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Background: Data on the effect of initial combination therapy with ambrisentan and tadalafil on long-term outcomes in patients with pulmonary arterial hypertension are scarce., Methods: In this event-driven, double-blind study, we randomly assigned, in a 2:1:1 ratio, participants with World Health Organization functional class II or III symptoms of pulmonary arterial hypertension who had not previously received treatment to receive initial combination therapy with 10 mg of ambrisentan plus 40 mg of tadalafil (combination-therapy group), 10 mg of ambrisentan plus placebo (ambrisentan-monotherapy group), or 40 mg of tadalafil plus placebo (tadalafil-monotherapy group), all administered once daily. The primary end point in a time-to-event analysis was the first event of clinical failure, which was defined as the first occurrence of a composite of death, hospitalization for worsening pulmonary arterial hypertension, disease progression, or unsatisfactory long-term clinical response., Results: The primary analysis included 500 participants; 253 were assigned to the combination-therapy group, 126 to the ambrisentan-monotherapy group, and 121 to the tadalafil-monotherapy group. A primary end-point event occurred in 18%, 34%, and 28% of the participants in these groups, respectively, and in 31% of the pooled-monotherapy group (the two monotherapy groups combined). The hazard ratio for the primary end point in the combination-therapy group versus the pooled-monotherapy group was 0.50 (95% confidence interval [CI], 0.35 to 0.72; P<0.001). At week 24, the combination-therapy group had greater reductions from baseline in N-terminal pro-brain natriuretic peptide levels than did the pooled-monotherapy group (mean change, -67.2% vs. -50.4%; P<0.001), as well as a higher percentage of patients with a satisfactory clinical response (39% vs. 29%; odds ratio, 1.56 [95% CI, 1.05 to 2.32]; P=0.03) and a greater improvement in the 6-minute walk distance (median change from baseline, 48.98 m vs. 23.80 m; P<0.001). The adverse events that occurred more frequently in the combination-therapy group than in either monotherapy group included peripheral edema, headache, nasal congestion, and anemia., Conclusions: Among participants with pulmonary arterial hypertension who had not received previous treatment, initial combination therapy with ambrisentan and tadalafil resulted in a significantly lower risk of clinical-failure events than the risk with ambrisentan or tadalafil monotherapy. (Funded by Gilead Sciences and GlaxoSmithKline; AMBITION ClinicalTrials.gov number, NCT01178073.).

Introduction: Two phosphodiesterase-type 5 (PDE-5) inhibitors, sildenafil and tadalafil, are approved for treatment of pulmonary arterial hypertension (PAH). It has not yet been observed if transition from sildenafil to tadalafil is beneficial in patients suffering from adverse reactions. Aim of this study was to analyze safety and long-term effects in PAH patients whose treatment was transitioned from sildenafil to tadalafil due to intolerable side-effects., Methods: A retrospective analysis of PAH-patients who were stable on sildenafil for >3 months and transitioned to tadalafil due to adverse events was performed. Data collected included demographics, PAH-etiology, WHO-functional class, 6 min walking distance (6MWD), echocardiography, lung function tests, and NTproBNP pre-transition and 3, 6, and 12 months post-transition., Results: Included were 13 PAH patients (8 females mean age 64 ± 10 years) who had been on sildenafil for a mean of 12 ± 8.4 months. In six patients (46.1 %) a switch to tadalafil was feasible and resulted in tolerable side effects and a stable clinical course with improvement of symptoms, 6MWD, stable echocardiographic findings, and NTproBNP-levels during a follow-up of 11 ± 3 months. In 5 out of 13 patients (38.5 %) adverse events occurred under tadalafil as well and therapy with PDE-5 inhibitors was discontinued. In two patients (15.4 %) sildenafil-treatment could be successfully restarted after an intermittent switch to tadalafil., Conclusions: The observations of this study indicate that a transition of sildenafil to tadalafil in case of intolerable side effects is a reasonable therapy option in about 50 % of the patients. These results should be verified by a larger prospective study.

Phosphodiesterase type 5 (PDE5) inhibitors are used for treating pulmonary arterial hypertension (PAH) in dogs. The long-acting PDE5 inhibitor tadalafil was recently approved for treatment of PAH in humans. Basic information related to the pharmacological and hemodynamic effects of tadalafil in dogs is scarce. In this study, the hemodynamic effects of tadalafil after intravenous (IV) and oral administration were investigated in a healthy vasoconstrictive PAH Beagle dog model induced by U46619, a thromboxane A2 mimetic. Six healthy Beagle dogs were anesthetized with propofol and maintained with isoflurane. Fluid-filled catheters were placed into the descending aorta to measure systemic arterial pressure and in the pulmonary artery to measure pulmonary arterial pressure (PAP). U46619 was infused via the cephalic vein to induce PAH. IV infusion of U46619 significantly elevated PAP from baseline in a dose-dependent manner. U46619-elevated PAP and pulmonary vascular resistance was significantly attenuated by the simultaneous infusion of tadalafil at 100 and 200 µg/kg/h. Likewise, oral administration of tadalafil at 1.0, 2.0, and 4.0 mg/kg significantly attenuated U46619-elevated PAP in a dose-dependent manner. U46619-elevated systolic and mean PAP decreased significantly 1 h after oral tadalafil administration at 4.0 mg/kg, and this effect was maintained for 6 h. In conclusion, tadalafil had a pharmacological effect in dogs and IV infusion of tadalafil induced pulmonary arterial relaxation, while oral administration of tadalafil decreased PAP. These results suggest that tadalafil may offer a new therapeutic option for treating dogs with PAH., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Purpose: Among phosphodiesterase type 5 inhibitors, tadalafil offers clinicians a once-daily alternative to 3 times daily sildenafil for the treatment of pulmonary arterial hypertension (PAH). This study assessed the safety and patient satisfaction with conversion from sildenafil to tadalafil., Methods: In this multicenter, prospective, 6-month study, patients with PAH were instructed to take their last dose of sildenafil in the evening and initiate tadalafil 40 mg/d the next morning. Patients completed the Treatment Satisfaction Questionnaire for Medication at baseline and 30, 90, and 180 days after transition to assess PAH symptoms and patient satisfaction. Safety was assessed on the basis of recorded adverse events (AEs)., Results: Of the 35 patients who met the study criteria, 56% were receiving ≥2 PAH therapies. At the time of transition, the sildenafil dose ranged from 40 to 300 mg/d, with 20% of the patients on >20 mg of sildenafil 3 times daily. Transition to tadalafil was generally well tolerated, and the incidence of common AEs, except for myalgia, appeared to decrease over time on tadalafil therapy. Five (14%) patients switched back to sildenafil. A greater percentage of patients were satisfied than were dissatisfied after conversion to tadalafil (55% vs 19% at 90 days), while 26% felt about the same degree of satisfaction. Conversion to tadalafil resulted in significant improvement in patient ratings of therapy convenience., Conclusions: Transition of patients from sildenafil to tadalafil was usually well tolerated, with improved convenience and may enhance treatment satisfaction., (© The Author(s) 2014.)

Background: There is no report documenting the plasma concentrations of tadalafil in children. This study was performed to evaluate the variability in the pharmacokinetics of tadalafil in children with pulmonary arterial hypertension (PAH) treated routinely with the drug., Methods: Plasma samples were taken twice (post- and predose) after repetitive oral administration, and the pharmacokinetic parameters (CL/F and V/F) in individual patients were estimated by the Bayesian method using the nonlinear mixed effects model. We also determined the unbound concentration of tadalafil using ultrafiltration., Results: Tadalafil was administered to 23 children aged between 0.25 and 17.4 years, with a mean age of 3.58 years. The mean (±SD) daily dose of tadalafil was 0.97 ± 0.41 mg/kg. Sixteen of the 23 children received bosentan concomitantly. The mean CL/F and V/F values of tadalafil were 0.149 L·h-1·kg-1 and 1.87 L/kg, respectively, which were higher than those reported in adults. No effects of age, bosentan, or the estimated glomerular filtration rate were observed on the CL/F value, indicating that other residual factors might account for the interindividual variability among children with PAH. The unbound tadalafil concentrations of the postdose samples ranged from 5.9 to 146 (46.9 ± 37.1) nmol/L, higher than the reported IC50 value of this phosphodiesterase-5 drug for humans (2-4 nmol/L, corresponding to 0.8-1.6 ng/mL)., Conclusions: We demonstrated variability in the total and unbound plasma concentrations of tadalafil in children. However, all children received the empirical doses of the drug; a mean dose of 0.97 mg·kg-1·d-1 showed sufficient unbound concentrations needed for half-maximal inhibition of human phosphodiesterase-5 in vitro. These observations may provide information for the proper use of tadalafil to treat children with PAH.

Pulmonary hypertension (PH) is a chronic disease characterized by a progressive increase in vasomotor tone, narrowing of the vasculature with structural remodeling, and increase in pulmonary vascular resistance. Current treatment strategies include nitric oxide therapy and methods to increase cGMP-mediated vasodilatation. cGMP-dependent protein kinases (PKG) are known mediators of nitric oxide- and cGMP-induced vasodilatation. Deletion of PKG-1 in mice has been shown to induce PH, however, the exact mechanisms by which loss of PKG-1 function leads to PH is not known. In a mouse model with a selective mutation in the NH2-terminus leucine zipper protein interaction domain of PKG-1α [leucine zipper mutant (LZM)], we found a progressive increase in right ventricular systolic pressure and right heart hypertrophy compared with wild-type (WT) mice and increased RhoA-GTPase activity in the lungs. When exposed to chronic hypoxia, LZM mice developed modestly enhanced right ventricular remodeling compared with WT mice. Tadalafil, a phosphodiesterase-5 inhibitor that increases cGMP levels, significantly attenuated hypoxia-induced cardiopulmonary remodeling in WT mice but had no effect in LZM mice. We conclude that a functional leucine zipper domain in PKG-1α is essential for maintenance of a low pulmonary vascular tone in normoxia and for cGMP-mediated beneficial effects of phosphodiesterase-5 inhibition in hypoxic cardiopulmonary remodeling., (Copyright © 2014 the American Physiological Society.)

Background and Objective: Interstitial lung diseases (ILD) are often associated with pulmonary hypertension (PH). This study aimed to evaluate the therapeutic benefit of phosphodiesterase-5 (PDE-5) inhibitors in pulmonary hypertension secondary to ILD., Methods: Patients with ILD and PH were treated with sildenafil or tadalafil. Right heart catheterization was performed before and after a minimum of 3-month treatment. In addition, lung function, 6-min walk distance (6MWD) and plasma brain natriuretic peptide (BNP) concentration were assessed., Results: Ten ILD patients (three female, mean age 64.4 ± 9.0 years, six with idiopathic pulmonary fibrosis (IPF), four with hypersensitivity pneumonitis, (HP)) with significant precapillary PH (mean pulmonary artery pressure (PAPm) ≥ 25 mmHg, pulmonary vascular resistance (PVR) > 280 dyn*s*cm(-5) ; pulmonary artery wedge pressure (PAWPm) ≤ 15 mmHg) were treated with either sildenafil (n = 5) or tadalafil (n = 5). Pulmonary haemodynamics were severely impaired at baseline (PAPm 42.9 ± 5.4 mmHg; cardiac index (CI) 2.7 ± 0.6 L/min/m2; PVR 519 ± 131 dyn × sec × cm(-5)). After mean follow-up of 6.9 ± 5.8 months an increase in CI (2.9 ± 0.7 L/min/m2 , P = 0.04) and a decrease in PVR (403 ± 190 dyn × sec × cm(-5) , P = 0.03) were observed. 6MWD and BNP did not change significantly., Conclusions: Our data suggest that treatment with PDE-5 inhibitors improves pulmonary haemodynamic patients with PH secondary to ILD., (© 2014 Asian Pacific Society of Respirology.)

Objective: To evaluate the therapy efficacy of iloprost combined with low dose tadalafil in adult congenital heart disease (CHD) patients with severe pulmonary arterial hypertension (PAH)., Methods: Adult CHD patients with severe PAH were included and divided into the sequential combination therapy group [iloprost: 10 µg/inhalation, 6 times per day for 6 months, and then add oral tadalafil (5 mg/d) till 12 months, n = 32] and upfront combination therapy group [iloprost: 10 µg/inhalation, 6 times per day combined with oral tadalafil (5 mg) for 12 months, n = 36]. Data on 6 min walking test (6MWT), Borg dyspnea score, oxygen saturation measurement, WHO classification, and cardiac catheterization were obtained at baseline, 6 and 12 months., Results: Seventy-two patients were enrolled in the study and 68 patients completed the study. Pulmonary vascular resistance (PVR) was significantly reduced in the sequential combination therapy group[ (12.96 ± 6.48 ) Wood U vs. (16.94 ± 8.11) Wood U, P < 0.05] and in the upfront combination therapy group [(12.45 ± 7.32) Wood U vs. (16.73 ± 9.28) Wood U, P < 0.05] while pulmonary blood flow [(6.77 ± 3.17) L/min vs. (5.08 ± 2.36) L/min, P < 0.05; (6.95 ± 3.32) L/min vs. (5.03 ± 2.32) L/min, P < 0.05], the 6 MWD were significantly increased [(458 ± 59) m vs. (427 ± 65) m, P < 0.05; (494 ± 59) m vs. (436 ± 62) m, P < 0.01], the Borg dyspnea score (2.04 ± 0.72 vs. 2.52 ± 0.79, P < 0.05; 1.72 ± 0.73 vs. 2.51 ± 0.77, P < 0.01) was significantly improved in both groups at 6 months compared to baseline levels. In the upfront combination therapy group, venous oxygen saturation [(68.4 ± 9.3)% vs. (62.9 ± 9.5)%, P < 0.05] and systemic oxygen saturation during exercise[ (87.2 ± 9.7)% vs. (83.1 ± 15.6)%, P < 0.05]at 6 months were also significantly improved compared to baseline. At month 12, significantly lowered pulmonary artery pressure, PVR, Rp/Rs and increased pulmonary blood flow and cardiac index were evidenced in both groups compared to baseline., Conclusion: Iloprost combined with low dose tadalafil regimen can effectively reduce PVR, increase 6MWD, and improve cardiopulmonary function in adults CHD patients with severe PAH. Compared with the sequential therapy regimen, the upfront combination therapy regimen can more rapidly improve the clinical symptoms of patients.

This prospective, double-blinded, randomized controlled study aimed to investigate the efficacy and safety of oral tadalafil in patients receiving background ambrisentan therapy. Current treatments for pulmonary arterial hypertension (PAH) remain insufficient, resulting in high mortality rates. The addition of oral tadalafil, a phosphodiesterase-5 inhibitor, to background ambrisentan may provide a safe and effective therapeutic strategy. A total of 124 patients who had been treated with ambrisentan for at least 4 months and had a stable 6-min walking distance (6MWD) and World Health Organization (WHO) functional class (FC) for at least 1 month were randomized to either the oral tadalafil or placebo group. Treatment differences in 6MWD, changes in FC, clinical worsening (CW) and adverse events were analyzed after 16 weeks of treatment. At week 16, the tadalafil group showed a significantly improved exercise capacity as assessed by the 6MWD (P<0.05). In addition, 5 (8.3%) patients receiving tadalafil add-on therapy had CW vs. 15 (23.4%) with placebo (P<0.05). No significant differences were found in adverse events or changes in hemodynamic parameters between the placebo and tadalafil groups. Tadalafil 40 mg was well-tolerated as add-on therapy to background ambrisentan. However, the data from this study are insufficient to prove the additional therapeutic benefits of tadalafil add-on therapy.

Background: Phosphodiesterase-5 (PDE5) inhibitors improve exercise capacity and quality of life in patients with idiopathic pulmonary arterial hypertension. However, whether such beneficial effects take place in selected populations with chronic obstructive pulmonary disease (COPD) remains uncertain. We aimed to assess the effects of tadalafil--a PDE5 inhibitor--on exercise capacity and quality of life in patients with COPD and mild pulmonary hypertension., Methods: We did a randomised, double-blind, parallel-group, placebo-controlled trial at three centres in Scotland, UK, between Sept 1, 2010, and Sept 1, 2012. Patients with moderate to severe COPD were randomly assigned (1:1), via centralised randomisation with a computer-generated sequence and block sizes of four, to receive daily tadalafil 10 mg or placebo for 12 weeks. Patients, study investigators, outcome assessors, and those administering drugs were masked to group allocation. The primary endpoint was the mean placebo-corrected difference between the baseline and final 6 min walk distance after 12 weeks. We measured change in quality of life at baseline, 8 weeks, and 12 weeks, with standardised questionnaires. Analysis was per protocol and by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01197469., Findings: 120 patients were randomly assigned to receive tadalafil (n=60) or placebo (n=60), of whom 56 (93%) versus 57 (95%) completed the study. At 12 weeks the difference in 6 min walking distance between the tadalafil and placebo groups was 0·5 m (95% CI -11·6 to 12·5; p=0·937). We recorded no statistically significant changes in quality of life (between-group difference on the St George's Respiratory Questionnaire -2·64 [95% CI -6·43 to 1·15]; Research and Development version 1 short-form-36 4·08 [-1·35 to 9·52]; Minnesota Living with Heart Failure questionnaire -2·31 [-7·06 to 2·45]). 19 (32%) of 60 patients in the treatment group had dyspepsia; the severity of dyspepsia ranged from mild to severe, with four (21%) of 19 patients needing a proton-pump inhibitor. Five (8%) of 60 participants had dyspepsia in the placebo group. Headache was noted in 17 (28%) patients in the treatment group versus 5 (8%) in the placebo group, but was mild in all patients. Two (3%) patients in the treatment group had facial flushing, which resulted in one withdrawal. Other withdrawals within the tadalafil group happened after a transient ischaemic attack and two deaths (ruptured abdominal aortic aneurysm and pneumonia)., Interpretation: Tadalafil does not improve exercise capacity or quality of life despite exerting pulmonary vasodilation., Funding: Chief Scientist Office for Scotland., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Pulmonary arterial hypertension (PAH) is a progressive disease. In recent years, phosphodiesterase type 5 inhibitors such as sildenafil have been used to treat this disease in children. Recently, tadalafil has been used in adults with similar efficacy but it has been used less often in children. This experimental study was carried out in 18 known patients aged 4-24 years in the Emam Hossein Hospital of Isfahan, Iran. All patients had been taking sildenafil for a few months to years. Patients underwent echocardiographic study, the 6-minute walk test (6MWT), and non-invasive pulse oximetry before and after the 6MWT. These tests were repeated again after sildenafil had been switched to tadalafil for 6 weeks. After 6 weeks of tadalafil prescription, the severity of some of the patients' symptoms decreased, but the New York Heart Association class of the patients did not change more. Mean ± standard deviation (SD) oxygen saturation while taking sildenafil and after 6 weeks of tadalafil were significantly different (p = 0.005). Furthermore, mean ± SD oxygen saturation after the 6MWT while taking sildenafil and after 6 weeks of tadalafil were significantly different (p = 0.036). The mean ± SD distances walked in this test while taking sildenafil and tadalafil were significantly different (p = 0.005). No significant side effects were seen; 15 patients continued tadalafil. Tadalafil may be a safe drug to treat children and young adults with PAH. We did not observe any significant side effects during usage; it improves functional capacity and oxygen saturation better than sildenafil in these patients, and requires fewer daily doses than sildenafil.

The development of orally active pulmonary vasodilators has been a major breakthrough in the treatment of pulmonary arterial hypertension (PAH). Orally active medications greatly enhanced patient access to PAH treatment and increased an interest in the diagnosis and treatment of this disease that still continues. Four different orally active drugs are currently available for the treatment of PAH and several more are undergoing evaluation. This article discusses the mechanisms by which endothelin receptor antagonists and phosphodiesterase-5 inhibitors mitigate pulmonary hypertensive responses, and reviews the most recent data concerning their efficacy and limitations in the treatment of PAH., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Aims: Tadalafil, a once-daily phosphodiesterase type 5 inhibitor (PDE-5I), offers clinicians an alternative to sildenafil, a 3-times-daily (t.i.d.) PDE-5I for treatment of pulmonary arterial hypertension (PAH). However, there are limited data describing the risks and benefits or recommended methodology of switching patients from sildenafil to tadalafil., Methods: Chart reviews were conducted on all World Health Organization group 1 patients on sildenafil for ≥ 3 months who transitioned to tadalafil with documented clinic visits and 6-min walk tests on both drugs. Most patients were transitioned by discontinuing sildenafil after the evening dose and initiating tadalafil 40 mg/day the next day. Data collected included demographics, PAH etiology, diagnostic hemodynamics, 6-min walk distance (6MWD), PDE-5I side effects, and concomitant medications. Data on B-type natriuretic peptide (BNP) levels were available for most patients also receiving endothelin receptor antagonists (ERAs)., Results: Medical records from 98 patients were evaluated. Most patients (92%) were on sildenafil for > 1 year, and 78% were receiving sildenafil 80-100 mg t.i.d. Ninety-seven percent of patients (95/98) were successfully transitioned and maintained on 40 mg/day. With a mean duration on tadalafil therapy of 243 ± 127 days at the time of analysis, 6MWD was unchanged. Patient-reported adverse events included headache (4%) and heartburn (2%). There was minimal change in BNP levels in the subset of patients receiving an ERA concomitantly., Conclusions: Transition from sildenafil to tadalafil 40 mg/day appears feasible without clinical deterioration or intolerable side effects. This study provides guidance to physicians considering transition from sildenafil to tadalafil for selecting patients., (© 2013 John Wiley & Sons Ltd.)

Introduction: Sildenafil citrate is a potent, selective phosphodiesterase type 5 inhibitor approved for the treatment of pulmonary arterial hypertension (PAH) and plays an important role in the management of the disease., Areas Covered: In this review, we focus on the current available information on the pharmacokinetics, pharmacodynamics, clinical efficacy and safety of sildenafil citrate in PAH through a MEDLINE literature search. Comparison of sildenafil citrate with tadalafil, another phosphodiesterase type 5 inhibitor was also performed., Expert Opinion: In the last few years, considerable progress has been made in the understanding and treatment of PAH. Sildenafil citrate has multiple advantages and whether it is first-line treatment alone or in combination for the mild form of the disease, it is one of the treatments of choice. In terms of its future use, more studies are still needed to better evaluate the benefit/risk balance of sildenafil citrate in pediatric populations.

Objectives/hypothesis: To assess the effect of tadalafil on auditory functions., Study Design: Prospective observational study in a tertiary care hospital., Methods: Twenty-five tadalafil naïve patients with erectile dysfunction or pulmonary artery hypertension were subjected to pure-tone and brainstem-evoked response audiometry before drug therapy, and 3 and 30 days following drug therapy. Results were compared using analysis of variance for repeated measures with Bonferonni correction., Results: Fifteen patients were taking tadalafil 10 mg for erectile dysfunction, and another 10 patients were on tadalafil 20 mg once daily for pulmonary artery hypertension. No statistically significant difference was found in hearing threshold at baseline and at follow-up (P > .05). However, three patients on tadalafil 20 mg showed a significant increase in hearing threshold at higher frequencies. There was no incidence of sudden sensorineural hearing loss in the study group., Conclusions: This is the first prospective and observational study that evaluated the effect of tadalafil on auditory functions with objective tests. Although there was no statistically significant result to confirm or refute the association between tadalafil and hearing impairment, increased threshold at higher frequencies after taking tadalafil supports the results from previous studies and hints at a possible relationship between the two. Similar large sample studies are warranted to know the exact association of phosphodiesterase-5 inhibitors on auditory functions., (Copyright © 2012 The American Laryngological, Rhinological and Otological Society, Inc.)

Smoking-related interstitial fibrosis (SRIF) is a relatively new term used to describe chronic interstitial fibrosis that can develop in smokers. The association of SRIF with pulmonary hypertension has not been described. We present a 55-year-old man with an extensive smoking history who presented for evaluation of insidious onset of dyspnoea on exertion and hypoxaemic respiratory failure. Physical examination was unremarkable. Pulmonary function testing demonstrated a marked reduction of the diffusion capacity with no obstruction or restriction. Ventilation perfusion scan showed no evidence of thromboembolic disease. High-resolution chest CT revealed minimal biapical pleural parenchymal scarring and subtle dependent atelectasis. Serological markers for connective tissue diseases were negative. Open lung biopsy was consistent with SRIF. Vascular intimal proliferation consistent with pulmonary hypertension was also noted. Right heart catheterisation yielded mild pulmonary hypertension and treatment was initiated with tadalafil and bosentan.

The purpose of this review is to evaluate the use of tadalafil as monotherapy and in combination regimens for the treatment of pulmonary arterial hypertension (PAH). A systematic English language search of the medical literature using PubMed was conducted between January 1960 and May 2012 using the search terms 'tadalafil', 'therapy', 'pulmonary (arterial) hypertension' and 'combination therapy'. Special emphasis was given to controlled clinical trials and case studies relevant for the use of tadalafil in PAH. The search revealed 113 relevant publications, 31 of which were clinical trials, 52 were reviews and 12 were case reports. Of these, 12 were clinical studies in human patients with PAH who were treated with tadalafil alone, and seven were clinical studies in human patients with PAH who were treated with tadalafil in combination with other agents. Only clinical studies in human patients were included. Exclusion criteria were monotherapy other than using tadalafil and any combination therapy that excluded tadalafil as part of the treatment regimen. Overall, 1353 human subjects were studied; 896 were treated with tadalafil alone while 457 subjects were treated with tadalafil in coadministration. Tadalafil appears to be an effective and a safe treatment option for patients with PAH. It improves clinical status, exercise capacity, hemodynamic parameters, compliance issues and quality of life and reduces the occurrence of clinical worsening. Tadalafil in combination therapy seems to be additive and synergistic in relaxing pulmonary vascular muscle cells but more clinical trials on human subjects are warranted.

The drugs tadalafil and sildenafil share the same mechanism. Although more research is necessary to solidify the recommendation of the routine use of tadalafil, human and dog data combined with pharmacokinetic data suggest that dogs may be safely treated for canine pulmonary arterial hypertension with tadalafil for the convenience of less frequent dosing, with effects similar to sildenafil. While more costly, the use of tadalafil has positive implications in improving compliance and, therefore, therapeutic outcomes in canine pulmonary arterial hypertension. This article explores the data for the use of tadalafil in canine pulmonary arterial hypertension and provides example compounded preparations.

Background: Sildenafil was the only phosphodiesterase-5 inhibitor available for the treatment of pulmonary arterial hypertension (PAH) until the approval and availability of once-daily tadalafil. Since no direct comparative study is likely to be performed between these agents, we sought to evaluate the feasibility of transitioning stable PAH patients from sildenafil to tadalafil., Methods: The primary end point was continuation on tadalafil without clinical deterioration. A functional outcome through an evaluation of serial change in the 6-min walk test distance (6MWD) was also performed., Results: Thirty-five patients on sildenafil qualified for the analysis, of which 85.7 % (30/35) were successfully transitioned. The remaining 14.3 % (5/30) (failure group) were switched back to sildenafil due to worsening symptoms. The mean pretransition 6MWD was 363 m, with an average change in the success group of +16.4 m (range = -64 to +140 m) compared to -45 m (range = -123 to +32 m) in the failure group at 1-3 months post switch (p = 0.02). All 30 patients in the success group remained on tadalafil, with an average improvement in the 6MWD of +37.04 m (range = -36.5 to +236.5 m) at 12 months post switch. The failure group had a higher daily sildenafil dose (180 vs. 115.5 mg; p = 0.06), with 42.8 % of patients at the highest sildenafil dose failing the transition., Conclusion: The transition from sildenafil to tadalafil is safe and generally well tolerated. Patients with more severe disease and those on higher doses of sildenafil are more likely to fail the transition and should be monitored closely post switch.

Rationale: Although commonly used as the primary outcome measure of clinical trials in pulmonary arterial hypertension (PAH), the minimal important difference (MID) of the 6-minute walk test (6MWT) has not been well defined for this population of patients., Objectives: To estimate the MID in the 6MWT in patients with PAH., Methods: Study subjects from the clinical trial of tadalafil in PAH, a 16-week, parallel-group, randomized clinical trial of patients who were treatment naive or on background therapy with an endothelin receptor antagonist, were eligible. 6MWT was performed using a standardized protocol. Distributional and anchor-based methods were used to estimate the MID; the latter method used the Physical Component Summary Score (PCS) of the Medical Outcomes Study 36-item short form (SF-36)., Measurements and Main Results: Four hundred five subjects were analyzed. Domains of the SF-36 were weakly to modestly associated with 6MWT. Change in the PCS of the SF-36 was most strongly associated with change in 6MWT (r = 0.40, P < 0.001) and thus was selected as the anchor for subsequent anchor-based analyses. Distributional analyses yielded estimates of the MID ranging from 25.1 to 38.5 m, whereas anchor-based analyses yielded an estimate of 38.6 m., Conclusions: Using both distributional and anchor-based methods, the estimated consensus MID in the 6MWT for PAH is approximately 33 m. These results have important implications for (1) assessing treatment responses from clinical trials and metaanalyses of specific PAH therapy, and (2) sample size calculations for future study design.

Objectives: The aim of this study was to evaluate the long-term safety and durability of efficacy of tadalafil for pulmonary arterial hypertension., Background: Tadalafil is an oral phosphodiesterase-5 inhibitor approved for PAH treatment. In the multicenter, placebo-controlled, randomized, 16-week PHIRST (Pulmonary Arterial Hypertension and Response to Tadalafil) study, tadalafil 40 mg improved exercise capacity and delayed clinical worsening., Methods: Eligible patients from PHIRST received once-daily tadalafil 20 mg (T20 mg) or 40 mg (T40 mg) (n = 357) in the double-blind, 52-week, uncontrolled extension study (PHIRST-2); 293 patients completed PHIRST-2. Durability of efficacy was explored using the 6-min walk distance (6MWD) test. Clinical worsening and changes in World Health Organization functional class were evaluated., Results: The safety profile of tadalafil in PHIRST-2 was similar to that in PHIRST, with typical phosphodiesterase-5 inhibitor adverse events. The 6MWDs achieved in PHIRST for the subset of patients receiving T20 mg and T40 mg in both PHIRST and PHIRST-2 (406 ± 67 m [n = 52] and 413 ± 81 m [n = 59] at PHIRST-2 enrollment, respectively) were maintained at PHIRST-2 completion (415 ± 80 m [n = 51] and 410 ± 78 m [n = 59], respectively). Numerically fewer patients who were on T40 mg in PHIRST and PHIRST-2 experienced World Health Organization functional class deterioration (6% [n = 5]) compared with those randomized to T20 mg (9% [n = 7]) across both studies. Post hoc analyses showed that background bosentan use and higher 6MWD at PHIRST baseline were associated with fewer clinical worsening events., Conclusions: Long-term treatment with tadalafil was well tolerated in patients with pulmonary arterial hypertension. In patients receiving either T20 mg or T40 mg, the improvements in 6MWD demonstrated in the 16-week PHIRST study appeared sustained for up to 52 additional weeks of treatment in PHIRST-2. (Pulmonary Arterial Hypertension and Response to Tadalafil Study; NCT00549302)., (Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

This study aimed to investigate the safety, tolerability, and effects of tadalafil on children with pulmonary arterial hypertension (PAH) after transition from sildenafil or after tadalafil received as initial therapy. A total of 33 pediatric patients with PAH were retrospectively evaluated. Of the 33 patients, 29 were switched from sildenafil to tadalafil. The main reason for the change from sildenafil was once-daily dosing. The average dose of sildenafil was 3.4 ± 1.1 mg/kg/day, and that of tadalafil was 1.0 ± 0.4 mg/kg/day. For 14 of the 29 patients undergoing repeat catheterization, statistically significant improvements were observed after transition from sildenafil to tadalafil in terms of mean pulmonary arterial pressure (53.2 ± 18.3 vs. 47.4 ± 13.7 mmHg; p < 0.05) and pulmonary vascular resistance index (12.2 ± 7.0 vs 10.6 ± 7.2 Units/m(2); p < 0.05). Clinical improvement was noted for four patients treated with tadalafil as initial therapy. The side effect profiles were similar for the patients who had transitioned from sildenafil to tadalafil including headache, nausea, myalgia, nasal congestion, flushing, and allergic reaction. Two patients discontinued tadalafil due to migraine or allergic reaction. One patient receiving sildenafil had no breakthrough syncope after transition to tadalafil. Tadalafil can be safely used for pediatric patients with PAH and may prevent disease progression.

Long-acting phosphodiesterase 5 (PDE5) inhibitor, tadalafil, was recently approved for the treatment of pulmonary hypertension. Apart from being a PDE5 inhibitor, tadalafil also possesses antioxidant activity. The aim of this study was to probe whether tadalafil has any beneficial effect over tempol owing to its antioxidant action in addition to PDE5 inhibitory activity. Albino Wistar rats were pretreated with tadalafil (10 mg/kg) or vehicle 2 h before hypoxic exposure, whereas tempol (20 mg/kg) was given 5 min before induction of hypoxia. Right ventricular systolic pressure (RVSP), mean arterial pressure (MAP), heart rate (HR), right ventricular contractility (RVdP/dtmax) and cardiac output (CO) were recorded while subjecting rats to acute hypoxia for 30 min. Lipid peroxidation and reduced glutathione were estimated in serum before and after hypoxia exposure. Tadalafil as well as tempol significantly prevented hypoxia-induced rise in RVSP (p < 0.001) and RVdP/dtmax (p < 0.05). Both tadalafil and tempol pretreatment partially prevented (p < 0.01) the rise in CO due to hypoxia. Tadalafil did not produce any significant change in MAP, whereas tempol led to a significant fall (p < 0.01) in MAP. Acute hypoxia increased the oxidative stress levels. Tadalafil pretreatment partially prevented hypoxia-induced oxidative stress, while tempol pretreatment completely prevented hypoxia-induced oxidative stress. Results suggest that tadalafil because of its antioxidant action in addition to PDE5 inhibitory activity is more appropriate for the prevention of hypoxic pulmonary hypertension than tempol. Tempol also produced undesirable systemic hypotension as side effect, which was not seen with tadalafil because of its pulmonary selective action.

Background: Tadalafil is a phosphodiesterase-5 (PDE-5) inhibitor that was approved by the US Food and Drug Administration (FDA) in 2009 for the treatment of pulmonary arterial hypertension (PAH)., Objective: The purpose of this review is to evaluate the pharmacology, pharmacokinetic properties, clinical efficacy, adverse effects, drug interactions, and dosage and administration of tadalafil in patients with PAH., Methods: A literature search of MEDLINE and International Pharmaceutical Abstracts (1960 through September 5, 2010) was conducted with the search terms tadalafil, pulmonary arterial hypertension, and phosphodiesterase-5 inhibitor. Data found from orignial research and case series published in English were screened for relevancy to pharmacology, pharmacokinetics, clinical efficacy and safety, and tolerability. Relevant articles from the bibliographies of the identified published articles were also obtained. Unpublished data and posters were obtained from the manufacturer of tadalafil and the FDA Web site., Results: By selectively inhibiting PDE-5, tadalafil causes nitric oxide-mediated vasodilation in the pulmonary vasculature. Tadalafil has a greater affinity (10,000-fold) for PDE-5 compared with the other PDE inhibitors and has a t(½) of 17.5 hours. In a controlled clinical study in patients with PAH, patients receiving tadalafil in a total daily dose of 40 mg had significant improvements in their 6-minute walk distance (33 m from baseline) and time to clinical worsening compared with those receiving placebo (both, P < 0.05). Tadalafil had adverse effects similar to placebo, with headache being the most commonly reported (42%)., Conclusions: In the small number of studies available, tadalafil was effective and well tolerated when used to treat patients with PAH. Compared with placebo, tadalafil was associated with significant improvements in exercise capacity and reduced time to clinical worsening (68% relative risk reduction; P = 0.038). There is limited evidence comparing tadalafil with sildenafil and vardenafil, and the studies are limited by short treatment durations., (Copyright © 2011 Elsevier HS Journals, Inc. All rights reserved.)

Tadalafil is a selective inhibitor of phosphodiesterase type-5 (PDE-5) that was originally developed for the treatment of male erectile dysfunction and recently approved for the treatment of pulmonary arterial hypertension (PAH). The antipulmonary hypertensive effects of nitric oxide and the natriuretic peptides are mediated via increasing intracellular cGMP and enzymatic degradation by PDE-5 is the major route of cGMP inactivation in the lung. Evidence is accruing that PDE-5 activity is increased in pulmonary vascular diseases and may contribute to the pathogenesis of PAH. The longer half-life of tadalafil allows for once-daily dosing as compared with three-times daily dosing for sildenafil, the only other PDE-5 inhibitor currently approved for treatment of PAH. This article reviews the role of cGMP and PDE-5 in PAH, presents the results of recent clinical trials and discusses the role of tadalafil in the treatment of this rare but difficult-to-treat disease.

Background: Tadalafil 40 mg orally once daily, was shown to be well-tolerated and efficacious for pulmonary arterial hypertension in a 16-week, double-blind, placebo (PBO)-controlled trial. Inclusion criteria included the option for background bosentan. Analyses of tadalafil in treatment-naive patients and as add-on to bosentan were pre-specified. Objectives were to provide safety and efficacy data for both groups., Methods: Groups analyzed included: treatment-naive + PBO; treatment-naive + tadalafil; background bosentan + PBO; and background bosentan + tadalafil. Patients randomized to tadalafil or PBO (N = 405) were analyzed by bosentan use (yes = 216, no = 189). Treatment differences in 6-minute walk distance (6MWD, PBO-adjusted), functional class (FC), clinical worsening (CW) and adverse events were assessed. Hazard ratios (HRs) with 95% confidence intervals (CIs) are presented for FC and CW., Results: At Week 16, PBO-adjusted 6MWD increases were 44 m (CI: 20 to 69 m; n = 37) for tadalafil 40 mg in treatment-naive patients and 23 m (CI: -2 to 48 m; n = 42) for tadalafil 40 mg add-on to bosentan. The 6MWD for treatment-naive and background bosentan PBO patients decreased by 3 m and increased by 19 m, respectively, at Week 16 compared with baseline. Two (5%) treatment-naive patients had CW with tadalafil 40 mg vs 8 (22%) with PBO (HR = 3.3, CI: 1.1 to 10.0). Two (5%) background bosentan patients had CW with tadalafil 40 mg add-on vs 5 (11%) for PBO add-on (HR = 1.9, CI: 0.4 to 10.2). Adverse events for tadalafil monotherapy and as add-on were similar., Conclusion: Tadalafil 40 mg was well-tolerated and provided clinical benefit in patients as monotherapy. It was also well-tolerated when added to background bosentan, but data are insufficient to conclude additional benefit., (Copyright © 2011 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Tadalafil, which was commercialized in 2009, is a potent and selective phosphodiesterase type 5 (PDE5) inhibitor, and may be a safe and effective therapeutic alternative for patients with class II and III pulmonary hypertension (PH) in the World Health Organization's classification--as stated in the Clinical Practice Guidelines for the Diagnosis and Treatment of PH of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS)--providing benefits in exercise tolerance, delaying clinical deterioration and improving quality of life. Given the greater half-life of this drug, allowing a single oral dose of 40 mg per day, tadalafil could improve therapeutic compliance--thus facilitating treatment adherence--among patients with PH., (Copyright © 2011 Sociedad Española de Neumología y Cirugía Torácica. Published by Elsevier Espana. All rights reserved.)

The pathology of pulmonary arterial hypertension (PAH) is characterized by vascular vasoconstriction, smooth muscle cell proliferation, and thrombosis. Experimental studies have shown the beneficial effect of phosphodiesterase type 5 (PDE-5) inhibitors on pulmonary vascular remodeling and vasodilatation. Randomized clinical trials in monotherapy or combination therapy have been conducted in PAH with sildenafil and tadalafil which significantly improve clinical status, exercise capacity and hemodynamics of PAH patients. Combination therapy of PDE-5 inhibitors with prostacyclin analogs and endothelin receptor antagonists may be helpful in management of PAH. The third PDE-5 inhibitor, vardenafil, is currently being investigated in PAH. Side effects are usually mild and transient and include headache, flushing, nasal congestion, digestive disorders, and myalgia.

Tadalafil is a selective cyclic guanosine monophosphate-specific phosphodiesterase type 5 inhibitor that is effective in improving exercise ability, the time to clinical worsening and health-related quality of life (HR-QOL) scores in patients with pulmonary arterial hypertension (PAH). In a large, 16-week, randomized, double-blind, placebo-controlled, multicentre, phase III trial (PHIRST) in patients aged >or=14 years with PAH (WHO group I), tadalafil 40 mg once daily (the recommended dosage) significantly increased the mean placebo-corrected 6-minute walk distance (6MWD) by 33 m from baseline (primary endpoint). In treatment-naive patients, tadalafil 40 mg once daily significantly increased the mean placebo-corrected 6MWD by 44 m at week 16, whereas in patients receiving bosentan 125 mg twice daily as background therapy there was a mean change of 23 m, which was not significant. Both the time to the first occurrence of clinical worsening and the incidence of clinical worsening were significantly reduced in recipients of tadalafil 40 mg once daily compared with recipients of placebo. Furthermore, at week 16, tadalafil improved most HR-QOL outcomes from baseline to a significantly greater extent than placebo. Preliminary data from an extension of the PHIRST trial suggest that the improvements in 6MWD are maintained for up to 1 year in recipients of tadalafil 20 or 40 mg once daily. Treatment with tadalafil was generally well tolerated, with adverse events that were transient in nature and of mild to moderate intensity.

Introduction: A joint Task Force of the ESC and of the ERS has developed guidelines on the diagnosis and treatment of pulmonary hypertension (PH) to provide updated information on the management of patients with this condition., State of the Art: The term pulmonary hypertension (PH) describes a group of devastating and life-limiting diseases, defined by mean pulmonary artery pressure >25 mmHg at rest. The diagnosis of PH requires a series of investigations intended to confirm the diagnosis, clarify the clinical group and the specific aetiology and an algorithm for this is proposed. Several drugs are currently approved to try to correct endothelial dysfunction. They lead to a significant improvement in the prognosis of patients who are in NYHA functional class II, III or IV. The evaluation of the severity of PH has a pivotal role in the choice of initial treatment and evaluation of the response to therapy in individual patients., Perspective: These guidelines should be widely disseminated and implemented in order to improve the management of patients with PH., Conclusion: These guidelines summarise recent advances in the understanding and management of PH., (Copyright 2010 SPLF. Published by Elsevier Masson SAS. All rights reserved.)

The aim of this study was to assess the effect of tadalafil (0.5, 2.5, and 10 mg/kg per day) on the progression of pulmonary arterial hypertension (PAH) in early treatment and on the survival rate in late treatment on the monocrotaline (MCT)-induced PAH rat model. Tadalafil was administered once daily to rats for 3 weeks from the day of MCT-injection or 21 days after the injection. With early treatment, tadalafil at 10 mg/kg per day prevented the development of PAH by maintaining mean pulmonary artery pressure within the normal range and attenuated right ventricular hypertrophy. With late treatment, tadalafil tended to increase the partial pressure of oxygen in arterial blood and dose-dependently improved the survival rate by 55%, 60%, and 70% at 0.5, 2.5, and 10 mg/kg per day, respectively, versus 40% in the MCT-control group. Both early and late treatments with tadalafil were associated with elevated lung cyclic guanosine monophosphate (cGMP). These results suggest that tadalafil relaxes pulmonary arteries by elevating cGMP in lungs and extend survival time by improving pulmonary hemodynamics even when treatment occurs in the late phase of PAH. Thus, it is expected that tadalafil may be an effective, once-daily treatment option in humans with PAH.

Phosphodiesterases are a class of proteins that primarily modulate intracellular levels of cyclic nucleotides such as cGMP and cAMP. Phosphodiesterase-5 (PDE5) is mainly involved in the smooth muscle cell cGMP inactivation. Chemical inhibition of PDE5 has recently become a valid therapeutic option of nitric oxide pathway potentiation via cell cGMP availability. More specifically, PDE5 inhibition appears successful for the treatment of idiopathic pulmonary arterial hypertension. Additional intriguing therapeutic properties are a protective effect on the myocardium through antihypertrophic and antiapoptotic mechanisms and on vascular function by improving endothelial responsiveness and tolerance to myocardial ischemia-reperfusion injury. These effects imply a potential usefulness in the treatment of coronary artery disease and heart failure. Evidence currently available for considering PDE5 inhibition an additional therapeutic opportunity in cardiovascular disorders is provided.

Background: Pulmonary arterial hypertension (PAH) is a rare, progressive lung disorder that impairs performance of daily activities and quality of life (QoL), leading to right heart failure and death. Treatment options include prostanoids, endothelin antagonists, and phosphodiesterase type 5 inhibitors (e.g., tadalafil). Currently there is no cure for PAH, but tadalafil has improved exercise capacity in these patients., Objectives: To explore the effect of tadalafil on health-related quality of life (HRQoL) measures., Research Design and Methods: The Pulmonary Arterial Hypertension and Response to Tadalafil (PHIRST) clinical trial examined the efficacy and tolerability of tadalafil for the treatment of PAH. The impact of tadalafil on HRQoL and exercise capacity, as measured by 6-minute walk test (6MW test), was also examined. Change from baseline to last non-missing post-baseline was examined for the SF-36, EQ-5D, and 6MW test, along with the relationship between HRQoL and 6MW test performance., Results: Tadalafil 40 mg showed significant improvement over placebo for six of eight SF-36 domains, and EQ-5D index scores. Also, the tadalafil 40-mg group showed significant improvement over placebo on the 6MW test (p < 0.001), but no clear relationship was found between 6MW test performance and HRQoL., Conclusion: Results suggest that tadalafil 40 mg may significantly improve HRQoL and exercise capacity for PAH patients. Limitations of this study include its relatively short nature limited to 16 weeks and the relative heterogeneity of the study population.

Pulmonary arterial hypertension (PAH) is a rare disease characterized by vascular proliferation and remodeling, resulting in a progressive increase in pulmonary arterial resistance, right heart failure, and death. The pathogenesis of PAH is multifactorial, with endothelial cell dysfunction playing an integral role. This endothelial dysfunction is characterized by an overproduction of vasoconstrictors and proliferative factors, such as endothelin-1, and a reduction of vasodilators and antiproliferative factors, such prostacyclin and nitric oxide. Phosphodiesterase type 5 (PDE-5) is implicated in this process by inactivating cyclic guanosine monophosphate, the nitric oxide pathway second messenger. PDE-5 is abundantly expressed in lung tissue, and appears to be upregulated in PAH. Three oral PDE-5 inhibitors are available (sildenafil, tadalafil, and vardenafil) and are the recommended first-line treatment for erectile dysfunction. Experimental studies have shown the beneficial effects of PDE-5 inhibitors on pulmonary vascular remodeling and vasodilatation, justifying their investigation in PAH. Randomized clinical trials in monotherapy or combination therapy have been conducted in PAH with sildenafil and tadalafil, which are therefore currently the approved PDE-5 inhibitors in PAH treatment. Sildenafil and tadalafil significantly improve clinical status, exercise capacity, and hemodynamics of PAH patients. Combination therapy of PDE-5 inhibitors with prostacyclin analogs and endothelin receptor antagonists may be helpful in the management of PAH although further studies are needed in this area. The third PDE-5 inhibitor, vardenafil, is currently being investigated in PAH. Side effects are usually mild and transient and include headache, flushing, nasal congestion, digestive disorders, and myalgia. Mild and moderate renal or hepatic failure does not significantly affect the metabolism of PDE-5 inhibitors, whereas coadministration of bosentan decreases sildenafil and tadalafil plasma levels. Due to their clinical effectiveness, tolerance profile, and their oral administration, sildenafil and tadalafil are two of the recommended first-line therapies for PAH patients in World Health Organization functional classes II or III.

The therapeutic effects of phosphodiesterase type 5 inhibitors in patients with pulmonary arterial hypertension (PAH) were reviewed. A double-blind, placebo-controlled study named SUPER-1 showed that sildenafil improved exercise capacity, WHO functional class, hemodynamics, and quality of life. Two randomized, double-blind, crossover studies, showed that sildenafil improved exercise tolerance and quality of life, and reduced estimated pulmonary artery systolic pressure. The dose independent effects of sildenafil on PAH are controversial. There are few case-reports that show vardenafil and tadalafil have benefits in PAH patients. A double-blind study of tadalafil in PAH patients is ongoing.

Despite the introduction of new drugs that have changed the course of pulmonary arterial hypertension (PAH), some patients are still refractory to treatment and deteriorate rapidly. Long-acting phosphodiesterase-5 inhibitors are a new class of drugs that are effective in PAH. This prospective study assessed the potential of combination therapy with prostacyclin and tadalafil for treatment of severe PAH. We report four cases of severe PAH that deteriorated despite prostacyclin therapy. Two patients had Eisenmenger syndrome, one had pulmonary hypertension associated with scleroderma and one had histiocytosis X. All were treated with tadalafil, 10-20 mg once daily, in addition to prostacyclin. After 3 months of treatment, all patients improved clinically, with an increase in mean 6MWD from 214 to 272 m. In three patients, the New York Heart Association functional class decreased from IV to III. Echocardiograms showed no significant changes in pulmonary arterial pressure. Although this study was limited by the small sample size, it suggests that tadalafil in combination with prostacyclin is an effective treatment for severe PAH. Tadalafil may be beneficial for the treatment of patients with advanced disease.

Objectives: Sildenafil, a phosphodiesterase-5 inhibitor, significantly improves oxygenation when used in animal models and patients with pulmonary hypertension. Tadalafil is a new and clinically available phosphodiesterase-5 inhibitor that, aside from causing pulmonary vasodilation, has been shown to increase cardiac output in pulmonary hypertensive adults. Its hemodynamic effects on the newborn, however, have not been tested. The objective was to evaluate the effect of tadalafil on central hemodynamics and arterial oxygenation in a piglet model of acute pulmonary hypertension., Design: Laboratory experiment., Setting: University laboratory., Subjects: Seven anesthetized and mechanically ventilated newborn piglets., Interventions: Pulmonary hypertension was induced and maintained in seven anesthetized and mechanically ventilated newborn piglets following acute exposure to 11% oxygen. The experimental animals received orla tadalafil (1 mg/kg), whereas the control animals were given an equal volume of normal saline. Systemic and pulmonary hemodynamic variables were measured, and the cardiac output and ejection fraction were obtained from two-dimensional echocardiogram and Doppler measurements in all animals. Serial arterial blood gases were also obtained, and the alveolar-arterial oxygen gradient was calculated., Measurements and Main Results: In contrast with the control animals, in which no significant changes were noted, in the experimental animals pulmonary arterial pressure decreased on average by 54% and cardiac output increased by 88% following tadalafil administration (p < .05). Tadalafil increased the PaO2 by 48% +/- 21% (p < .01), likely as a result of a 74% +/- 13% reduction in the alveolar-arterial oxygen gradient (p < .01)., Conclusions: In a newborn animal model of acute pulmonary hypertension, oral tadalafil administration reduces pulmonary vascular resistance and increases arterial oxygenation by increasing cardiac output and reducing the lung shunt fraction. This previously untested compound deserves additional investigation in laboratory models of persistent pulmonary hypertension of the newborn.

Background: Pulmonary artery hypertension is a disorder with limited treatment options and poor prognosis. We studied the effect of tadalafil, a selective phosphodiesterase type 5 inhibitor, in patients with this disease., Methods and Results: In thirteen patients (5 males, 8 females) aged 15-70 years, with pulmonary artery hypertension (7 with congenital heart disease, 4 with chronic pulmonary thromboembolism and 2 with primary pulmonary hypertension), tadalafil was added to their baseline therapy at 10 mg OD for two weeks and if tolerated well, increased to 20 mg OD for the next two weeks. After four weeks of therapy, all thirteen patients had subjective improvement in the form of overall well being and objective improvement as measured by duration of exercise on treadmill following Bruce protocol from a baseline of 350.54+/-255.06 seconds to 479.54+/-195.00 seconds (p<0.01). There was improvement in NYHA functional class in eleven patients. Two patients, though showed no improvement in functional class, had subjective improvement in effort tolerance and objective improvement as measured by duration of exercise on TMT. Hemodynamic parameters showed a trend towards improvement, mean pulmonary artery mean pressure decreased from 63.5+/-26.2 mmHg to 62.2+/-24.8 mmHg (p>0.05), mean pulmonary blood flow increased from 3.26+/-1.04 L/min to 3.44+/-1.26 L/min (p>0.05), mean total pulmonary vascular resistance decreased from 1858.6+/-1138.9 dyne-sec.cm-5 to 1737.3+/-1017.2 dyne-sec.cm-5 (p>0.05)., Conclusion: Oral tadalafil was well tolerated and had a beneficial effect in patients with pulmonary artery hypertension irrespective of age, sex and underlying etiology. Patient had improved effort tolerance and a trend towards improved pulmonary hemodynamics.