Macitentan(CAS:441798-33-0)

Macitentan, CAS number 441798-33-0, is the core API of third-generation dual endothelin receptor antagonists for global pulmonary arterial hypertension (PAH) treatment. Approved by FDA in 2013 under the brand name Opsumit, it has become an essential raw material for standardized therapy of rare cardiovascular diseases by virtue of three unique strengths: sustained receptor binding, intervention in disease progression and improved long-term prognosis. It is widely adopted in generic drug manufacturing, compound formulation R&D and international pharmaceutical export business. Macitentan appears as white to off-white crystalline powder with stable chemical properties, non-hygroscopic feature and strong light stability. Strict control over chiral impurities and related substances enables it to meet global pharmacopoeia specifications, supporting industrial mass production of oral film-coated tablets and dispersible tablets.

In terms of pharmacological mechanism, Macitentan blocks the binding between endothelin-1 and ETA, ETB receptors via dual antagonistic pathways. Endothelin-1 acts as a powerful vasoconstrictor; in PAH patients, overactivated endothelin system continuously triggers pulmonary arteriole contraction, vascular smooth muscle hyperplasia and vascular wall fibrosis, gradually elevating pulmonary vascular resistance and pulmonary arterial pressure to aggravate right heart load. Macitentan exhibits far higher affinity for ETA receptors and maintains stable occupancy on pulmonary arterial smooth muscle receptors to block pathological cascades for long periods. Its active in-vivo metabolite also retains endothelin antagonistic activity, extending systemic efficacy to achieve 24-hour stable therapeutic effect with once-daily oral administration. Different from short-acting competitors, Macitentan not only dilates pulmonary blood vessels temporarily, but also suppresses vascular remodeling to slow irreversible pulmonary artery lesions fundamentally, drastically cutting risks of clinical deterioration, hospitalization and long-term adverse cardiovascular events for PAH patients.

Clinically, Macitentan is exclusively indicated for adult patients with WHO Group 1 pulmonary arterial hypertension at WHO Functional Class II and III, covering idiopathic, heritable, connective tissue disease-associated and postoperative congenital heart disease-related PAH. It can be applied as monotherapy for long-term maintenance or combined with PDE5 inhibitors such as sildenafil and tadalafil to build multi-pathway synergistic regimens, effectively increasing 6-minute walking distance, reducing pulmonary vascular resistance and improving right ventricular function. The landmark Phase 3 SERAPHIN trial validated that long-term Macitentan treatment significantly reduces clinical worsening endpoints of PAH, making it a guideline-preferred API to optimize long-term patient prognosis. Its applicable population includes adults and children over 2 years old with PAH, supporting both in-hospital long-term management and home chronic disease maintenance.

Regarding industrial production and clinical safety, Macitentan adopts mature and controllable synthetic process with consistent batch purity and qualified limits for heavy metals and residual solvents, fitting continuous large-scale production for pharmaceutical factories. The standard clinical dosage is 10 mg once daily with favorable overall tolerance. Only mild adverse reactions such as slight anemia and nasopharyngitis occur in a small number of patients, which can be well managed via regular blood routine and liver function monitoring. Macitentan carries embryo-fetal toxicity risk, so standardized contraception is required for women of childbearing age, with safety warnings directly applicable to finished drug instructions. As a scarce special API for pulmonary hypertension, Macitentan maintains steady global market demand and irreplaceable competitiveness in rare disease drug R&D and high-end cardiovascular generic drugs. With rising global awareness of PAH diagnosis and treatment, Macitentan holds broad and sustainable development prospects in the pharmaceutical industry.