IMPAHCT: A randomized phase 2b/3 study of inhaled imatinib for pulmonary arterial hypertension

AV-101 (imatinib) powder for inhalation, an investigational dry powder inhaled formulation of imatinib designed to target the underlying pathobiology of pulmonary arterial hypertension, was generally well tolerated in healthy adults in a phase 1 single and multiple ascending dose study. Inhaled Imatinib Pulmonary Arterial Hypertension Clinical Trial (IMPAHCT; NCT05036135) is a phase 2b/3, randomized, double-blind, placebo-controlled, dose-ranging, and confirmatory study. IMPAHCT is designed to identify an optimal AV-101 dose (phase 2b primary endpoint: pulmonary vascular resistance) and assess the efficacy (phase 3 primary endpoint: 6-min walk distance), safety, and tolerability of AV-101 dose levels in subjects with pulmonary arterial hypertension using background therapies. The study has an operationally seamless, adaptive design allowing for continuous recruitment. It includes three parts; subjects enrolled in Part 1 (phase 2b dose-response portion) or Part 2 (phase 3 intermediate portion) will be randomized 1:1:1:1 to 10, 35, 70 mg AV-101, or placebo (twice daily), respectively. Subjects enrolled in Part 3 (phase 3 optimal dose portion) will be randomized 1:1 to the optimal dose of AV-101 and placebo (twice daily), respectively. All study parts include a screening period, a 24-week treatment period, and a 30-day safety follow-up period; the total duration is ∼32 weeks. Participation is possible in only one study part. IMPAHCT has the potential to advance therapies for patients with pulmonary arterial hypertension by assessing the efficacy and safety of a novel investigational drug-device combination (AV-101) using an improved study design that has the potential to save 6-12 months of development time. ClinicalTrials.gov Identifier: NCT05036135.

AV-101, a novel inhaled dry-powder formulation of imatinib, in healthy adult participants: a phase 1 single and multiple ascending dose study

Background

Oral imatinib has been shown to be effective, but poorly tolerated, in patients with advanced pulmonary arterial hypertension (PAH). To maintain efficacy while improving tolerability, AV-101, a dry powder inhaled formulation of imatinib, was developed to deliver imatinib directly to the lungs.

Methods

This phase 1, placebo-controlled, randomised single ascending dose (SAD) and multiple ascending dose (MAD) study evaluated the safety/tolerability and pharmacokinetics of AV-101 in healthy adults. The SAD study included five AV-101 cohorts (1 mg, 3 mg, 10 mg, 30 mg, 90 mg) and placebo, and a single-dose oral imatinib 400-mg cohort. The MAD study included three AV-101 cohorts (10 mg, 30 mg, 90 mg) and placebo; dosing occurred twice daily for 7 days.

Results

82 participants (SAD n=48, MAD n=34) were enrolled. For the SAD study, peak plasma concentrations of imatinib occurred within 3 h of dosing with lower systemic exposure compared to oral imatinib (p<0.001). For the MAD study, systemic exposure of imatinib was higher after multiple doses of AV-101 compared to a single dose, but steady-state plasma concentrations were lower for the highest AV-101 cohort (90 mg) compared to simulated steady-state oral imatinib at day 7 (p=0.0002). Across AV-101 MAD dose cohorts, the most common treatment-emergent adverse events were cough (n=7, 27%) and headache (n=4, 15%).

Conclusions

AV-101 was well tolerated in healthy adults, and targeted doses of AV-101 significantly reduced the systemic exposure of imatinib compared with oral imatinib. An ongoing phase 2b/phase 3 study (IMPAHCT; clinicaltrials.gov identifier NCT05036135) will evaluate the safety/tolerability and clinical benefit of AV-101 for PAH.

Acute Corticotropin-Releasing Factor Receptor Type 2 Agonism Results in Sustained Symptom Improvement in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Background

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex multi-symptom disease with widespread evidence of disrupted systems. The authors hypothesize that it is caused by the upregulation of the corticotropin-releasing factor receptor type 2 (CRFR2) in the raphé nuclei and limbic system, which impairs the ability to maintain homeostasis. The authors propose utilizing agonist-mediated receptor endocytosis to downregulate CRFR2.

Materials and Methods

This open-label trial tested the safety, tolerability and efficacy of an acute dose of CT38s (a short-lived, CRFR2-selective agonist, with no known off-target activity) in 14 ME/CFS patients. CT38s was subcutaneously-infused at one of four dose-levels (i.e., infusion rates of 0.01, 0.03, 0.06, and 0.20 μg/kg/h), for a maximum of 10.5 h. Effect was measured as the pre-/post-treatment change in the mean 28-day total daily symptom score (TDSS), which aggregated 13 individual patient-reported symptoms.

Results

ME/CFS patients were significantly more sensitive to the transient hemodynamic effects of CRFR2 stimulation than healthy subjects in a prior trial, supporting the hypothesized CRFR2 upregulation. Adverse events were generally mild, resolved without intervention, and difficult to distinguish from ME/CFS symptoms, supporting a CRFR2 role in the disease. The acute dose of CT38s was associated with an improvement in mean TDSS that was sustained (over at least 28 days post-treatment) and correlated with both total exposure and pre-treatment symptom severity. At an infusion rate of 0.03 μg/kg/h, mean TDSS improved by -7.5 ± 1.9 (or -25.7%, p = 0.009), with all monitored symptoms improving.

Conclusion

The trial supports the hypothesis that CRFR2 is upregulated in ME/CFS, and that acute CRFR2 agonism may be a viable treatment approach warranting further study.

Clinical Trial Registration

ClinicalTrials.gov, identifier NCT03613129.

A Randomized, Double-Blind, Placebo-Controlled Study of Pulsed, Inhaled Nitric Oxide in Subjects at Risk of Pulmonary Hypertension Associated With Pulmonary Fibrosis

BACKGROUND

The interstitial lung diseases include a variety of disorders, many of which are characterized by fibrotic changes (fILD). Of the fILDs, Idiopathic pulmonary fibrosis is the most common. Pulmonary hypertension (PH) frequently complicates fILD and is associated with impaired functional capability, lower physical activity, and significantly reduced life expectancy. There is no proven treatment for patients with fILD-PH. We report results from the first cohort of a phase 2b/3 trial with pulsed inhaled nitric oxide (iNO) in patients with fILD-PH.

METHODS

Subjects in cohort 1 were randomized to iNO 30 μg/kg ideal body weight/h (iNO30) or placebo for 8 weeks of blinded treatment; subjects then transitioned to open-label extension (OLE) on iNO30 followed by dose escalation to iNO45 then iNO75. Activity monitoring was used to assess changes in daily activity. Safety and efficacy were evaluated.

RESULTS

Twenty-three patients were randomized to iNO30 and 18 to placebo. During blinded treatment, iNO30 subjects showed an average improvement in moderate/vigorous physical activity (MVPA) and remained stable in overall activity. Placebo subjects showed an average drop of 26% in MVPA and a 12% drop in overall activity. The iNO group had an improvement in oxygen saturation. During OLE, subjects maintained their activity levels including placebo subjects who transitioned from a decline to a maintenance in all activity parameters. Inhaled nitric oxide at all doses (30, 45, and 75) was safe and well tolerated.

CONCLUSIONS

Treatment with iNO30 demonstrated clinically and statistically significant benefit in MVPA and clinically significant benefit in overall activity. In the OLE, higher doses of iNO were also safe and well tolerated while showing maintenance in activity parameters.

Enhancing Insights into Pulmonary Vascular Disease through a Precision Medicine Approach. A Joint NHLBI-Cardiovascular Medical Research and Education Fund Workshop Report

The Division of Lung Diseases of the NHLBI and the Cardiovascular Medical Education and Research Fund held a workshop to discuss how to leverage the anticipated scientific output from the recently launched "Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics" (PVDOMICS) program to develop newer approaches to pulmonary vascular disease. PVDOMICS is a collaborative, protocol-driven network to analyze all patient populations with pulmonary hypertension to define novel pulmonary vascular disease (PVD) phenotypes. Stakeholders, including basic, translational, and clinical investigators; clinicians; patient advocacy organizations; regulatory agencies; and pharmaceutical industry experts, joined to discuss the application of precision medicine to PVD clinical trials. Recommendations were generated for discussion of research priorities in line with NHLBI Strategic Vision Goals that include: (1) A national effort, involving all the stakeholders, should seek to coordinate biosamples and biodata from all funded programs to a web-based repository so that information can be shared and correlated with other research projects. Example programs sponsored by NHLBI include PVDOMICS, Pulmonary Hypertension Breakthrough Initiative, the National Biological Sample and Data Repository for PAH, and the National Precision Medicine Initiative. (2) A task force to develop a master clinical trials protocol for PVD to apply precision medicine principles to future clinical trials. Specific features include: (a) adoption of smaller clinical trials that incorporate biomarker-guided enrichment strategies, using adaptive and innovative statistical designs; and (b) development of newer endpoints that reflect well-defined and clinically meaningful changes. (3) Development of updated and systematic variables in imaging, hemodynamic, cellular, genomic, and metabolic tests that will help precisely identify individual and shared features of PVD and serve as the basis of novel phenotypes for therapeutic interventions.

Clinical and hemodynamic improvements after adding ambrisentan to background PDE5i therapy in patients with pulmonary arterial hypertension exhibiting a suboptimal therapeutic response (ATHENA-1)

OBJECTIVE

Pulmonary arterial hypertension (PAH) is a condition which may lead to right ventricular failure and premature death. While recent data supports the initial combination of ambrisentan (a selective ERA) and tadalafil (a PDE5i) in functional class II or III patients, there is no published data describing the safety and efficacy of ambrisentan when added to patients currently receiving a PDE5i and exhibiting a suboptimal response. The ATHENA-1 study describes the safety and efficacy of the addition of ambrisentan in this patient population.

METHODS

PAH patients with a suboptimal response to current PDE5i monotherapy were assigned ambrisentan in an open-label fashion and evaluated for up to 48 weeks. Cardiopulmonary hemodynamics (change in PVR as primary endpoint) were evaluated at week 24 and functional parameters and biomarkers were measured through week 48. Time to clinical worsening (TTCW) and survival are also described.

RESULTS

Thirty-three subjects were included in the analysis. At week 24, statistically significant improvements in PVR (-32%), mPAP (-11%), and CI (+25%) were observed. Hemodynamic improvements at week 24 were further supported by improvements in the secondary endpoints: 6-min walk distance (+18 m), NT-proBNP (-31%), and maintenance or improvement in WHO FC in 97% of patients. Adverse events were consistent with known effects of ambrisentan.

CONCLUSION

The hemodynamic, functional, and biomarker improvements observed in the ATHENA-1 study suggests that the sequential addition of ambrisentan to patients not having a satisfactory response to established PDE5i monotherapy is a reasonable option.

Initial combination therapy with ambrisentan and tadalafil in connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH): subgroup analysis from the AMBITION trial

Background

Patients with connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH), in particular systemic sclerosis (SSc), had an attenuated response compared with idiopathic PAH in most trials. Thus, there is uncertainty regarding the benefit of PAH-targeted therapy in some forms of CTD-PAH.

Objective

To explore the safety and efficacy of initial combination therapy with ambrisentan and tadalafil versus ambrisentan or tadalafil monotherapy in patients with CTD-PAH and SSc-PAH enrolled in the AMBITION trial.

Methods

This was a post hoc analysis of patients with CTD-PAH and SSc-PAH from AMBITION, an event-driven, double-blind trial in patients with WHO functional class II/III PAH. Treatment-naive patients were randomised 2:1:1 to once-daily initial combination therapy with ambrisentan plus tadalafil or monotherapy with ambrisentan or tadalafil, respectively. The primary endpoint was time to the first clinical failure event (first occurrence of death, hospitalisation for worsening PAH, disease progression or unsatisfactory long-term clinical response).

Results

In the primary analysis set (N=500), 187 patients had CTD-PAH, of whom 118 had SSc-PAH. Initial combination therapy reduced the risk of clinical failure versus pooled monotherapy in each subgroup: CTD-PAH (HR 0.43 (95% CI 0.24 to 0.77)) and SSc-PAH (0.44 (0.22 to 0.89)). The most common AE was peripheral oedema, which was reported more frequently with initial combination therapy than monotherapy in the two PAH subgroups. The relative frequency of adverse events between those on combination therapy versus monotherapy was similar across subgroups.

Conclusions

This post hoc subgroup analysis provides evidence that CTD-PAH and SSc-PAH patients benefit from initial ambrisentan and tadalafil combination therapy.

Trial registration number

NCT01178073, post results.

Ambrisentan response in connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) - A subgroup analysis of the ARIES-E clinical trial

OBJECTIVE

Pulmonary arterial hypertension (PAH) is a condition which may lead to right ventricular failure and early mortality and is an important complication in patients with connective tissue disease (CTD). Previously, the endothelin A selective receptor antagonist, ambrisentan, demonstrated efficacy and safety in treating patients with PAH due to WHO Group I etiologies. These analyses describe the 3-year efficacy and safety of ambrisentan in patients specifically with CTD associated PAH (CTD-PAH).

METHODS

Patients with CTD-PAH participating in the ARIES-1 and -2 clinical trials and their long-term extension were evaluated. Efficacy evaluations including 6-min walk distance (6MWD), clinical worsening, and survival were collected at routine study visits. Additional analyses of 6MWD categorical (30 m) breakpoints were conducted to determine any relationship between 6MWD and a prognostic threshold for survival.

RESULTS

124 patients with CTD-PAH were evaluated. 62.6%, 57.3%, and 58.2% of CTD-PAH patients treated with ambrisentan exhibited increases in 6MWD at 1-, 2-, and 3- years respectively. At 3 years, 64% of patients were free from clinical worsening and 76% of patients were still alive (Kaplan-Meier estimates). Identified factors holding prognostic relevance for survival include: baseline functional class, CTD-PAH subgroup, patient sex, improvement in 6MWD ≥30 m over the first 12 weeks of treatment, the most recent 6MWD, and a 6MWD absolute threshold of 222 m.

CONCLUSION

These first analyses of the 3-year treatment of CTD-PAH patients with ambrisentan revealed fewer clinical worsening events and improved survival compared to historical controls. Key exercise parameters were also identified which appear important in guiding treatment.

Phase I safety study of ranolazine in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) causes right ventricular ischemia, dysfunction, and failure. PAH patients may benefit from antianginal agents based on a shared pathophysiology with left ventricular ischemia. A single-center, randomized, placebo-controlled trial (1∶1) to assess the acute vasoreactivity and safety of ranolazine in PAH was conducted. Plasma samples for pharmacokinetic (PK) studies were drawn during hemodynamic measurements at 0, 60, 90, 120, 240, and 360 minutes from a Swan-Ganz catheter. All patients received 500-mg doses, uptitrated to 1,000 mg at week 4, monthly evaluations, and a complete objective assessment after 12 weeks, followed by an open-label extension. Thirteen patients were randomized and 12 enrolled (6 ranolazine, 6 placebo). All patients completed the acute phase; 10 completed the 12-week study. There were no acute changes in invasive hemodynamics. At 12 weeks ranolazine was well tolerated. Only 1 of the 5 patients on ranolazine had a serum concentration considered to be in the therapeutic range. Two serious adverse events required early withdrawal (both in the ranolazine group); gastrointestinal complaints were the most common adverse event. Efficacy measures did not demonstrate any differences between treatment groups. During the open-label trial, 2 additional patients reached a therapeutic concentration. Ranolazine in PAH appears safe, without acute hemodynamic effects after a 500-mg dose. Ranolazine administrated to PAH patients receiving background PAH therapies did not consistently reach therapeutic levels. Future studies should first perform PK analysis in PAH patients receiving PAH therapies and explore the safety and tolerability of the higher doses perhaps necessary to achieve therapeutic levels in PAH patients. (

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT01757808.).

Approach to assessing the economic impact of insulin-related hypoglycaemia using the novel Local Impact of Hypoglycaemia Tool

AIM

To provide estimates of the costs of severe and non-severe insulin-related hypoglycaemia in the UK using the Local Impact of Hypoglycaemia Tool.

METHODS

Rates of hypoglycaemia were extracted from the UK Hypoglycaemia Study Group observational study. The costs of severe and non-severe hypoglycaemic episodes in insulin-treated adults with Type 1 and Type 2 diabetes were estimated from UK data sources. The rates and costs were then applied to specific populations to give an estimate of the cost of insulin-related hypoglycaemia for the UK, a specific locality, or a user-defined population. User-specific rates and costs could also be applied.

RESULTS

The estimated cost of a hypoglycaemic episode can range from as much as £2,152 for severe episodes (for which the patient is admitted to hospital) to as little as £1.67 for non-severe episodes. With a UK population of 64.1 million, the total estimated cost of managing insulin-related hypoglycaemia is £468.0 m per year (£295.9 m for severe episodes, £172.1 m for non-severe episodes). On a local health economy level, using a hypothetical general population of 100 000, the total cost of managing insulin-related hypoglycaemia is estimated to be £730,052 per year (£461,658 for severe and £268,394 for non-severe episodes).

CONCLUSIONS

The Local Impact of Hypoglycaemia Tool highlights the economic burden of insulin-related hypoglycaemia. Non-severe episodes are often overlooked because of their low individual cost, but their high frequency makes the cumulative cost substantial. The Local Impact of Hypoglycaemia Tool also shows clinicians and budget-holders the economic impact of lower rates of hypoglycaemia.

Initial Use of Ambrisentan plus Tadalafil in Pulmonary Arterial Hypertension

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.).

Pulmonary hypertension in idiopathic pulmonary fibrosis with mild-to-moderate restriction

The clinical course of pulmonary hypertension (PH) in idiopathic pulmonary fibrosis (IPF) is not known except in advanced disease.488 subjects in a placebo-controlled study of ambrisentan in IPF with mild-moderate restriction in lung volume, underwent right heart catheterisation (RHC) at baseline and 117 subjects (24%) had repeated haemodynamic measurements at 48 weeks. The subjects were categorised into a) World Health Organization (WHO) Group 3 PH (PH associated with pulmonary disease), n=68 (14%); b) WHO Group 2 PH (PH associated with left-sided cardiac disease), n=25 (5%); c) no PH but elevated pulmonary artery wedge pressure (PAWP), n=21 (4%); and d) no PH but without elevation of PAWP, n=374 (77%). The WHO Group 3 PH subjects had a lower diffusion capacity, 6MWD and oxygen saturation compared to the subjects with no PH. There was no significant change in mean pulmonary arterial pressure with ambrisenten or placebo after 12 months. Subjects with IPF associated with WHO Group 3 PH had impaired gas exchange and exercise capacity compared to patients without PH. An additional 9% of the subjects had haemodynamic evidence of subclinical left-ventricular dysfunction. Pulmonary artery pressures remained stable over 1 year in the majority of the cohort.

Does treatment response to ambrisentan vary by pulmonary arterial hypertension severity? Implications for clinicians and for the design of future clinical trials

BACKGROUND

Recent clinical trials in pulmonary arterial hypertension have included World Health Organization functional classes I and II patients. However, the impact of baseline functional class and other measures of severity on outcomes has not been evaluated in detail.

METHODS

Outcomes at 12 weeks for patients grouped by functional class, haemodynamics, brain natriuretic peptide (BNP) level and 6-min walk distance (6MWD) were evaluated for patients in the Ambrisentan in Pulmonary Arterial Hypertension, Randomized, Double-Blind, Placebo-Controlled, Multicenter Efficacy Study 1 and 2 (ARIES)-1 and 2 pivotal trials of ambrisentan, a once-daily oral endothelin-1 antagonist. Long-term outcomes in the ARIES-E extension study were also evaluated.

RESULTS

At 12 weeks, ambrisentan-treated patients with both early and late functional class showed similar improvement in 6MWD relative to placebo. However, patients with more severe disease tended to have greater improvement in 6MWD after grouping by other measures of severity. This included higher baseline BNP level, shorter baseline 6MWD and more severe baseline haemodynamics (p < 0.05 for BNP and p = NS for other comparisons, analysed as interaction terms). During long-term open label follow-up, maintenance of 6MWD improvement, freedom from clinical worsening and survival were also numerically worse for patients who were functional class III/IV at baseline.

CONCLUSIONS

Patients with both less severe and more severe PAH benefited from ambrisentan therapy vs. placebo in 12-week clinical trials and during long-term follow up, but greater improvement vs. placebo was seen for those with higher BNP levels.

Evaluation of the endothelin receptor antagonists ambrisentan, bosentan, macitentan, and sitaxsentan as hepatobiliary transporter inhibitors and substrates in sandwich-cultured human hepatocytes

Background

Inhibition of the transporter-mediated hepatobiliary elimination of bile salts is a putative mechanism for liver toxicity observed with some endothelin receptor antagonists (ERAs).

Methods

Sandwich-cultured human hepatocytes were used to study the hepatobiliary distribution and accumulation of exogenous taurocholate, ERAs and endogenous bile acids. The molecular mechanisms for findings in hepatocytes or clinical observations were further explored using either vesicular assays (efflux transporters) or transfected cell-lines (uptake transporters). Inhibition constants (IC₅₀) were measured for the human hepatobiliary transporters bile salt export pump (BSEP), sodium taurocholate cotransporting polypeptide (NTCP), multidrug resistance protein 2 (MRP2), P-glycoprotein (Pgp), breast cancer resistance protein (BCRP), organic anion-transporting polypeptide 1B1 (OATP1B1) and OATP1B3.

Results

The ERAs showed dose-dependent reductions in exogenous taurocholate cellular accumulation in human hepatocytes, with macitentan having the greatest effect. Consistent with their effects on bile acids, the ERAs inhibited bile transporters. IC₅₀ values for OATP1B1 and OATP1B3 ranged from 2 µM for macitentan to 47 µM for ambrisentan. Macitentan and bosentan also inhibited NTCP with IC₅₀ values of 10 and 36 µM, respectively. Similar to previously reported findings with sitaxsentan, BSEP inhibition was observed for bosentan and macitentan with IC₅₀ values of 42 and 12 µM, respectively. In contrast, ambrisentan showed little or no inhibition of these transporters. Other transporters tested were weakly inhibited by the ERAs. Accumulation in hepatocytes was also a factor in the effects on bile transport. Macitentan demonstrated the greatest accumulation in human hepatocytes (∼100x) followed by sitaxsentan (∼40x), bosentan (∼20x) and ambrisentan (∼2x).

Conclusions

Significant differences in the inhibition of hepatic transporters were observed between the evaluated ERAs in vitro. Macitentan had the highest level of cellular accumulation and caused the greatest effects on bile acid distribution in human hepatocytes followed by sitaxsentan and bosentan. Ambrisentan showed a low potential to affect bile acids.

Effectiveness of spironolactone plus ambrisentan for treatment of pulmonary arterial hypertension (from the [ARIES] study 1 and 2 trials)

In translational models of pulmonary arterial hypertension (PAH), spironolactone improves cardiopulmonary hemodynamics by attenuating the adverse effects of hyperaldosteronism on endothelin type-B receptor function in pulmonary endothelial cells. This observation suggests that coupling spironolactone with inhibition of endothelin type-A receptor-mediated pulmonary vasoconstriction may be a useful treatment strategy for patients with PAH. We examined clinical data from patients randomized to placebo or the selective endothelin type-A receptor antagonist ambrisentan (10 mg/day) and in whom spironolactone use was reported during ARIES-1 and -2, which were randomized, double-blind, placebo-controlled trials assessing the effect of ambrisentan for 12 weeks on clinical outcome in PAH. From patients randomized to placebo (n = 132) or ambrisentan (n = 67), we identified concurrent spironolactone use in 21 (15.9%) and 10 (14.9%) patients, respectively. Compared with patients treated with ambrisentan alone (n = 57), therapy with ambrisentan + spironolactone improved change in 6-minute walk distance by 94% at week 12 (mean ± SE, +38.2 ± 8.1 vs +74.2 ± 27.4 m, p = 0.11), improved plasma B-type natriuretic peptide concentration by 1.7-fold (p = 0.08), and resulted in a 90% relative increase in the number of patients improving ≥1 World Health Organization functional class (p = 0.08). Progressive illness, PAH-associated hospitalizations, or death occurred as an end point for 5.3% of ambrisentan-treated patients; however, no patient treated with ambrisentan + spironolactone reached any of these end points. In conclusion, these pilot data suggest that coupling spironolactone and endothelin type-A receptor antagonism may be clinically beneficial in PAH. Prospective clinical trials are required to further characterize our findings.

Baseline and follow-up 6-min walk distance and brain natriuretic peptide predict 2-year mortality in pulmonary arterial hypertension

BACKGROUND

Six-minute walk distance (6MWD) and brain natriuretic peptide (BNP) levels at baseline and after initiation of treatment have been associated with survival in patients with pulmonary arterial hypertension. Our objective was to determine the individual and additive ability of pretreatment and posttreatment 6MWD and BNP to discriminate 2-year survival in patients with pulmonary arterial hypertension.

METHODS

We included patients enrolled in two randomized clinical trials of ambrisentan who had 2-year follow-up (N 5 370). 6MWD and BNP were assessed before and after 12 weeks of treatment. Receiver operating characteristic curve analyses were performed to identify optimal cutoffs that defi ned subgroups with a high 2-year mortality. Classifi cation and regression tree analysis was used to determine the incremental prognostic value of combined assessments.

RESULTS

6MWD at baseline and after 12 weeks of therapy were similarly discriminatory of 2-year survival (c-statistics 5 0.77 [95% CI 0.70-0.84] and 0.82 [95% CI 0.75-0.88], respectively), whereas change in 6MWD from baseline to week 12 was not discriminating. The same observation was true of BNP at baseline and after 12 weeks of therapy (c-statistics 5 0.68 [95% CI 0.60-0.76] and 0.74 [95% CI 0.66-0.82], respectively). After consideration of baseline 6MWD, there was no prognostic information added by the week 12 6MWD or BNP at either time point.

CONCLUSIONS

6MWD and BNP values at baseline or week 12 identifi ed a population with an elevated risk of death at 2 years. A repeat assessment of 6MWD or BNP after 12 weeks of ambrisentan therapy did not provide additional prognostic information beyond that obtained from baseline values.

Clinical pharmacokinetics and drug-drug interactions of endothelin receptor antagonists in pulmonary arterial hypertension

The authors review the basic pharmacology and potential for adverse drug-drug interactions (DDIs) of bosentan and ambrisentan, the 2 endothelin receptor antagonists currently approved for pulmonary arterial hypertension (PAH) treatment. Bosentan, an endothelin (ET) receptor-type ET(A) and ET(B) antagonist, is metabolized to active metabolites by and an inducer of cytochrome P450 (CYP)2C9 and CYP3A. Ambrisentan, a selective ET(A) receptor antagonist, is metabolized primarily by uridine 5'diphosphate glucuronosyltransferases (UGTs) 1A9S, 2B7S, and 1A3S and, to a lesser extent, by CYP3A and CYP2C19. Drug interactions observed with bosentan DDI studies have demonstrated a potential for significant clinical implications during PAH management: bosentan is contraindicated with cyclosporine A and glyburide, and additional monitoring/dose adjustments are required when coadministered with hormonal contraceptives, simvastatin, lopinavir/ritonavir, and rifampicin. As bosentan carries a boxed warning regarding risks of liver injury and showed dose-dependant increases in serum aminotransferase abnormalities, drug interactions that increase bosentan exposure are of particular clinical concern. Ambrisentan DDI studies performed to date have shown only one clinically relevant DDI, an interaction with cyclosporine A that requires ambrisentan dose reduction. As the treatment of PAH moves toward multimodal combination therapy, scrutiny should be placed on ensuring that drug combinations achieve maximal clinical benefit while minimizing side effects.

Safety, tolerability and pharmacokinetics of an intravenous bolus of sildenafil in patients with pulmonary arterial hypertension

AIMS

To assess pharmacokinetics and pharmacodynamics of a 10 mg intravenous sildenafil bolus in pulmonary arterial hypertension (PAH) patients stabilized on 20 mg sildenafil orally three times daily.

METHODS

Pharmacokinetic parameters were calculated using noncompartmental analysis.

RESULTS

After an acute increase, plasma concentrations stabilized within the range reported previously for a 20 mg oral tablet. At 0.5 h, mean ± SD changes from baseline were -8.4 ± 11.7 mmHg (systolic pressure), -2.6 ± 7.3 mmHg (diastolic pressure) and -3.5 ± 10.4 beats min(-1) (heart rate). There was no symptomatic hypotension.

CONCLUSIONS

Although further research is warranted, a 10 mg sildenafil intravenous bolus appears to provide similar exposure, tolerability and safety to the 20 mg tablet.

Hemodynamic effects of sildenafil citrate and isosorbide mononitrate in men with coronary artery disease and erectile dysfunction

INTRODUCTION

Mild hemodynamic effects have been reported with sildenafil citrate therapy.

AIM

To compare the hemodynamic effects of sildenafil and isosorbide mononitrate (ISMN) in men with coronary artery disease and erectile dysfunction.

METHODS

A total of 31 men aged 35 years or older with coronary artery disease (at least 50% narrowing of the left main stem or at least 70% narrowing of any other coronary artery) and erectile dysfunction (receiving medication for erectile dysfunction or scoring less than 26 out of a maximum score of 30 on the erectile function domain questions of International Index of Erectile Function) were randomized to sildenafil 100 mg (n = 10), ISMN 40 mg (n = 11), or placebo (n = 10) in this single-dose multicenter study.

MAIN OUTCOME MEASURES

Hemodynamic parameters were measured at baseline, 1, 2, 4, and 6 hours post dose.

RESULTS

Compared with baseline, cardiac index increased slightly with sildenafil (0.29 L/min/m2 at 1 hour) and decreased slightly with placebo (-0.12 L/min/m2 at 4 hours) and ISMN (-0.14 L/min/m2 at 1 hour). The stroke volume index increased from baseline at each time point post dose with sildenafil (4.4 mL/m2 at 2 hours), but decreased with ISMN (-5.8 mL/m2 at 1 hour) and placebo (-2.8 mL/m2 at 4 hours). ISMN reduced mean arterial pressure more than sildenafil did (-22 vs. -10 mm Hg at 2 hours, respectively). Both sildenafil and ISMN increased heart rate (4 vs. 7 beats/minute at 1 hour, respectively) and decreased systemic vascular resistance, but sildenafil produced greater reductions in pulmonary vascular resistance. There were no serious adverse events in the sildenafil group.

CONCLUSIONS

Sildenafil 100 mg was well tolerated and induced smaller changes in central and peripheral hemodynamic pressures compared with ISMN 40 mg. Moreover, sildenafil selectively reduced pulmonary resistance, which may have clinical importance in pulmonary hypertension.

Past, present, and future: a 7-year update of Viagra (sildenafil citrate)

More than 30 million men are estimated to have erectile dysfunction (ED) in the United States. Worldwide, ED is estimated to affect more than 150 million men, and that number is expected to exceed 300 million men by the year 2025. The prevalence of ED ranges from 7% in men aged 18-29 years to 85% in men aged 76-85 years. In addition, a recent report showed that 68% of patients with ED aged 18 years and older have at least one comorbid diagnosis of hypertension, hyperlipidaemia, diabetes or depression, and research suggests that ED may be an early indicator of systemic vascular disease. Viagra (sildenafil citrate), the first-in-class phosphodiesterase type 5 (PDE5) inhibitor, was introduced in 1998 for the treatment of ED. In the 7 years since its market launch, more than 750,000 physicians have prescribed sildenafil to more than 23 million men, helping establish an excellent safety and efficacy record. Clinical studies have demonstrated that sildenafil successfully treats ED of varied organic, psychogenic or mixed aetiology, and is effective in men with ED and comorbidities such as hypertension, hyperlipidaemia, diabetes or depression. Sildenafil was a breakthrough medication that addressed a previously unfulfilled medical need. The impact of sildenafil has stimulated academic, clinical and industrial research to better understand the nature of sexual function and develop better treatment and management for sexual dysfunctions such as ED. With the advent of other erectogenic therapies for the treatment of ED, this 7-year update will focus on the unique history and development of sildenafil, its current use and applications and its future directions and indications. Special emphasis is placed on the impact of sildenafil on our understanding of sexual health and on the extensive safety and efficacy data that have been amassed from numerous clinical trials.

Sildenafil citrate does not reduce exercise tolerance in men with erectile dysfunction and chronic stable angina

AIMS

The aim of this study was to evaluate whether sildenafil, used for treatment of erectile dysfunction (ED), affects the exercise tolerance and ischaemic threshold in men with exercise-induced angina not taking nitrates.

METHODS

This was a double-blind placebo-controlled study in men with ED and chronic stable angina, assessing the effect of sildenafil on time to limiting angina during incremental treadmill exercise. Patients remained on their antianginal therapy and received a 100-mg dose of sildenafil or placebo 1h prior to treadmill exercise. Other measurements included times to onset of angina, 1-mm ST-segment depression, and total exercise time.

RESULTS

Adjusted treatment differences for the time to limiting angina, time to onset of angina, total exercise time, and time to 1-mm ST-segment depression were (mean+/-SE) 20+/-10s (95% CI, 1-39; P=0.040), 32+/-11s (95% CI, 11-53; P=0.004), 20+/-10s (95% CI, 0-39; P=0.049), and 12+/-17s (95% CI, -21 to 45, P=0.48), respectively, in favour of sildenafil. There were no serious treatment-related adverse events.

CONCLUSIONS

Sildenafil was well tolerated and did not adversely affect any exercise parameter in men with coronary artery disease and ED. Favourable trends in total exercise duration and times to onset of angina and limiting angina were recorded with sildenafil use.

Pseudoephedrine is without ergogenic effects during prolonged exercise

This study was designed to measure whether a single dose of 120 mg pseudoephedrine ingested 120 min before exercise influences performance during 1 h of high-intensity exercise. The effects of exercise on urinary excretion of the drug were also studied. Ten healthy male cyclists were tested on two occasions, separated by at least 7 days, by using a randomly assigned, double-blind, placebo-controlled, crossover design. Exercise performance was tested during a 40-km trial on a laboratory cycle ergometer, and skeletal muscle function was measured during isometric contractions. On a third occasion, subjects ingested 120 mg pseudoephedrine but did not exercise [control (C)]. Pseudoephedrine did not influence either time trial performance [drug (D) vs. placebo: 58.1 +/- 1.4 (SE) vs. 58.7 +/- 1.5 min] or isometric muscle function. Urinary pseudoephedrine concentrations were significantly increased 1 h after exercise (D vs. C: 114.3 +/- 27.2 vs. 35.4 +/- 13.1 micrograms/ml; P < 0.05). Peak plasma pseudoephedrine concentrations (P < 0.05) but not time taken to reach peak plasma concentrations or the area under the plasma pseudoephedrine concentration vs. time curve was significantly increased in the total group with exercise (D vs. C). In three subjects, plasma pseudoephedrine concentrations were not influenced by exercise. Only these subjects showed increased urinary pseudoephedrine excretion during exercise. We conclude that a single therapeutic dose of pseudoephedrine did not have a measurable ergogenic effect during high-intensity exercise of 1-h duration, but plasma drug concentrations and urinary excretion were altered by exercise. These findings have practical relevance to doping control regulations in international sporting competitions.

Gender affects doxorubicin pharmacokinetics in patients with normal liver biochemistry

We studied the variability in doxorubicin pharmacokinetics in 27 patients, all of whom had normal liver biochemistry tests. Blood samples were collected after the first cycle of single-agent doxorubicin given as an i.v. bolus and plasma levels were measured by high-performance liquid chromatography (HPLC). The relationship of doxorubicin clearance (dose/AUC) with biochemical tests (AST, bilirubin, alkaline phosphatase, albumin, creatinine) and physical characteristics (age, gender, height, weight, tumour type) was investigated. The 6 men had a significantly higher doxorubicin clearance than did the 21 women (median values, 59 and 27 lh-1 m-2, respectively; P = 0.002). Doxorubicin clearance was significantly lower in patients with breast cancer than in those with other tumours (median values, 26 and 53 lh-1 m-2, respectively; P = 0.0008). The other biochemical and physical parameters did not correlate with doxorubicin clearance. However, in multivariate analysis, gender was the only factor predicting doxorubicin clearance (r2 = 40%). The ratio of the AUCs for doxorubicinol and doxorubicin (R) was higher in the men than in the women (median values, 0.62 and 0.36, respectively; P = 0.03). We conclude that gender may be an important determinant of doxorubicin clearance in patients with normal liver biochemistry.

Extensor hallucis longus coaptation to tibialis anterior: a treatment for paralytic drop foot

Between June 1982 and April 1983, a procedure to coapt the extensor hallucis longus (EHL) to the tibialis anterior was performed in eight post-polio patients to correct drop foot and to enable the EHL to be a more efficient dorsiflexor of ankle. Although at early follow-up, every patient was able to actively dorsiflex the ankle against gravity, at final review, (mean follow-up 7.8 years), only two patients could still do so. Three patients developed a cock-up toe deformity or dorsiflexion deformity of great toe. We have attributed the poor final results to stretching of the coaptation. Use of splints or orthosis for a longer period postoperatively and a more carefully designed physical therapy may have yielded better results. Alternatively, if the EHL is anchored to navicular bone better results may be obtained.

Phase II trial of idarubicin in patients with advanced lymphoma

A phase II trial of idarubicin was performed in 24 patients with advanced lymphoma. The drug was administered in a dose of 10-15 mg/m2 i.v. or 15-70 mg/m2 p.o. (single dose) every 3 weeks. There were four partial responses and four minor responses. All but one of the responders had received prior doxorubicin therapy. The toxicities were myelosuppression, nausea and vomiting, and alopecia. Two patients with compromised cardiac function were observed to have further deterioration in the ejection fraction as measured by gated cardiac scan after idarubicin therapy. Further assessment of the activity of idarubicin against lymphoma is recommended in less heavily pretreated patients. The cardiac toxicity should be carefully monitored in future studies.

Precision in the diagnosis of meniscal lesions: a comparison of clinical evaluation, arthrography, and arthroscopy

We assessed the accuracy of clinical evaluation, arthrography, and arthroscopy in the diagnosis of meniscal lesions in fifty knees in which arthrotomy was performed for disabling symptoms after evaluation by these three methods. At surgery, forty-seven menisci were removed, of which forty-four were abnormal and three were normal. In three patients with normal menisci, loose bodies were found in two and the exploration was negative in one. In the forty-four knees with a meniscal lesion, a correct diagnosis was made clinically forty time, arthrographically thirty-nine times, and arthroscopically thirty-two times. Most errors occurred in the knees with posterior horn lesions of the medial meniscus. Clinical diagnosis was least accurate for lesions of the lateral meniscus (four missed) and arthroscopy was least accurate for lesions of the posterior horn of the medial meniscus (ten missed). Arthrography appeared to provide collateral evidence of lesions not seen directly. Based on this study it was concluded that even with negative findings by arthroscopy and arthrography it still may be necessary occasionally to remove a meniscus on the basis of the clinical evaluation.

Homicide in the West of Scotland

Between 1953 and 1974 the author made psychiatric examinations for the prosecution of 400 persons, 367 males and 33 females, accused of the murders of 307 victims, 194 males and 113 females. The 367 males were accused of 273 murders, 172 male and 101 female victims, and the 33 females were accused of 34 murders, 22 male and 13 females victims. The salient features amongst the accused were maleness, youthfulness, the causal importance of alcohol, the rarity of suicide after murder an the high percentage of psychiatrically normal persons: in these last two respects the picture differed from that reported in England and Wales. The normality of these Scottish accused was further shown by the finding that in the decade 1965 to 1974 no material psychiatric abnormality was seen in 90 per cent of the males examined.

Murder in the west of Scotland

It has been increasingly the practice in Scotland for Procurators-Fiscal to obtain psychiatric opinions on the mental state of all persons accused of murder. Between 1953 and 1964 I made 66 such examinations, mainly in the Glasgow area; because of other commitments none were carried out between July 1955 and March 1958. The official Criminal Statistics for England and Wales (1) show that during the eleven years from 1953 to 1963 the number of persons found guilty of murder was 395 and of manslaughter 969; comparable figures for Scotland (3) were 43 and 148.