Opsumit Dosing
The recommended dose of Opsumit (macitentan) is 10 mg once daily by mouth. 1
Key Dosing Details
- Standard dose: 10 mg orally once daily
- No titration required: Unlike some other PAH medications, macitentan does not require dose titration—start at the therapeutic dose
- No higher doses: Doses higher than 10 mg once daily have not been studied in PAH patients and are not recommended 1
- Administration: Can be taken with or without food
Important Pre-Treatment Requirements
Before initiating Opsumit in females of reproductive potential, you must exclude pregnancy through testing 1. This is a critical safety requirement given the drug's teratogenic potential and boxed warning for embryo-fetal toxicity.
Clinical Context
Macitentan is an endothelin receptor antagonist (ERA) approved for pulmonary arterial hypertension (WHO Group I) to reduce disease progression and hospitalization risk 1. The 10 mg daily dose demonstrated a 45% reduction in the composite endpoint of morbidity and mortality in the pivotal SERAPHIN trial 2, 3.
Guidelines support macitentan at this dose for WHO Functional Class II-III PAH patients, with evidence showing it delays time to clinical worsening and improves functional class 2. The 2023 guidelines confirm the standard dosing as 10 mg daily orally 4.
Monitoring Considerations
While the dose itself is straightforward, monitor:
- Liver enzymes before initiation and during treatment as clinically indicated (risk of hepatotoxicity with all ERAs) 1
- Hemoglobin levels periodically (anemia is a known effect) 1
- Pregnancy status monthly in females of reproductive potential 1
The simplicity of once-daily dosing without titration makes macitentan more convenient than some other PAH therapies like riociguat (which requires dose titration) or bosentan (which requires twice-daily dosing and more intensive liver monitoring) 2, 5.