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Endothelin Receptor Antagonist (ERA) — Pulmonary Arterial Hypertension

Macitentan

Brand names: Opsumit

Macitentan is an orally active endothelin receptor antagonist used in the long-term treatment of pulmonary arterial hypertension.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It blocks endothelin-1 binding at endothelin ETA and ETB receptors, reducing pulmonary vascular vasoconstriction and remodelling.

Prescribing in practice

  • Endothelin receptor antagonists are teratogenic and are contraindicated in pregnancy; women of childbearing potential must use reliable contraception and have pregnancy excluded before and during treatment under a pregnancy prevention programme.
  • It can cause hepatotoxicity and clinically significant anaemia, so liver function and haemoglobin should be checked before and during treatment.
  • Avoid concomitant strong CYP3A4 inducers or inhibitors, which alter exposure.

Monitoring

Monitor haemoglobin and liver function tests before starting and periodically during treatment, and confirm continued non-pregnancy in women of childbearing potential.

Counselling the patient

  • This medicine can seriously harm an unborn baby, so use effective contraception and report any possible pregnancy immediately.
  • Report unusual tiredness, breathlessness, jaundice or dark urine.
  • Attend for regular blood tests as arranged.

Evidence & guidelines

The SERAPHIN trial showed macitentan reduced morbidity and mortality events in pulmonary arterial hypertension.

Reference: SERAPHIN Trial 2013; NICE TA459 (Macitentan for PAH); ESC/ERS PAH Guidelines 2022; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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