1. Interaction of ambrisentan with clarithromycin and its modulation by polymorphic SLCO1B1
Christoph Markert & Regina Hellwig. Eur J Clin Pharmacol (2013) 69:1785–1793
This was an open-label, monocenter, one-sequence crossover clinical trial in which participants were exposed to oral ambrisentan (Volibris®; GlaxoSmithKline GmbH & Co. KG, Munich, Germany) 5 mg once-daily on study days 1 and 3–14, and twice-daily 500 mg clarithromycin (Klacid® Pro; Abbott Arzneimittel GmbH, Hannover, Germany) orally on study days 11–14 (Fig. 1). Oral doses of 3 mg midazolam (3 ml of Dormicum®, 5 mg/5 ml solution for infusion; Roche Pharma AG, Grenzach-Wyhlen, Germany) were administered in 200 ml tap water to determine CYP3A baseline activity at least 1 day prior to the start of ambrisentan treatment and on study days 1, 10, and 14 to monitor CYP3A activity changes during the study. On each study day the participants arrived at approximately 7 a.m. at the Clinical Research Center after an overnight fast. Pre-dose blood samples were taken and blood pressure and heart rate were determined. At approximately 8 a.m. ambrisentan was administered together with midazolam on study days 1, 10, and 14. Clarithromycin was administered at 7.45 a.m. and 7.45 p.m. on study days 11–14. On study day 11 the first tablet of clarithromycin was administered immediately after the 24 h post-dose blood drawing of day 10 (approximately 8.15 a.m.). The participants remained fasted until 4 h post-ambrisentan dosing on each study day.
2. Design and Rationale for the Endothelin-1 Receptor Antagonism in the Prevention ofMicrovascular Injury in Patients with non-ST Elevation Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention (ENDORA-PCI) Trial
Kevin Liou & Nigel Jepson & Nicolas Buckley. Cardiovasc Drugs Ther (2016) 30:169–175
Ambrisentan is an orally active endothelin receptor antagonist which is selective for the ERA . Selective inhibition of ERA inhibits phospholipase C mediated vasoconstriction, whilst preserving nitric oxide and prostacyclin production, cGMP and cAMPmediated vasodilation, and ET−1clearance that is associated with the ERB. Ambrisentan is absorbed rapidly in humans, with maximum plasma concentration reached 1.5 h after oral administration. It is metabolized and excreted predominantly through the liver, with no dose adjustment required for the elderly patients. Ambrisentan was initially trialled in humans as a therapeutic agent for symptomatic idiopathic pulmonary arterial hypertension and pulmonary hypertension associated with connective tissue disease.
3. An Update on Medical Therapy for Pulmonary Arterial Hypertension
Yan Wu & Dermot S. O’Callaghan & Marc Humbert. Curr Hypertens Rep
As distinct from bosentan, ambrisentan is a highly selective ET-A receptor antagonist with a sufficiently long half-life to allow once daily dosing. The evidence supporting the clinical benefits of ambrisentan as a therapy for PAHismainly derived from the ARIES 1 and 2 studies. Data from the two studies showed that ambrisentan taken over 12 weeks significantly improved 6MWD in PAH patients. Associated extension study data also confirmed that continuation of treatment for two years was associated with sustained improvements in exercise capacity and a reduced risk of clinical worsening and death.
4. Current Approaches to the Treatment of Systemic-Sclerosis-Associated Pulmonary Arterial Hypertension (SSc-PAH)
Vincent Sobanski & David Launay & Eric Hachulla & Marc Humbert. Curr Rheumatol Rep (2016) 18: 10
In a subanalysis of Study-351 and BREATHE-1 on the dual endothelin-A (ET-A) and ET-B receptor antagonis bosentan, Denton et al. have focused on 66 CTD-PAH (79 % with SSc). Bosentan did not change significantly 6MWD or TTCW at 12 or 16 weeks. Launay et al. described the 1-year outcome of SSc-PAH treated with bosentan as a first-line therapy. Although the CI tended to increase, the 6MWD did not significantly change at 1-year and survival was significantly worse than in the IPAH cohort. Of note, bosentan is also labeled for the prevention of recurrent digital ulcers in SSc. Badesch et al. compared the efficacy of ambrisentan, a selective ET-A receptor antagonist, in IPAH and CTD-PAH, and found consistent trends of increased exercise capacity in IPAH (+58 m) and CTD-PAH (+19 m) in these trials, but changes in 6MWD were not significant in CTD-PAH. A similar difference was found in a 24-week single-arm, open-label study (ARIES-3). A recent RCT evaluating ambrisentan in idiopathic pulmonary fibrosis (IPF) was terminated early because of an increased risk for disease progression and hospitalizations. However, patients with CTD were excluded and it is therefore unknown if a worsening of ILD could be seen in SSc using ambrisentan. We do not use ambrisentan in our daily practice in SSc-PAH patients with some level of ILD.