Medication Information Leaflet

What is this medication for?

Bosentan is used to treat pulmonary arterial hypertension. It is an endothelin receptor antagonist (ERA) that lowers the pressure in the pulmonary arteries (blood vessels in the lungs that transfer oxygen into the blood) by blocking the effects of endothelin. It may have the potential to reverse some of the damage done by the condition. This should also improve symptoms such as breathlessness and increase your ability to exercise.

This medication may also be used for other conditions as determined by your doctor.

How should I take or use this medication?

• Do not stop taking your medication without checking with your healthcare professional as it may make your condition worse.
• You may take this medication with or without food.
• This medication is initially started at a lower dose. Your condition will be monitored closely. Your doctor may later adjust your dosage to better control your condition.

What should I do if I forget to take or use this medication?

If you forget to take a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose. Then take your next dose at the usual time. Do not take two doses to make up for the missed dose.

What precautions should I take when taking or using this medication?

Inform your healthcare professional if:

• You are allergic to this medication or any of the other ingredients of this medication.
• You are pregnant, planning to become pregnant, or breastfeeding.
  • As this medication may cause birth defects, female patients of childbearing age should take precautions by using at least 2 reliable methods of contraception to avoid pregnancy. If you suspect you may be pregnant, inform your doctor as soon as possible.
  • You should not become pregnant for at least 1 month after stopping this medication.
• You have or have had liver or kidney disease.
• You are taking any other medications, including supplements, traditional medications and herbal remedies.

What are some common side effects of this medication?

These side effects may be minimized by starting with a lower dose and may improve or go away with time. Inform your healthcare professional if it becomes bothersome or does not go away.

• Flushing, low blood pressure, fainting or headache
  • Rise slowly from a sitting or lying position to reduce giddiness when changing position
• Leg swelling (oedema)
• Flu-like symptoms such as nose and throat irritation, stuffy nose or back pain

What are some rare but serious side-effects that I need to seek medical advice immediately?

• The symptoms of a drug allergy include one or more of the following:
• Swollen face/eyes/lips/tongue
• Difficulty in breathing
• Itchy skin rashes over your whole body

Other rare but serious side effects include:

• Changes in liver function: Signs include dark urine or light coloured stools, nausea, vomiting, loss of appetite, stomach pain, yellowing of your eyes or skin.
• Low haemoglobin levels (anaemia): Signs include feeling more tired, weak or shortness of breath.

These side-effects are usually not significant, they are often treatable once detected early. You will need frequent blood tests to monitor for them.

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

What food or medication should I avoid when I take or use this medication?

Avoid taking grapefruit when you are taking this medicine as grapefruit may interact with your medicine and increase the risk of side-effects.

Some medications may interact with Bosentan and affect their effectiveness or increase the risk of side-effects. However, these medications may also be important for your treatment. Inform your healthcare professional of the other medications you are currently taking. Examples include:

• Glibenclamide/ Glyburide, a diabetes medication
• Cyclosporine, a medication for suppression of the immune system
• Medications for bacterial infections (e.g. clarithromycin, erythromycin)
• Medications for fungal infections (e.g. itraconazole, ketoconazole) 

Consult your healthcare professional if you are unsure whether your existing medications can be taken together with this medication.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children.

How do I throw away this medication safely?

Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.

Disclaimer

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore.

Last updated on Sept 2020