Last Updated November 2008
What is bosentan?
Bosentan is an oral medication used to treat pulmonary arterial hypertension (PAH). It was approved by the Food and Drug Administration (FDA) in 2001 for the treatment of pulmonary arterial hypertension in patients with New York Heart Association (NYHA) Class III or IV symptoms. Bosentan is part of a class of medications called endothelin receptor antagonists or ERAs.
How does bosentan work?
Bosentan works by blocking the effects of a substance called endothelin, which is made by the body in increased amounts in patients with PAH. Endothelin causes blood vessels to narrow (constrict). It also causes scarring and overgrowth of the muscle in the walls of the blood vessels in the lungs. By blocking the action of endothelin, bosentan can lead to a reduction in the blood pressure in the lungs and to improvement in activity level and wellbeing. Improved exercise capacity and increased sense of wellbeing have been demonstrated in short-term studies of Tracleer. Open label studies suggest favorable long-term results in many patients, with some patients requiring addition of or change to other therapies. A recent study suggested that it may improve survival in NYHA class III patients compared to historical controls. Another recent study shows that it delays time to clinical worsening in NYHA class II patients. It has also been shown to improve 6 minute walk distance and hemodynamics in patients with congenital heart disease with Eisenmengers syndrome (right to left shunting).
How is bosentan given?
Bosentan is a pill that is taken orally twice a day. The initial dose for most patients is 62.5 mg twice a day. If there are no problems or side effects after one month, the dose is increased to 125 mg twice a day, which is the FDA approved dose.
What are the frequent side effects of bosentan?
Bosentan is generally well tolerated by patients with minimal side effects.
Reported side effects include nasal congestion, headache, flushing, and lower extremity swelling.
The red blood cell count or hematocrit may decrease in some patients but is rarely important.
Bosentan can interact with cholesterol reducing medications, decreasing their effectiveness.
The major potential side effect of bosentan is damage to the liver. in The development of abnormal liver function tests (LFTs), measured in blood samples to greater than 3 times the upper limit of normal is observed in about 10% of patients receiving this medication. However, bosentan has been given to thousands of patients without any reports of permanent liver damage.
Bosentan may decrease the effectiveness of hormonal contraceptives given by any route. Hormonal contraceptives should not be used alone for the prevention of pregnancy during treatment with bosentan.
Bosentan has been shown to be harmful to the growing fetus in rats. Therefore, pregnancy should be avoided in women treated with bosentan
Bosentan may lower sperm counts and decrease the ability to father children; this may be irreversible.
Monitoring for side effects of bosentan:
Because of the potential for damage to the liver, liver function tests must be obtained on a monthly basis as long as a patient is receiving bosentan.
Because of the potential harm to the fetus, women of childbearing potential must also have a monthly pregnancy test.
Hematocrit (blood count) should be monitored at least once every three months.
In patients receiving cholesterol lowering medications, cholesterol levels should also be checked at the end of the first month of therapy, as well as every six months, to determine if dosing should be adjusted.
How do patients obtain bosentan?
Bosentan must be prescribed by a physician and insurance approval must be obtained prior to starting therapy. Once approved by insurance, bosentan is then sent directly to patients by any of the four specialty pharmacies: Accredo Health Inc., Pharma Care Specialty Pharmacy or Caremark. Bosentan can only be obtained through the Tracleer Access Program.
Will insurance pay for bosentan?
The cost of bosentan is about $50,000 per year.
Most insurance will pay for bosentan prescriptions; however, insurance plans with a percentage type co-payment may result in substantial costs to the patient. There are organizations that may help defer some of this cost from the patient to a foundation, provided that the patient qualifies for such assistance.
Medicaid and most state-run insurance programs will pay for bosentan. Medicare will also cover bosentan in most cases under the part D component of that program. Co-payment costs may be substantial using this method, so patients are encouraged to apply for medical assistance through their state or through other organizations available to patients who are prescribed bosentan.
Do not take bosentan if:
- You are pregnant, plan to become pregnant, or become pregnant during treatment with bosentan. Notify your treating physician immediately if you become pregnant while receiving bosentan.
- Your blood tests show possible liver injury before starting therapy.
- You are taking cyclosporine-A, glyburide or ketaconazole.
Could a patient be allergic to bosentan?
This is possible, although such reports are rare.
Pregnant and nursing women
Use of bosentan is contraindicated in pregnancy. If a patient becomes pregnant while taking bosentan, she should immediately notify the prescribing physician. It is not known whether bosentan passes into breast milk
Use in children
Bosentan has been studied in children and appears to be safe. However, the dose may need to be adjusted and should be discussed with the prescribing physician.
