Clinical efficacy and safety of switch from bosentan to macitentan in children and young adults with pulmonary arterial hypertension

Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term event-driven study. Aim Few studies compared the clinical efficacy and safety of switch from bosentan to macitentan only in adult patients with pulmonary arterial hypertension. We aimed to evaluate the clinical efficacy and safety of switch from bosentan to macitentan in children and young adults. This is a single-institution, 24-week prospective study. Patients ⩾12 years of age with idiopathic/heritable pulmonary arterial hypertension or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan therapy were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors and inhaled prostanoids was allowed. Outcome measures included change from baseline to week 24, in the 6-minute walk distance, functional class, oxygen saturation at rest/after 6-minute walk distance test, systolic pulmonary artery pressure estimated by echocardiography, and brain natriuretic peptide levels. Safety end points included adverse events laboratory abnormalities. A total of 13 patients - 5 male and 8 female - completed the study. The mean age was 20.3±6.5 years (12-35) and weight was 54.0±14.5 kg (27-75). Five patients were ⩽18 years of age. Macitentan improved 6-minute walk distance from baseline (mean: 466±35 m (300-590)), at 12 weeks (mean: 494±78 m (325-590), +28 m) (p0.05). None of the patients had anaemia, hepatotoxicity, and peripheral oedema. Our study is the first study that showed that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension and is well tolerated without any adverse events.