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Endothelin Receptor Antagonist (ERA) — Pulmonary Arterial Hypertension Pregnancy: Contraindicated — teratogenic; mandatory pregnancy prevention

Macitentan

Brand names: Opsumit

Adult dose

Dose: 10 mg once daily
Route: Oral
Frequency: Once daily
Max: 10 mg/day
No titration required. Take with or without food. Mandatory pregnancy prevention programme — monthly pregnancy test and two forms of contraception required. SERAPHIN trial: event-driven outcomes (morbidity/mortality) used as endpoint — first ERA to demonstrate mortality benefit.

Paediatric dose

Route:
Seek specialist opinion — not licensed in paediatrics

Dose adjustments

Renal

No dose adjustment required

Hepatic

Avoid in severe hepatic impairment — hepatically metabolised

Clinical pearls

  • SERAPHIN trial (2013): macitentan 10 mg OD reduced composite of morbidity/mortality by 45% vs placebo in PAH — landmark outcomes-based trial for ERA
  • Fewer drug-drug interactions than bosentan — less CYP induction; no contraindication with statins or warfarin monitoring issues
  • Anaemia more pronounced than bosentan — Hb monitoring important
  • Once-daily dosing improves adherence vs bosentan BD
  • Now preferred over bosentan in most PAH centres based on outcomes data and simpler interaction profile

Contraindications

  • Pregnancy
  • Women of childbearing potential without reliable contraception
  • Severe hepatic impairment
  • Concurrent strong CYP3A4 inducers (rifampicin — reduces macitentan levels)

Side effects

  • Anaemia (very common — more than bosentan)
  • Nasopharyngitis
  • Bronchitis
  • Headache
  • Hepatotoxicity (less than bosentan)
  • Flushing
  • Peripheral oedema
  • Teratogenicity

Interactions

  • Strong CYP3A4 inducers (rifampicin, carbamazepine) — reduce macitentan levels significantly — avoid
  • Strong CYP3A4 inhibitors (ketoconazole, ritonavir) — increase macitentan levels — use with caution
  • Hormonal contraceptives — less CYP induction than bosentan, but additional contraception still recommended

Monitoring

  • Haemoglobin monthly for 3 months then 3-monthly
  • LFTs (less frequent than bosentan — but still monitor)
  • Pregnancy test monthly
  • Blood pressure
  • 6MWD and RHC response

Reference: BNFc; BNF 90; SERAPHIN Trial 2013; NICE TA459 (Macitentan for PAH); ESC/ERS PAH Guidelines 2022. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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