Sildenafil citrate therapy for pulmonary arterial hypertension

Switching Strategy in the Management of Patients with Pulmonary Arterial Hypertension. The REPLACE Study Results

The article is devoted to topical issues of management of patients with pulmonary arterial hypertension and strategies for switching to riociguat therapy in patients with insufficient clinical response against the background of phosphodiesterase type 5 (PDE-5) inhibitors. The role of the NO metabolic pathway in the development of pulmonary arterial hypertension (PAH) was shown. From the standpoint of pathogenesis, the importance of the effect of medication on this pathway through soluble guanylate cyclase (sGC) has been assessed. The effects of the drug riociguat, the only member of the sGC stimulant class approved for the treatment of PAH, are associated with a dual mechanism of action: riociguat sensitizes the sGC enzyme to endogenous NO by stabilizing the NO-sGC bond, and also directly stimulates the latter through another site of the bond, regardless of NO. The favorable efficacy and safety profile of riociguat has been demonstrated in the PATENT-1,2 studies. During therapy, patients showed an improvement in exercise tolerance, functional class, and a number of other indicators. Studies that indicate the feasibility of using a change in therapy in clinical practice are reviewed. In particular, the article provides a detailed analysis of the REPLACE study. It demonstrated a significantly greater likelihood of achieving clinical improvement and a significant decrease in the rate of development of clinical deterioration when switching patients with PAH from PDE-5 inhibitors to riociguat. This therapy was well tolerated and can be considered as a strategy for managing patients at intermediate risk with insufficient patient response to PDE-5 inhibitors. In conclusion, the need to plan the need for specific therapy for pulmonary arterial hypertension in the region is noted in order to rapidly escalate therapy to achieve a low risk of mortality in these patients.

Phosphodiesterase 5 (PDE5): Structure-function regulation and therapeutic applications of inhibitors

Phosphodiesterase 5 (PDE5) is one of the most well-studied phosphodiesterases (PDEs) that specifically targets cGMP typically generated by nitric oxide (NO)-mediated activation of the soluble guanylyl cyclase. Given the crucial role of cGMP generated through the activation of this cellular signaling pathway in a variety of physiologically processes, pharmacological inhibition of PDE5 has been demonstrated to have several therapeutic applications including erectile dysfunction and pulmonary arterial hypertension. While they are designed to inhibit PDE5, the inhibitors show different affinities and specificities against all PDE subtypes. Additionally, they have been shown to induce allosteric structural changes in the protein. These are mostly attributed to their chemical structure and, therefore, binding interactions with PDE catalytic domains. Therefore, understanding how these inhibitors interact with PDE5 and the structural basis of their selectivity is critically important for the design of novel, highly selective PDE5 inhibitors. Here, we review the structure of PDE5, how its function is regulated, and discuss the clinically available inhibitors that target phosphodiesterase 5, aiming to better understand the structural bases of their affinity and specificity. We also discuss the therapeutic indications of these inhibitors and the potential of repurposing for a wider range of clinical applications.

NO-sensitive guanylyl cyclase in the lung

In the late 1960s, several labatories identified guanylyl cyclase (GC) as the cGMP-producing enzyme. Subsequently, two different types of GC were described that differed in their cellular localization. Primarily found in the cytosol, nitric oxide (NO)-sensitive guanylyl cyclase (NO-GC) acts as receptor for the signalling molecule NO, in contrast the membrane-bound isoenzyme is activated by natriuretic peptides. The lung compared with other tissues exhibits the highest expression of NO-GC. The enzyme has been purified from lung for biochemical analysis. Although expressed in smooth muscle cells (SMCs) and in pericytes, the function of NO-GC in lung, especially in pericytes, is still not fully elucidated. However, pharmacological compounds that target NO-GC are available and have been implemented for the therapy of pulmonary arterial hypertension. In addition, NO-GC has been suggested as drug target for the therapy of asthma, acute respiratory distress syndrome and pulmonary fibrosis.

Targeted Drugs for Treatment of Pulmonary Arterial Hypertension: Past, Present, and Future Perspectives

Pulmonary arterial hypertension (PAH) is a devastating disease that can lead to right ventricular failure and premature death. Although approved drugs have been shown to be safe and effective, PAH remains a severe clinical condition, and the long-term survival of patients with PAH is still suboptimal. Thus, potential therapeutic targets and new agents to treat PAH are urgently needed. In recent years, a variety of related pathways and potential therapeutic targets have been found, which brings new hope for PAH therapy. In this perspective, not only are the marketed drugs used to treat PAH summarized but also the recently developed novel pharmaceutical therapies currently in clinical trials are discussed. Furthermore, the advances in natural products as potential treatment for PAH are also updated.

Assessment of the REPLACE study composite endpoint in riociguat-treated patients in the PATENT study

The goal of treatment in patients with pulmonary arterial hypertension is to achieve a low risk status, indicating a favorable long-term outcome. The REPLACE study investigated the efficacy of switching to riociguat in patients with pulmonary arterial hypertension and an insufficient response to phosphodiesterase-5 inhibitors. In this post hoc analysis, we applied the REPLACE composite endpoint of clinical improvement to the placebo-controlled PATENT-1 study of riociguat in pulmonary arterial hypertension and its long-term extension, PATENT-2. Clinical improvement was defined as ≥2 of the following in patients who completed the study without clinical worsening: ≥10% or ≥30 m improvement in 6-minute walking distance; World Health Organization functional class I or II; ≥30% decrease in N-terminal prohormone of brain natriuretic peptide. At PATENT-1 Week 12, patients treated with riociguat were more likely to achieve the composite endpoint vs. placebo (P < 0.0001), with similar results in pretreated (P = 0.0189) and treatment-naïve (P < 0.0001) patients. Achievement of the composite endpoint at Week 12 was associated with a 45% reduction in relative risk of death and a 19% reduction in relative risk of clinical worsening in PATENT-2. Overall, these data suggest that use of the REPLACE composite endpoint in patients with pulmonary arterial hypertension is a valid assessment of response to treatment.

Rational Design of 2-Chloroadenine Derivatives as Highly Selective Phosphodiesterase 8A Inhibitors

To validate the hypothesis that Tyr748 is a crucial residue to aid the discovery of highly selective phosphodiesterase 8A (PDE8A) inhibitors, we identified a series of 2-chloroadenine derivatives based on the hit clofarabine. Structure-based design targeting Tyr748 in PDE8 resulted in the lead compound 3a (IC₅₀ = 0.010 μM) with high selectivity with a reasonable druglike profile. In the X-ray crystal structure, 3a bound to PDE8A with a different mode from 3-isobutyl-1-methylxanthine (a pan-PDE inhibitor) and gave a H-bond of 2.7 Å with Tyr748, which possibly interprets the 220-fold selectivity of 3a against PDE2A. Additionally, oral administration of compound 3a achieved remarkable therapeutic effects against vascular dementia (VaD), indicating that PDE8 inhibitors could serve as potential anti-VaD agents.

Oral drugs used to treat persistent pulmonary hypertension of the newborn

Introduction:Persistent Pulmonary Hypertension of the Newborn (PPHN) is a life-threatening neonatal condition, mostly treated with inhaled nitric oxide (iNO), intravenous prostaglandins, oral bosentan, sildenafil and tadalafil. However, the utility of non-oral agents is limited in PPHN for their side effects and inconvenient deliveries. Therefore, oral agents such as bosentan, sildenafil and tadalafil are becoming appealing for their satisfactory efficacy, easy mode of administration and acceptable side effects. Areas covered: We conducted a comprehensive search on Pubmed, Scopus, Web of Sciences concerning the use of bosentan, sildenafil and tadalafil to treat PPHN and summarized their efficacy, safety and pharmacokinetics. Expert opinion: Current randomized controlled trials (RCTs) have demonstrated the favorable responses and tolerable side effects of bosentan and sildenafil. Nevertheless, those RCTs are small and only one study has described the pharmacokinetics of sildenafil in neonates. Accordingly, bosentan, sildenafil and tadalafil remain off-label in clinical use. More well-designed RCTs with large samples and long-term follow-up and pharmacometrics studies are needed to demonstrate the efficacy, safety and pharmacokinetics of bosentan, sildenafil and tadalafil in PPHN.

Safety and effect of sildenafil on treating paediatric pulmonary arterial hypertension: a meta-analysis on the randomised controlled trials

BACKGROUND

Efficacy of sildenafil in treating paediatric pulmonary arterial hypertension is controversial. This systematic review aimed to explore the safety and effect of sildenafil on treating paediatric pulmonary arterial hypertension (PAH) through meta-analysis.

METHODS AND RESULTS

In this study, the electronic databases, including the Cochran Library database, EMBASE, and MEDLINE were systemically retrieved to identify the related randomised controlled trials (RCTs). Two reviewers had independently completed study selection, data collection, and assessment of the bias risk. Amongst 938 articles researched according to our retrieval strategy, 15 papers that involved 673 cases had been screened. Relative to control group, the sildenafil group had markedly reduced mortality (RR = 0.25, 95% CI: 0.12-0.51; p < 0.0001), but difference within the mortality was not statistically significant between high- and low-dose sildenafil groups (p = 0.152). Nonetheless, difference of the mean pulmonary arterial pressure between sildenafil as well as control group was of no statistical significance. Differences in the length of hospital stay and the incidences of pulmonary hypertensive crisis between children with PAH and controls were of no statistical significance. However, the summary estimate favoured that sildenafil reduced the duration of mechanical ventilation time, as well as the length of ICU stay and inotropic support.

CONCLUSIONS

Sildenafil therapy reduces the mortality of PAH patients, but its effects on the haemodynamic outcomes and other clinical outcomes are still unclear.

Functional Measurement of CYP2C9 and CYP3A4 Allelic Polymorphism on Sildenafil Metabolism

Aim

We aimed to systematically examine the effects of enzymatic activity of 38 human CYP2C9 alleles and 21 human CYP3A4 alleles, including wild-type CYP2C9.1 and CYP3A4.1, which contain the 24 CYP2C9 novel alleles (*36–*60) and 6 CYP3A4 novel alleles (*28–*34) newly found in the Chinese population, on sildenafil metabolism through in vitro experiment.

Methods

The recombinant cytochrome P450 alleles protein of CYP2C9 and CYP3A4 expressed in insect baculovirus expression system were reacted with 10–500 µM sildenafil for 30 minutes at 37°C, and the reaction was terminated by cooling to −80°C immediately. Next, we used ultra-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection system to detect sildenafil and its active metabolite N-desmethyl sildenafil.

Results

The intrinsic clearance (Vmax/Km) values of most CYP2C9 variants were significantly altered when compared with the wild-type CYP2C9*1, with most of these variants exhibiting either reduced Vmax and/or increased Km values. Four alleles (CYP2C9*11, *14, *31, *49) exhibited no markedly decreased relative clearance (1-fold). The relative clearance of the remaining thirty-three variants exhibited decrease in different levels, ranging from 1.81% to 88.42%. For the CYP3A4 metabolic pathway, when compared with the wild-type CYP3A4*1, the relative clearance values of four variants (CYP3A4*3, *10, *14 and *I335T) showed significantly higher relative clearance (130.7–134.9%), while five variants (CYP3A4*2, *5, *24, *L22V and *F113I) exhibited sharply reduced relative clearance values (1.80–74.25%), and the remaining nine allelic variants showed no statistical difference. In addition, the kinetic parameters of two CYP3A4 variants (CYP3A4*17 and CYP3A4*30) could not be detected, due to the defect of the CYP3A4 gene.

Conclusion

These findings were the first evaluation of all these infrequent CYP2C9 and CYP3A4 alleles for sildenafil metabolism; when treating people who carry these CYP2C9 and CYP3A4 variants, there should be more focus on the relation of dose intensity, side effects and therapeutic efficacy when administering sildenafil. The study will provide fundamental data on effect of CYP2C9 and CYP3A4 allelic variation on sildenafil metabolism for further clinical research.

Novel composite clinical endpoints and risk scores used in clinical trials in pulmonary arterial hypertension

This manuscript on endpoints incorporates the broad experience of members of Pulmonary Vascular Research Institute’s Innovative Drug Development Initiative as an open debate platform for academia, the pharmaceutical industry and regulatory experts surrounding the future design of clinical trials in pulmonary hypertension. It reviews our current understanding of endpoints used in phase 2 and 3 trials for pulmonary hypertension and discusses in detail the value of newer approaches. These include the roles of composite endpoints and how these can be developed and validated. The newer concept of risk analysis is also discussed, including how such risk scores might be utilised as endpoints in clinical trials.

Management of Pulmonary Arterial Hypertension

Purpose of Review

This review focuses on the therapeutic management and individualized approach to Group 1 pulmonary arterial hypertension (PAH), utilizing Food and Drug Administration-approved PAH-specific therapies and various interventional and surgical options for PAH.

Recent Findings

The paradigm for the optimal management of PAH has shifted in recent years. Upfront combination therapy with an endothelin receptor antagonist and a phosphodiesterase 5 inhibitor is now widely accepted as standard of care. In addition, there is increasing emphasis on starting prostanoids early in order to delay time to clinical worsening. However, less is known regarding which prostanoid agent to initiate and the optimum time to do so. In order to facilitate shared decision-making, there is an increasing need for decision tools based on guidelines and collective clinical experiences to navigate between pharmacologic and interventional treatments, as well as explore innovative, therapeutic pathways for PAH.

Summary

The management of PAH has become increasingly complex. With a growing number of PAH-specific therapies, intimate knowledge of the therapeutics and the potential barriers to adherence are integral to providing optimal care for this high-risk patient population. While current PAH-specific therapies largely mediate their effects through pulmonary vasodilation, ongoing research efforts are focused on ways to disrupt the mechanisms leading to pulmonary vascular remodeling. By targeting aberrations identified in the metabolism and proliferative state of pulmonary vascular cells, novel PAH treatment pathways may be just on the horizon.

PDE5 Inhibitors in Type 2 Diabetes Cardiovascular Complications

Pharmacological inhibition of Phosphodiesterase type 5 (PDE5) proved its efficacy treating several pathological conditions, such as erectile dysfunction and pulmonary hypertension. Nowadays, its benefits on cardiovascular diseases are well documented, particularly in the treatment of type 2 diabetes (T2DM)-related cardiovascular complications. In this context, treatment of T2DM with PDE5 inhibitors, such as sildenafil, tadalafil or vardenafil ameliorates endothelial dysfunction both in patients and animal models through an augmented flow mediated dilation rate and an up-regulation of endothelial markers; it also reduces the inflammatory state by down-regulating inflammatory cytokines expression and improves diabetic cardiomyopathy and ischemia-reperfusion injury mainly through the activation of NO-cGMP-PKG pathway. The present review summarizes the state of art on PDE5 inhibition in the treatment of cardiovascular complications in T2DM.

[The achievements of the modern specific therapy of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: focus on the stimulator of soluble guanylate cyclase riociguat]

Currently, treatment of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) is focused on three signaling pathways: the NO pathway, the endothelin pathway, and the prostacyclin pathway. Riociguat is the only representative of stimulators of the soluble guanylate cyclase (sGC) class that is approved for the treatment of PAH and inoperable and persistent/recurrent CTEPH. The review presents data from clinical trials showing a positive effect of riociguat on the functional and hemodynamic profile of patients with PAH and CTEPH. In recent years there has been much discussion about the possibility of optimizing therapy by switching to drugs that affect a single pathogenesis target. Thus, sGC stimulants have obvious advantages over phosphodiesterase type 5 (PDE-5) inhibitors, including the ability of riociguat to exert pharmacological effects (due to a NO-independent mechanism of action) even in conditions of reduced NO production. Switching from PDE-5 to riociguat may be safe and appropriate, according to clinical trials presented in the review. In accordance with the guidelines for the diagnosis and treatment of pulmonary hypertension of the Eurasian Association of cardiologists from 2019, this strategy is approved when PDE5 therapy is ineffective in patients with PAH FC III (WHO).

Repurposing of medications for pulmonary arterial hypertension

This manuscript on drug repurposing incorporates the broad experience of members of the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative as an open debate platform for academia, the pharmaceutical industry and regulatory experts surrounding the future design of clinical trials in pulmonary hypertension. Drug repurposing, use of a drug in a disease for which it was not originally developed, in pulmonary arterial hypertension has been a remarkable success story, as highlighted by positive large phase 3 clinical trials using epoprostenol, bosentan, iloprost, and sildenafil. Despite the availability of multiple therapies for pulmonary arterial hypertension, mortality rates have modestly changed. Moreover, pulmonary arterial hypertension patients are highly symptomatic and frequently end up on parental therapy and lung transplant waiting lists. Therefore, an unmet need for new treatments exists and drug repurposing may be an important avenue to address this problem.

Clinical trial design in phase 2 and 3 trials for pulmonary hypertension

This article on clinical trial design incorporates the broad experience of members of the Pulmonary Vascular Research Institute's (PVRI) Innovative Drug Development Initiative (IDDI) as an open debate platform for academia, the pharmaceutical industry and regulatory experts surrounding the future design of clinical trials in pulmonary hypertension. It is increasingly clear that the design of phase 2 and 3 trials in pulmonary hypertension will have to diversify from the traditional randomised double-blind design, given the anticipated need to trial novel therapeutic approaches in the immediate future. This article reviews a wide range of differing approaches and places these into context within the field of pulmonary hypertension.

Pediatric Pulmonary Arterial Hypertension

Pulmonary hypertension (PH), the syndrome of increased pressure in the pulmonary arteries, is associated with significant morbidity and mortality for affected children and is associated with a variety of potential underlying causes. Several pulmonary arterial hypertension-targeted therapies have become available to reduce pulmonary artery pressure and improve outcome, but there is still no cure for most patients. This review provides a description of select causes of PH encountered in pediatrics and an update on the most recent data pertaining to evaluation and management of children with PH. Available evidence for specific classes of PH-targeted therapies in pediatrics is discussed.

Current and emerging therapeutic approaches to pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a progressive and fatal lung disease of multifactorial etiology. Most of the available drugs and FDA-approved therapies for treating pulmonary hypertension attempt to overcome the imbalance between vasoactive and vasodilator mediators, and restore the endothelial cell function. Traditional medications for treating PAH include the prostacyclin analogs and receptor agonists, phosphodiesterase 5 inhibitors, endothelin-receptor antagonists, and cGMP activators. While the current FDA-approved drugs showed improvements in quality of life and hemodynamic parameters, they have shown only very limited beneficial effects on survival and disease progression. None of them offers a cure against PAH, and the median survival rate remains less than three years from diagnosis. Extensive research efforts have led to the emergence of innovative therapeutic approaches in the area of PAH. In this review, we provide an overview of the current FDA-approved therapies in PAH and discuss the associated clinical trials and reported-side effects. As recent studies have led to the emergence of innovative therapeutic approaches in the area of PAH, we also focus on the latest promising therapies in preclinical studies such as stem cell-based therapies, gene transfer, and epigenetic therapies.

The effect of Riociguat on cardiovascular function and efficiency in healthy, juvenile pigs

INTRODUCTION

Riociguat is a soluble guanylate cyclase stimulator approved for the treatment of pulmonary hypertension. Its effect on cardiometabolic efficiency is unknown. A potential cardiac energy sparing effect of this drug could imply a positive prognostic effect, particularly in patients with right heart failure from pulmonary hypertension.

METHOD

We infused Riociguat in six healthy juvenile pigs and measured the integrated cardiovascular effect and myocardial oxygen consumption. To assess the interplay with NO-blockade on cardiac function and efficiency we also administered the NO-blocker L- NAME to the animals after Riociguat.

RESULTS AND DISCUSSION

Infusion of 100 µg/kg Riociguat gave modest systemic vasodilatation seen as a drop in coronary and systemic vascular resistance of 36% and 26%, respectively. Right and left ventriculoarterial coupling index (Ees/Ea), stroke work efficiency (SWeff), and the relationship between left ventricular myocardial oxygen consumption (MVO₂ ) and total mechanical work (pressure-volume area; PVA) were unaffected by Riociguat. In contrast, systemic and pulmonary vasoconstriction induced by L-NAME (15 mg/kg) shifted the Ees/Ea ratio toward reduced SWeff in both systemic and pulmonary circulation. However, there was no surplus oxygen consumption, that was measured by the MVO₂ /PVA relationship after L-NAME in Riociguat-treated pigs. This suggests that Riociguat can reduce the NO-related cardiometabolic inefficiency previously observed by blocking the NO pathway.

The Role of Phosphodiesterase-5 Inhibitors in COVID-19: An Exploration of Literature From Similar Pathologies

Coronavirus Disease 2019 (COVID-19) has had a devastating impact on the ability of highly trained healthcare providers to render sufficient care, due to both the significant demand on resources and the unique nature of this disease that make it resistant to traditional therapies. This review sought to determine the potential role of phosphodiesterase-5 inhibitors (PDE-5) in the management of COVID-19 by extrapolating relevant data and clinical studies from other related disease states, including acute respiratory distress syndrome, acute lung injury, and high altitude pulmonary edema. Following a literature search, 4 reports were analyzed and included in this review. While the heterogenicity of data and the small number of trials included limit the interpretation and applicability, it was consistently demonstrated that PDE-5 inhibitors lowered pulmonary arterial pressures. The overall benefit of these agents is seemingly dependent upon the etiology of the respiratory failure, which warrants expanded clinical investigation for COVID-19.

Pharmacologic therapy for pulmonary artery hypertension

PURPOSE OF REVIEW

Pulmonary arterial hypertension (PAH) is a disease that carries a significant mortality left untreated. This article aims to review pharmacotherapeutics for PAH.

RECENT FINDINGS

PAH-specific therapies have evolved over the last three decades and have expanded from one therapy in the 1990s to 14 FDA-approved medications. Current therapies are directed at restoring the imbalance of vasoactive mediators that include nitric oxide, endothelin and prostacyclin. Although these agents are effective as monotherapy, recent trials have promulgated the strategy of upfront combination therapy. The availability of oral prostacyclin agonists has also allowed for expanded treatment options. Risk assessment is vital in guiding therapy for PAH patients. There is ongoing focus on targeting pathological mechanisms of the disease via novel therapies and repurposing existing drugs.

SUMMARY

There is an array of medications available for the treatment of PAH. Prudent combination of therapies to maximize treatment effect can improve morbidity and mortality. This article reviews the data supporting these therapies and attempts to outline an approach to patient management.

An immunochromatographic strip sensor for sildenafil and its analogues

In this study, a new hapten of sildenafil (Sild) was successfully synthesized and a sensitive monoclonal antibody (mAb) against Sild was produced based on this new hapten. The subclass of the mAb was IgG2a, and the half-maximal inhibitory concentration (IC50) of the mAb was 0.53 ng mL-1. Next, an immunochromatographic assay (ICA) was established for detecting Sild and its analogues in functional foods, where the visual detection limit (vLOD) and cut-off values were 0.5 and 20 μg kg-1, respectively. With the aid of a strip scan reader, the ICA can measure Sild with an LOD of 0.7 μg kg-1 and a line range of detection between 1.40 and 13.11 μg kg-1. The whole test process takes only 15 min. Therefore, the ICA provides a useful tool for the on-site detection and rapid initial screening of Sild in functional food samples.

The effect of sildenafil on pulmonary haemodynamics in a canine model of chronic embolic pulmonary hypertension

The effects of different doses of orally administered sildenafil on pulmonary haemodynamics in dogs with pulmonary hypertension (PH) have not been documented in an invasive and quantitative manner. In this study, we examined the effects of oral sildenafil using a canine model of chronic embolic PH (CEPH). This CEPH model was created by repeatedly injecting microspheres through a catheter into the pulmonary artery under general anaesthesia at regular weekly intervals over several months. The CEPH dogs received 1, 2 or 4 mg/kg of sildenafil orally twice a day for seven days. Then, haemodynamic measurements including pulmonary artery pressure (PAP), systemic artery pressure (SAP), pulmonary artery wedge pressure (PAWP), right atrial pressure (RAP) and cardiac output (CO) were obtained after seven days of sildenafil administration via right heart catheterisation and oscillometric blood pressure measurements. Sildenafil was well tolerated in this study. Sildenafil administered at doses of 2 and 4 mg/kg significantly decreased systolic PAP compared with before administration. In addition, all doses of sildenafil significantly decreased the mean and diastolic PAP. Furthermore, 4 mg/kg of sildenafil significantly decreased PAP compared with 1 mg/kg. Sildenafil also significantly decreased pulmonary vascular resistance without notable changes in SAP or systemic vascular resistance. The PAWP, RAP and CO did not increase significantly at any doses. In conclusion, the oral administration of sildenafil to CEPH models decreased PAP in a dose-dependent manner.

Long-term survival outcome for pre-capillary pulmonary hypertension at a Japanese single center

In recent years, several treatment options for patients with pre-capillary pulmonary hypertension (PH) have improved the short-term prognosis. However, the long-term survival for pre-capillary PH has not been well investigated. This study sought to investigate the long-term survival for pre-capillary PH in Kurume University Hospital. A total of 144 patients with pre-capillary PH (110 women, mean age 55.1 ± 17.9 years) were enrolled. The maximal duration of followup was 15 years with a mean followup of 5.77 years. The 15 year survival was 59.1% for pre-capillary PH, 68.5% for pulmonary arterial hypertension (PAH), and 44.3% for chronic thromboembolic PH. The 5 year survival was 50.9% for PH due to lung disease (PH-LD), indicating the worst in the pre-capillary PH subgroups. The survival for portopulmonary hypertension was the lowest among PAH groups, and PAH associated with connective tissue disease and congenital heart disease decreased 10 years after diagnosis. A 6 min walk distance and elevated brain natriuretic peptide were significantly associated with survival outcome in pre-capillary PH patients and diastolic pulmonary arterial pressure was related to survival for PH-LD. The survivals were different among pre-capillary PH groups in our hospital. Above all, the long-term survival was better than in previous reports.

Relationship between treatment of erectile dysfunction and future risk of cardiovascular disease: A nationwide cohort study

Aims

Erectile dysfunction is associated with increased risk of cardiovascular disease; however, little is known about patients seeking treatment for erectile dysfunction. This study investigated the risk of cardiovascular disease for patients receiving medication for erectile dysfunction.

Methods and results

This nationwide cohort study included 71,710 men aged 40–80 years receiving their first erectile dysfunction medication from 2000 to 2012. Their adjusted risk of cardiovascular events in time intervals after the first erectile dysfunction medication was compared to the general male population using multivariate Poisson regression models and was expressed as a risk ratio (RR). The risk for overall cardiovascular disease was decreased in the first 3 years: the RR in the first year was 0.92 (95% confidence interval [CI] 0.87–0.97, p = 0.003; incidence: 23.68 per 1000 patient-years), and after 1–3 years the RR was 0.94 (95% CI 0.90–0.97, p = 0.002; incidence: 24.92 per 1000 patient-years). After 3 years, there was no significant difference. The risk of myocardial infarction was decreased in all time intervals: the RR in the first year was 0.60 (95% CI 0.50–0.73, p &lt; 0.001; incidence: 1.82 per 1000 patient-years), after 1–3 years the RR was 0.72 (95% CI 0.63–0.82, p &lt; 0.001; incidence: 2.16 per 1000 patient-years) and after 3 years the RR was 0.80 (95% CI 0.73–0.88, p &lt; 0.001; incidence: 2.25 per 1000 patient-years). The risk of heart failure was decreased in the first 3 years.

Conclusion

Receiving medication for erectile dysfunction was associated with a decreased risk of myocardial infarction and cardiovascular diseases for the first 3 years.

Phosphodiesterases in the Liver as Potential Therapeutic Targets of Cirrhotic Portal Hypertension

Liver cirrhosis is a frequent condition with high impact on patients' life expectancy and health care systems. Cirrhotic portal hypertension (PH) gradually develops with deteriorating liver function and can lead to life-threatening complications. Other than an increase in intrahepatic flow resistance due to morphological remodeling of the organ, a functional dysregulation of the sinusoids, the smallest functional units of liver vasculature, plays a pivotal role. Vascular tone is primarily regulated by the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway, wherein soluble guanylate cyclase (sGC) and phosphodiesterase-5 (PDE-5) are key enzymes. Recent data showed characteristic alterations in the expression of these regulatory enzymes or metabolite levels in liver cirrhosis. Additionally, a disturbed zonation of the components of this pathway along the sinusoids was detected. This review describes current knowledge of the pathophysiology of PH with focus on the enzymes regulating cGMP availability, i.e., sGC and PDE-5. The results have primarily been obtained in animal models of liver cirrhosis. However, clinical and histochemical data suggest that the new biochemical model we propose can be applied to human liver cirrhosis. The role of PDE-5 as potential target for medical therapy of PH is discussed.

Phenotypes of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic morbidity in preterm infants. In the absence of effective interventions, BPD is currently a major therapeutic challenge. Several risk factors are known for this multifactorial disease that results in disrupted lung development. Inflammation plays an important role and leads to persistent airway and pulmonary vascular disease. Since corticosteroids are potent anti-inflammatory agents, postnatal corticosteroids have been used widely for BPD prevention and treatment. However, the clinical responses vary to a great degree across individuals, and steroid-related complications remain major concerns. Emerging studies on the molecular mechanism of lung alveolarization during inflammatory stress will elucidate the complicated pathway and help discover novel therapeutic targets. Moreover, with the advances in metabolomics, there are new opportunities to identify biomarkers for early diagnosis and prognosis prediction of BPD. Pharmacometabolomics is another novel field aiming to identify the metabolomic changes before and after a specific drug treatment. Through this "metabolic signature," a more precise treatment may be developed, thereby avoiding unnecessary drug exposure in non-responders. In the future, more clinical, genetic, and translational studies would be required to improve the classification of BPD phenotypes and achieve individualized care to enhance the respiratory outcomes in preterm infants.

Transplant Operative Considerations in Pulmonary Hypertension With Severe Right Heart Failure

Over the past several decades, the operation of choice for end-stage lung disease secondary to severe pulmonary hypertension (PH) has shifted from heart-lung transplantation (HLT) to bilateral lung transplantation (BLT). This change has maintained excellent long-term outcomes and is appropriate for the majority of patients presenting with end-stage disease in need of transplantation. However, a distinct subset of patients with severe PH have an excessive early mortality within 90 days of transplantation. Based on the different causes of this early mortality compared to BLT recipients with other indications, right heart failure and refractory primary graft dysfunction appear to play a significant role. It is therefore critical to identify this subset of patient during their evaluation for transplant. This distinction would allow specific patient referral for HLT, which may mitigate those causes of early mortality. Similarly, there is a subgroup of BLT recipients for severe PH that fail to recover right ventricular function, with suboptimal long-term functional status that is independent of early survival. Identification and referral for HLT of these patients may also be important. In this manuscript, we describe our institutional approach and consideration for the risks of early mortality from right heart failure and primary graft dysfunction, as well failure of right ventricular recovery long term. The described evaluation is used to ascertain those patients with severe PH who may benefit from an HLT over BLT.

In Silico studies of novel Sildenafil self-emulsifying drug delivery system absorption improvement for pulmonary arterial hypertension

Sildenafil is a potent selective inhibitor of phosphosdiesterase-5 previously used in erectile dysfunction and subsequently approved in 2005 for pulmonary arterial hypertension treatment. Since oral administration of sildenafil shows pharmacokinetic problems with mean absolute bioavailability of 41%, the goal of this work was to develop a novel sildenafil self-emulsifying drug delivery system (SEDDS) for oral absorption improvement and management of dosage. One pharmaceutical solution and four SEDDS containing sildenafil were successfully obtained and SEDDS formed O/W nanoemulsion with droplet size less than 300 nm. The stability studies evidenced that the SEDDS containing 3.3% w/w of sildenafil yielded the best results. The safety of 2-pyrrolidone/isobutanol in oral formulations was assessed in mice and no lethality was achieved in the placebo groups with LD50 of 490 mg/Kg for SEDDS II-3.3, suggesting it as a safe excipient for humans. Therewithal, in silico studies using PBPK models provided the pharmacokinetic profile of sildenafil SEDDS. Subsequently, in silico evaluation indicated that the sildenafil SEDDS droplet size influenced its bioavailability, enhancing absorption, assuring a good pharmacokinetic profile. These findings suggest that the formulations developed here presented the potential to enhance drug oral absorption with the possibility to control drug dosage as they are liquid pharmaceutical formulations.

Niclosamide attenuates lung vascular remodeling in experimental pulmonary arterial hypertension

Despite advances in medical therapy, pulmonary arterial hypertension (PAH) remains an inexorably progressive and highly lethal disease. Signal transducer and activator of transcription (STAT)-3 is one of the main intracellular transcription factors implicated in PAH vascular remodeling. We hypothesized that niclosamide, a STAT3 inhibitor, would reduce vascular remodeling in an established pulmonary arterial hypertension model, thus enhancing cardiac function. Male Wistar rats were treated either with monocrotaline (60 mg/kg), to induce PAH, or saline (C group) by intraperitoneal injection. On day 14, PAH animals were randomly assigned to receive oral (1) saline (PAH-SAL); (2) niclosamide (75 mg/kg/day) (PAH-NICLO); (3) sildenafil (20 mg/kg/day) (PAH-SIL); or (4) niclosamide + sildenafil (PAH-NICLO + SIL), once daily for 14 days. On day 28, right ventricular systolic pressure was lower in all treated groups compared to PAH-SAL. Pulmonary vascular collagen content was lower in PAH-NICLO (37 ± 3%) and PAH-NICLO + SIL (37 ± 6%) compared to PAH-SAL (68 ± 4%), but not in PAH-SIL (52 ± 1%). CD-34, an endothelial cell marker, was higher, while vimentin, a mesenchymal cell marker, was lower in PAH-NICLO and PAH-NICLO + SIL compared to PAH-SAL, suggesting attenuation of endothelial-mesenchymal transition. Expression of STAT3 downstream targets such as transforming growth factor (TGF)-β, hypoxia-inducible factor (HIF)-1, and provirus integration site for Moloney murine leukemia virus (PIM-1) in lung tissue was reduced in PAH-NICLO and PAH-NICLO + SIL compared to PAH-SAL. In conclusion, niclosamide, with or without sildenafil, mitigated vascular remodeling and improved right ventricle systolic pressure. This new role for a well-established drug may represent a promising therapy for PAH.

The endothelin receptor antagonist macitentan for the treatment of pulmonary arterial hypertension: A cross-species comparison of its cytochrome P450 induction pattern

The dual endothelin receptor antagonist macitentan was approved in 2013 for the treatment of pulmonary arterial hypertension. Macitentan is an inducer of cytochrome P450 expression in vivo in animal species but not in man. In rat and dog, changes in P450 expression manifest as autoinduction upon repeat dosing. The induction pattern, however, significantly differed between both species, and between male and female rats. While macitentan exposure steadily declined with dose in the dog, P450 induction was saturable in the rat reaching levels of 40%-60% and 60%-80% at steady-state in male and female animals, respectively. The nature and number of P450 enzymes involved in macitentan clearance were identified as a major reason for the observed species differences. In the dog, macitentan was metabolized by a single P450 enzyme, that is, Cyp3a12, whereas several members of the Cyp2c and Cyp3a families were involved in the rat. Macitentan selectively upregulated Cyp3a expression in rat, whereas the expression of the Cyp2c enzymes involved in macitentan metabolism remained mostly unchanged, eventually leading to a higher contribution of Cyp3a upon induction. Macitentan also induced CYP3A4 expression in human hepatocytes via initial activation of the human pregnane X receptor. No such induction was evident in humans at the therapeutic macitentan dose of 10 mg as shown in a clinical drug-drug interaction study with the CYP3A4 substrate sildenafil.

Effect of Coronavirus Disease 2019 in Pulmonary Circulation. The Particular Scenario of Precapillary Pulmonary Hypertension

The Coronavirus Disease of 2019 (COVID-19) has supposed a global health emergency affecting millions of people, with particular severity in the elderly and patients with previous comorbidities, especially those with cardiovascular disease. Patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) could represent an especially vulnerable population because of the high mortality rates reported for respiratory infections. However, the number of COVID-19 cases reported among PAH and CTEPH patients is surprisingly low. Furthermore, the clinical picture that has been described in these patients is far from the severity that experts would expect. Endothelial dysfunction is a common feature between patients with PAH/CTEPH and COVID-19, leading to ventilation/perfusion mismatch, vasoconstriction, thrombosis and inflammation. In this picture, the angiotensin-converting enzyme 2 plays an essential role, being directly involved in the pathophysiology of both clinical entities. Some of these common characteristics could explain the good adaptation of PAH and CTEPH patients to COVID-19, who could also have obtained a benefit from the disease's specific treatments (anticoagulant and pulmonary vasodilators), probably due to its protective effect on the endothelium. Additionally, these common features could also lead to PAH/CTEPH as a potential sequelae of COVID-19. Throughout this comprehensive review, we describe the similarities and differences between both conditions and the possible pathophysiological and therapeutic-based mechanisms leading to the low incidence and severity of COVID-19 reported in PAH/CTEPH patients to date. Nevertheless, international registries should look carefully into this population for better understanding and management.

Phosphodiesterase Inhibitors: Could They Be Beneficial for the Treatment of COVID-19?

In March 2020, the World Health Organization declared the severe acute respiratory syndrome corona virus 2 (SARS-CoV2) infection to be a pandemic disease. SARS-CoV2 was first identified in China and, despite the restrictive measures adopted, the epidemic has spread globally, becoming a pandemic in a very short time. Though there is growing knowledge of the SARS-CoV2 infection and its clinical manifestations, an effective cure to limit its acute symptoms and its severe complications has not yet been found. Given the worldwide health and economic emergency issues accompanying this pandemic, there is an absolute urgency to identify effective treatments and reduce the post infection outcomes. In this context, phosphodiesterases (PDEs), evolutionarily conserved cyclic nucleotide (cAMP/cGMP) hydrolyzing enzymes, could emerge as new potential targets. Given their extended distribution and modulating role in nearly all organs and cellular environments, a large number of drugs (PDE inhibitors) have been developed to control the specific functions of each PDE family. These PDE inhibitors have already been used in the treatment of pathologies that show clinical signs and symptoms completely or partially overlapping with post-COVID-19 conditions (e.g., thrombosis, inflammation, fibrosis), while new PDE-selective or pan-selective inhibitors are currently under study. This review discusses the state of the art of the different pathologies currently treated with phosphodiesterase inhibitors, highlighting the numerous similarities with the disorders linked to SARS-CoV2 infection, to support the hypothesis that PDE inhibitors, alone or in combination with other drugs, could be beneficial for the treatment of COVID-19.

Vascular Metabolic Mechanisms of Pulmonary Hypertension

Pulmonary hypertension (PH) is a severe and progressive disease characterized by increased pulmonary vascular resistance leading to right heart failure and death. In PH, the cellular metabolisms including those of the three major nutrients (carbohydrate, lipid and protein) are aberrant in pulmonary vascular cells. Glucose uptake, glycolysis, insulin resistance, sphingolipid S1P, PGE₂, TXA₂, leukotrienes and glutaminolysis are upregulated, and phospholipid-prostacyclin and L-arginine-nitric oxide pathway are compromised in lung vascular cells. Fatty acid metabolism is disordered in lung endothelial cells and smooth muscle cells. These molecular mechanisms are integrated to promote PH-specific abnormal vascular cell proliferation and vascular remodeling. This review summarizes the recent advances in the metabolic reprogramming of glucose, fatty acid, and amino acid metabolism in pulmonary vascular remodeling in PH and the mechanisms for how these alterations affect vascular cell fate and impact the course of PH.

Guidelines for the Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare form of pulmonary hypertension characterized by a progressive obliterative vasculopathy of the distal pulmonary arterial circulation that usually leads to right ventricular failure and death. Over the last 25 years, more than a dozen drugs representing five drug classes have been developed and approved for the treatment of this devastating disease. Due to the small number of patients afflicted by PAH, most health care providers have little experience with its management. To address this gap in medical knowledge, treatment guidelines have been developed by professional organizations and expert committees. Over the last few years, these guidelines have been updated to address findings from recent clinical trials and ongoing experience with these drugs. This review provides an update on the most recently published treatment guidelines for pharmacologic treatment of PAH and incorporates them into a contemporary approach to the treatment of this disease.

Type 5 phosphodiesterase (PDE5) and the vascular tree: From embryogenesis to aging and disease

•

Vascular development depends on the timely differentiation of endothelial and smooth muscle cells.

•

Vascular aging and vascular disease are influenced by endothelial and vascular smooth muscle cell compartments.

•

A survey of the literature on the role of PDE5 in vascular development, aging and disease is reported.

•

The role of PDE5 on vascular development, aging and disease needs to be further investigated by its genetic ablation.

Vascular tree development depends on the timely differentiation of endothelial and vascular smooth muscle cells. These latter are key players in the formation of the vascular scaffold that offers resistance to the blood flow. This review aims at providing an overview on the role of PDE5, the cGMP-specific phosphodiesterase that historically attracted much attention for its involvement in male impotence, in the regulation of vascular smooth muscle cell function. The overall goal is to underscore the importance of PDE5 expression and activity in this cell type in the context of the organs where its function has been extensively studied.

Complications in Idiopathic Pulmonary Fibrosis: Focus on Their Clinical and Radiological Features

Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease with uncertain origins and pathogenesis; it represents the most common interstitial lung disease (ILD), associated with a pathological pattern of usual interstitial pneumonitis (UIP). This disease has a poor prognosis, having the most lethal prognosis among ILDs. In fact, the progressive fibrosis related to IPF could lead to the development of complications, such as acute exacerbation, lung cancer, infections, pneumothorax and pulmonary hypertension. Pneumologists, radiologists and pathologists play a key role in the identification of IPF disease, and in the characterization of its complications-which unfortunately increase disease mortality and reduce overall survival. The early identification of these complications is very important, and requires an integrated approach among specialists, in order to plane the correct treatment. In some cases, the degree of severity of patients having IPF complications may require a personalized approach, based on palliative care services. Therefore, in this paper, we have focused on clinical and radiological features of the complications that occurred in our IPF patients, providing a comprehensive and accurate pictorial essay for clinicians, radiologists and surgeons involved in their management.

Site-Selective Copper-Catalyzed Azidation of Benzylic C-H Bonds

Site selectivity represents a key challenge for non-directed C-H functionalization, even when the C-H bond is intrinsically reactive. Here, we report a copper-catalyzed method for benzylic C-H azidation of diverse molecules. Experimental and density functional theory studies suggest the benzyl radical reacts with a CuII-azide species via a radical-polar crossover pathway. Comparison of this method with other C-H azidation methods highlights its unique site selectivity, and conversions of the benzyl azide products into amine, triazole, tetrazole, and pyrrole functional groups highlight the broad utility of this method for target molecule synthesis and medicinal chemistry.

Pulmonary Hypertension Phenotypes in Systemic Sclerosis: The Right Diagnosis for the Right Treatment

Systemic sclerosis is an auto-immune disease characterized by skin involvement that often affects multiple organ systems. Pulmonary hypertension is a common finding that can significantly impact prognosis. Molecular pathophysiological mechanisms underlying pulmonary hypertension in systemic sclerosis can be extremely heterogeneous, leading to distinct clinical phenotypes. In addition, different causes of pulmonary hypertension may overlap within the same patient. Since pulmonary hypertension treatment is very different for each phenotype, it is fundamental to perform an adequate diagnostic work-up to properly and promptly identify the prevalent mechanism underlying pulmonary hypertension in order to start the right therapies. When pulmonary hypertension is caused by a primary vasculopathy of the small pulmonary arteries, treatment with pulmonary vasodilators, often in an initial double-combination regimen, is indicated, aimed at reducing the mortality risk profile. In this review, we describe the different clinical phenotypes of pulmonary hypertension in the scleroderma population and discuss the utility of clinical tools to identify the presence of pulmonary vascular disease. Furthermore, we focus on systemic sclerosis-associated pulmonary arterial hypertension, highlighting the advances in the knowledge of right ventricular dysfunction in this setting and the latest updates in terms of treatment with pulmonary vasodilator drugs.

Pulmonary hypertension in pregnancy: experience from 45 cases at a tertiary care center

Objective: Pulmonary hypertension (PH) is a rare maternal cardiac disorder associated with high maternal and fetal mortality. The objective of our study was to evaluate the maternal and fetal outcomes in pregnant women with PH in a single health center.Study design: 45 pregnant patients with PH, who had undergone antenatal follow-up and delivery at the department of gynecology and obstetrics at a referral center were retrospectively investigated. Maternal and perinatal outcomes were evaluated and descriptive statistics were reported.Results: According to the WHO classification; 35 patients (78%) were in Group 1; 9 patients (20%) in Group 2 and one patient (2%) were in Group 3. Thirty-three of the cases (73%) had mild, 8 (18%) moderate and 4 (9%) severe PH. The mean delivery week was 35.5. Twenty-four of the cases (56%) delivered before the 37th week and the remaining 19 cases (44%) in the 37th week or later. Rate of cesarean section delivery was 88%. Only one case of maternal death was reported, who was initially diagnosed with PAH during pregnancy. This patient had severe PH and was in Group 1 according to the WHO classification.Conclusion: While the mortality rates related to PH were reported to be between 30% and 56% several decades ago, recent studies have reported the mortality rates between 5% and 25%. It is believed that the decline in the maternal mortality depended on the developments in the treatment alternatives and multidisciplinary management. However, PH is still a serious condition which requires a multidisciplinary approach and a well-planned obstetric management.

Effect of sildenafil on neuroinflammation and synaptic plasticity pathways in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a chronic immuno-inflammatory disease of the central nervous system characterized by demyelination and axonal damage. Cognitive changes are common in individuals with MS since inflammatory molecules secreted by microglia interfere with the physiological mechanisms of synaptic plasticity. According to previous data, inhibition of PDE5 promotes the accumulation of cGMP, which inhibits neuroinflammation and seems to improve synaptic plasticity and memory. The present study aimed to evaluate the effect of sildenafil on the signaling pathways of neuroinflammation and synaptic plasticity in experimental autoimmune encephalomyelitis (EAE). C57BL/6 mice were divided into three experimental groups (n = 10/group): (a) Control; (b) EAE; (c) EAE + sild (25 mg/kg/21 days). Sildenafil was able to delay the onset and attenuate the severity of the clinical symptoms of EAE. The drug also reduced the infiltration of CD4+ T lymphocytes and their respective IL-17 and TNF-α cytokines. Moreover, sildenafil reduced neuroinflammation in the hippocampus (assessed by the reduction of inflammatory markers IL-1β, pIKBα and pNFkB and reactive gliosis, as well as elevating the inhibitory cytokines TGF-β and IL-10). Moreover, sildenafil induced increased levels of NeuN, BDNF and pCREB, protein kinases (PKA, PKG, and pERK) and synaptophysin, and modulated the expression of the glutamate receptors AMPA and NMDA. The present findings demonstrated that sildenafil has therapeutic potential for cognitive deficit associated with multiple sclerosis.

Echocardiographic Changes with Positive Airway Pressure Therapy in Obesity Hypoventilation Syndrome. Long-Term Pickwick Randomized Controlled Clinical Trial

Rationale: Obesity hypoventilation syndrome (OHS) has been associated with cardiac dysfunction. However, randomized trials assessing the impact of long-term noninvasive ventilation (NIV) or continuous positive airway pressure (CPAP) on cardiac structure and function assessed by echocardiography are lacking.Objectives: In a prespecified secondary analysis of the largest multicenter randomized controlled trial of OHS (Pickwick Project; N = 221 patients with OHS and coexistent severe obstructive sleep apnea), we compared the effectiveness of three years of NIV and CPAP on structural and functional echocardiographic changes.Methods: At baseline and annually during three sequential years, patients underwent transthoracic two-dimensional and Doppler echocardiography. Echocardiographers at each site were blinded to the treatment allocation. Statistical analysis was performed using a linear mixed-effects model with a treatment group and repeated measures interaction to determine the differential effect between CPAP and NIV.Measurements and Main Results: A total of 196 patients were analyzed: 102 were treated with CPAP and 94 were treated with NIV. Systolic pulmonary artery pressure decreased from 40.5 ± 1.47 mm Hg at baseline to 35.3 ± 1.33 mm Hg at three years with CPAP, and from 41.5 ± 1.56 mm Hg to 35.5 ± 1.42 with NIV (P < 0.0001 for longitudinal intragroup changes for both treatment arms). However, there were no significant differences between groups. NIV and CPAP therapies similarly improved left ventricular diastolic dysfunction and reduced left atrial diameter. Both NIV and CPAP improved respiratory function and dyspnea.Conclusions: In patients with OHS who have concomitant severe obstructive sleep apnea, long-term treatment with NIV and CPAP led to similar degrees of improvement in pulmonary hypertension and left ventricular diastolic dysfunction.Clinical trial registered with www.clinicaltrials.gov (NCT01405976).

Pulmonary arterial hypertension specific therapy: The old and the new

Pulmonary arterial hypertension (PAH) is a vascular disorder associated with high morbidity and mortality rate and is characterized by pulmonary vascular remodeling and increased pulmonary vascular resistance, ultimately resulting in right ventricular failure and death. Over the past few decades, significant advances in the understanding of the epidemiology, pathogenesis, and pathophysiology of pulmonary arterial hypertension have occured. This has led to the development of disease specific treatment including prostanoids, endothelin receptor antagonists, phosphodiesterase inhibitors, and soluble guanylate cyclase stimulators. These therapies significantly improve exercise capacity, quality of life, pulmonary hemodynamics, but none of the current treatments are actually curative and long-term prognosis remains poor. Thus, there is a clear need to develop new therapies. Several potential pharmacologic agents for the treatment of pulmonary arterial hypertension are under clinical development and some promising results with these treatments have been reported. These agents include tyrosine protein kinase inhibitors, rho-kinase inhibitors, synthetically produced vasoactive intestinal peptide, antagonists of the 5-HT2 receptors, and others. This article will review several of these promising new therapies and will discuss the current evidence regarding their potential benefit in pulmonary arterial hypertension.

An update on the diagnosis and treatment of pediatric pulmonary hypertension

INTRODUCTION

Pulmonary hypertension (PH) is a heterogeneous disease that mainly affects the pulmonary arterioles, leading to significant morbidity and mortality. Pulmonary hypertension in children from birth to adolescence presents important differences from that of adults. The majority of pediatric pulmonary arterial hypertension (PAH) cases are idiopathic or associated with congenital heart disease. However, the management of pediatric PAH mainly depends on the results of evidence-based adult studies and the clinical experiences of pediatric experts.

AREAS COVERED

This article briefly reviews the recent updates on the definition, classification, and diagnostic evaluation of pediatric PAH and their impact on treatment strategies. The main purpose of this review is to discuss the current pediatric therapies, as well as the prospective therapies, in terms of therapeutic targets, actions, side effects, and dosages.

EXPERT OPINION

Although there is no cure for PAH, recent advances in the form of new treatment options have improved the quality of life and survival rates of PAH patients. PAH-targeted drugs and treatment strategies for adult PAH have not been sufficiently studied in children. However, the growing scientific activity in that field will surely change the treatment option recommendations in pediatric PH from experience-based to evidence-based in the near future.