Ambrisentan

How it works

It selectively blocks the endothelin-A receptor, opposing endothelin-1-mediated pulmonary vasoconstriction and vascular remodelling. This reduces pulmonary vascular resistance and right-heart afterload.

Prescribing in practice

• It is teratogenic and contraindicated in pregnancy, so women of childbearing potential require reliable contraception and pregnancy testing before and during treatment — the dominant safety requirement.
• Endothelin antagonists commonly cause fluid retention and peripheral oedema and can worsen heart failure, so monitor weight and volume status.
• It may reduce haemoglobin and, unlike some agents in the class, carries a lower but still relevant need to monitor liver function per the SPC.

Monitoring

Monitor pregnancy status in at-risk women, haemoglobin, signs of fluid retention and liver function as directed during therapy.

Counselling the patient

• Effective contraception is essential as this drug can seriously harm a pregnancy.
• Report swelling, rapid weight gain or worsening breathlessness.
• Mention any unusual tiredness so anaemia can be checked.

Evidence & guidelines

The ARIES trials showed ambrisentan improves exercise capacity and delays clinical worsening in pulmonary arterial hypertension, supporting its licensed specialist use.