Outcome of pulmonary hypertension subjects transitioned from intravenous prostacyclin to oral bosentan

Transition from parenteral prostacyclins to selexipag: safety and feasibility in selected patients

There are limited data regarding the feasibility of transitioning from intravenous prostacyclins to selexipag in pulmonary arterial hypertension patients. We present a case series of successful transitions from intravenous prostacyclins to selexipag in the majority of carefully selected five stable pulmonary arterial hypertension patients using a standardized protocol in the outpatient setting.

EXPRESS: Switching to riociguat: A potential treatment strategy for the management of CTEPH and PAH

Currently, five classes of drug are approved for the treatment of pulmonary arterial hypertension (PAH): phosphodiesterase 5 inhibitors (PDE5i); endothelin receptor antagonists; prostacyclin analogs; the IP receptor agonist selexipag; and the soluble guanylate cyclase (sGC) stimulator riociguat. For patients with inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH), riociguat is currently the only approved pharmacotherapy. Despite the development of evidence-based guidelines on appropriate use of specific drugs, in clinical practice patients are often prescribed PAH-targeted therapies off label or at inadequate doses.

PDE5i are the most often prescribed class of drugs as initial therapy, either alone or in combination with other drug classes. However, a proportion of patients receiving PAH therapies do not reach or maintain treatment goals. As PDE5i and riociguat target different molecules in the nitric oxide-sGC-cyclic guanosine monophosphate (NO-sGC-cGMP) signaling pathway, for patients with PAH without an initial or sustained response to PDE5i, there is a biological rationale for switching to riociguat. However, robust data from randomized controlled trials on the safety and efficacy of switching are lacking, as is formal guidance for clinicians. Here we review studies of sequential combination therapy, and trial data and case studies that have investigated switching between PAH-approved therapies, particularly from PDE5i to riociguat in patients with PAH with an insufficient response to PDE5i, and in patients with CTEPH who were receiving off-label treatment. These studies summarize the current evidence and practical real-life experience on the concept of switching treatments.

Right ventricular afterload predicts long-term transition from parenteral to oral treprostinil in pulmonary arterial hypertension

Despite the increasing trends, reports on long-term follow-up are limited on transitioning from parenteral to oral treprostinil therapy in patients with pulmonary arterial hypertension (PAH). We investigated both the effectiveness of parenteral to oral treprostinil transition and the characteristics associated with transition failure over a duration of two years. The study included 37 Group I functional class I and II patients with PAH on combination therapy. Patients were excluded if cardiac index ≤2.2 L/min/m², right atrial pressure ≥11 mmHg, or 6-min walk distance ≤250 m. Patients were categorized as successful (_STransition) or unsuccessful (_UTransition) transition based on clinical stability, or a parenteral comparator (_CParenteral) if they remained on parenteral therapy (no transition). All patients underwent two right heart catheterizations, one at enrollment and a second post transition. Of 24 total transition patients, 46% were classified as _UTransition. _UTransition occurred on average 577 days post transition. Both _UTransition and _STransition had similar hemodynamics at diagnosis and treprostinil dose before and after transition. Before transition, the pulmonary vascular resistance (PVR) was significantly higher in the _UTransition (6.7 ± 2 WU) vs. _STransition group (3.5 ± 1.5 WU). At follow-up catheterization, the _UTransition group demonstrated further increases in PVR, greater than the _CParenteral group, without recovery despite “rescue” therapy in the _UTransition group. A pre-transition PVR of 4.16 WU discriminated the _UTransition from the _STransition group. While a subset of PAH patients on combination therapy may be safely transitioned from parenteral to oral treprostinil, caution should be exercised in patients with elevated baseline PVR to avoid irreversible destabilization.

A systematic review of transition studies of pulmonary arterial hypertension specific medications

Pulmonary arterial hypertension (PAH) is a progressive potentially fatal disease. Multiple pharmacologic options are now available, which facilitated transitions between different therapeutic options, although the evidence for such transitions has not been well described. We sought to review the evidence supporting the safety and/or efficacy of transitioning between PAH-specific medications. We performed a systematic review of all published studies in the Medline database between 1 January 2000 and 30 June 2016 reporting on any transition between the currently Food and Drug Administration (FDA)-approved PAH-specific medications. Studies reporting on three or more adult patients published in the English language reporting on transitions between FDA-approved PAH medications were extracted and tabulated. Forty-one studies met the selection criteria, nine of which included less than eight patients (and thus were reported separately in the supplement), for a total of 32 studies. Transitioning from parenteral epoprostenol to parenteral treprostinil appears to be safe and efficacious in patients who have less severe disease and more favorable hemodynamics. Transitioning from a prostacyclin analogue to an oral medication may be successful in patients who have favorable hemodynamics and stable disease. There is conflicting evidence supporting the transition from a parenteral to an inhaled prostacyclin analogue, even in patients who are on background oral therapy. Currently, the only evidence in support of transitioning between oral PDE5 inhibitors is from sildenafil to tadalafil. Patients on higher doses of sildenafil are more likely to fail. In patients with liver abnormalities due to bosentan or sitaxentan, the transition to ambrisentan appears to be safe and can result in clinical improvement. Studies regarding PAH medication transitions are limited. Patients who have less severe disease, better functional status, and are on lower medications doses may be more successful at transitioning.

Transition from prostacyclin analogue infusion to oral therapy in patients with pulmonary arterial hypertension: a 5-year follow-up

Transition from prostacyclin analogue infusion to oral therapy in patients with pulmonary arterial hypertension (PAH) is possible with acceptable short- and midterm results. However, there is a paucity of data on long-term outcomes after successful transition. Using a predefined protocol, transition to oral therapy was attempted in 22 patients with clinically stable PAH. Clinical and hemodynamic data were retrospectively collected at baseline as well as during and after transition. Parameters for successful versus nonsuccessful transition were also evaluated. All patients had severe PAH at baseline and showed clinical and hemodynamic improvement with prostacyclin analogue infusion. Initial oral agents used for transition were bosentan (63.6%), sildenafil (31.8%), and tadalafil (4.5%). Combination therapy was used in 68% of the patients. Successful transition was achieved in 11 patients (50%) with a mean transition duration of 16 months. After successful transition, clinical and hemodynamic parameters remained stable at midterm (mean, 18 months) and long-term (mean, 60 months) follow-up. Compared with the successful transition group, patients who experienced failure were older, had a higher frequency of idiopathic PAH, and had worse hemodynamic parameters during treatment with prostacyclin analogue alone, as well as during the transition period. In conclusion, successful transition from prostacyclin analogue infusion to oral therapy can be achieved in a significant proportion of patients with clinically stable PAH. After an initial successful transition, patients were able to maintain clinical and hemodynamic stability at the mid- and long-term follow-up.

Withdrawal of epoprostenol therapy in a patient with pulmonary hypertension associated with Sjögren's syndrome

Pulmonary arterial hypertension (PAH) is a rare complication, but a significant prognostic factor in patients with Sjögren's syndrome (SjS). Despite its efficacy, the long-term use of intravenous epoprostenol is sometimes complicated by adverse effects, such as catheter-related infection. This case involves a 38-year-old woman with PAH associated with SjS (PAH-SjS) who was transitioned from treatment with long-term intravenous epoprostenol therapy to combination oral therapy containing bosentan and tadalafil. She has remained in stable condition for more than two years following epoprostenol discontinuation. The details of this report suggest that long-term epoprostenol therapy can be safely tapered off and replaced with combination oral therapy in carefully selected patients with PAH-SjS.

Combination therapy in pulmonary arterial hypertension

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

Regulation of rat intrapulmonary arterial tone by arachidonic acid and prostaglandin E2 during hypoxia

AIMS

Arachidonic acid (AA) and its metabolites, prostaglandins (PG) are known to be involved in regulation of vascular homeostasis including vascular tone and vessel wall tension, but their potential role in Hypoxic pulmonary vasoconstriction (HPV) remains unclear. In this study, we examined the effects of AA and PGE2 on the hypoxic response in isolated rat intrapulmonary arteries (IPAs).

METHODS AND RESULTS

We carried out the investigation on IPAs by vessel tension measurement. Isotetrandrine (20 µM) significantly inhibited phase I, phase IIb and phase IIc of hypoxic vasoconstriction. Both indomethacin (100 µM) and NS398 attenuated KPSS-induced vessel contraction and phase I, phase IIb and phase IIc of HPV, implying that COX-2 plays a primary role in the hypoxic response of rat IPAs. PGE2 alone caused a significant vasoconstriction in isolated rat IPAs. This constriction is mediated by EP4. Blockage of EP4 by L-161982 (1 µM) significantly inhibited phase I, phase IIb and phase IIc of hypoxic vasoconstriction. However, AH6809 (3 µM), an antagonist of EP1, EP2, EP3 and DP1 receptors, exerted no effect on KPSS or hypoxia induced vessel contraction. Increase of cellular cAMP by forskolin could significantly reduce KPSS-induced vessel contraction and abolish phase I, phase II b and phase II c of HPV.

CONCLUSION

Our results demonstrated a vasoconstrictive effect of PGE2 on rat IPAs and this effect is via activation of EP4. Furthermore, our results suggest that intracellular cAMP plays dual roles in regulation of vascular tone, depending on the spatial distribution of cAMP and its coupling with EP receptor and Ca(2+) channels.

Hemodynamic stability after transitioning between endothelin receptor antagonists in patients with pulmonary arterial hypertension

BACKGROUND

Maintenance of a favourable hemodynamic profile is central to therapeutic success in pulmonary arterial hypertension (PAH). There is little information about the safety of transitioning patients between oral therapies for PAH. Endothelin receptor antagonists (ERAs) have been a therapeutic mainstay in PAH, providing benefit to many patients. Three ERAs, bosentan, sitaxsentan, and ambrisentan have been approved for clinical use. Sitaxsentan was voluntarily withdrawn from the market in late 2010 resulting in the need to quickly transition a large number of stable patients.

METHODS

We transitioned 30 clinically stable patients to either ambrisentan or bosentan. Patients underwent a right heart catheterization, measurement of serum N-terminal pro-brain natriuretic peptide (NT-proBNP), and assessment of functional class before changing ERA and again 4 months later. We present a retrospective analysis of those data.

RESULTS

Of the 30 patients transitioned (15 to ambrisentan, 15 to bosentan), 23 had complete hemodynamic data. No significant change was observed in the groups in right atrial, mean pulmonary artery, and pulmonary artery wedge pressures, or in cardiac output, pulmonary vascular resistance, or NT-proBNP levels. There was no change in World Health Organization functional class. Four ambrisentan and 2 bosentan-treated patients reported fluid retention, and 3 bosentan-treated patients had elevation of hepatic transaminases. Two of the patients had a right atrial pressure increase of ≥5 mm Hg, and 4 had pulmonary artery wedge pressure increase of ≥5 mm Hg.

CONCLUSIONS

Transitioning between ERAs in stable PAH patients does not result in hemodynamic or clinical deterioration during the first 4 months posttransition. A minority of patients have developed increased cardiac filling pressures.

Transition from intravenous epoprostenol to oral or subcutaneous therapy in pulmonary arterial hypertension: a retrospective case series and systematic review

BACKGROUND

Intravenous epoprostenol, a prostaglandin analogue, has been a mainstay of therapy for patients with advanced pulmonary arterial hypertension (PAH) since the early 1990s. This medication has multiple side effects, and sudden discontinuation is potentially associated with severe sequelae. Several recent case series have described the transition from intravenous to newer oral or subcutaneous therapies. A case series detailing the authors' experience with such transitions, and a systematic lierature review is presented.

METHODS

All consecutive PAH patients seen at the Vancouver Pulmonary Hypertension Clinic (Vancouver, British Columbia) between June 1995 and July 2009 were reviewed for cases in which weaning or transition from intravenous epoprostenol was attempted. The Cochrane Collaboration, Cochrane Register of Controlled Trials, Journals@Ovid, MEDLINE, EMBASE and Papers First were searched using predefined key words for publications describing transition of PAH patients from parenteral prostanoids to oral or subcutaneous agents.

RESULTS

Of the six patients who attempted, all transitioned successfully to oral or subcutaneous agents, having been on intravenous epoprostenol for a mean of 3.8 years (range 1.8 to 9.75 years). Five are living, surviving a mean of 5.5 years after transition. The literature search yielded nine studies and, of 127 patients described, 82 transitioned successfully. The length of pretransition prostanoid treatment (range 1.7 to 7.6 years) and the posttransition follow-up period (range two months to 70 months) were shorter than for patients described in the present study.

CONCLUSIONS

Given the rarity of PAH, the absolute numbers of patients transitioned from intravenous epoprostenol are still low. With the advent of new therapies, these numbers will hopefully increase; continued study is necessary to identify factors that are predictive of success.

Effect of transition from sitaxsentan to ambrisentan in pulmonary arterial hypertension

Introduction:

Currently available endothelin receptor antagonists for treating pulmonary arterial hypertension block either the endothelin (ET) receptor A or both A and B receptors. Transition from one endothelin receptor antagonist to another may theoretically alter side-effects or efficacy. We report our experience of a transition from sitaxsentan to ambrisentan, both predominant ET_A receptor antagonists, in pulmonary arterial hypertension patients.

Methods:

At Baylor Pulmonary Hypertension Center, 18 patients enrolled in the open-label extension phase of the original sitaxsentan studies (Sitaxsentan To Relieve ImpaireD Exercise) were transitioned to ambrisentan (from July 2007 to September 2007) at the time of study closure. Pre-transition (PreT), 1 month (1Mth) and 1 year (1Yr) post-transition assessments of 6-minute walk distance (6MWD), brain naturetic peptide (BNP) levels, WHO functional class (WHO FC), Borg dyspnea score (BDS), oxygen saturation, liver function, and peripheral edema were compared.

Results:

6MWD was 356 ± 126 m at PreT, 361 ± 125 m at 1Mth, and 394 ± 114 m at 1Yr (mean ± SD). There was no difference in the walk distance at 1Mth and 1Yr post transition compared with PreT (P = 0.92, 0.41 respectively). Oxygen saturation was no different at 1Mth and 1Yr to PreT level (P = 0.49 and P = 0.06 respectively). BNP was 178 ± 44 pg/mL at PreT, 129 ± 144 pg/mL at 1Mth and 157 ± 201 at 1Yr. Peripheral edema was present in 7/18 patients at PreT, in 8/16 patients at 1Mth, and in 6/13 patients at 1Yr post transition. Proportions of patients with edema over these 3 time points did not change significantly (P = 0.803). At 1Yr, 2 patients had died, 1 had undergone lung transplantation, 1 had relocated, and 1 patient was started on intravenous prostacyclin therapy. Over 3 points (baseline, 1 month, and 1 year), there was no significant change in function class (P = 0.672).

Conclusion:

Our limited data suggest that ET_A receptor antagonists can be switched from one to another with sustained exercise capacity and maintained WHO FC with no increase in incidence of peripheral edema.