Zoledronic acid belongs to a group of drugs called bisphosphonates. It can be used to:
- help protect the bones from the effects of some treatments for early breast cancer
- reduce the risk of early breast cancer coming back – this is called adjuvant treatment
- reduce a raised calcium level in the blood caused by cancer that has spread to the bones
- treat bone weakness or pain caused by myeloma or by breast cancer that has spread to the bones.
Early breast cancer means the cancer has not spread beyond the breast or nearby lymph nodes.
Cancer that has spread to the bones is called secondary bone cancer. It happens when cells from the original (primary) cancer spread to form a new tumour (secondary cancer or metastasis) in thebone.
Myeloma is a cancer of a type of blood cell called plasma cells. The abnormal plasma cells build up inside bones, causing pain and weakness.
Bones are living and constantly renew themselves. This helps bones keep their strength and shape.
Inside the bones, there are two types of bone cell:
- osteoclasts, which break down and remove old bone
- osteoblasts, which build new bone.
When we are children and young adults our bones keep getting thicker and stronger. But, as we get older, osteoclasts begin to remove more bone than osteoblasts make. This means our bones slowly become thinner (less dense). In some people, too much bone is lost and they have an in-creased risk of bone fractures.
Myeloma and some secondary bone cancers make chemicals that cause osteoclasts to destroy more bone. This means that more bone is destroyed than rebuilt. The affected bone becomes weak and painful and can break more easily.
Bones contain calcium, which gives them strength. A bone affected by secondary cancer or mye-loma may lose calcium from the bones into the blood. A raised level of calcium in the blood is called hypercalcaemia. This may cause you to have symptoms including:
- feeling sick (nausea)
Zoledronic acid reduces the activity of the osteoclasts. This can help reduce pain and strengthen the bone.
It also reduces the amount of calcium that is lost from the bones. This helps calcium levels in the blood return to normal.
How long zoledronic acid is given for depends on why you are having the treatment.
- If you are having zoledronic acid to help prevent the cancer coming back, you will have an infusion once every 6 months for 3 to 5 years.
- If you are having zoledronic acid to reduce pain or strengthen your bones, your doctor will talk to you about how long you may need to have it for. You may need to have it for as long as it is working. It can take 2 to 3 months before you notice the full effects.
- If you are having zoledronic acid to lower calcium levels in your blood, it is usually given as a single dose.
We explain the most common side effects of this treatment here. We also include some less common side effects.
You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.
Serious and life-threatening side effects
Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.
Contact the hospital
Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.
We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.
Sometimes pain in muscles or bones gets worse for a short time when you start taking zoledronic acid. If this happens, your doctor can prescribe painkillers for you until it gets better.
- a high temperature
- pains in your muscles or joints.
Tell your doctor if these effects do not get better within 2 days or are causing problems. It may be helpful to take mild painkillers such as paracetamol. Your doctor, nurse or pharmacist can give you advice.
Rarely, this treatment may cause an allergic reaction.
Signs of an allergic reaction can include:
- a faster heartbeat
- swelling in your face
- skin reactions
- pain in your back, tummy or chest
- a rash or bruising on your skin
- flu-like symptoms.
Tell the nurse straight away if you think you may be having an allergic reaction. If you develop these symptoms when you are at home, contact the hospital straight away on the number you have been given. They can give you advice.
Numbness or tingling
You may notice numbness or tingling around the mouth, or in the fingers and toes. This may be caused by low levels of calcium in your blood. You will have regular blood tests to check your calcium levels. Contact your doctor straight away if you have these symptoms.
You may be asked to take calcium and vitamin D supplements, unless you are having this treatment to lower the levels of calcium in your blood. Your doctor will let you know if any supplements are needed.
Effect on the kidneys
This treatment can affect how your kidneys work. Drinking plenty of fluids will help your kidneys work well. You will have blood tests to check how well your kidneys are working. Tell your doctor if:
- you feel generally unwell
- have any swelling of your face, arms, legs or tummy
- you notice a change in how often you pass urine (pee).
Red or sore eyes
Tell your doctor if you have red or sore eyes. They can prescribe eye drops to help.
This treatment may cause changes in the blood. For example, it can cause low levels of red blood cells (anaemia). Symptoms of anaemia include feeling very tired and breathless. Your doctor can do blood tests to check this.
This is not common, but it is important to tell your doctor if you are getting headaches. They will advise you about what medicines to take. It is also important to drink plenty of fluids.
You may feel sick or be sick (vomit) during treatment. This is usually mild. Your doctor can prescribe anti-sickness tablets to help.
Take the drugs exactly as your nurse or pharmacist tells you to. It is easier to prevent sickness than treat it after it has started.
Pain in the thigh, hip or groin
Rarely, people having this treatment develop a break (fracture) in their thigh bone without any obvious cause. Sometimes both thigh bones are affected.
If you have any thigh, hip or groin pain, tell your doctor and mention that you are taking bisphosphonates. They can arrange tests to check the thigh bones for any signs of weakness or fracture.
Rarely, this treatment can affect the jawbone. Healthy bone in the jaw becomes damaged and dies. This is called osteonecrosis of the jaw (ONJ). It can cause:
- loosening of the teeth
- problems with the way the gums heal.
The risk of jaw problems is higher after some types of dental treatment and in people who have gum disease or dentures that do not fit well.
It is important to avoid having any dental treatment that could affect your jawbone when you are having bisphosphonates. This includes having a tooth or root removed or dental implants put in. You can still have fillings, gum treatments or a scale and polish.
To reduce your risk of developing jaw problems your doctor will advise you to:
- have a full dental check-up before starting treatment
- look after your teeth and gums during treatment (ask your dentist for advice)
- tell your dentist you are taking a bisphosphonate before having any dental treatment.
Tell your cancer specialist and dentist straight away if you at any time you develop:
- swelling or redness in your gums
- numbness or heaviness in your jaw
- loose teeth.
Very rarely, bones in the outer ear may be affected by this treatment. Always tell your doctor if you have any:
- ear pain
- discharge from your ear
- ear infections.
You should also let them know if you notice any other changes in your ears or hearing.
Going into hospital
Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:
- medicines you have been prescribed
- medicines you buy in a shop or chemist
- vitamins, herbal drugs and complementary therapies.
Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.
You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.
You are advised not to breastfeed while having this treatment, or for some time after treatment finishes. This is because the drugs could be passed to the baby through breast milk.
Your doctor or nurse can give you more information.