Oral sirolimus for vascular malformations

What is a vascular malformation?

A vascular malformation is a group of abnormal blood vessels. These can form in the skin, soft tissues, or inside organs. They can affect veins, arteries, lymphatic vessels, or a mix of these. They might be present at birth but can become noticeable as your child grows. Symptoms can include swelling, pain, bleeding, or problems with nearby organs or tissues.

What is sirolimus?

Sirolimus (also called Rapamune in Canada) is a medicine that helps reduce abnormal blood and lymphatic vessel growths. It works by blocking a protein called mTOR, which is involved in cell growth and blood vessel formation. Sirolimus is often used in larger doses to prevent organ rejection after transplants, but it can also help manage certain vascular malformations. It helps with symptoms like pain, stiffness, reduced movement, infections, and abnormal clotting, but it is not a cure.

Why is sirolimus recommended for my child?

Your child’s doctor might recommend sirolimus if their vascular malformation is:

Causing significant pain or discomfort
Leading to frequent infections, swelling, or bleeding
Affecting a vital organ or causing breathing or feeding problems
Not responding to other treatments, like sclerotherapy or surgery

How is sirolimus given?

Sirolimus is taken by mouth as a liquid (1mg/mL) or tablet (1mg), once or twice a day. The liquid should be stored in the fridge and can last for 30 days once opened. It can be taken with or without food but should be consistent to ensure proper absorption. If diluting the solution in water or orange juice, follow the instructions provided, and always wash hands before handling the medicine. The dosage will be adjusted based on your child's size and response to the medicine. Your doctor will explain the specific dosing instructions.

What to expect with sirolimus treatment

Monitoring blood levels

Your child will need regular blood tests to check the medication levels in their body. These tests help the doctor adjust the dose to ensure it is safe and effective.

Regular check-ups

Your child will also need regular follow-up appointments to monitor their health, check for side effects, and see how well the vascular malformation is responding to the treatment. This may include physical exams, imaging tests (like ultrasounds or MRIs), and blood work.

What are the possible side effects of sirolimus?

Common side effects include:

Fever, headache, fatigue, nausea, stomach pain, or constipation
Low red or white blood cells, abnormal liver function, high cholesterol, slow healing, mouth sores
Increased risk of infections; report any signs of infection to your doctor promptly

Rare but serious side effects:

Heart fluid accumulation, blood clots, or lymphoma
Severe allergic reactions, including breathing difficulties or chest pain—seek immediate medical attention if these occur

Drug interactions

Sirolimus can interact with other medications, like certain antibiotics, antifungals, anti-epileptics, and blood pressure medications. Avoid grapefruit and grapefruit juice during treatment, as they can interfere with the drug’s effectiveness.

Important reminders

Store sirolimus safely out of children's reach and keep the oral solution refrigerated.
If your child vomits after taking sirolimus, consult your doctor for advice.
Avoid live vaccines while on sirolimus, but inactivated vaccines are safe.
Minimize sun exposure to reduce the risk of skin cancer; use protective clothing and sunscreen.

How long will my child need to take sirolimus?

The length of sirolimus treatment varies depending on the severity of the vascular malformation and how well your child responds to the medication. Some children may need to take it for several months to years, while others may use it intermittently.

Frequently asked questions

Will sirolimus cure my child’s vascular malformation?

Sirolimus is not a cure, but it can help control the symptoms and slow the growth of the vascular malformation. Some malformations may become less noticeable over time with treatment.

How quickly will we see results?

It can take several weeks to months before noticeable improvements occur. Your doctor will monitor your child’s progress and adjust the treatment plan as needed.

Is sirolimus safe for long-term use?

Many children can take sirolimus safely for long periods, but it requires regular monitoring to check for side effects. Your child’s doctor will review the benefits of the medication versus the risks.

What if my child misses a dose?

Give it as soon as you remember, unless it’s close to the time for the next dose. Do not give a double dose to make up for the missed one. If you're unsure, contact your doctor for advice.

Questions?

For more general information about vascular anomalies/Canadian resources, visit the Vascular Anomalies Canada website.

If you are a current CHEO patient and have any questions or concerns, please reach out to our office:
CHEO Vascular Anomalies Clinic 613-737-7600 ext. 2326