Macitentan

How it works

Macitentan blocks endothelin receptors on pulmonary vascular smooth muscle, antagonising the vasoconstrictor and proliferative actions of endothelin-1 to reduce pulmonary vascular resistance.

Prescribing in practice

• It is teratogenic — pregnancy must be excluded before starting and reliable contraception used throughout, typically within a pregnancy prevention programme.
• Monitor for anaemia and a fall in haemoglobin, which is a recognised class effect of endothelin receptor antagonists.
• Check liver function and review interacting drugs, as strong CYP3A4 inducers and inhibitors affect exposure.

Monitoring

Monitor haemoglobin and liver function at baseline and periodically, alongside functional status, fluid retention and pregnancy status in those at risk.

Counselling the patient

• Use effective contraception and do not become pregnant while taking this medicine.
• Report unusual tiredness or breathlessness, which may indicate anaemia, and any ankle swelling.

Evidence & guidelines

Macitentan is recommended for pulmonary arterial hypertension by NICE and delivered through designated specialist centres.