ACUTE EFFECTS OF SILDENAFIL IN PATIENTS WITH PRIMARY PULMONARY HYPERTENSION RECEIVING EPOPROSTENOL

Combination Therapy for Pulmonary Arterial Hypertension: A Systematic Review and Meta-analysis

BACKGROUND

Combination therapy (CT) for patients with pulmonary arterial hypertension (PAH) has been recommended for many years, despite weak evidence of efficacy over monotherapy (MT). A previous meta-analysis comparing CT vs MT with pulmonary vasodilators failed to demonstrate a clear reduction in clinical worsening events.

METHODS

We searched for relevant articles in PubMed, EMBASE, the Cochrane Database, and clinicaltrials.gov; we also manually searched review articles and conference abstracts from 1980-December 2015. Target articles were double-blinded studies of 2 or more pulmonary vasodilators given in combination vs monotherapy for treatment of patients with PAH. The principal outcome of interest was "combined clinical worsening" (CCW) events (including but not limited to death or hospitalization). Data on physiological outcomes were also explored. Meta-analysis was performed using the DerSimonian and Laird random-effects model.

RESULTS

We extracted data from 18 randomized controlled trials (RCTs) (N = 4162). CT was associated with a significant 38% reduction of risk of CCW (15 RCTs: n = 3906; risk ratio [RR], 0.62; 95% confidence interval [CI], 0.50-0.77). This reduction in risk was driven by a reduction in nonfatal end points (12 RCTs: n = 2611; RR, 0.56; 95% CI, 0.40-0.78) and not by a reduction of mortality (12 RCTs: n = 2717; RR, 0.79; 95% CI, 0.53-1.17). CT was also associated with improvement in 6-minute walking distance (10 RCTs: n = 1553; weighted mean difference [WMD], +23.0 m; 95% CI, 15.9-30.1), improved functional class (9 RCTs: n = 1737; RR, 1.26; 95% CI, 1.05-1.51), and beneficial effects on pulmonary hemodynamics such as cardiac index (WMD, +0.35 L/min/m; 95% CI, 0.14-0.56).

CONCLUSIONS

In this highly comprehensive meta-analysis, CT reduces the risk of CCW events in patients with PAH and brings physiological improvement.

Survival with sildenafil and inhaled iloprost in a cohort with pulmonary hypertension: an observational study

Background

Combination therapy is frequently used to treat patients with pulmonary hypertension but few studies have compared treatment regimens. This study examined the long-term effect of different combination regimens of inhaled iloprost and oral sildenafil on survival and disease progression.

Methods

This was a retrospective study of patients in the Giessen Pulmonary Hypertension Registry who received iloprost monotherapy followed by addition of sildenafil (iloprost/sildenafil), sildenafil monotherapy followed by addition of iloprost (sildenafil/iloprost), or upfront combination therapy (iloprost + sildenafil). The primary outcome was transplant-free survival (Kaplan–Meier analysis). When available, haemodynamic parameters and 6-minute-walk distance were evaluated.

Results

Overall, 148 patients were included. Baseline characteristics were similar across treatment groups; however, the iloprost + sildenafil cohort had higher mean pulmonary vascular resistance and pulmonary arterial pressure than the others. Transplant-free survival differed significantly between groups (P = 0.007, log-rank test). Cumulative transplant-free survival was highest for patients who received iloprost/sildenafil (1 year survival: iloprost/sildenafil, 95.1 %; sildenafil/iloprost, 91.8 %; iloprost + sildenafil, 62.9 %); this group also remained on monotherapy significantly longer than the sildenafil/iloprost group (median 17.0 months vs 7.0 months, respectively; P = 0.004). Compared with pre-treatment values, mean 6-minute-walk distance increased significantly for all groups 3 months after beginning combination therapy.

Conclusions

In this observational study of patients with pulmonary hypertension receiving combination therapy with iloprost and sildenafil, cumulative transplant-free survival was highest in those who received iloprost monotherapy initially. However, owing to the size and retrospective design of this study, further research is needed before making firm treatment recommendations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0164-2) contains supplementary material, which is available to authorized users.

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.

Dual therapy in IPAH and SSc-PAH. A qualitative systematic review

BACKGROUND

Use of endothelin receptor antagonists (ERA), phosphodiesterase type-5 (PDE-5) inhibitors and prostaglandin analogues has resulted in improved outcomes in idiopathic pulmonary arterial hypertension (IPAH) and systemic sclerosis-associated PAH (SSc-PAH) patients. However, patients often deteriorate on monotherapy. The objective of this study is to evaluate the effect of dual therapy on outcomes in IPAH and SSc-PAH.

METHODS

A systematic review of MEDLINE (1950-2011), EMBASE (1980-2011) and CINAHL (inception-2011) was conducted to identify studies that evaluated the effect of any dual combination of ERA, PDE-5 inhibitors or prostaglandin analogues on 6-min walk distance (6MWD), functional class (FC), haemodynamics, quality-of-life (QoL) or time-to-clinical-worsening in IPAH or SSc-PAH. A standardized form was used to abstract design, sample size, aetiology, outcome and treatment effect.

RESULTS

Twenty-six observational studies and 6 randomized trials were identified. Using combination PDE-5 inhibitor and prostaglandin analogues, 6/7 studies reported improvement in 6MWD, 6/8 studies reported improvement in FC, 6/6 studies reported improvement in haemodynamics and 1 trial demonstrated improvement in QoL and time-to-clinical-worsening. Using combination ERA and prostaglandin analogues, 4/6 studies and 1 trial reported improvement in 6MWD, 3/3 studies and 1 trial reported improvement in FC, 4/5 studies and 1 trial reported improvement in PAP. Using combination ERA and PDE-5 inhibitor, 4/7 studies reported an improvement in 6MWD, and 2/6 report improvement in FC.

CONCLUSION

The evidence suggests a beneficial effect of dual therapy in IPAH and SSc-PAH, particularly those who are deteriorating on monotherapy. Research should focus on subsets of patients to identify the optimal timing and combination of dual therapy.

Long-term treatment with sildenafil citrate in pulmonary arterial hypertension: the SUPER-2 study

BACKGROUND

The long-term safety and tolerability of sildenafil treatment of pulmonary arterial hypertension (PAH) were assessed.

METHODS

Two hundred fifty-nine of 277 randomized and treated patients completed a 12-week, double-blind, placebo-controlled trial (SUPER-1 [Sildenafil Use in Pulmonary Arterial Hypertension]) of oral sildenafil in treatment-naive patients with PAH (96% functional class II/III) and entered an open-label uncontrolled extension study (SUPER-2) that continued until the last patient completed 3 years of sildenafil treatment. Patients titrated to sildenafil 80 mg tid; one dose reduction for tolerability was allowed during the titration phase.

RESULTS

The median duration of sildenafil treatment across SUPER-1 and SUPER-2 was 1,242 days (range, 1-1,523 days); 170 patients (61%) completed both studies, and 89 patients discontinued from SUPER-2. After 3 years, 87% of 183 patients on treatment were receiving sildenafil 80 mg tid. Of patients remaining under follow-up, 3%, 10%, and 18% were receiving a second approved PAH therapy at 1, 2, and 3 years, respectively. At 3 years post-SUPER-1 baseline, 127 patients had an increased 6-min walk distance (6MWD); 81 improved and 86 maintained functional class. Most adverse events were of mild or moderate severity. At 3 years, 53 patients had died (censored, n = 37). Three-year estimated survival rate was 79%; if all censored patients were assumed to have died, 3-year survival rate was 68%. No deaths were considered to be treatment related.

CONCLUSIONS

Long-term treatment of PAH initiated as sildenafil monotherapy was generally well tolerated. After 3 years, the majority of patients (60%) who entered the SUPER-1 trial improved or maintained their functional status, and 46% maintained or improved 6MWD.

Combination therapy and new types of agents for pulmonary arterial hypertension

This review assesses the available evidence supporting the use of drug combinations for the management of the various forms of pulmonary arterial hypertension (PAH). Ongoing and forthcoming randomized trials evaluating this strategy are also highlighted. Furthermore, new types of agents to treat PAH in the future are explored.

Sildenafil for pulmonary arterial hypertension: when blue turns into white

Pulmonary arterial hypertension is a life-threatening, rare disease characterised by vasoconstriction and vascular remodelling of pulmonary artery vessels. Pulmonary arterial hypertension can occur without an obvious cause or can be secondary. Until several years ago, therapeutic approaches were represented mainly by 'conventional therapy' (anticoagulants, calcium channel blockers, diuretics and digoxin, and oxygen therapy). But recently 'specific therapies' (i.e., therapies targeting specific pathogenic pathways) have become available; these are therapies represented by prostacyclin and its derivatives, endothelin receptor antagonists or phosphodiesterase-5 inhibitors. Sildenafil citrate is a phosphodiesterase-5 inhibitor and is the second oral pharmacological agent recently approved for the treatment of pulmonary arterial hypertension. Sildenafil has demonstrated short- and long-term clinical efficacy in the treatment of various forms of pulmonary arterial hypertension, either alone or in combination with other agents, but its safety profile needs further assessment.

First experience with an oral combination therapy using bosentan and sildenafil for pulmonary arterial hypertension

BACKGROUND

New oral substances such as beraprost, bosentan and sildenafil have proven effective in different forms of pulmonary arterial hypertension (PAH), both alone and in combination with standard treatment such as intravenous and inhaled prostacyclins. However, there are few reports so far on the effect of a combination of exclusively oral substances. In this paper, we present our initial findings of treatment using a combination of these oral substances in a heterogeneous group of patients with different forms of PAH.

MATERIALS AND METHODS

Eleven patients with a median age of 12.9 years (5.5-54.7 years) with both idiopathic PAH and forms associated with congenital cardiac defects (PAH-CHD) with a mean pulmonary arterial pressure > 25 mmHg were enrolled in an observational, open-label, prospective, single-centre study. Either combination treatment with bosentan and sildenafil was started initially, or an existing bosentan treatment was complemented with sildenafil given as an add-on therapy. Mean doses given were 2.3 +/- 0.6 mg kg(-1) for bosentan and 2.1 +/- 0.9 mg kg(-1) for sildenafil. Clinical status, exercise capacity, and haemodynamics were assessed at baseline and at the end of the observation period after a mean follow-up time of 1.1 years (0.5-2.5 years).

RESULTS

No major side effects regarding liver function and blood pressure regulation were noted. One patient died of sudden death elsewhere. Most patients were in New York Heart Association (NYHA) functional class III. Clinical improvement was about one NYHA class (mean 2.8 +/- 0.4-1.6 +/- 0.8, P = 0.001), which was associated with an increase of transcutaneous oxygen saturation (89.9 +/- 9.9-92.3 +/- 7.1%; P = 0.037), maximum oxygen uptake (18.1 +/- 6.8-22.8 +/- 10.4 mL kg(-1) x min; P = 0.043), and 6-minute walking distance (351 +/- 58-451 +/- 119 m; P = 0.039). Mean pulmonary arterial pressure measured invasively decreased (62 +/- 12-46 +/- 18 mmHg; P = 0.041).

CONCLUSIONS

In our patient group, a combination of oral bosentan and sildenafil proved to be safe and effective. Clearly, randomized, double-blind, placebo-controlled studies are warranted to define the role and type of combination therapies in PAH.

Sildenafil for pulmonary hypertension

OBJECTIVE

To evaluate the efficacy of sildenafil for treatment of pulmonary hypertension.

DATA SOURCES

Literature retrieval was accessed through MEDLINE (1977-March 2005), Cochrane Library, and International Pharmaceutical Abstracts (1977-March 2005) using the terms sildenafil and pulmonary hypertension. In addition, reference citations from publications identified were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All articles in English identified from the data sources were evaluated. Studies including >5 patients with primarily adult populations were included in the review.

DATA SYNTHESIS

The treatment of pulmonary hypertension is challenging. Sildenafil has recently been studied as monotherapy and in combination with other vasodilators in the management of pulmonary hypertension. Eight hemodynamic studies and 12 clinical trials were reviewed (1 retrospective, 3 double-blind, 8 open-label). Sildenafil reduced pulmonary arterial hypertension and pulmonary vascular resistance/peripheral vascular resistance index and tended to increase cardiac output/cardiac index compared with baseline. Sildenafil was comparable to nitric oxide and at least as effective as iloprost or epoprostenol in terms of its pulmonary vasoreactivity. Combination therapy with iloprost, nitric oxide, or epoprostenol resulted in enhanced and prolonged pulmonary vascular effects. Clinical trials suggest that sildenafil improves exercise tolerance and New York Heart Association functional class, but large, randomized controlled trials are needed to confirm these findings. Overall, sildenafil was well tolerated.

CONCLUSIONS

Overall, sildenafil is a promising and well-tolerated agent for management of pulmonary hypertension. Further well-designed trials are warranted to establish its place in the treatment of pulmonary hypertension.