data on the use of combination therapy in PAH. There are few randomized, placebo-controlled trial data to strongly support efficacy of most combination therapy, particularly oral combination therapy.

Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic and progressive disease leading to right heart failure and ultimately death if untreated. The first classification of PH was proposed in 1973. In 2008, the fourth World Symposium on PH held in Dana Point (California, USA) revised previous classifications. Currently, PH is devided into five subgroups. Group 1 includes patients suffering from idiopathic or familial PAH with or without germline mutations. Patients with a diagnosis of PAH should systematically been screened regarding to underlying mutations of BMPR2 gene (bone morphogenetic protein receptor type 2) or more rarely of ACVRL1 (activine receptor-like kinase type 1), ENG (endogline) or Smad8 genes. Pulmonary veno occusive disease and pulmonary capillary hemagiomatosis are individualized and designated as clinical group 1'. Group 2 'Pulmonary hypertension due to left heart diseases' is divided into three sub-groups: systolic dysfonction, diastolic dysfonction and valvular dysfonction. Group 3 'Pulmonary hypertension due to respiratory diseases' includes a heterogenous subgroup of respiratory diseases like PH due to pulmonary fibrosis, COPD, lung emphysema or interstitial lung disease for exemple. Group 4 includes chronic thromboembolic pulmonary hypertension without any distinction of proximal or distal forms. Group 5 regroup PH patients with unclear multifactorial mechanisms. Invasive hemodynamic assessment with right heart catheterization is requested to confirm the definite diagnosis of PH showing a resting mean pulmonary artery pressure (mPAP) of ≥ 25 mmHg and a normal pulmonary capillary wedge pressure (PCWP) of ≤ 15 mmHg. The assessment of PCWP may allow the distinction between pre-capillary and post-capillary PH (PCWP > 15 mmHg). Echocardiography is an important tool in the management of patients with underlying suspicion of PH. The European Society of Cardiology and the European Respiratory Society (ESC-ERS) guidelines specify its role, essentially in the screening proposing criteria for estimating the presence of PH mainly based on tricuspid regurgitation peak velocity and systolic artery pressure (sPAP). The therapy of PAH consists of non-specific drugs including oral anticoagulation and diuretics as well as PAH specific therapy. Diuretics are one of the most important treatment in the setting of PH because right heart failure leads to fluid retention, hepatic congestion, ascites and peripheral edema. Current recommendations propose oral anticoagulation aiming for targeting an International Normalized Ratio (INR) between 1.5-2.5. Target INR for patients displaying chronic thromboembolic PH is between 2–3. Better understanding in pathophysiological mechanisms of PH over the past quarter of a century has led to the development of medical therapeutics, even though no cure for PAH exists. Several specific therapeutic agents were developed for the medical management of PAH including prostanoids (epoprostenol, trepoprostenil, iloprost), endothelin receptor antagonists (bosentan, ambrisentan) and phosphodiesterase type 5 inhibitors (sildenafil, tadalafil). This review discusses the current state of art regarding to epidemiologic aspects of PH, diagnostic approaches and the current classification of PH. In addition, currently available specific PAH therapy is discussed as well as future treatments.

Combination therapy in pulmonary arterial hypertension

Many potential therapeutic options are now available for patients with pulmonary arterial hypertension. Interest has emerged in using therapies in various combinations. Retrospective experience has suggested that this approach is common and can be efficacious. Data are emerging supporting the benefit of combination therapy; however, limitations and questions remain about this strategy. This report reviewed the rationale for combination therapy and summarized the results from clinical trials.

Pulmonary arterial hypertension: new insights into the optimal role of current and emerging prostacyclin therapies

Pulmonary arterial hypertension (PAH), which is a subset of pulmonary hypertension, is a group of diseases distinguished by vascular remodeling of the small pulmonary arteries with associated elevated pulmonary arterial pressure and right ventricular failure. This progressive and sometimes fatal disease occurs as an idiopathic disease or as a component of other disease states. Estimates of the incidence of PAH have varied from 5 to 52 cases/1 million population. Symptoms begin with shortness of breath with exertion and progress to dyspnea with normal activities and, finally, dyspnea at rest. Untreated patients with PAH have a 1-, 3-, and 5-year survival rate of 68%, 48%, and 34%, respectively. Treated, the survival rates improve to 91% to 97% after 1 year and 84% to 91% after 2 years. The current definition of PAH consists of 3 specific hemodynamic assessments confirmed by right heart catheterization findings. One of several important pathophysiologic mechanisms involved in PAH is pulmonary vascular remodeling, which is caused by endothelial and smooth muscle cell hyperproliferation. This is coincident with overexpression of the vasoconstrictor endothelin-1 and a reduction in the vasodilators nitric oxide and prostacyclin, which further impedes proper vasomotor tone, among other effects. Prostacyclin therapies augment the decreased prostacyclin levels in patients with PAH. The currently approved prostacyclins for the treatment of PAH include epoprostenol, iloprost, and treprostinil. Among the 3 medications, the delivery options include intravenous infusion, subcutaneous infusion, and inhaled formulations. Epoprostenol has been shown to have a positive effect on survival in patients with PAH. All prostacyclins have demonstrated improvements in functional class, exercise tolerance, and hemodynamics in patients with PAH. Intravenously and subcutaneously administered formulations of prostacyclins require continuous infusion pump administration, which presents clinical challenges for both the patient and the care provider. Dosing must be individualized and also presents a clinical challenge. Inhaled formulations seem efficacious in moderately symptomatic patients with PAH and might be appropriate when combined with an oral medication. Combination therapies are commonly used in clinical practice, with the decision to do so based on randomized controlled trial data and case study evidence. The present report provides an overview of PAH, the scientific rationale for treatment with prostacyclin therapy, and the benefits and risks of prostacyclin therapy, both as monotherapy and combined with other medications approved for the treatment of PAH.

The beneficial impact of fasudil and sildenafil on monocrotaline-induced pulmonary hypertension in rats: a hemodynamic and biochemical study

Pulmonary arterial hypertension (PAH) still cannot be cured effectively, hence the search for novel treatments continues. The effects of sildenafil (25 mg/kg body weight) and fasudil (30 mg/kg body weight) given alone or in combination, on normalization of right ventricular pressure (RVP), right ventricle mass, as well as the levels of several biomarkers (HDL-C, BNP, VEGF-A), were assessed in a rat model of monocrotaline (MCT)-induced PAH. MCT (60 mg/kg body weight) induced clear PAH in male Wistar rats. After 21 days, a significant decrease in RVP accompanied by a reduction of right ventricular hypertrophy - a significant decrease in the right ventricle/left ventricle plus septum ratio - as a result of sildenafil or fasudil administration was assessed. The administration of fasudil and sildenafil alone or in combination caused a significant decrease in plasma BNP level as compared to MCT-treated rats. Fasudil alone or with sildenafil, but not sildenafil alone, significantly increased HDL-C level as compared to MCT-treated rats. Fasudil and sildenafil given alone or in combination caused a significant increase in plasma VEGF-A level as compared to rats exposed to MCT.

Combination Pharmacotherapy in the Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disorder of the small pulmonary arteries characterized by progressive fibrotic and proliferative changes that result in an increased pulmonary vascular resistance. It is a progressive and debilitating disease that leads to right ventricular dysfunction, impairment in activity tolerance and eventually right-sided heart failure, and premature death. The treatment goals for PAH include improvement in symptoms, improvement in functional class and exercise class, decreased morbidity, and preventing mortality. Combination therapy in the treatment of PAH is an emerging therapeutic option. Combining therapies with differing mechanisms of action will maximize therapeutic benefits such as symptom control and increased rate of survival. The updated 2007 American College of Chest Physicians evidence-based clinical practice guidelines recommend combination therapy in functional classes III and IV if there is no improvement with current therapy or if there is deterioration in class. PAH monotherapy has been shown to improve symptoms, but the patients’ hemodynamic parameters may not be normalized, leading to further pulmonary vascular remodeling. Combination therapy offers an additional option for those patients who are unable to stabilize on monotherapy.

Dual therapy in IPAH and SSc-PAH. A qualitative systematic review

BACKGROUND

Use of endothelin receptor antagonists (ERA), phosphodiesterase type-5 (PDE-5) inhibitors and prostaglandin analogues has resulted in improved outcomes in idiopathic pulmonary arterial hypertension (IPAH) and systemic sclerosis-associated PAH (SSc-PAH) patients. However, patients often deteriorate on monotherapy. The objective of this study is to evaluate the effect of dual therapy on outcomes in IPAH and SSc-PAH.

METHODS

A systematic review of MEDLINE (1950-2011), EMBASE (1980-2011) and CINAHL (inception-2011) was conducted to identify studies that evaluated the effect of any dual combination of ERA, PDE-5 inhibitors or prostaglandin analogues on 6-min walk distance (6MWD), functional class (FC), haemodynamics, quality-of-life (QoL) or time-to-clinical-worsening in IPAH or SSc-PAH. A standardized form was used to abstract design, sample size, aetiology, outcome and treatment effect.

RESULTS

Twenty-six observational studies and 6 randomized trials were identified. Using combination PDE-5 inhibitor and prostaglandin analogues, 6/7 studies reported improvement in 6MWD, 6/8 studies reported improvement in FC, 6/6 studies reported improvement in haemodynamics and 1 trial demonstrated improvement in QoL and time-to-clinical-worsening. Using combination ERA and prostaglandin analogues, 4/6 studies and 1 trial reported improvement in 6MWD, 3/3 studies and 1 trial reported improvement in FC, 4/5 studies and 1 trial reported improvement in PAP. Using combination ERA and PDE-5 inhibitor, 4/7 studies reported an improvement in 6MWD, and 2/6 report improvement in FC.

CONCLUSION

The evidence suggests a beneficial effect of dual therapy in IPAH and SSc-PAH, particularly those who are deteriorating on monotherapy. Research should focus on subsets of patients to identify the optimal timing and combination of dual therapy.

Obesity hypoventilation syndrome: a state-of-the-art review

Obesity hyoventilation syndrome (OHS) is defined as the triad of obesity, daytime hypoventilation, and sleep-disordered breathing in the absence of an alternative neuromuscular, mechanical or metabolic explanation for hypoventilation. During the last 3 decades the prevalence of extreme obesity has markedly increased in the United States and other countries. With such a global epidemic of obesity, the prevalence of OHS is bound to increase. Patients with OHS have a lower quality of life, with increased healthcare expenses, and are at higher risk of developing pulmonary hypertension and early mortality, compared to eucapnic patients with sleep-disordered breathing. OHS often remains undiagnosed until late in the course of the disease. Early recognition is important, as these patients have significant morbidity and mortality. Effective treatment can lead to significant improvement in patient outcomes, underscoring the importance of early diagnosis. This review will include disease definition and epidemiology, clinical characteristics of the syndrome, pathophysiology, and morbidity and mortality associated with it. Lastly, treatment modalities will be discussed in detail.

Phosphodiesterase-5 inhibitors in management of pulmonary hypertension: safety, tolerability, and efficacy

Pulmonary arterial hypertension (PAH) is a progressive disease that causes severe disability and has no cure. Over the past 20 years, a variety of treatment options have evolved for the management of PAH. With an expanded therapeutic armamentarium come more complex decisions regarding treatment options. Agent selection depends upon several factors including efficacy, side effect profile, and cost, as well as convenience of administration. We have undertaken a review of phosphodiesterase-5 (PDE-5) inhibitors in PAH with a focus on efficacy and safety. A literature search was conducted using the Medline and Cochrane Central Register of Controlled Trials databases (1966-February 2010) for relevant randomized clinical studies. Overall, 10 studies met our inclusion criteria. Sildenafil was the most commonly studied agent, followed by tadalafil and vardenafil. Most trials found that the PDE-5 inhibitors significantly improved exercise capacity and lowered pulmonary pressures. However, there were conflicting results regarding these agents' impact on improving cardiac function and functional class. Overall, these medications were effective and well tolerated with a relatively benign side effect profile. The PDE-5 inhibitors are an important option in treating PAH. While most of the published clinical data involved sildenafil, the other PDE-5 inhibitors show promise as well. Further studies are needed to determine the optimal doses of this therapeutic drug class, as well as its effects as adjunctive therapy with other agents in PAH.

A dosing/cross-development study of the multikinase inhibitor sorafenib in patients with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) and cancer share elements of pathophysiology. This provides an opportunity for the cross-development of anticancer agents that can be used in improving PAH care. The adaptation of new drugs across these disease populations warrants a structured approach. This study was a 16-week, phase Ib, single-center, open-label trial of the multikinase/angiogenesis inhibitor sorafenib. In order to assess the safety of sorafenib in PAH, patients with advanced but stable disease on parenteral prostanoids (with or without oral sildenafil) were initiated on treatment at the lowest active dosage administered to cancer patients: 200 mg daily. Patients underwent weekly clinical evaluations and monthly functional testing and dose escalations to a final dosage of 400 mg twice daily. Among 12 patients (10 of them women), sorafenib was well tolerated at 200 mg twice daily. The most common adverse events were moderate skin reactions on the hands and feet and alopecia. Our conclusion was therefore that this is a tolerable dosing regimen for testing the therapeutic activity of sorafenib in PAH patients.

Sildenafil for the treatment of pulmonary hypertension in pediatric patients

Sildenafil is a phosphodiesterase 5 inhibitor widely used for the treatment of pulmonary hypertension in children. Despite limited available safety and efficacy evidence, use of sildenafil continues to increase. To date, sildenafil use for pediatric pulmonary hypertension has been characterized for 193 children through 16 studies and 28 case series and reports. The primary efficacy data suggest that sildenafil is beneficial for facilitating the weaning of inhaled nitric oxide in children after cardiac surgery. Compiled safety data suggest that sildenafil is well tolerated among children with idiopathic pulmonary arterial hypertension and pulmonary arterial hypertension associated with congenital heart disease. This review summarizes the available data describing the use, safety, and efficacy of sildenafil for children with pulmonary hypertension.

Pulmonary hypertension: diagnosis and management

Pulmonary arterial hypertension is a progressive, symptomatic, and ultimately fatal disorder for which substantial advances in treatment have been made during the past decade. Effective management requires timely recognition and accurate diagnosis of the disorder and appropriate selection among therapeutic alternatives. Despite progress in treatment, obstacles remain that impede the achievement of optimal outcomes. The current article provides an overview of the pathobiologic mechanisms of pulmonary arterial hypertension, including genetic substrates and molecular and cellular mechanisms, and describes the clinical manifestations and classification of pulmonary arterial hypertension. The article also reviews established approaches to evaluation and treatment, with emphasis on the appropriate application of calcium channel blockers, prostacyclin analogues, endothelin receptor antagonists, and phosphodiesterase 5 inhibitors. In addition, the authors discuss unresolved issues that may complicate patient management, such as the clinical importance of mild or exercise-related pulmonary arterial hypertension, and they identify avenues by which treatment may advance in the future through the use of combination treatment, outcomes assessment, and exploration of alternative pharmacologic strategies.

Pulmonary hypertension: diagnosis and management

Pulmonary arterial hypertension is a progressive, symptomatic, and ultimately fatal disorder for which substantial advances in treatment have been made during the past decade. Effective management requires timely recognition and accurate diagnosis of the disorder and appropriate selection among therapeutic alternatives. Despite progress in treatment, obstacles remain that impede the achievement of optimal outcomes. The current article provides an overview of the pathobiologic mechanisms of pulmonary arterial hypertension, including genetic substrates and molecular and cellular mechanisms, and describes the clinical manifestations and classification of pulmonary arterial hypertension. The article also reviews established approaches to evaluation and treatment, with emphasis on the appropriate application of calcium channel blockers, prostacyclin analogues, endothelin receptor antagonists, and phosphodiesterase 5 inhibitors. In addition, the authors discuss unresolved issues that may complicate patient management, such as the clinical importance of mild or exercise-related pulmonary arterial hypertension, and they identify avenues by which treatment may advance in the future through the use of combination treatment, outcomes assessment, and exploration of alternative pharmacologic strategies.

Review: Therapeutic advances in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction, in situ thrombosis, and vascular remodeling of small pulmonary arteries inducing increased pulmonary arterial resistance. Conventional treatment is based on life style modification and nonspecific treatment (warfarine, diuretics, oxygen). Calcium channel blockers are vasodilatators that have been shown to be of great efficacy in a very specific subpopulation of patients with PAH. For the majority of patients, specific PAH therapies are still lacking. Numerous studies evaluating prostacyclin agonists, endothelin-receptor antagonists, and phosphodiesterase type 5 inhibitors are now available to guide therapeutic choices. Despite those important advances there is still no cure for PAH. Fortunately, research is ongoing and many drugs show promises.

Acute effects of the combination of sildenafil and inhaled treprostinil on haemodynamics and gas exchange in pulmonary hypertension

BACKGROUND

Inhaled treprostinil was recently developed for the treatment of pulmonary arterial hypertension (PAH). We investigated the safety and acute haemodynamic effects of the combination oral sildenafil and inhaled treprostinil in an open label study in patients with precapillary pulmonary hypertension.

METHODS AND PATIENTS

Inhaled nitric oxide (20ppm; n=50), sildenafil (50mg; n=50) and inhaled treprostinil (15microg; n=25 or 30microg; n=25) were applied in subsequent order during right heart catheter investigation to consecutive patients with pulmonary arterial hypertension (PAH; n=28), non-operable chronic thromboembolic pulmonary hypertension (CTEPH; n=17) and pulmonary fibrosis associated pulmonary hypertension (n=5).

RESULTS

Inhaled nitric oxide reduced pulmonary vascular resistance (PVR) to 87.3+/-5.1% of baseline values, reduced mean pulmonary arterial pressure (PAP) to 89.7+/-3.5% and increased cardiac output (CO) to 102.4+/-2.9%. Sildenafil reduced PVR to 80.1+/-5.0%, mPAP to 86.5+/-2.9% and increased CO to 103.8+/-3.2%. Treprostinil, inhaled 1h after sildenafil, reduced PVR to 66.3+/-3.8%, mPAP to 77.8+/-3.3%, and increased CO to 107.1+/-3.3% (mean+/-95% confidence interval). Subgroup analysis showed similar acute haemodynamic effects in PAH and CTEPH patients. Ventilation/perfusion distribution measurement in six patients with pre-existing gas exchange limitations was not changed by sildenafil and treprostinil. Relevant side effects were not observed.

CONCLUSION

The combination of sildenafil and inhaled treprostinil was well tolerated and induced additive, pulmonary selective vasodilatation in pulmonary hypertension patients. This could be of relevance also for long-term treatment of PAH and CTEPH patients.

Treprostinil for the treatment of pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) is a severely disabling disorder characterized by sustained elevations of pulmonary arterial pressure, ultimately leading to right-heart failure and death. Pulmonary arterial hypertension (PAH) usually occurs in the absence of an evident cause (idiopathic PAH) or may be associated with connective tissue disease, HIV infection, congenital heart disease, chronic liver disease or result from the use of toxic agents and anorexigens.

OBJECTIVE/METHOD

Intravenous epoprostenol has been widely used in patients with PAH, leading to long-term clinical benefits and improved survival. Epoprostenol has to be delivered through a permanently implanted Intravenous catheter. This may expose patients to potentially life-threatening complications. Thus, more stable compounds and alternative modes of prostacyclin delivery have been sought.

CONCLUSION

Treprostinil sodium is a stable prostacyclin analogue, sharing pharmacologic actions similar to epoprostenol with comparable haemodynamic effects. Treprostinil is chemically stable at room temperature and has a long half-life (2 - 4 h), making this drug suitable for subcutaneous administration, with practical benefits in avoiding the risk of line infection and thrombosis, and cardiovascular reactions due to abrupt drug discontinuation.

An evidence-based approach to the management of pulmonary arterial hypertension

PURPOSE OF REVIEW

Evidence-based therapies and guidelines for pulmonary arterial hypertension are critiqued.

RECENT FINDINGS

Morbidity and mortality in pulmonary arterial hypertension reflects failure of right ventricular compensation for increased afterload caused by obstructive pulmonary arterial remodeling. This predominantly reflects excessive proliferation/impaired apoptosis of smooth muscle and endothelial cells, rather than vasoconstriction. To exclude confounding effects of cardiac output and left ventricular end-diastolic pressure, the diagnosis of pulmonary arterial hypertension should require a pulmonary vascular resistance >3 Wood-units, not simply a mean pulmonary arterial pressure >25 mmHg. A 'positive' response (20% fall in pulmonary arterial pressure/pulmonary vascular resistance PAP/PVR) to acute, selective, pulmonary vasodilators (e.g. inhaled nitric oxide), occurs in 20% of patients, portends a favorable prognosis and justifies a trial of calcium channel blockers. Randomized controlled trials support treatment of NYHA class III pulmonary arterial hypertension with oral endothelin antagonists or phosphodiesterase-5 inhibitors. Prostacyclin analogues (inhaled/subcutaneous) are useful adjunctive therapies. Intravenous epoprostenol remains the therapeutic mainstay for class IV PAH. Emerging antiproliferative-proapoptotic therapies that merit investigator-initiated clinical trials include: statins, Imatinib, NONO-ates, anti-survivin, potassium channel modulation, and dichloroacetate.

SUMMARY

The diagnostic criteria for pulmonary arterial hypertension should be revised to include PVR. Sildenafil's efficacy and price recommend it as a first-line oral therapy. New pulmonary arterial hypertension-regression therapies and therapeutic combinations offer the potential for cure of pulmonary arterial hypertension.

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.

Combination therapy and new types of agents for pulmonary arterial hypertension

This review assesses the available evidence supporting the use of drug combinations for the management of the various forms of pulmonary arterial hypertension (PAH). Ongoing and forthcoming randomized trials evaluating this strategy are also highlighted. Furthermore, new types of agents to treat PAH in the future are explored.

[Pulmonary arterial hypertension--experience of Centro Hospitalar de Vila Nova de Gaia]

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a serious and progressive disease, potentially fatal in a few years. Until the 1990s the only effective treatment for this disease was pulmonary/cardiopulmonary transplant. Over the last few years several drugs have emerged that have modified the course of the disease.

AIMS

To characterise patients with PAH followed at Centro Hospitalar de V.N.Gaia between 2000 and 2006. To raise awareness of this entity.

MATERIAL AND METHODS

Retrospective analysis of all patients with PAH or chronic thromboembolic pulmonary hypertension (CTEPH) followed at our Hospital.

RESULTS

In this period 11 patients were observed, 7 women and 4 men, with a mean age of 43 y. Five patients had idiopathic PAH, three had CTEPH, two had PAH associated with interauricular communication and one had PAH associated with CREST Syndrome. At the time of diagnosis most patients were in NYHA/ /WHO Functional Class III/IV, mean systolic pulmonary artery pressure was 98+/-32 mm Hg and mean distance walked in the 6-minute walk test was 401 m. Initial treatment: Three patients had inhaled iloprost, two subcutaneous treprostinil, three oral bosentan, one oral sildenafil and two patients under- went surgery. Mean follow-up time was 28.1 months. Five patients recovered, three are stable, one worsened and two died.

CONCLUSIONS

PAH is a serious illness which requires a multidisciplinary approach with the need for complex and expensive therapies. Diagnosis in initial sta- ges is essential for an effective treatment.

Management of Pulmonary Arterial Hypertension With a Focus on Combination Therapies

Pulmonary arterial hypertension (PAH) is a rare but frequently fatal condition marked by vasoconstriction and vascular remodeling within small pulmonary arteries. The pathobiology of PAH involves imbalances in a multitude of endogenous mediators, which promote aberrant cellular growth, vasoconstriction and hemostasis within the pulmonary vascular tree. The mechanisms promoting these pathologic effects are complex. This complexity is highlighted by the many overlapping secondary messenger systems through which these mediators work. In light of this natural redundancy, it is not surprising that many of the drugs used to treat PAH, which have shown short-term efficacy, fall "short of the mark" in reversing or halting the progression of this disease in the long run. This very redundancy in pathways makes the case for the use of combination of drugs with differing mechanisms of action to treat PAH. Similar to what is now accepted as the standard of care for the treatment of cancer and left ventricular dysfunction, combination therapy has the greatest promise for inducing the most complete vascular remodeling of the pulmonary vasculature by "shutting down" as many of these pathologic pathways as possible. Combination therapies involving existing therapies or new agents with improved pharmacokinetic and/or pharmacodynamic properties represent an emerging clinical paradigm for patients with sub-optimally managed disease. As emerging data in this field of therapy comes to fruition, further reductions in the morbidity and mortality associated with PAH will manifest. The goal of this report is to review the philosophy of combination therapy and present the available data in this area of study.