A review of prostaglandin analogs in the management of patients with pulmonary arterial hypertension

Pulmonary Arterial Hypertension in Women

Pulmonary arterial hypertension (PAH) is characterized by pathological hemodynamic elevation in pulmonary artery pressure. Development of international registries over the last decade has raised awareness about the disease, leading to the development of new and improved therapies. Paradigm shifts such as these warrant review of existing literature regarding PAH, especially in females, as the disease continues to affect women more than males. The aim of this review is to provide an update on the classification, pathophysiology, diagnosis, and treatment of PAH while focusing specifically on its impact on women.

Safety and tolerability of subcutaneous treprostinil in newborns with congenital diaphragmatic hernia and life-threatening pulmonary hypertension

BACKGROUND

Prolonged pulmonary hypertension (PH) is highly predictive for pulmonary morbidity and death in infants with congenital diaphragmatic hernia (CDH).

OBJECTIVES

To report the effects and tolerability of subcutaneous treprostinil in newborns with severe CDH and late life-threatening PH.

METHODS

We recorded clinical and echocardiography data before and after starting subcutaneous treprostinil, on patients with severe CDH and late PH, refractory to inhaled nitric oxide and oral sildenafil.

RESULTS

14 patients were treated with treprostinil (gestational age: 39.1±2.0weeks; birth weight: 3200±600g). Prior to treatment, the pre- and post-ductal SpO2 difference (Δ SpO2) was 14±10%. Treprostinil was initiated at a median age of 12days [5-157]. After starting treprostinil, ΔSpO2 decreased to 3% at day 7 (p<0.05), and the mean blood flow velocities in the right pulmonary arteries increased by 110% (p<0.05). 2 of the 14 patients died. At the age of follow up (12months to 3years), the 12 surviving infants were all weaned from respiratory support and discharged home.

CONCLUSION

The subcutaneous treprostinil improves pulmonary hemodynamics and outcomes in infants with CDH and life-threatening PH. We suggest that the treatment should be considered in infants with severe CDH and late PH.

TYPE OF STUDY

Case series with no comparison group.

LEVEL OF EVIDENCE

Level IV.

Structural development of 1,2,3,4-tetrahydroisoquinoline-type positive allosteric modulators of prostacyclin receptor (IPPAMs) to improve metabolic stability, and investigation of metabolic fate

We synthesized a series of 1,2,3,4-tetrahydroisoquinoline-type positive allosteric modulators of prostacyclin receptor (IPPAMs), aiming to improve the metabolic stability of the previously identified hit compound IPPAM-3 (2). Our results indicated that the 3-position of the 2-substituted phenyl ring in this series of IPPAM-3 derivatives is a hot spot for metabolism catalyzed by human hepatic microsomes. This conclusion was confirmed by the finding that 8, in which the 3-position is blocked by a fluorine substituent, exhibited superior metabolic stability (t_1/2 21min versus 7min for parent compound 2). The primary route of metabolism of 8 was found to be oxidative defluorination, i.e., ipso-substitution of the fluorine atom to a hydroxyl group, affording catechol derivative 12. The primary metabolite 12 underwent further hydroxylation mainly on the 1,2,3,4-tetrahydroisoquinoline moiety. These findings should be helpful for design of IPPAMs with longer duration of action.

Clinical pharmacology, efficacy, and safety of selexipag for the treatment of pulmonary arterial hypertension

INTRODUCTION

Selexipag is the first oral, non-prostanoid, selective prostacyclin receptor (IP receptor) agonist, approved for the long-term treatment of pulmonary arterial hypertension (PAH) in adult patients. Areas covered: This article reviews the clinical pharmacology, efficacy, and safety of selexipag in the treatment of PAH. Expert opinion: Selexipag is the first oral drug that selectively targets the prostacyclin pathway, and has evidence of long-term efficacy and safety. In the global phase 3 study GRIPHON (NCT01106014) in PAH patients, selexipag significantly reduced the risk of the primary composite outcome of morbidity/mortality (M/M). The adverse events in the selexipag group were consistent with the known side effects of prostacyclin, including headache, nausea, jaw pain, and diarrhea. Importantly, selexipag was efficacious and safe irrespective of whether or not patients were already receiving other PAH therapies. With selexipag approval, triple oral combination therapy addressing three important pathways is available for patients with PAH. Selexipag has one major metabolite, ACT-333679, which is also a selective IP receptor agonist, with 37-fold higher potency than selexipag. Pharmacokinetic properties of ACT-333679 permit twice-daily dosing of selexipag, providing a more convenient treatment compared to prostacyclin or its analogs. For patients with moderate hepatic impairment a once-daily regimen is recommended.

Kidney dysfunction in patients with pulmonary arterial hypertension

Pulmonary arterial hypertension (PH) and chronic kidney disease (CKD) both profoundly impact patient outcomes, whether as primary disease states or as co-morbid conditions. PH is a common co-morbidity in CKD and vice versa. A growing body of literature describes the epidemiology of PH secondary to chronic kidney disease and end-stage renal disease (ESRD) (WHO group 5 PH). But, there are only limited data on the epidemiology of kidney disease in group 1 PH (pulmonary arterial hypertension [PAH]). The purpose of this review is to summarize the current data on epidemiology and discuss potential disease mechanisms and management implications of kidney dysfunction in PAH. Kidney dysfunction, determined by serum creatinine or estimated glomerular filtration rate, is a frequent co-morbidity in PAH and impaired kidney function is a strong and independent predictor of mortality. Potential mechanisms of PAH affecting the kidneys are increased venous congestion, decreased cardiac output, and neurohormonal activation. On a molecular level, increased TGF-β signaling and increased levels of circulating cytokines could have the potential to worsen kidney function. Nephrotoxicity does not seem to be a common side effect of PAH-targeted therapy. Treatment implications for kidney disease in PAH include glycemic control, lifestyle modification, and potentially Renin-Angiotensin-Aldosterone System (RAAS) blockade.

Selexipag in Pulmonary Arterial Hypertension: Most Updated Evidence From Recent Preclinical and Clinical Studies

Pulmonary arterial hypertension (PAH) is a relatively rare disease that, due to its chronic nature, has always been difficult to treat effectively. Selexipag is an oral prostacyclin (PGI₂ ) agonist that was approved by US Food and Drug Administration (US FDA) in December 2015 for the treatment of PAH. After its success in phase 1 and phase 2 clinical trials regarding the convenient oral twice-daily dosing and low side-effect profile, selexipag raised the hope of controlling the disease progression in PAH patients. In the recently completed multicentered phase 3 study (GRIPHON), selexipag has been shown to reduce death and hospitalization due to PAH significantly, an effect that was consistent across different ranges of maintenance dose. In the same study selexipag use was also associated with an increase in 6-minute walk distance (a measure of symptom severity) from baseline, but no significant improvement in all-cause mortality could be observed. The results of the ongoing phase 3 studies (TRITON and TRANSIT-1) are expected to throw some more light on the safety and efficacy of this novel molecule across various treatment scenarios. Hence, our article aims to summarize all the available information from preclinical and clinical studies published to date on the pharmacodynamics, pharmacokinetics, efficacy, safety (in general and in scenarios such as hepatic and renal function impairment), significant drug interactions (with warfarin and antiretroviral drugs), and clinical significance of oral selexipag in patients with PAH.

Practical considerations for therapies targeting the prostacyclin pathway

Therapies that target the prostacyclin pathway play a key role in the treatment of both early- and late-stage pulmonary arterial hypertension, and provide significant clinical benefits for patients. A number of agents have been approved, which are administered via intravenous, subcutaneous, inhaled or oral routes. The use of these therapies is associated with practical challenges, relating to the need for up-titration and their routes of administration. We discuss here a number of measures that can be taken to support patients and healthcare professionals in order to address the complexities of using these therapies and to encourage compliance. Providing patients with timely information and education, together with practical advice on managing their medication and associated equipment, assists patients with day-to-day management of therapy. Referral to patient associations and support groups can be of further benefit. With an effective management plan and an experienced multidisciplinary team, the use of therapies that target the prostacyclin pathway can be optimised.

Practical support for patients and HCPs to facilitate the use of therapies that target the PGI₂ pathway in PAHhttp://ow.ly/468S305Dl6m

Selexipag in the treatment of pulmonary arterial hypertension: design, development, and therapy

Pulmonary arterial hypertension is characterized by abnormalities in the small pulmonary arteries including increased vasoconstriction, vascular remodeling, proliferation of smooth muscle cells, and in situ thrombosis. Selexipag, a novel, oral prostacyclin receptor agonist, has been shown to improve hemodynamics in a phase II clinical trial and reduce clinical worsening in a large phase III clinical trial involving patients with pulmonary arterial hypertension. In this paper, we describe the prostacyclin signaling pathway, currently available oral prostanoid medications, and the development and clinical use of selexipag.

Comparison of hyperbaric oxygen versus iloprost treatment in an experimental rat central retinal artery occlusion model

PURPOSE

Central retinal artery occlusion (CRAO) is one of the serious ophthalmological emergencies with poor visual prognosis. Iloprost is a stable prostacyclin analogue and has prominent anti-edema, anti-inflammatory, vasodilatory, and antiagregant effects. The main objective of this work was to investigate iloprost as an alternative agent versus hyperbaric oxygen (HBO) in the treatment of CRAO.

METHODS

Twenty-eight healthy Wistar albino male rats were randomly assigned into control (n = 7, sham operation), HBO (n = 7), iloprost (n = 7), and sham groups (n = 7). CRAO model was created through optic nerve exploration and ligation. Full-thickness retina (FTR), outer nuclear layer (ONL), inner nuclear layer (INL) and ganglion cell layer (GCL) thickness were measured on Hematoxylin/Eosin (H&E) stained retinal sections and immunohistochemical analysis including terminal deoxynucleotidyl transferase-mediated biotindeoxyuridine triphosphate nick-end labeling (TUNEL) assay was performed to determine the apoptotic index (AI).

RESULTS

AI values of HBO (0.204 ± 0.067) and iloprost (0.197 ± 0.052) groups were significantly lower than sham (0.487 ± 0.046) group (p < 0.001). Any significant difference was found between the HBO and iloprost groups in terms of AI (p = 0.514). A statistically significant increase in thickness of FTR, ONL, INL and GCL was detected in HBO, iloprost and sham groups compared to the control group (p = 0.002). FTR, ONL, INL and GCL thickness were significantly thinner in HBO and iloprost groups than in the sham group (p = 0.002). A significant lesser increase was observed in all the retinal layers thickness in iloprost group versus HBO group (p = 0.002) except for INL (p = 0.665).

CONCLUSIONS

The study results demonstrated anti-edema, neuroprotective, and anti-apoptotic effects of iloprost quantitatively; thus, iloprost may be a beneficial alternative agent in the treatment of CRAO.

Portopulmonary hypertension

Portopulmonary hypertension (PoPH) refers to the condition that pulmonary arterial hypertension (PAH) occur in the stetting of portal hypertension. The development of PoPH is thought to be independent of the severity of portal hypertension or the etiology or severity of liver disease. PoPH results from excessive vasoconstriction, vascular remodeling, and proliferative and thrombotic events within the pulmonary circulation that lead to progressive right ventricular failure and ultimately to death. Untreated PoPH is associated with a poor prognosis. As PoPH is frequently asymptomatic or symptoms are generally non-specific, patients should be actively screened for the presence of PoPH. Two-dimensional transthoracic echocardiography is a useful non-invasive screening tool, but a definitive diagnosis requires invasive hemodynamic confirmation by right heart catheterization. Despite a dearth of randomized, prospective data, an ever-expanding clinical experience shows that patients with PoPH benefit from therapy with PAH-specific medications including with endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and/or prostanoids. Due to high perioperative mortality, transplantation should be avoided in those patients who have severe PoPH that is refractory to medical therapy.

[Treatment of acute and chronic right ventricular failure]

Acute or chronic right ventricular failure is an often misdiagnosed cause of cardiopulmonary insufficiency. In addition to clinical symptoms or laboratory testing, echocardiography and invasive hemodynamic measurement by means of right-heart catheterization are essential for diagnosis and treatment control. In case of acute right ventricular failure, adequate symptomatic treatment of the life-threatening situation is important. Main issues are maintenance of coronary artery perfusion pressure and myocardial oxygen delivery as well as reduction of right ventricular afterload. In persistent right ventricular failure extracorporeal or intracorporeal assist devices are increasingly used as bridging or destination therapy. On a long-term basis, the targeted therapy of the underlying disease is crucial.

Perioperative management of patients with pulmonary hypertension for non-cardiac surgery

Pulmonary hypertension (PH) is associated with significant morbidity and mortality. While the advent of disease-modifying therapies in the treatment of PH has dramatically increased the life expectancy of these patients, they remain at high risk for perioperative complications. Outcome studies suggest that patients with PH undergoing non-cardiac surgery have higher morbidity and mortality than those without, independent of severity. Despite these risks, more and more of these patients are presenting for non-cardiac surgery. Patients with rheumatologic disorders in particular often have pulmonary arterial hypertension (PAH), a group that is associated with a poorer prognosis. Yet, these patients invariably develop debilitating joint diseases and not uncommonly present for elective surgery. Preoperatively, patients with PH should be appropriately risk stratified based on functional class, etiology, exercise capacity, pulmonary hemodynamics, and the risk of surgery. If the risks and benefits assessment proves favorable, they should undergo optimization prior to surgery, with any chronic therapy continuing without cessation through the perioperative period. A multidisciplinary approach involving all intraoperative physicians is imperative to forming a safe intraoperative plan based on the inherent physiology underlying the patient's disease. Finally, because complications in this patient population often occur postoperatively, patients should be monitored in an appropriate setting with a goal of preventing right ventricular dysfunction. In this review article, we focus on the evaluation, risk stratification, and optimization of patients with PH undergoing non-cardiac surgery.

Recent advances in targeting the prostacyclin pathway in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe disease characterised by increased pulmonary vascular resistance, which leads to restricted pulmonary arterial blood flow and elevated pulmonary arterial pressure. In patients with PAH, pulmonary concentrations of prostacyclin, a prostanoid that targets several receptors including the IP prostacyclin receptor, are reduced. To redress this balance, epoprostenol, a synthetic prostacyclin, or analogues of prostacyclin have been given therapeutically. These therapies improve exercise capacity, functional class and haemodynamic parameters. In addition, epoprostenol improves survival among patients with PAH. Despite their therapeutic benefits, treatments that target the prostacyclin pathway are underused. One key factor is their requirement for parenteral administration: continuous intravenous administration can lead to embolism and thrombosis; subcutaneous administration is associated with infusion-site pain; and inhalation is time consuming, requiring multiple daily administrations. Nevertheless, targeting the prostacyclin pathway is an important strategy for the management of PAH. The development of oral therapies for this pathway, as well as more user-friendly delivery devices, may alleviate some of the inconveniences. Continued improvements in therapeutic options will enable more patients with PAH to receive medication targeting the prostacyclin pathway.

New pharmacotherapy options for pulmonary arterial hypertension

INTRODUCTION

Epoprostenol was the first targeted therapy available for the treatment of pulmonary arterial hypertension (PAH). Since then great advances in our knowledge of the disease have been made and the spectrum of therapeutic options for PAH has expanded. After an overview of current available treatments, this article describes the new pharmacotherapy options and their place in the management of PAH.

AREAS COVERED

This paper is based on a literature search and the review of studies published on PAH pharmacotherapy using the MEDLINE database.

EXPERT OPINION

The last decade has been particularly important in PAH management with the emergence of six new molecules, the development of novel routes of administration and improvement of pharmacokinetics. Moreover, pediatric formulations have been developed. However, further research is required to inform clinicians regarding optimal choices of combination therapies (progressive add-on therapy or upfront combination therapy, selection of associated molecules regarding the patient's profile...), to continue to improve the quality of life of patients with new drugs and to reach the ultimate goal of curing the disease.

Effect of lopinavir/ritonavir on the pharmacokinetics of selexipag an oral prostacyclin receptor agonist and its active metabolite in healthy subjects

AIMS

This study investigated the effect of a fixed dose combination of lopinavir/ritonavir on the pharmacokinetics (PK) of selexipag and its active metabolite ACT-333679.

METHODS

This was an open label, randomized, single centre, two way, crossover study. Twenty healthy male subjects were treated with a single dose of 400 µg selexipag alone and in combination with multiple doses of lopinavir/ritonavir (400/100 mg) twice daily.

RESULTS

The results showed that lopinavir/ritonavir approximately doubled the exposure to selexipag. The area under the plasma concentration-time curve from time zero to infinity (AUC(0,∞) and the maximum plasma concentration (Cmax) of selexipag were 2.2- and 2.1-fold higher, respectively, than under selexipag alone, with a 90% confidence interval (CI) of the geometric mean ratio (GMR) of 1.9, 2.7 and 1.7, 2.6, respectively. For ACT-333679, the clinically more relevant component of selexipag, systemic exposure was increased by 8% (GMR of AUC(0,∞) 1.1, 90% CI 0.9, 1.3), when lopinavir/ritonavir was co-administered with selexipag. The most frequently reported adverse event (AE) was headache. A single dose of selexipag, administered either alone or together with multiple doses of lopinavir/ritonavir, was safe and well tolerated.

CONCLUSIONS

Lopinavir/ritonavir does not affect the PK parameters of selexipag and ACT-333679 to a clinically relevant extent. Therefore, adaptation of the selexipag dose is not required when co-administered with inhibitors of the organic anion-transporting polypeptide (OATP) 1B1/ 1B3, P-glycoprotein (P-gp) and/or CYP3A4.

Pharmacokinetics and Tolerability of the Novel Oral Prostacyclin IP Receptor Agonist Selexipag

PURPOSE

Targeting the prostacyclin pathway is an effective treatment option for pulmonary arterial hypertension (PAH). Patients with PAH have a deficiency of prostacyclin and prostacyclin synthase. Selexipag is an orally available and selective prostacyclin receptor (IP receptor) agonist. Selexipag is hydrolyzed to its active metabolite ACT-333679, also a selective and potent agonist at the IP receptor.

METHODS

In this phase I study the pharmacokinetics (PK) and tolerability of single and multiple ascending doses of selexipag were investigated in a double-blind, placebo-controlled manner in 64 healthy male subjects. An additional group of 12 subjects received an open-label dose of selexipag 400 μg in the fasted condition and after a meal.

RESULTS

Maximum plasma concentrations of selexipag and ACT-333679 were reached within 2.5 and 4 h, respectively, with mean half-lives of 0.7-2.3 and 9.4-14.22 h. In the presence of food, exposure to ACT-333679 was decreased by 27 %. The most frequent adverse event was headache. Selexipag was well tolerated up to a single dose of 400 μg and multiple doses of 600 μg following an up-titration step. No relevant treatment-related effects on vital signs, clinical laboratory, and electrocardiogram (ECG) parameters were detected.

CONCLUSION

Selexipag exhibits a good tolerability profile and PK properties that warrant further investigation.

EP3 receptor deficiency attenuates pulmonary hypertension through suppression of Rho/TGF-β1 signaling

Pulmonary arterial hypertension (PAH) is commonly associated with chronic hypoxemia in disorders such as chronic obstructive pulmonary disease (COPD). Prostacyclin analogs are widely used in the management of PAH patients; however, clinical efficacy and long-term tolerability of some prostacyclin analogs may be compromised by concomitant activation of the E-prostanoid 3 (EP3) receptor. Here, we found that EP3 expression is upregulated in pulmonary arterial smooth muscle cells (PASMCs) and human distal pulmonary arteries (PAs) in response to hypoxia. Either pharmacological inhibition of EP3 or Ep3 deletion attenuated both hypoxia and monocrotaline-induced pulmonary hypertension and restrained extracellular matrix accumulation in PAs in rodent models. In a murine PAH model, Ep3 deletion in SMCs, but not endothelial cells, retarded PA medial thickness. Knockdown of EP3α and EP3β, but not EP3γ, isoforms diminished hypoxia-induced TGF-β1 activation. Expression of either EP3α or EP3β in EP3-deficient PASMCs restored TGF-β1 activation in response to hypoxia. EP3α/β activation in PASMCs increased RhoA-dependent membrane type 1 extracellular matrix metalloproteinase (MMP) translocation to the cell surface, subsequently activating pro-MMP-2 and promoting TGF-β1 signaling. Activation or disruption of EP3 did not influence PASMC proliferation. Together, our results indicate that EP3 activation facilitates hypoxia-induced vascular remodeling and pulmonary hypertension in mice and suggest EP3 inhibition as a potential therapeutic strategy for pulmonary hypertension.

A thorough QT study in the context of an uptitration regimen with selexipag, a selective oral prostacyclin receptor agonist

The effects of selexipag and its active metabolite ACT-333679 on cardiac repolarization were assessed in a thorough QT study as per International Conference on Harmonisation E14 guidance. In this randomized, double-blind, placebo/positive-controlled, parallel-group study, healthy male and female subjects were randomized to receive escalating doses of selexipag (n=91) or placebo/moxifloxacin (n=68). Ascending multiple doses of selexipag in the range of 400-1,600 μg or placebo were administered twice daily for 21 days. Following a nested crossover design, subjects in the moxifloxacin/placebo treatment group received a single oral 400 mg dose of moxifloxacin on day 2 or 24. The primary endpoint (QT interval correction using individualized formula [QTcI]) was chosen based on a prospectively defined test applied to on-treatment data. The mean baseline-adjusted placebo-corrected ΔQTcI (ΔΔQTcI) for selexipag was small at all time points and never exceeded 1.4 msec (upper bound of 90% confidence interval [CI], 3.9 msec) on 800 μg or -0.7 msec (upper bound of 90% CI, 2.1 msec) on 1,600 μg. The mean ΔΔQTcI peak effect for moxifloxacin was 7.5 msec (lower bound of 90% CI, 4.8 msec). The exposure-response analysis did not demonstrate a relevant relationship between plasma concentrations of selexipag or ACT-333679 and ΔΔQTcI but, in contrast, a positive slope within the expected range for moxifloxacin. In conclusion, selexipag does not have an effect on cardiac repolarization.

The role of combination therapy in managing pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a complex, progressive disease with several pathobiological mechanisms, including the endothelin, nitric oxide and prostacyclin pathways. Current treatments for PAH target one of these pathways and, in more severe cases or instances of disease worsening, may be combined with a view to target multiple pathways in parallel. Treatment combination is performed sequentially (as an intensification from initial monotherapy) or upfront (use of two or more therapies in treatment-naïve patients). Whilst combination therapy has been historically considered to be an option for the treatment of PAH, supporting evidence was typically limited to expert opinion, clinical experience and registry data.

Data from randomised controlled trials on sequential combination therapy in particular has grown in recent years, resulting in a change in the level of recommendations in the latest update to the PAH treatment algorithm. However, short-term trials have shown inconsistent results, and have not been powered to assess morbidity/mortality outcomes. More recent data from long-term trials suggest a potential clinical benefit associated with sequential combination therapy.

In this review we will introduce the concept of combination therapy, consider the latest evidence for both sequential and upfront combination therapy, and discuss additional considerations when initiating combination therapy in clinical practice.

Epoprostenol (Veletri®, Caripul®): a review of its use in patients with pulmonary arterial hypertension

A bioequivalent formulation of intravenous epoprostenol containing the excipients arginine and sucrose (epoprostenol AS) (Veletri®, Caripul®) is approved in the USA, UK, and other countries for the treatment of pulmonary arterial hypertension (PAH), and has improved thermal stability compared with epoprostenol containing glycine and mannitol (epoprostenol GM) (Flolan®). Epoprostenol, a synthetic prostacyclin, is a potent pulmonary vasodilator. Epoprostenol GM was originally approved for use as a long-term continuous infusion in patients with PAH nearly 20 years ago in the USA; however, this formulation has limited stability at room temperature, and requires the use of cooling or frequent medication changes during administration. The prolonged thermal stability of epoprostenol AS compared with epoprostenol GM allows for its extended administration at room temperature and/or refrigerated storage of prepared solutions. This article summarizes the pharmacology of epoprostenol AS and reviews its therapeutic use in adult patients with PAH. In clinical trials, epoprostenol AS provided sustained efficacy in terms of hemodynamic and symptomatic outcomes, and was generally well tolerated after transitioning from stable epoprostenol GM therapy and during an open-label extension study. Furthermore, there was a significant increase in the treatment convenience with epoprostenol AS compared with epoprostenol GM. Therefore, epoprostenol AS is a valuable therapeutic option that has the potential to overcome some of the limitations of long-term intravenous epoprostenol therapy in patients with PAH.

Long Term Stability Evaluation of Prostacyclin Released from Biomedical Device through Turbiscan Lab Expert

Therapeutic guidelines indicate prostacyclin as the first line of treatment in inflammation and vascular diseases. Prostacyclins prevent formation of the platelet plug involved in primary hemostasis by inhibiting platelet activation and, combined with thromboxane, are effective vasodilators in vascular damage. Trans-Atlantic Inter-Society Consensus Document on Management of Peripheral Arterial Disease II guidelines indicates prostacyclins; in particular, Iloprost, as the first therapeutic option for treating peripheral arterial disease. However, therapeutic efficacy of Iloprost has witnessed several drawbacks that have occurred in patients receiving repeated weekly administration of the drug by intravenous infusions. Adverse reactions arose under perfusion with Iloprost for 6 h and patient compliance was drastically decreased. Biomedical devices could provide a suitable alternative to overcome these drawbacks. In particular, elastomeric pumps, filled with Iloprost isotonic solution, could slowly release the drug, thus decreasing its side effects, representing a valid alternative to hospitalization of patients affected by peripheral arterial disease. However, the home therapy treatment of patients requires long-term stability of Iloprost in solution-loaded elastomeric pumps. The aim of this work was to investigate the long-term stability of Iloprost isotonic solution in biomedical devices using Turbiscan technology. Turbiscan Lab Expert (L'Union, France) predicts the long-term stability of suspensions, emulsions and colloidal formulations by measuring backscattering and transmission of particulates dispersed in solution. The formulations were evaluated by measuring the variation of physical-chemical properties of colloids and suspensions as a function of backscattering and transmission modifications. In addition, the release profile of Iloprost isotonic solution from the biomedical device was evaluated.

Targeted delivery of genes to endothelial cells and cell- and gene-based therapy in pulmonary vascular diseases

Pulmonary arterial hypertension (PAH) is a devastating disease that, despite significant advances in medical therapies over the last several decades, continues to have an extremely poor prognosis. Gene therapy is a method to deliver therapeutic genes to replace defective or mutant genes or supplement existing cellular processes to modify disease. Over the last few decades, several viral and nonviral methods of gene therapy have been developed for preclinical PAH studies with varying degrees of efficacy. However, these gene delivery methods face challenges of immunogenicity, low transduction rates, and nonspecific targeting which have limited their translation to clinical studies. More recently, the emergence of regenerative approaches using stem and progenitor cells such as endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) have offered a new approach to gene therapy. Cell-based gene therapy is an approach that augments the therapeutic potential of EPCs and MSCs and may deliver on the promise of reversal of established PAH. These new regenerative approaches have shown tremendous potential in preclinical studies; however, large, rigorously designed clinical studies will be necessary to evaluate clinical efficacy and safety.

Optimal management of pulmonary arterial hypertension: prognostic indicators to determine treatment course

Pulmonary arterial hypertension (PAH) is a rapidly progressive pulmonary vascular disease with a multifactorial etiopathogenesis that can result in right-sided heart failure and death. A number of studies indicate that an early therapeutic intervention yields better results on disease progression as compared to delayed treatment. In this review, we will analyze treatment strategies that may be used for monitoring disease progression and for guiding treatment decisions. Several factors (ie, symptoms, functional class, exercise capacity as assessed by a walking test and cardiopulmonary stress testing, hemodynamic parameters, cardiac magnetic resonance imaging, and plasma levels of biochemical markers) have been prognostic of survival. These indicators may be used both at the time of diagnosis and during treatment follow-up. No resolutive therapy is currently available for PAH; however, in the last decade, the advent of specific pharmacological treatments has given new hope to patients suffering from this debilitating disease with a poor prognosis. Combination drug therapies offer increased benefits over monotherapy, and current guidelines recommend a sequential “add on” design approach for patients in functional class II–IV. The goal-oriented “treat to target” therapy sets the timing for treatment escalation in case of inadequate response to currently known prognostic indicators. To date, further longitudinal studies should be urgently conducted to identify new goals that may improve therapeutic strategies in order to optimize personalized treatment in PAH patients.

Improved survival of Korean patients with idiopathic pulmonary arterial hypertension after the introduction of targeted therapies

OBJECTIVES

We compared the survival of patients with idiopathic pulmonary arterial hypertension (IPAH), receiving conventional and targeted therapies.

BACKGROUND

IPAH is an incurable disease with high mortality. To manage IPAH, several targeted therapies have been used in Korea.

METHODS

We performed a retrospective study of 71 patients diagnosed with IPAH in a tertiary hospital between January 1994 and February 2013. Patients were classified into "conventional therapy group" (treated with conventional therapies and/or beraprost) and "targeted therapy group" (treated with targeted therapies other than beraprost).

RESULTS

The median age of the patients was 33 years and 50 patients were female. The survival rate at 1, 3, 5, and 10 years was 80.1% 62.0%, 51.5%, and 26.8%, respectively. The survival rate in the targeted therapy group was greater than in the conventional therapy group (p-value = 0.026).

CONCLUSIONS

We believe targeted therapies would improve survival benefits in IPAH patients.

The current approach into signaling pathways in pulmonary arterial hypertension and their implication in novel therapeutic strategies

Many mediators and signaling pathways, with their downstream effectors, have been implicated in the pathogenesis of pulmonary hypertension. Currently approved drugs, representing an option of specific therapy, target NO, prostacyclin or ET-1 pathways and provide a significant improvement in the symptomatic status of patients and a slower rate of clinical deterioration. However, despite such improvements in the treatment, PAH remains a chronic disease without a cure, the mortality associated with PAH remains high and effective therapeutic regimens are still required. Knowledge about the role of the pathways involved in PAH and their interactions provides a better understanding of the pathogenesis of the disease and may highlight directions for novel therapeutic strategies for PAH. This paper reviews some novel, promising PAH-associated signaling pathways, such as RAAS, RhoA/ROCK, PDGF, PPAR, and TGF, focusing also on their possible interactions with well-established ones such as NO, ET-1 and prostacyclin pathways.

Longterm treatment with endothelin receptor antagonist bosentan and iloprost improves fingertip blood perfusion in systemic sclerosis

OBJECTIVE

To evaluate the longterm effects of endothelin-1 (ET-1) antagonism on peripheral blood perfusion (PBP) in patients with systemic sclerosis (SSc).

METHODS

Twenty-six patients with SSc already receiving cyclic intravenous iloprost (ILO) for severe Raynaud phenomenon were enrolled. Thirteen patients continued the treatment for a further 3 years (ILO group) and 13 patients, because of the appearance of digital ulcers, received in addition bosentan (BOS; 125 mg twice/day) for 3 years (ILO + BOS group). Both PBP at fingertips and nailfold microangiopathy were evaluated yearly by laser Doppler flowmetry and nailfold videocapillaroscopy, respectively.

RESULTS

A progressive significant increase of PBP was observed in the ILO + BOS group during the 3 followup years (p = 0.0007, p = 0.0002, p = 0.01, respectively). In contrast, an insignificant progressive decrease of PBP was observed in the ILO group. Difference of perfusion between the PBP evaluations at basal temperature and at 36 °C (to test capillary dilation capacity), was found progressively decreased during the 3-year followup only in the ILO group (p = 0.05, p = 0.26, p = 0.09, respectively). A progressive increase of nailfold capillary number was observed only in the ILO + BOS group after 2 and 3 years of followup (p = 0.05).

CONCLUSION

Longterm treatment of SSc patients with ET-1 antagonism, in combination with ILO, seems to increase fingertip blood perfusion, as well as both capillary dilation capacity and number.

Sex differences in the pulmonary circulation: implications for pulmonary hypertension

Pulmonary arterial hypertension (PAH), a form of pulmonary hypertension, is a complex disease of multifactorial origin. While new developments regarding pathophysiological features and therapeutic options in PAH are being reported, one important fact has emerged over the years: there is a sex difference in the incidence of this disease such that while there is a higher incidence in females, disease outcomes are much worse in males. Accordingly, recent attention has been focused on understanding the features of sex differences in the pulmonary circulation and the contributory mechanisms, particularly sex hormones and their role in the pathological and pathophysiological features of PAH. However, to date, there is no clear consensus whether sex hormones (particularly female sex steroids) are beneficial or detrimental in PAH. In this review, we highlight some of the most recent evidence regarding the influence of sex hormones (estrogen, testosterone, progesterone, dehydroepiandrosterone) and estrogen metabolites on key pathophysiological features of PAH such as proliferation, vascular remodeling, vasodilation/constriction, and inflammation, thus setting the stage for research avenues to identify novel therapeutic target for PAH as well as potentially other forms of pulmonary hypertension.

Long-term survival of Japanese patients with pulmonary arterial hypertension treated with beraprost sodium, an oral prostacyclin analogue

OBJECTIVE

Beraprost was developed as the first oral prostacyclin analog to treat patients with pulmonary arterial hypertension (PAH). Although this drug demonstrates improvements in the patient's exercise capacity and symptoms, it carries a weak recommendation in the PAH evidence-based treatment algorithm due to a lack of durability of effects. However, this therapy remains a major treatment method in Japan due to its availability and inexpensive cost. The purpose of this study was to elucidate whether this drug exhibits durable effects on sustained overall survival.

METHODS

A comparison of survival benefits was completed among patients undergoing treatment with beraprost (n=35) or conventional therapy (n=44). In addition, the estimated survival calculated using the equation developed by the National Institutes of Health Registry was used for the analysis.

RESULTS

Although no significant differences were observed between the two groups using the Kaplan-Meier survival curve, a statistical difference was observed between the patients receiving high-dose beraprost therapy (>120 μg) and those receiving conventional therapy (5- and 10-year survival: 71.1% and 49.4% vs. 37.7% and 21.2%, respectively; p=0.0466). Moreover, the cumulative survival rates in the patients receiving beraprost were slightly better than the estimated survival rates. In the PAH patients with connective tissue diseases, a tendency towards better survival outcomes was observed in the group treated with beraprost.

CONCLUSION

This study suggests the survival benefits of high-dose beraprost therapy for patients with PAH. The retrospective nature of this study, however, makes it difficult to conclude definitively that beraprost exerts significant beneficial effects on survival.

Prostaglandin E1 increases the blood flow rate of saphenous vein grafts in patients undergoing off-pump coronary artery bypass grafting

OBJECTIVE

To compare the effects of prostaglandin E1 (PGEl) versus placebo on blood flow rate in coronary artery bypass grafts.

DESIGN

A prospective, randomized, double-blinded study.

SETTING

A teaching hospital.

PARTICIPANTS

Forty-six patients with stable angina scheduled for isolated elective OPCAB were recruited and randomized into group PGE1 and group placebo.

INTERVENTION

Following randomization, the patients in the PGE1 group (Group PGE1, n = 23) received a continuous intravenous infusion of PGEl (10 ng/kg/min) after endotracheal intubation and the placebo group (Group placebo, n = 23) received the same volume of normal saline. The infusion administration was removed after leaving the intensive care unit.

MEASUREMENTS AND MAIN RESULTS

The grafts' blood flow rate was measured with a transit time flowmeter at 10 minutes and 30 minutes after coronary artery grafting. The hemodynamic parameters, including mean arterial pressure (MAP), heart rate, and SvO2, VO2I, DO2I, ERO2 monitored by a pulmonary artery catheter, were recorded. The blood flow of the saphenous vein grafts was significantly higher in the PGE1 group than the placebo group at both 10 and 30 minutes after coronary artery grafting. At the 10-minute mark, the graft flow was 54.9 ± 31.4 mL/min versus 47.3 ± 24.6 mL/min in venous nonsequential grafts to the left coronary artery for group PGE1 and placebo (p = 0.000). Corresponding values at 30 minutes were 60.1 ± 27.8 mL/min versus 48.4 ± 26.3 mL/min (p = 0.002). In the venous non-sequential grafts to the right coronary artery, a tendency of blood flow also was found to be higher in the PGE1 group than in the placebo group at 10-minutes (52.7 ± 29.4 mL/min versus 49.3 ± 23.8 mL/min, p = 0.048) and the 30-minutes (58.6 ± 26.5 mL/min, 50.9 ± 25.9 mL/min, p = 0.037). The blood flow rate of the left internal mammary artery (LIMA) grafts in group PGE1 was higher than that in the placebo group but did not reach statistical significance. The VO2I, DO2I, and ERO2 in the 2 groups at the 2 time points did not reach statistical significance. The cardiac index (CI) in group PGE1 was higher than that of the placebo group at T3 and T4 (p = 0.035 and p = 0.012, respectively). The lactate (LAC) at the end of the operation (T2), 4 hours after the operation (T3), and 24 hours after operation (T4) in the placebo group were higher than that of group PGE1 (p = 0.023, p = 0.015, and p = 0.043, respectively). The oxygenation saturation of the mixed venous blood (SvO2) in the 2 groups was decreased but without significant difference.

CONCLUSION

PGE1 significantly increased the flow rate in anastomosed saphenous vein grafts, and its beneficial effects on hemodynamics and oxygen metabolism were observed.

Prostacyclin and its analogues in pulmonary artery hypertension: a meta-analysis

OBJECTIVE

Individual studies examining the effects of prostacyclin and its analogues on pulmonary artery hypertension (PAH) have reported controversial results. This study aims to evaluate the efficacy of these agents for PAH by a meta-analysis based on randomized controlled trials (RCTs).

RESEARCH DESIGN AND METHODS

We systematically searched Pubmed, MEDLINE, EMBASE, ISI Web of Science, and the Cochrane Library through April 2012. All published RCTs reporting the effects of treatment with prostacyclin or its analogues in PAH were included. Summary statistics were calculated using a random effects model.

RESULTS

A total of 14 RCTs with 1606 participants were analyzed. Overall, prostacyclin and its analogues increased 6-minute walk distance (6-MWD) (weighted mean differences [WMD]=18.78 meters, 95% confidence interval [CI]: 11.21 to 26.35; p<0.01) and improved NYHA functional class status (odds ratios [OR]=3.98, 95% CI: 1.70 to 9.34; p=0.001) compared with the control. Moreover, these agents led to statistically significant reductions in mean pulmonary artery pressure (mPAP) (WMD=-4.63 mmHg, 95% CI: -6.81 to -2.44; p<0.01) and pulmonary vascular resistance (PVR) (standardized mean difference [SMD] = -0.69, 95% CI: -0.96 to -0.43; p<0.01). Notably, there were distinct effects on these endpoints observed in pooled subgroup analyses based on agent class (all p for interaction<0.01). In addition, PAH-specific therapy appeared to have superiority over the control in reducing the incidence of all-cause death (OR=0.49, 95% CI: 0.26 to 0.94; p=0.03). However, there existed a substantial publication bias, which appeared to markedly impact the overall result of 6-MWD.

CONCLUSIONS

PAH-specific treatment with prostacyclin and its analogues significantly improved exercise capacity, cardiopulmonary hemodynamics, and lowered all-cause mortality in patients with PAH.

A review of cardiac transplantation

Perioperative anesthetic management for cardiac transplantation is reviewed. Recent developments in adult cardiac transplantation are noted. This review includes demographics and historical results, recipient and donor selection and evaluation, mechanical circulatory support and heart transplantation techniques, and patient management immediately postimplantation.

Pulmonary arterial hypertension: classification and therapy with a focus on prostaglandin analogs

Pulmonary arterial hypertension, part of the larger spectrum of disorders causing pulmonary hypertension, is a complex and progressive disease of multiple etiologies that ultimately leads to vascular remodeling, right-sided heart failure, and death. Advances in treatment over the past 15 to 20 years have dramatically reduced the morbidity and mortality of the disease, but often have significant drawbacks. Of the more recently approved therapies, the prostaglandin analogs have been shown to have the greatest therapeutic benefit but are also the most difficult to administer, many being given as continuous intravenous infusions in the ambulatory setting. After a case presentation highlighting some of the challenges that accompany treatment with these agents, this article reviews the diagnosis and classification of pulmonary hypertension and pulmonary arterial hypertension and gives a brief overview of the various other pharmacologic agents used in its treatment. A more comprehensive review of the biochemistry of prostaglandins and the pharmacology and clinical use of this class of drugs follows. Recommended treatment guidelines are also discussed.

Inhaled treprostinil for the treatment of pulmonary arterial hypertension

Treprostinil is a prostacyclin derivative approved for the treatment of pulmonary arterial hypertension by intravenous, subcutaneous and inhalational administration. Unlike its precursor epoprostenol, treprostinil is chemically stable at room temperature and neutral pH, and its plasma half-life is longer. In addition to promoting smooth muscle relaxation in the pulmonary vasculature, treprostinil has suppressive effects on platelet aggregation, smooth muscle proliferation and inflammation. A Phase III study, investigating the addition of inhaled treprostinil to oral bosentan or sildenafil, confirmed significant improvements in exercise capacity and quality of life. This review examines the pharmacodynamics, pharmacokinetics, clinical efficacy and safety of inhaled treprostinil for use in pulmonary arterial hypertension.

Longterm effects of endothelin receptor antagonism on microvascular damage evaluated by nailfold capillaroscopic analysis in systemic sclerosis

OBJECTIVE

Systemic sclerosis (SSc) is characterized by microvascular injury, fibrosis, and hypoxia of involved tissues. The vasoactive peptide endothelin-1 (ET-1) seems to be implicated in these events. Using nailfold videocapillaroscopy (NVC), we evaluated longterm effects of ET-1 antagonist treatment on nailfold microvascular damage in patients with SSc, over a 3-year followup period.

METHODS

Thirty patients with SSc (mean age 64 ± 5 yrs, mean disease duration 8 ± 1 yrs) were recruited during their programmed standard treatment protocols. At baseline (T0), 15 patients with SSc (mean age 63 ± 15 yrs, mean disease duration 7 ± 3 yrs), already receiving cyclic intravenous infusion of iloprost (5 continuous days, average 80 μg/day, every 3 mo), continued the treatment for a further 3 years (ILO group). The remaining 15 patients with SSc (mean age 68 ± 13 yrs, mean disease duration 8 ± 4 yrs), although they continued the same cyclic intravenous iloprost treatment as the previous group, also received bosentan 125 mg twice a day for 3 years (ILO+BOS group). Qualitative analysis (scleroderma patterns) and semiquantitative scoring of the microvascular damage were performed by validated routine NVC methods.

RESULTS

During followup, a statistically significant increase of capillary number was observed in the ILO+BOS group (p < 0.02), with a significant and progressive increase of angiogenesis (p < 0.01). In contrast, the ILO group showed a statistically significant decrease of capillary number (p < 0.05). After 3 years the number of capillaries was significantly higher in the ILO+BOS group than in the ILO group (p < 0.05). The score for giant capillaries decreased significantly in both groups of patients with SSc (p < 0.05).

CONCLUSION

In this open study, longterm treatment with ET-1 receptor antagonist in combination with iloprost was found to interfere with progression of nailfold microvascular damage in patients with SSc, as assessed by NVC over a 3-year followup period.

Clinical pharmacology and efficacy of inhaled iloprost for the treatment of pulmonary arterial hypertension

Similar to other prostanoids, iloprost is a potent vasodilator with considerable antiproliferative and anti-thrombotic properties, although the relevance of its ability to affect platelet aggregation in this subset of patients is unrecognized. The pathogenesis of pulmonary arterial hypertension (PAH) is a multifactorial and complex process secondary to an innate deficiency of substances that induce vasodilation and an overproduction of substances producing vasoconstriction. The production of endothelial vasoactive mediators such as nitric oxide, prostacyclin, endothelin-1, thromboxane and serotonin affect the growth of smooth muscle cells, which facilitate the development of structural remodeling changes that are characteristic of PAH. There have been remarkable advances in understanding the pathologic processes that are responsible for increasing pulmonary vascular resistance and that result in elevated pulmonary artery pressures in order to reverse and prevent progression of the disease process. The goals of treatment in these patients are to alleviate the patients' symptoms, to improve functional capacity and to prevent the progression of the disease. The prostacyclin analogs, such as iloprost, have given hope to these patients who struggle under the burdens of this complex disease.

Effect of prostaglandin I2 analogs on cytokine expression in human myeloid dendritic cells via epigenetic regulation

Prostaglandin I(2) (PGI(2)) analog is regarded as a potential candidate for treating asthma. Human myeloid dendritic cells (mDCs) play a critical role in the pathogenesis of asthma. However, the effects of PGI(2) analog on human mDCs are unknown. In the present study, circulating mDCs were isolated from six healthy subjects. The effects of PGI(2) analogs iloprost and treprostinil on cytokine production, maturation and T-cell stimulatory function of human mDCs were investigated. Tumor necrosis factor (TNF)-α and interleukin (IL)-10 were measured by enzyme-linked immunosorbent assay. The expression of costimulatory molecules was investigated by flow cytometry. T-cell stimulatory function was investigated by measuring interferon (IFN)-γ, IL-13 and IL-10 production by T cells cocultured with iloprost-treated mDCs. Intracellular signaling was investigated by Western blot and chromatin immunoprecipitation. We found that iloprost and treprostinil induced IL-10, but suppressed TNF-α production in polyinosinic-polycytidylic acid (poly I:C)-stimulated mDCs. This effect was reversed by the I-prostanoid (IP), E-prostanoid (EP) receptor antagonists or intracellular free calcium (Ca(2+)) chelator. Forskolin, an adenyl cyclase activator, conferred a similar effect. Iloprost and treprostinil increased intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels, and iloprost also increased intracellular Ca(2+). Iloprost suppressed poly I:C-induced mitogen-activated protein kinase (MAPK) phospho-p38 and phospho-activating transcription factor (ATF)2 expression. Iloprost downregulated poly I:C-induced histone H3K4 trimethylation in the TNFA gene promoter region via suppressing translocation of histone 3 lysine 4 (H3K4)-specific methyltransferases MLL (mixed lineage leukemia) and WDR5 (WD repeat domain 5). Iloprost-treated mDCs inhibited IL-13, IFN-γ and IL-10 production by T cells. In conclusion, PGI(2) analogs enhance IL-10 and suppress TNF-α expression through the IP/EP2/EP4 receptors-cAMP and EP1 receptor-Ca(2+) pathway. Iloprost suppressed TNF-α expression via the MAPK-p38-ATF2 pathway and epigenetic regulation by downregulation of histone H3K4 trimethylation.

Role of cyclooxygenase-1-mediated prostacyclin synthesis in endothelium-dependent vasoconstrictor activity of porcine interlobular renal arteries

This study aimed to determine whether PGI2 would be evoked by the endogenous endothelial B2 receptor agonist bradykinin (BK) in the porcine interlobular renal artery and, if so, to determine how it would influence the vasomotor reaction, and the specific cyclooxygenase (COX) isoform(s) involved in its synthesis. The production of the PGI2 metabolite 6-keto-PGF1α was analyzed with HPLC-mass spectroscopy, while vasomotor reaction to PGI2 or BK was determined with isometric force measurement. Results showed that BK evoked an increase in the production of 6-keto-PGF1α, which was abolished by endothelial denudation that removed COX-1 expression, or was reduced by COX-1 inhibition. Interestingly, PGI2 evoked a potent contraction, which was prevented by antagonizing thromboxane-prostanoid (TP) receptors and was not enhanced by antagonizing the vasodilator PGI2 (IP) receptors. The IP receptor agonists MRE-269 and iloprost did not induce any relaxation. Moreover, iloprost, which is also a PGI2 analog, caused a contraction, which was sensitive to TP receptor antagonism, but was to a significantly lesser extent than that of PGI2. Indeed, IP receptors were not detected by RT-PCR or Western blotting in the vessel. Following nitric oxide synthase (NOS) inhibition, BK also evoked an endothelium-dependent contraction, which was blocked by TP receptor antagonism. In addition, inhibition of COX-1 (but not COX-2) impeded the vasoconstrictor activity of BK and expedited the relaxation induced by the agonist in NOS-intact vessels. These results demonstrate that in the porcine interlobular renal artery BK evokes endothelial COX-1-mediated PGI2 synthesis, which mainly leads to the activation of TP receptors and a vasoconstrictor response, possibly due to a scarcity of vasodilator activity mediated by IP receptors. Also, our data suggested that the effect of a PGI2 analog on TP receptors could be reduced compared with that of PGI2 due to modified structure as with iloprost.