Treprostinil for pulmonary hypertension

Approaches to nutrition and feeding in congenital diaphragmatic hernia

In patients with congenital diaphragmatic hernia1, nutrition can represent a challenge both in the short and long term. Its failure to resolve can have a significant impact on multiple aspects of the lives of patients with congenital diaphragmatic hernia (CDH), ranging from lung function to neurodevelopment. In this review, we will describe the causes of nutritional problems in patients with CDH, their consequences, and possible strategies to address them.

Transition from Intravenous Epoprostenol to Treprostinil Due to Intolerable Side Effects in Patients With Pulmonary Arterial Hypertension

Intravenous epoprostenol improves exercise capacity and survival in patients with pulmonary arterial hypertension (PAH); however, it has side effects. Reviewing the side effects associated with epoprostenol and treprostinil is essential for improving the long-term treatment strategies for PAH. This retrospective review included patients with PAH who transitioned from intravenous epoprostenol to intravenous treprostinil owing to intolerable side effects, including high cardiac output symptoms, ascites, and thrombocytopenia. Of the 85 patients who received epoprostenol at our hospital between 2013 and 2021, 16 (11 women), with a median age of 33 (range 26 to 40) years (including 12 with idiopathic PAH, 3 with hereditary PAH, and 1 with connective tissue disease pulmonary hypertension), had to switch from intravenous epoprostenol to treprostinil owing to the side effects. After transitioning, epoprostenol-associated intolerable side effects, such as high cardiac output symptoms, ascites, and thrombocytopenia, were ameliorated. In conclusion, for patients with PAH who have intolerable side effects from epoprostenol and have difficulty in continuing treatment, switching from epoprostenol to treprostinil may be an option. Switching treatment leads to better adherence and improved long-term prostacyclin therapy.

Management of pregnant patients with pulmonary arterial hypertension

Pregnant individuals with pulmonary arterial hypertension (PAH) have significantly high risks of maternal and perinatal mortality. Profound changes in plasma volume, cardiac output and systemic vascular resistance can all increase the strain being placed on the right ventricle, leading to heart failure and cardiovascular collapse. Given the complex network of opposing physiological changes, strict contraception and reduction of hemodynamic fluctuations during pregnancy are important methods of minimizing the risk of maternal mortality and improving the outcomes following pregnancy. In this review, we discuss the recent research progress into pre-conception management and the various therapeutic strategies for pregnant individuals with PAH.

A narrative review on adverse effects of dasatinib with a focus on pharmacotherapy of dasatinib-induced pulmonary toxicities

Chronic myeloid leukemia (CML), a myeloproliferative disorder caused by the over activity of BCR-ABL1 (breakpoint cluster region-Abelson), has been successfully treated by Tyrosine kinase inhibitors (TKIs). While imatinib is known as the first-line treatment of CML, in some cases other TKIs including dasatinib, nilotinib, bosutinib, and ponatinib may be preferred. Dasatinib, a second-generation TKI, inhibits multiple family kinases including BCR-ABL, SRC family kinases, receptor kinases, and TEC family kinases. It is effective against most imatinib-resistant cases except T315I mutation. Despite the superiority of dasatinib in its hematologic and cytogenetic responses in CML compared to imatinib, its potentially harmful pulmonary complications including pleural effusion (PE) and pulmonary arterial hypertension (PAH) may limit its use. Appropriate management of these serious adverse reactions is critical in both improving the quality of life and the outcome of the patient. In this narrative review, we will scrutinize the pulmonary complications of dasatinib and focus on the management of these toxicities.

Treatment of pulmonary arterial hypertension: A review of drugs available for advanced therapy

Pulmonary hypertension (PH) has traditionally been considered a rare disease with a uniformly poor prognosis. However, this was prior to the introduction of advanced therapies for this condition, and more recent registries in the treatment era have shown 5-year survival rates of up to 65%. Prior to 2000, there was only one licensed therapy for pulmonary arterial hypertension (PAH); less than 20 years later, the US Food and Drug Administration has approved 14 different medications for PAH. This review aims to summarise for the general pulmonologist the evidence for the current internationally available advanced therapies for PAH (World Health Organization Group I disease), which is characterised haemodynamically by the presence of precapillary PH in the absence of another cause. The benefit of these agents, either alone or in combinations, is now undisputed and their use is advocated in all current international guidelines for PAH. The improvement in survival of patients with PAH over the concurrent timeline emphasises the importance both of the availability and usage of effective therapies and of patients being seen in specialist centres, where physicians are familiar with using these therapies.

Safety, efficacy and Management of subcutaneous treprostinil infusions in the treatment of severe pediatric pulmonary hypertension

BACKGROUND

Continuous intravenous epoprostenol was the first treatment approved for pulmonary arterial hypertension (PAH) but administration through a central venous line carries risks of thrombosis and sepsis, particularly in children. We sought to evaluate the safety, efficacy and management of subcutaneous (SC) treprostinil in children with PAH.

METHODS

Fifty-six children (median age 65, range 1-200 months) were treated with SC treprostinil. Clinical status, echocardiography, NT-proBNP, and site pain and infection were evaluated. Right heart catheterization was performed in 54 patients before starting SC treprostinil infusion and was repeated at 6 months in 31 patients.

RESULTS

Treatment was well tolerated in 79% of patients. Site pain resistant to simple analgesics occurred in 12 patients (21%), but could be managed in 9/12 children. At 6 months, 3 patients had died, 4 had received a Potts shunt and 1 underwent lung transplantation. Among the 48 treated patients, 40 (83%) showed significant improvement in WHO functional class, 6 minute walk distance, NT-proBNP and pulmonary vascular resistance (p < 0.01 for all parameters). At last follow-up (median 37 months), ten patients had died, 2 underwent a lung transplantation and 8 underwent a Potts shunt. In 30 of the 36 remaining treated patients, improvement of clinical status was sustained. No children developed sepsis and 12 had minor site infections.

CONCLUSION

Subcutaneous treprostinil infusion is an effective therapy without serious side effects in children with PAH. Site pain can be managed with simple analgesics in most children.

Advanced therapies for the management of adults with pulmonary arterial hypertension due to congenital heart disease: a systematic review

Pulmonary arterial hypertension (PAH) secondary to congenital heart disease (CHD) is the third most common cause of PAH, and it is becoming increasingly common as improvements in the management of CHD have led to increased life expectancy for these patients. The medical management of PAH due to CHD (PAH-CHD) is largely the same as what has been used for the treatment of idiopathic PAH, though the body of literature supporting this management decision is very small. There are currently few studies available which specifically focus on the treatment of PAH-CHD. The purpose of this literature review is to compare the results of those studies that assessed the response to medical therapy among adults with PAH-CHD; studies were excluded if they focused on paediatric patients, did not include an assessment of 6 min walking distance or specifically assessed combination therapies. This review found that riociguat, bosentan, epoprostenol and sildenafil were all capable of improving functional capacity and haemodynamic parameters in patients with PAH-CHD, but whether this corresponds to an increase in mortality remains to be seen. Limitations of this review include the small sample size and variable duration of the included studies, which makes drawing direct comparisons between studies and the study drugs difficult. The lack of large, randomised double-blind clinical trials comparing different drugs head to head highlights an area that is ripe for ongoing medical research, the results of which may help shape future treatment algorithms tailored specifically for adults with PAH-CHD.

Effect of gemfibrozil and rifampicin on the pharmacokinetics of selexipag and its active metabolite in healthy subjects

AIMS

Based on in vitro data, there is evidence to suggest that cytochrome P450 (CYP) 2C8 is involved in the metabolism of selexipag and its active metabolite, ACT-333679. The present study evaluated the possible pharmacokinetic interactions of selexipag with gemfibrozil, a strong CYP2C8 inhibitor, and rifampicin, an inducer of CYP2C8.

METHODS

The study consisted of two independent parts, each conducted according to an open-label, randomized, crossover design. The pharmacokinetics and safety of selexipag and ACT-333679 were studied following single-dose administration either alone or in the presence of multiple-dose gemfibrozil (part I) or rifampicin (part II) in healthy male subjects.

RESULTS

Gemfibrozil had comparatively small effects on selexipag (less than 2-fold difference in any pharmacokinetic variable) but, with respect to ACT-333679, increased the maximum plasma concentration (C_max ) 3.6-fold [90% confidence interval (CI) 3.1, 4.3] and the area under the plasma concentration-time curve from zero to infinity (AUC_0-∞ ) 11.1-fold (90% CI 9.2, 13.4). The marked increased exposure to ACT-333679, which mediates the majority of the pharmacological activity of selexipag, was accompanied by significantly more adverse events such as headache, nausea and vomiting. Coadministration of rifampicin increased the C_max of selexipag 1.8-fold (90% CI 1.4, 2.2) and its AUC0_-∞ 1.3-fold (90% CI 1.1, 1.4); its effects on ACT-333679 were to increase its C_max 1.3-fold (90% CI 1.1, 1.6), shorten its half-life by 63% and reduce its AUC0_-∞ by half (90% CI 0.45, 0.59).

CONCLUSION

Concomitant administration of selexipag and strong inhibitors of CYP2C8 must be avoided, whereas when coadministered with inducers of CYP2C8, dose adjustments of selexipag should be envisaged.

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.

Chronic thromboembolic pulmonary arterial hypertension: a review of the literature and novel therapeutic approaches

Chronic thromboembolic pulmonary hypertension is defined as pulmonary hypertension (PH) caused by single or recurrent pulmonary emboli and is characterized by chronic obstruction of the pulmonary arteries leading to increased vascular resistance and PH. Also, progressive remodeling may occur in occluded and nonoccluded territories. Better understanding of the underlying mechanisms and risk factors could improve diagnosis and allow appropriate interventions. Pulmonary endarterectomy is an established approach and is considered the definitive treatment for chronic PH, resulting from thromboembolic disease. Furthermore, percutaneous transluminal pulmonary angioplasty is technically feasible, especially for those with peripheral-type of the disease. In addition, several agents, including prostanoids, endothelin receptor antagonists and phosphodiesterase type-5 inhibitors, have been tested in selected patients yielding promising results. Several novel agents are under investigation, and extensive research is currently in progress aiming to resolve uncertainties in the understanding and treatment of the disease.

The mechanistic basis of prostacyclin and its stable analogues in pulmonary arterial hypertension: Role of membrane versus nuclear receptors

Pulmonary arterial hypertension (PAH) is a progressive disease of distal pulmonary arteries in which patients suffer from elevated pulmonary arterial pressure, extensive vascular remodelling and right ventricular failure. To date prostacyclin (PGI2) therapy remains the most efficacious treatment for PAH and is the only approved monotherapy to have a positive impact on long-term survival. A key thing to note is that improvement exceeds that predicted from vasodilator testing strongly suggesting that additional mechanisms contribute to the therapeutic benefit of prostacyclins in PAH. Given these agents have potent antiproliferative, anti-inflammatory and endothelial regenerating properties suggests therapeutic benefit might result from a slowing, stabilization or even some reversal of vascular remodelling in vivo. This review discusses evidence that the pharmacology of each prostacyclin (IP) receptor agonist so far developed is distinct, with non-IP receptor targets clearly contributing to the therapeutic and side effect profile of PGI2 (EP3), iloprost (EP1), treprostinil (EP2, DP1) along with a family of nuclear receptors known as peroxisome proliferator-activated receptors (PPARs), to which PGI2 and some analogues directly bind. These targets are functionally expressed to varying degrees in arteries, veins, platelets, fibroblasts and inflammatory cells and are likely to be involved in the biological actions of prostacylins. Recently, a highly selective IP agonist, selexipag has been developed for PAH. This agent should prove useful in distinguishing IP from other prostanoid receptors or PPAR binding effects in human tissue. It remains to be determined whether selectivity for the IP receptor gives rise to a superior or inferior clinical benefit in PAH.

Capsaicin 8% patch for treprostinil subcutaneous infusion site pain in pulmonary hypertension patients

BACKGROUND

Treprostinil sodium improves haemodynamics and symptoms in pulmonary arterial hypertension (PAH) patients, but its subcutaneous (s.c.) administration can produce severe local site pain, and lead to discontinuation of vital treatment. Treprostinil is a prostacyclin analogue which stimulates prostacyclin receptors in skin nociceptor terminals, resulting in pain and cutaneous hypersensitivity, for which current pain remedies have limited effect. Capsaicin 8% patch relieves neuropathic pain for 3 months after a single 60 min cutaneous application; we investigated whether its pre-application can reduce s.c. trepostinil-induced pain.

METHODS

A single-centre, double-blind, randomized, placebo-controlled, crossover study was conducted to assess the safety and efficacy of a single capsaicin 8% patch pre-application for s.c. treprostinil pain in 11 PAH patients, relative to control patch with low-dose capsaicin 0.075% cream.

RESULTS

The primary efficacy endpoint, mean difference between the two treatment arms in an 11-point numerical pain rating scale from baseline to 2 weeks after patch applications, was significantly lower on the capsaicin 8% patch treatment arm [P=0.01, mean difference=-1.47 units, 95% credible interval (CI): -2. 59 to -0.38] in the patients who completed the study per protocol, although intention-to-treat analysis did not show significant difference (P=0.28). Heat pain thresholds were decreased (P=0.027, mean difference=5.43°C, 95% CI: 0.71-10.21) and laser Doppler flux increased (P=0.016, mean difference=370 units, 95% CI: 612 to 127.9) at the application site immediately after capsaicin 8% patch, confirming activity.

CONCLUSIONS

Further investigation of the efficacy of capsaicin 8% patch in this indication is warranted.

Successful management of an acute subdural hematoma in a patient dependent on continuous treprostinil infusion therapy

Treprostinil is a synthetic analog of prostacyclin, which is used for treatment of pulmonary arterial hypertension (PAH). Continuous subcutaneous administration of treprostinil has been proven in randomized controlled trials to improve quality of life, hemodynamics, and 5-year survival in patients with PAH. The efficacy of treprostinil has been attributed to its vasodilatory and antiplatelet effects. Unfortunately, the efficacy of treprostinil in the treatment of PAH is rapidly reversed upon cessation of the continuous infusion. Furthermore, cases of patients rapidly declining or succumbing to disease progression upon cessation of treprostinil have raised significant concern regarding discontinuation of this medication. To date, there are no reports of emergency craniotomies performed in the setting of continuous subcutaneous infusion of treprostinil. The authors report a case of a patient with PAH, treated with continuous administration of subcutaneous treprostinil as well as warfarin, who developed an acute subdural hematoma (SDH). Despite adequate INR (international normalized ratio) correction, the patient eventually underwent an emergency craniotomy for evacuation of the SDH while on continuous treprostinil administration. This case highlights the neurosurgical dilemma regarding the appropriate management of acute SDHs in patients receiving continuous treprostinil infusion.

Subcutaneous implantation of a new intravenous pump system for prostacyclin treatment in patients with pulmonary arterial hypertension

BACKGROUND

Intravenous prostacyclin treatment is a well recognized option in patients suffering from pulmonary arterial hypertension (PAH), and remains the gold standard of treatment. However, intravenous prostacyclin treatment involves several limitations, because the available battery-driven pump systems carry the risk of line infections, catheter-related embolisms, thrombosis, and delivery system malfunctions.

CASE REPORT

We report for the first time, to the best of our knowledge, on the safe transition procedure from subcutaneous to intravenous treprostinil in a 74-year-old woman suffering from severe PAH (New York Heart Association functional class III), using a new implantable, gas-driven, intravenous pump device (LenusPro, Tricumed/OMT, Frittlingen, Germany).

CONCLUSIONS

This implantable pump system may overcome the well-known limitations and risks of commonly used delivery systems, and thus may provide a new option for continuous intravenous prostacyclin treatment in patients with PAH.

Binding and activity of the prostacyclin receptor (IP) agonists, treprostinil and iloprost, at human prostanoid receptors: treprostinil is a potent DP1 and EP2 agonist

The prostacyclin analogues, iloprost and treprostinil are extensively used in treating pulmonary hypertension. Their binding profile and corresponding biochemical cellular responses on human prostanoid receptors expressed in cell lines, have now been compared. Iloprost had high binding affinity for EP1 and IP receptors (Ki 1.1 and 3.9 nM, respectively), low affinity for FP, EP3 or EP4 receptors, and very low affinity for EP2, DP1 or TP receptors. By contrast, treprostinil had high affinity for the DP1, EP2 and IP receptors (Ki 4.4, 3.6 and 32 nM, respectively), low affinity for EP1 and EP4 receptors and even lower affinity for EP3, FP and TP receptors. In functional assays, iloprost had similar high activity in elevating cyclic AMP levels in cells expressing the human IP receptor and stimulating calcium influx in cells expressing EP1 receptors (EC50 0.37 and 0.3 nM, respectively) with the rank order of activity on the other receptors comparable to the binding assays. As with binding studies, treprostinil elevated cyclic AMP with a similar high potency in cells expressing DP1, IP and EP2 receptors (EC50 0.6, 1.9 and 6.2 nM, respectively), but had low activity at the other receptors. Activation of IP, DP1 and EP2 receptors, as with treprostinil, can all result in vasodilatation of human pulmonary arteries. However, activation of EP1 receptors can provoke vasoconstriction, and hence may offset the IP-receptor mediated vasodilator effects of iloprost. Treprostinil may therefore differ from iloprost in its overall beneficial pulmonary vasorelaxant profile and other pharmacological actions, especially in diseases where the IP receptor is down-regulated.

Prostacyclins in pulmonary arterial hypertension: the need for earlier therapy

Pulmonary arterial hypertension (PAH) is a rare but serious condition, which if untreated, is associated with a 2-3-year median survival time. A number of treatment options are available for PAH, leading to improvements in exercise capacity, symptoms, and hemodynamics. However, the disease remains incurable and most patients will ultimately progress to right heart failure and death. Three classes of drugs are currently available to improve PAH outcomes, although this review will focus solely on a class of potent vasodilators known as prostacyclins. Currently, four prostacyclin analogs are licensed for the treatment of PAH: epoprostenol, treprostinil, and iloprost in the USA and some European countries, and beraprost in Japan and Korea. Prostacyclins have become the treatment of choice in patients with severe PAH, but there is also evidence to suggest that their earlier use may also benefit patients with mild-to-moderate disease. This review discusses the advantages of prostacyclins in terms of their usefulness in patients whose condition has deteriorated following monotherapy with other agents, and their integral role in combination therapy. The latter appears to offer the potential for pulmonary vasculature remodeling and could be regarded as an emerging paradigm to treat and prevent the progression of PAH.

Add-on therapy with subcutaneous treprostinil for refractory pediatric pulmonary hypertension

OBJECTIVE

To evaluate the efficacy and tolerability of subcutaneous (SC) treprostinil, a prostacyclin analogue, in young children with refractory pulmonary arterial hypertension.

STUDY DESIGN

Eight children (median age, 4 years) received SC treprostinil therapy after failure of combined oral treatment (n = 7) or because of severe complications with intravenous epoprostenol (n = 1). Treprostinil was delivered through an SC catheter at gradually increasing doses to an average of 40 ng/kg/min, depending on the presence of adverse effects.

RESULTS

Seven patients demonstrated early significant improvement (in functional class, hemodynamics, and/or 6-minute walk distance; P <.05), and 6 had a sustained good response. Site pain could be effectively managed in all but one child.

CONCLUSIONS

Treprostinil may be a potentially valuable rescue therapy in children with refractory pulmonary arterial hypertension, but further study in a larger number of patients is needed.

Inhaled treprostinil and pulmonary arterial hypertension

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

Subcutaneous treprostinil in pulmonary arterial hypertension: Practical considerations

Treprostinil, which is available for subcutaneous (SC) and intravenous (IV) administration, has demonstrated efficacy in increasing exercise capacity, reducing signs and symptoms of pulmonary arterial hypertension (PAH), and improving cardiopulmonary hemodynamics in patients with PAH; however, the infusion site pain commonly experienced with SC treprostinil has limited its use. Prospective and observational clinical studies have shown that the dose of SC treprostinil can be escalated at a higher rate than described in early clinical trials to achieve symptom relief, in part because of favorable tolerability of treatment and the apparent dose independence of site pain. In addition, pain management protocols that include non-pharmacologic and pharmacologic (i.e., topical and systemic) approaches provide analgesic relief from infusion site pain. With experience, physicians and patients have recognized that some infusion sites are better than others, and the frequency of site rotation can be reduced to improve tolerability. Dosing to achieve rapid onset of efficacy and proactively managing infusion site pain enhance the likelihood for a patient with PAH to maintain and derive benefit from SC treprostinil therapy.