Zanvastro (zilganersen) is used to treat Alexander disease, a rare condition that affects the brain and spinal cord. Zanvastro is injected into the fluid around the spinal cord by a health care provider. It's typically given once every three months.
Like all medicines, Zanvastro can cause side effects. Some are mild and go away on their own, while others need prompt medical attention.
Keep reading to learn about the common and serious side effects reported with Zanvastro, tips that may help you manage them, and signs that mean it's time to call your health care provider.
This article doesn't include every possible side effect of Zanvastro. Tell your health care provider about any symptoms that concern you or don't go away, even if they aren't listed here.
Common Zanvastro Side Effects
The most commonly reported side effects of Zanvastro include:
- Vomiting
- Back pain
- Cough
- Headache
- Headache after the spinal injection procedure (post-lumbar puncture headache)
- Joint pain
- Sore throat
- Trouble swallowing
In most cases, these side effects are mild to moderate and improve within a few days. Tell your health care provider if any of these symptoms feel severe, last a long time, or get in the way of daily activities.
Serious Side Effects of Zanvastro
Less common but more serious side effects of Zanvastro include:
- Aseptic meningitis (inflammation around the brain and spinal cord that isn't caused by infection)
- Increases in white blood cells or protein in the fluid around your spinal cord, found through routine monitoring
If you have symptoms that feel serious or life-threatening, see a doctor right away.
Below, you'll find more details on these side effects, including tips that may help you manage them.
Tips for Managing Zanvastro Side Effects
Headache, including headache after the spinal injection
Headache is a commonly reported side effect of Zanvastro. Some people also develop a specific type of headache related to the lumbar puncture procedure itself, called a post-lumbar puncture headache. This type of headache is often worse when you sit up or stand, and it tends to ease when you lie flat. It happens because of a small amount of spinal fluid leaking out around the site where the needle was inserted.
To help manage headache:
- Rest in a quiet, dark room if needed.
- Lie flat for some time after your injection, if your health care provider recommends it.
- Drink enough fluids throughout the day.
- Some people may benefit from an over-the-counter pain reliever, but check with your health care provider or pharmacist first to make sure it's safe for you.
Contact your health care provider if your headache is severe, doesn't improve after lying down, or comes along with a fever, stiff neck, nausea, or sensitivity to light. These can be signs of a more serious problem (see "Aseptic meningitis" below).
Vomiting
Vomiting was one of the most commonly reported side effects in people treated with Zanvastro.
These tips may help manage it:
- Take small sips of clear fluids to avoid dehydration.
- Eat light, bland foods when you feel able.
- Avoid strong smells or foods that tend to trigger nausea.
Contact your health care provider right away if vomiting is ongoing, severe, or comes with signs of dehydration, such as dizziness, a dry mouth, or dark-colored urine.
Back pain and joint pain
Back pain and joint pain were both commonly reported with Zanvastro. This may be related to the injection procedure itself in some people.
Symptoms may include aching in your back or joints, stiffness, and general soreness.
These tips may help ease them:
- Use a heating pad or warm compress, or try a cold pack for up to 10 minutes at a time.
- Do some gentle stretches or light activity, if your health care provider says it's okay.
- Rest during flare-ups of pain.
An over-the-counter pain reliever may help, but check with your health care provider or pharmacist before taking one. Contact your health care provider if pain is severe, doesn't improve, or interferes with daily activities.
Cough
Cough was commonly reported in people treated with Zanvastro. It's often mild and temporary.
These tips may help ease your cough:
- Stay well hydrated with water or warm fluids such as tea.
- Use cough drops or throat lozenges.
- Use a humidifier to add moisture to the air.
Contact your health care provider if your cough is severe, doesn't go away, or happens along with a fever, chest pain, or trouble breathing.
Sore throat and trouble swallowing
Some people treated with Zanvastro reported a sore throat or new or worsened trouble swallowing.
These tips may help manage the conditions:
- Gargle with warm salt water to soothe a sore throat.
- Try throat lozenges or warm fluids.
- Eat smaller bites, chew food thoroughly, and sit upright during and after meals if swallowing feels difficult.
- Choose softer foods that are easier to swallow.
Contact your health care provider if a sore throat or swallowing trouble is severe, worsens, or makes it hard to eat or drink enough fluids.
Aseptic meningitis and changes in spinal fluid
Aseptic meningitis is the inflammation of the tissue surrounding the brain and spinal cord. Unlike the infectious form of meningitis, aseptic meningitis isn't caused by a germ. It's sometimes called chemical or drug-induced meningitis, and it has been reported with Zanvastro.
Symptoms of aseptic meningitis include:
- Severe headache
- Stiff neck
- Fever
- Nausea or vomiting
- Sensitivity to light
Contact your health care provider right away if you or your child gets these symptoms after a Zanvastro injection. Your health care provider may want to examine you and may order tests to check for this condition.
Separately, routine monitoring during studies also picked up increases in white blood cells or protein in the fluid around the spinal cord in some people, often without any symptoms at all. This is typically found through lab testing done around the time of your injection, not something you'd notice on your own.
If you develop aseptic meningitis, your health care provider may pause your treatment or give you a steroid medicine before future doses to help keep it from happening again. These decisions are made by your care team. Don't start, stop, or change any medicine on your own, including around the timing of your Zanvastro doses.
Reducing Your Risk of Zanvastro Side Effects
The following tips may help reduce your risk of side effects:
- Attend all follow-up appointments and lab tests your health care provider recommends, especially around the time of your injection.
- Keep track of any new or worsening symptoms, and share them with your health care provider.
- Tell your health care provider right away about headache, fever, stiff neck, or other symptoms that develop after an injection.
- Don't skip or delay scheduled doses without talking to your care team first.
Your health care provider can adjust your treatment plan as needed based on how you respond to Zanvastro.