Tadalafil therapy for pulmonary arterial hypertension

Role of phosphodiesterases in adult-onset pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by increased mean pulmonary artery pressure (mPAP) due to vasoconstriction and structural changes in the small pulmonary arteries (PAs); proliferation of pulmonary artery smooth muscle cells (PASMCs) contributes to the remodeling. The abnormal pathophysiology in the pulmonary vasculature relates to decreased cyclic nucleotide levels in PASMCs. Phosphodiesterases (PDEs) catalyze the hydrolysis of cAMP and cGMP, thereby PDE inhibitors are effective in vasodilating the PA and decreasing PASMC proliferation. Experimental studies support the use of PDE3, PDE5, and PDE1 inhibitors in PAH. PDE5 inhibitors such as sildenafil are clinically approved to treat different forms of PAH and lower mPAP, increase functional capacity, and decrease right ventricular hypertrophy, without decreasing systemic arterial pressure. New evidence suggests that the combination of PDE inhibitors with other therapies for PAH may be beneficial in treating the disease. Furthermore, inhibiting PDEs in the heart and the inflammatory cells that infiltrate the PA may offer new targets to reduce right ventricular hypertrophy and inhibit inflammation that is associated with and contributes to the development of PAH. This chapter summarizes the advances in the area and the future of PDEs in PAH.

Bosentan for the treatment of adult pulmonary hypertension

Pulmonary hypertension is a severe progressive disease with a marked morbidity and a high mortality attributed to right heart failure. Bosentan, a dual endothelin receptor antagonist, is an effective and well-tolerated oral therapy for the management of pulmonary arterial hypertension (PAH; WHO group 1 pulmonary hypertension). Bosentan improves cardiopulmonary hemodynamics, exercise capacity, WHO functional class and quality of life, as well as delaying time to clinical worsening in patients with PAH. This article reviews the role of endothelin-1 in the pathogenesis and progression of PAH, the diagnosis of PAH and the pharmacology of bosentan, and summarizes the current available evidence for the safety and efficacy of bosentan for the treatment of PAH as a monotherapy and combination therapy, as well as its role in the management of other forms of pulmonary hypertension.

Lung involvement in systemic sclerosis

Scleroderma is a multisystem disease characterized by a severe inflammatory process and exuberant fibrosis. Lung involvement is a frequent complication and a leading cause of morbidity and mortality in this syndrome. Two major pulmonary syndromes are associated with scleroderma; a pulmonary vascular disorder evolving over time into relatively isolated pulmonary arterial hypertension (PAH), and interstitial lung disease (ILD). Each syndrome, when present, is a cause of morbidity and significantly reduces survival of scleroderma patients when compared to patients free of lung complication. When pulmonary hypertension and ILD are combined, survival is further reduced. Current therapy appears to have no meaningful effect on either condition and, thus, there is a need for better understanding of underlying pathogenic mechanisms. This review focuses on clinical, diagnostic, and therapeutic features of PAH and ILD as well as other frequent but less debilitating lung complications of scleroderma.

Recent trends in pulmonary arterial hypertension

Pulmonary hypertension is a serious and unrelenting pulmonary vascular disorder that affects the functional quality of patients and significantly decreases their life span. If diagnosed early, with the number of new therapeutic options that are available, a better quality of life can be provided for a protracted length of time. It is likely that the available treatment will change the natural course of the disease and perhaps prolong survival. As symptoms are often subtle in the early stages of the disease it is imperative that physicians are aware of the manifestations of this condition. A thorough investigation of patients suspected of this condition is essential so that appropriate treatment can be initiated promptly. The routine workup of a patient suspected to have pulmonary hypertension could easily be carried out in any well-equipped peripheral hospital in many affluent and advanced countries. However, it must be mentioned that in some less advanced countries the necessary work up can only be done in major teaching hospitals. Both pulmonologists and cardiologists should be aware of the pathophysiology of pulmonary arterial hypertension, the workup and the treatment options that are available. Patients with refractory pulmonary hypertension should be referred to these research centers for enrolment into any ongoing drug trials as well as for evaluation for heart-lung, single lung, or double lung transplantation. This paper is primarily aimed at pulmonologists and cardiologists taking care of these patients. Unless indicated otherwise this paper mainly deals with WHO group 1 pulmonary hypertension which is designated pulmonary arterial hypertension. Extensive review of the literature spanning the last 30 years was made through Medline using titles such as primary pulmonary hypertension, pulmonary arterial hypertension, secondary pulmonary hypertension, and pulmonary vascular diseases.

Nitrite in pulmonary arterial hypertension: therapeutic avenues in the setting of dysregulated arginine/nitric oxide synthase signalling

Pulmonary arterial hypertension (PAH) is an insidious disease of the small pulmonary arteries that is progressive in nature and results in right heart strain/hypertrophy and eventually failure. The aetiologies may vary but several common pathophysiological changes result in this phenotype, including vasoconstriction, thrombosis, and vascular proliferation. Data suggest that nitric oxide (NO) signalling is vasoprotective in the setting of PAH. The classic arginine-NO synthase (NOS)-NO signalling pathway may represent an adaptive response that is eventually dysregulated during disease progression. Dysregulation occurs secondary to NOS enzyme down-regulation, enzymatic uncoupling, and arginine catabolism by vascular and red cell arginases and by direct NO inactivation via catabolic reactions with superoxide or cell-free plasma haemoglobin (in the case of haemolytic disease). The anion nitrite, which has recently been recognized as a source of NO that circumvents the arginine-NOS pathway, may serve as an additional adaptive signalling pathway that is now appreciated to have a vasoregulatory role in the pulmonary and systemic vasculature. Inhaled nebulized sodium nitrite is a relatively potent pulmonary vasodilator in the setting of hypoxia and is also anti-proliferative in multiple experimental models of pulmonary hypertension. Multiple nitrite reductases have been shown to be relevant in the conversion of nitrite to metabolically active NO, including deoxy-haemoglobin and myoglobin in the circulation and heart, respectively, and xanthine oxidoreductase in the lung parenchyma.

Current therapeutic approaches to pulmonary arterial hypertension

Pulmonary hypertension is a heterogeneous hemodynamic and pathophysiological state that is observed in a number of clinical conditions, which have been divided into six diagnostic groups. Although the increase in pulmonary pressure observed in these clinical groups may be similar, underlying disease mechanisms, diagnostic methods, and prognostic and therapeutic consequences are completely different. Pulmonary arterial hypertension is associated with several rare conditions that have comparable clinical and hemodynamic characteristics and exhibit virtually identical anatomical and pathological alterations in the lung microcirculation. These conditions include idiopathic and familial forms of the disease and disease forms associated with connective tissue disease, congenital heart defects involving systemic-to-pulmonary arterial shunts, portal hypertension, and HIV infection. It has been shown that treatment with specific drugs (e.g. prostanoids, endothelin-receptor antagonists and phosphodiesterase type-5 inhibitors) is effective in these patients and that these drugs can also be administered in various combinations. An evidence-based treatment algorithm has been developed for these patients. In patients with pulmonary hypertension due to left heart disease or lung disease, treatment focuses on the underlying condition and there is no convincing evidence that agents approved for pulmonary arterial hypertension are effective. For patients with chronic thromboembolic pulmonary hypertension, the treatment of choice is pulmonary endarterectomy. However, drugs intended specifically for the treatment of pulmonary arterial hypertension may be considered in inoperable cases or after suboptimal surgery.

Targeted oral therapies in the treatment of pulmonary arterial hypertension

Recent advances in our understanding of the pathophysiology of pulmonary arterial hypertension (PAH) have led to the US FDA's approval of eight drugs for its treatment. Although guidelines for the use of PAH therapies are available and regularly updated, there is a lack of information on how these agents differ and what characteristics may enable one agent to be of greater relative clinical utility than another. Oral agents may be compared across a variety of measures, including clinical efficacy, safety and tolerability, dosing and pharmacology, potential for drug interactions, treatment adherence and suitability for use in combination regimens. Although no large, prospective, head-to-head trial has been conducted with oral agents for PAH, data from placebo-controlled studies indicate that the enrolled patient populations were remarkably homogeneous with respect to demographic and disease severity parameters. In general, data suggest that these agents improve functional capacity, delay disease progression and improve haemodynamics. Additionally, long-term sustainability of response has been demonstrated. However, there was no consistently superior agent across the primary and secondary endpoints assessed in these trials, and the magnitudes of improvements were in a fairly defined range across agents. Consequently, treatment choice may shift to other aspects such as drug safety and tolerability, potential for drug interactions, dosing convenience, treatment adherence, effect on quality of life and access to medication. In this review, the four targeted oral agents approved for the treatment of PAH in the US are reviewed, and clinical results are placed into context.

Inhaled treprostinil and pulmonary arterial hypertension

Multiple conditions result in development of pulmonary hypertension. Pulmonary arterial hypertension (PAH) is the subclassification of pulmonary hypertension, in which known or unknown underlying conditions lead to similar intrinsic alterations in the pulmonary vasculature. PAH is a progressive condition characterized by restricted blood flow through the pulmonary circulation leading to poor survival in the absence of effective therapy. Over the last two decades, new therapeutic agents have substantially improved the course and prognosis for PAH patients. Three available classes of drugs, ie, prostacyclins, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors provide multiple options for treatment of PAH. Endothelin receptor antagonists and phosphodiesterase-5 inhibitors are administered orally, whereas prostacyclin therapies are delivered by continuous intravenous or subcutaneous infusion, or as aerosols by nebulization. Because of the risks and inconveniences associated with administration, prostacyclins are typically reserved for patients with more advanced disease or progression despite oral therapy. Inhaled administration may be a safer and easier route for prostacyclin administration. Treprostinil is a prostacyclin analog that has been demonstrated to be effective when administered by continuous subcutaneous or intravenous infusion, and more recently by nebulization.

Management of pulmonary arterial hypertension in children

In this review we discuss the new anti- Pulmonary Arterial Hypertension [PAH] drugs and the available data on their use in paediatric PAH. Treatment of patients with PAH, children and adults, is aimed at a reduction of symptoms, survival and improvement of haemodynamics as well as exercise capacity. PAH may reflect significant different disease conditions in infants and children when compared to PAH in adults. In contrast to adult PAH, characterized mainly by idiopathic PAH and PAH associated with connective tissue disease, more than half of the cases of PAH in children are associated with congenital heart disease. Therefore, efficacy of PAH drugs in these diseases can not be extrapolated from that in adults with PAH.

Pulmonary arterial hypertension in adults with congenital heart disease

Pulmonary arterial hypertension (PAH) is a common problem in adult patients with congenital heart disease. We review available data on aetiology, clinical presentation, prognosis and management of PAH in this setting. In addition, we discuss general management strategies and emerging disease-targeting therapies.

Treprostinil increases the number and angiogenic potential of endothelial progenitor cells in children with pulmonary hypertension

Background

Pulmonary vasodilators in general and prostacyclin therapy in particular, have markedly improved the outcome of patients with pulmonary arterial hypertension (PAH). As endothelial dysfunction is a key feature of PAH, and as endothelial progenitor cells (EPC) may contribute to vascular repair in PAH, we suspected that prostacyclin therapy might enhance EPC numbers and functions. In the present study, objectives were to determine whether EPC may contribute to vasodilator treatment efficacy in PAH.

Methods

We quantified CD34+ cells, CFU-Hill and ECFC (endothelial colony forming cells) in peripheral blood from children with idiopathic PAH (n = 27) or PAH secondary to congenital heart disease (n = 52). CD34+ were enumerated by flow cytometry, CFU-Hill and ECFC by a culture assay. ECFC grown ex vivo were tested for their angiogenic capacities before and after prostacyclin analog therapy (subcutaneous treprostinil).

Results

ECFC counts were significantly enhanced in the 8 children treated with treprostinil, while no change was observed in children receiving oral therapy with endothelin antagonists and/or PDE5 inhibitors. CD34+ cell and CFU-Hill counts were unaffected. ECFC from patients treated with treprostinil had a hyperproliferative phenotype and showed enhanced angiogenic potential in a nude mouse preclinical model of limb ischemia.

Conclusions

ECFC may partly mediate the clinical benefits of prostanoids in pulmonary arterial hypertension.

Pulmonary hypertension in systemic sclerosis

OBJECTIVES

To discuss the clinical subtypes, pathogenesis, pathology, diagnostic evaluation, treatment options, and prognosis of pulmonary hypertension in systemic sclerosis (SSc-PH) and highlight its fundamental differences from idiopathic pulmonary arterial hypertension (IPAH).

METHODS

A Medline search for articles published between January 1969 and June 2010 was conducted using the following keywords: scleroderma, systemic sclerosis, pulmonary hypertension, pulmonary arterial hypertension, pulmonary veno-occlusive disease, pathogenesis, pathology, investigation, treatment, and prognosis. The essential differences from IPAH in pathogenesis and histopathologic findings were highlighted and the limitations of some of the investigations used were emphasized. The differences in response to currently accepted therapy and prognosis were also reviewed.

RESULTS

In scleroderma, pulmonary hypertension can be present in isolation or along with interstitial lung disease and left heart disease. In SSc-PH, the unique histopathologic findings in the lungs include intimal fibrosis, absence of plexiform lesions, and a high prevalence of pulmonary veno-occlusive disease-like lesions. Both "6-minute walk test" and NT-proBNP have their limitations in the evaluation of SSc-PH. For treatment, calcium channel blockers are ineffective and anticoagulation should be used with caution. Currently approved therapies are not as effective and prognosis is much worse in SSc-PH compared with IPAH.

CONCLUSIONS

SSc-PH is a complex condition with poorer response to therapy and worse outcome compared with that of IPAH. Recent findings have shed some light about the pathophysiology and pathogenesis of SSc-PH. Further research in this area is warranted to better understand the complex pathogenesis and devise better therapeutic strategies.

Imatinib in pulmonary arterial hypertension patients with inadequate response to established therapy

RATIONALE

Pulmonary arterial hypertension (PAH) is a progressive condition with a poor prognosis. Platelet-derived growth factor receptor (PDGFR) signaling plays an important role in its pathobiology.

OBJECTIVES

To assess safety, tolerability, and efficacy of the PDGFR inhibitor imatinib in patients with PAH.

METHODS

Patients with PAH in functional classes II-IV were enrolled in a 24-week randomized, double-blind, placebo-controlled pilot study. Patients received imatinib (an inhibitor of PDGFR activity) 200 mg orally once daily (or placebo), which was increased to 400 mg if the initial dose was well tolerated. The primary endpoints were safety and change from baseline in the 6-minute-walk distance (6MWD). Secondary endpoints included hemodynamics and functional classification.

MEASUREMENTS AND MAIN RESULTS

Fifty-nine patients enrolled (imatinib [n = 28]; placebo [n = 31]); 42 completed the study. Dropouts were equally matched between the two groups. In the intention-to-treat (ITT) population there was no significant change in the 6MWD (mean ± SD) in the imatinib versus placebo group (+22 ± 63 versus -1.0 ± 53 m). There was a significant decrease in pulmonary vascular resistance (imatinib -300 ± 347 versus placebo -78 ± 269 dynes · s · cm⁻⁵, P < 0.01) and increase in cardiac output (imatinib +0.6 ± 1.2 versus placebo -0.1 ± 0.9 L/min, P = 0.02). Serious adverse events occurred in 11 imatinib recipients (39%) and 7 placebo recipients (23%). Three deaths occurred in each group. Post hoc subgroup analyses suggest that patients with greater hemodynamic impairment may respond better than patients with less impairment.

CONCLUSIONS

These data from a Phase II study are consistent with imatinib being well tolerated in patients with PAH, and provide proof of concept for further studies evaluating its safety, tolerability, and efficacy in PAH. Clinical trial registered with www.clinicaltrials.gov (NCT00477269).

Pulmonary hypertension in women

Female predominance in pulmonary arterial hypertension (PAH) has been known for several decades and recent interest in the effects of sex hormones on the development of disease has substantially increased our understanding of this epidemiologic observation. Basic science data suggest a beneficial effect of estrogens in the pulmonary vasculature both acutely and chronically, which seems to contradict the known predilection in women. Recent human and rodent data have suggested that altered levels of estrogen, differential signaling and altered metabolism of estrogens in PAH may underlie the gender difference in this disease. Studies of the effects of sex hormones on the right ventricle in animal and human disease will further aid in understanding gender differences in PAH. This article focuses on the effects of sex hormones on the pulmonary vasculature and right ventricle on both a basic science and translational level.

Pulmonary hypertension in dogs: diagnosis and therapy

Pulmonary hypertension (PH) has been recognized as a clinical syndrome for many years in veterinary medicine, but routine accurate clinical diagnosis in dogs was greatly enhanced by widespread use of echocardiography and Doppler echocardiography. Most cases of PH in veterinary medicine can be categorized as precapillary or postcapillary. These subsets of patients often differ with regard to clinical presentation, response to therapy, and prognosis. Effective medical therapy is now available to treat this often-devastating clinical complication of common chronic diseases, making accurate diagnosis even more important to patient longevity and quality of life.

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.

Management of dyspnea in advanced pulmonary arterial hypertension

PURPOSE OF REVIEW

Pulmonary hypertension leads to progressive increase in pulmonary vascular resistance, heart failure, and death. Pulmonary arterial hypertension (PAH) is a subset of pulmonary hypertension affecting small pulmonary arteries and not associated with underlying heart or lung disease. Dyspnea and exercise intolerance are hallmarks of PAH and are used to monitor disease progression. This review focuses on recent advances in the pathophysiology and treatment of dyspnea in PAH.

RECENT FINDINGS

The etiological classification of pulmonary hypertension and World Health Organization functional class clinical classification, as used to guide management, have recently been revised. Dyspnea and PAH disease progression are best assessed by cardiopulmonary exercise testing and the six-minute walk test. Understanding of the molecular pathogenesis of PAH has led to new classes of treatments, including prostacyclin analogues, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors. Prostanoids have the longest track record in treatment of PAH but a short half-life and cumbersome delivery systems limit their utility. More convenient endothelin receptor antagonists are becoming mainstream in PAH management. Phosphodiesterase-5 inhibitors improve exercise capacity and quality of life, although long-term outcome data are pending. Combination therapy with different medication classes appears promising for progressive disease.

SUMMARY

Establishing the cause and clinical severity of pulmonary hypertension is critical for management. The pathophysiology of dyspnea in PAH is complex and related to pulmonary vascular resistance. Although disease-specific treatments are now available, a cure for PAH remains elusive and trials of combination treatments to improve symptoms and outcomes are ongoing.

Clinical worsening in trials of pulmonary arterial hypertension: results and implications

PURPOSE OF REVIEW

Time to clinical worsening (TTCW) can be used to assess disease progression associated with pulmonary arterial hypertension (PAH). As a consequence, it is highly relevant to patients, clinicians, and regulatory agencies. The majority of clinical trials of PAH-specific drug therapies have included TTCW as a secondary endpoint; this article summarizes the results of randomized controlled clinical trials in PAH, specifically with respect to the clinical worsening endpoint.

RECENT FINDINGS

Some trials have demonstrated a treatment-related delay in TTCW and others have not. Recent results suggest that TTCW shows particular promise in detecting disease progression, even in mildly affected patients. Definitions of clinical worsening have also varied across clinical trials; although all have agreed on the inclusion of all-cause death and hospitalization due to PAH in the definition, the inclusion of additional parameters defining 'disease progression' has differed.

SUMMARY

There is a need for a clear and uniform definition of TTCW that can be tailored to the study population being investigated; the endpoint may require adaptation for patients in different functional classes and with different causes. Consistency of event reporting within a trial may be improved by employing a committee to adjudicate events. Trials are beginning to include TTCW as a primary endpoint; the results will be important in establishing the validity of whether this parameter should become the endpoint of choice in PAH trials in the future.

Novel therapeutic targets for hypertension

Despite the existence of established, effective therapies for hypertension, new methods of blood pressure and cardiovascular risk reduction are still needed. Novel approaches are targeted towards treating resistant hypertension, improving blood-pressure control, and achieving further risk reduction beyond blood-pressure lowering. Modulation of the renin-angiotensin-aldosterone system (RAAS) provides the rationale for current antihypertensive therapies, including the relatively new agents eplerenone and aliskiren. Novel targets for antihypertensive therapy are also likely to be RAAS-related. The stimulation of angiotensin II type 2 receptors, or supplementation with renalase, could counteract the effects of angiotensin II type 1 receptor stimulation or catecholamine release. Combined angiotensin-converting-enzyme and neutral endopeptidase blockade decreases blood pressure, but is associated with a high incidence of angioedema. Aldosterone synthase inhibitors might improve tolerability in aldosterone antagonism. A (pro)renin-receptor blocker could prevent the deleterious angiotensin-independent actions of renin that are not inhibited by aliskiren. Finally, new minimally invasive surgical procedures have revived the concept of renal denervation, and could be a therapeutic option for patients with resistant hypertension. All of these strategies are exciting prospects, but which of them will prove valuable in clinical setting remains to be discovered.

Bosentan

IMPORTANCE TO THE FIELD

Pulmonary arterial hypertension (PAH) is a morbid condition with high mortality if left untreated. Bosentan is an effective treatment option for group 1 pulmonary arterial hypertension. Bosentan improves exercise tolerance and functional class and delays the time to clinical worsening in these patients. Investigation is ongoing to determine its efficacy in other groups of pulmonary hypertension.

AREAS COVERED IN THIS REVIEW

This review provides a background on endothelin activity in PAH, as a rationale for the use of bosentan in this disease. It also presents evidence from key clinical trials of bosentan and discusses future directions in the study of bosentan to help the clinician better understand the role of bosentan in PAH management.

WHAT THE READER WILL GAIN

i) An understanding of the rationale for using endothelin receptor antagonists in treating PAH; ii) an understanding of the clinical evidence to support bosentan for the treatment of PAH; and iii) an understanding of how to use bosentan optimally in the treatment of PAH.

TAKE HOME MESSAGE

Bosentan is an effective and safe treatment for patients with PAH. Patients with suspected PAH should be evaluated carefully as the use of bosentan in non-group 1 pulmonary hypertension is still being investigated. Patients on bosentan should be monitored with monthly liver transaminase testing. Coadministration with other drugs should be reviewed carefully as drug-drug interactions may be important.

Emerging drugs for pulmonary hypertension

IMPORTANCE OF THE FIELD

Pulmonary arterial hypertension (PAH) is a clinical syndrome characterized by structural narrowing of the small pulmonary arteries that often culminates in fatal right heart failure.

AREAS COVERED IN THIS REVIEW

PubMed was searched for PAH and treatment. Data from scientific meetings and pharmaceutical websites are also included. There are currently eight FDA approved drugs for PAH that fall into one of three classes: prostacyclins, endothelin-receptor antagonists and PDE-5 inhibitors. All have important limitations and morbidity and mortality remain high. Several new agents with similar mechanisms of action are in clinical development. Multiple novel therapeutic targets are being explored. New applications for PAH therapies, such as pulmonary hypertension due to left heart and lung disease, are also being investigated.

WHAT THE READER WILL GAIN

An understanding of currently available drugs and those in clinical development for pulmonary hypertension.

TAKE HOME MESSAGE

Drugs targeting the pulmonary vasculature have been an extremely active area of basic and clinical research for the past 20 years and will continue to be so for the foreseeable future. Considerable progress has been made, and yet there continues to be a great unmet medical need for developing more efficacious therapies.

Update on the clinical utility of sildenafil in the treatment of pulmonary arterial hypertension

Sildenafil is an orally administered phosphodiesterase type 5 inhibitor that is approved for the treatment of pulmonary arterial hypertension (PAH). The hemodynamic effects of sildenafil are mitigated primarily via potentiating the effects of endogenous nitric oxide, leading to smooth muscle cell relaxation and reductions in pulmonary arterial pressures and pulmonary vascular resistance. When added to standard background therapy in patients with idiopathic or associated PAH from congenital heart disease, anorexigen use, or connective tissue disease, sildenafil treatment results in improved exercise capacity as measured by 6 minute walk distance, improved hemodynamics, and favorable changes in quality of life. Sildenafil use is contraindicated with concomitant nitrate administration, and caution should be exercised when used in combination with antihypertensive agents due to risks of precipitating hypotension. Side effects are generally mild, and include flushing, headaches, and epistaxis. The combination of sildenafil with intravenous epoprostenol is safe and well tolerated, and further improves exercise capacity. Sildenafil is approved only for treatment of PAH, and although emerging data suggest a potential role in treating other types of pulmonary hypertension, larger trials are required to confirm these findings.

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.

Evidence for the use of combination targeted therapeutic approaches for the management of pulmonary arterial hypertension

The last decade has witnessed a remarkable increase in the number of effective treatment options available for the management of patients with pulmonary arterial hypertension. In this regard, agents belonging to the therapeutic classes that specifically target the prostacyclin, endothelin and nitric oxide pathways have shown the greatest efficacy in clinical studies to date. These various drug treatments have individually been shown to confer improvements in symptoms, exercise capacity, pulmonary haemodynamics and possibly survival in different patient subgroups. However, pulmonary arterial hypertension is characterised by dysregulation of a variety of pathways. In addition, disease worsening is inevitable for the majority of patients receiving monotherapy. As a consequence, there is increasing interest in the use of treatment combinations in order to target multiple targets with the aim of restoring normal pulmonary vascular function in order to improve clinical status. Indeed, use of multiple specific-treatment regimens is now part of routine clinical practice and is emphasized in recently published therapeutic guidelines. This review details the rationale for the different combination strategies and examines the clinical evidence in favour of some of the approaches that have been evaluated.

[Pulmonary circulation: contributions of the year 2009]

A significant number of studies on pulmonary circulation diseases have been published in 2009 that are likely to have a notable clinical impact. Anticoagulant treatment is on the verge of a significant change with the arrival of new oral drugs that have an inhibitory effect over factor X (rivaroxaban, apixaban) or thrombin (dabigatran). New studies have shown an efficacy comparable to enoxaparin in the prevention of thromboembolic disease and in some cases a lower risk of haemorrhage. Also interesting is a study on the incidence of pulmonary thromboembolism in patients with chronic obstructive pulmonary disease, a little known aspect. A study that demonstrates some efficacy of rosuvastatin in the prevention of thromboembolic disease, something that could change our current practices. Pulmonary hypertension (PH) continues to produce numerous publications. One French study has shown a relatively low risk of developing PH in patients with systemic sclerosis over a period of 3 years. As regards treatment, ambrisentan seems to confirm it lower risk of hepatoxicity compared to other endothelin antagonists. A new phosphodiesterase-5 inhibitor, tadalafil, has made a strong impact on the PH scene during this year. Its results are similar to other oral drugs with a convenient posology. The surgical treatment of PH due to chronic thromboembolism in one of the hospitals of our country has been present with results that, particularly in the past few years, are perfectly comparable to other centres of excellence. To summarise, 2009 has continued to provide important news in the area of pulmonary circulation.

Pharmacotherapy of systemic sclerosis

IMPORTANCE OF THE FIELD

Systemic sclerosis (SSc) is an uncommon autoimmune disease with variable degrees of fibroproliferation in blood vessels and certain organs of the body. There is currently no cure. The purpose of this article is to review the current literature regarding pathogenesis and treatment of complications of SSc.

AREAS COVERED IN THIS REVIEW

All available articles regarding research related to SSc pathogenesis and treatment listed in the PubMed database were searched; relevant articles were then reviewed and used as sources of information for this review.

WHAT THE READER WILL GAIN

This review attempts to highlight for the reader some current thought regarding mechanisms of SSc pathogenesis and how autoimmunity relates to vascular changes and fibrogenesis of the disease, as well as providing a review of results of completed clinical trials and current ongoing clinical trials that address organ-specific or global therapies for this disease. This can aid physicians who provide medical care for patients with SSc.

TAKE HOME MESSAGE

SSc is a complex autoimmune disease, the pathogenesis of which, although not completely understood, is under active study; new insights into pathogenesis are continually being discovered. Although there is no effective disease-modifying treatment for patients with SSc, quality of life, morbidity and mortality can be improved by using targeted therapy directed at affecting the consequences of damage to lungs, blood vessels, kidneys and the gastrointestinal tract. Innovative approaches to treating SSc are under intense investigation.