Opsumit (Macitentan)

Opsumit is an endothelin receptor antagonist used in the management of pulmonary arterial hypertension, a disease affecting the pulmonary vascular endothelium.

• Pulmonary arterial hypertension (PAH): Improves exercise capacity and delays disease progression.
• WHO Group 1 PAH: Reduces risk of clinical worsening.
• Chronic thromboembolic pulmonary hypertension (CTEPH) after surgical evaluation: Supports long‑term management.

• Macitentan selectively binds to endothelin‑A and endothelin‑B receptors on vascular smooth‑muscle cells, blocking the vasoconstrictive and proliferative actions of endothelin‑1. This antagonism leads to sustained vasodilation, reduced vascular remodeling, ​and improved hemodynamics in the pulmonary circulation.

Common Side Effects

• Headache
• Nasopharyngitis
• Peripheral edema
• Fatigue
• Upper respiratory tract infection
• Dizziness

Serious or Rare Side Effects

• Liver enzyme elevation
• Anemia
• Pulmonary edema
• Severe hypotension
• Drug‑induced hepatitis
• Embryonic toxicity (risk to fetus).

Patients should be evaluated before initiating therapy and monitored regularly throughout treatment.

• Baseline liver function tests: Perform before starting and periodically during therapy.
• Hemoglobin monitoring: Check periodically for anemia.
• Pregnancy avoidance: Effective contraception required for women of childbearing potential.
• Drug interactions: Review concomitant medications for potential interactions.
• Renal impairment: Use with caution in patients with reduced kidney function.
• Store at below 25°C: Keep in the original packaging, protect from moisture.

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