Tracleer (bosentan) is a medicine used to treat pulmonary arterial hypertension (PAH) and to reduce the number of new digital ulcers (painful finger or toe sores) in patients with systemic sclerosis (scleroderma). It belongs to a class called endothelin receptor antagonists (ERAs).

Bosentan works by blocking endothelin-1, a substance that causes blood vessels to tighten and narrow. In PAH, this helps relax the pulmonary blood vessels and reduces the pressure on the right side of the heart. In systemic sclerosis, blocking endothelin helps reduce the vessel spasm that leads to digital ulcers.

Treatment usually starts at 62.5 mg twice daily for the first four weeks, then increases to 125 mg twice daily as the maintenance dose.

Take with or without food, consistently at the same times each day. Swallow tablets whole.

Do not stop taking Tracleer suddenly without speaking to your PAH specialist. PAH can worsen rapidly if treatment is stopped.

Liver function tests are mandatory before starting Tracleer and monthly during treatment.

Take the missed dose as soon as you remember. If it is nearly time for your next dose, skip and continue your schedule. Never take two doses at once.

Contact your doctor or emergency services. Symptoms of overdose include severe low blood pressure, nausea, and flushing.

• Store below 30°C
• Keep in the original packaging
• Keep out of reach of children

Common side effects:

• Headache
• Flushing
• Anaemia (low red blood cells): haemoglobin is checked regularly
• Oedema (swelling, particularly of the legs and ankles)
• Liver enzyme elevations: very common and the main reason for mandatory monthly liver monitoring

Serious side effects:

• Liver toxicity: significant liver enzyme elevation may require stopping treatment. Monthly liver function tests are non-negotiable
• Fetal harm: bosentan causes severe birth defects. It must not be used during pregnancy. Two reliable forms of contraception are required for women of childbearing potential during treatment and for one month after stopping

Like other ERAs, Tracleer is only available through a controlled distribution programme due to the risk of fetal harm.

Bosentan is a potent inducer of liver enzymes (CYP3A4 and CYP2C9), meaning it speeds up the metabolism of many other medicines:

• Hormonal contraceptives: bosentan significantly reduces the effectiveness of oral, implant, injectable, and patch contraceptives. Two non-hormonal forms of contraception must be used
• Ciclosporin: bosentan and ciclosporin together cause reciprocal increases in each other's levels and toxicity. Avoid combination
• Glyburide (glibenclamide): avoid. Risk of liver toxicity
• Statins: bosentan reduces levels of many statins. Monitor for effectiveness
• Sildenafil and other PDE5 inhibitors: combination is used in PAH but mutual drug level changes must be considered

Your PAH team and pharmacist will review all your medicines carefully before and during treatment.

Why do I need monthly liver tests?

Bosentan commonly elevates liver enzymes and can occasionally cause significant liver damage. The liver tests (specifically ALT and AST) provide early warning of liver toxicity before serious harm occurs. If levels rise above certain thresholds, your dose may be reduced or Tracleer may need to be stopped. These tests are not optional: they are a safety requirement that continues for the entire duration of treatment.

Can I use hormonal contraception with Tracleer?

No. Bosentan is a potent inducer of liver enzymes that metabolise hormonal contraceptives, dramatically reducing their effectiveness. Combined oral contraceptives, the progesterone-only pill, contraceptive implants, patches, and injections are all significantly less effective when taken with bosentan. Two forms of non-hormonal contraception (such as condoms plus a barrier method or copper IUD) must be used throughout treatment and for at least one month after stopping.

Ace provides accurate and independent information medically reviewed on prescription medications. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment.