As new medications for pulmonary hypertension are approved and marketed, it is important to evaluate their efficacy, both absolutely and relative to tried-and-true products. Macitentan, marketed under the name Opsumit by Actelion, is approved to treat pulmonary arterial hypertension patients under the World Health Organization classification of Group 1 in the United States and Functional Classes 2 and 3 in the European Union. It was recently reviewed in an article published in Drugs and found to be a useful treatment option with the added benefit of once-daily administration.
Treatment with macitentan is indicated to delay disease progression and minimize hospitalizations from pulmonary arterial hypertension. During the large, randomized, placebo-controlled SERAPHIN study, doses of 10 mg per day were shown to reduce morbidity and mortality. In the same study, macitentan-receiving patients experienced an enhanced health-related quality of life relative to placebo-receiving patients and had greater exercise capacity and haemodynamic parameters.
Macitentan is a potent, dual endothelin (ET) receptor antagonist. ET-1 is involved in the pathogenesis of pulmonary arterial hypertension, most likely as a result of its role in vasodilation and vasoconstriction. By antagonizing both ET-A and ET-B, macitentan has the potential to affect smooth muscle cells, fibroblasts, cardiac myocytes, endothelial cells, and macrophages, all of which can contribute to pulmonary hypertension development and progression.
Importantly, patients tolerate macitentan therapy. Although haemoglobin levels decrease during treatment, it is a side effect expected of ET receptor antagonists and not unique to macitentan. In fact, the decrease in haemoglobin has been shown to subside in the long-term and is not progressive. Other common side effects experienced by macitentan-receiving patients were upper respiratory tract infection, nasopharyngitis, headache, anemia, and bronchitis.
Although a number of pulmonary hypertension treatment options exist, macitentan is another valuable addition to the portfolio of medications.