Macitentan is an endothelin receptor antagonist with a high affinity for both endothelin A and B receptors in pulmonary arterial smooth muscle. It inhibits endothelin-mediated activation of second messenger systems that cause vasoconstriction and cell proliferation.1
The efficacy and safety of macitentan in patients with symptomatic pulmonary arterial hypertension (PAH) were assessed in a double-blind phase III study (n=742).2
Patients were randomised to receive either placebo or macitentan at 3mg (unlicensed dose) or 10mg once daily, in addition to their existing therapy with phosphodiesterase-5 inhibitors or oral/inhaled prostanoids.1,2
The primary endpoint, time to first occurrence of a morbidity or mortality event (death, atrial septostomy, lung transplantation, other worsening of PAH or initiation of iv or sc prostanoids) occurred in 46.4% of patients in the placebo group, 38% of those who received macitentan 3mg and 31.4% of those given macitentan 10mg. Overall, 37.2% of patients taking placebo experienced worsening of their PAH symptoms (most frequent primary endpoint) compared with 24.4% of those treated with macitentan 10mg (p<0.001).1,2
Reduced risk of death
Macitentan 10mg daily reduced the risk of death due to PAH or hospitalisation for PAH (secondary endpoint) by 20.7% (p<0.001) compared with placebo. In addition, patients who received macitentan 10mg daily also experienced functional improvement at month 6, as observed by a mean increase from baseline in 6-minute walking distance of 12.5m (p=0.008) compared with placebo.2
The most common adverse effects of macitentan were nasopharyngitis, headache and anaemia.1,2
- Opsumit Summary of Product Characteristics, December 2013.
- Pulido T et al. N Engl J Med 2013; 369: 809–18.
Further information: Actelion