Lapatinib is a drug used primarily to treat women with advanced breast cancer. It can also be used to treat other types of cancer as part of a research trial.
WHAT IS LAPATINIB?
Lapatinib is a type of treatment called a tyrosine kinase inhibitor. Kinases are important proteins for the body that regulate the way cells grow and divide.
HOW DOES LAPATINIB WORK?
Lapatinib acts by blocking signals within the cancer cells that make them grow and divide. Blocking the signals causes them to die. Lapatinib stops the action of two proteins:
- erbB1, also known as epidermal growth factor receptor (EGFR)
- erbB2, also known as HER2.
There are tests to check the level of EGFR or HER2. These will tell you if you're likely to benefit from lapatinib. The test can be done at the same time as diagnosis or samples of cancer cells from previous biopsies or surgery.
WHEN IS LAPATINIB USED?
Lapatinib is used mainly to treat people with HER2-positive breast cancer that has spread to other parts of the body (advanced or metastatic breast cancer).
It is either given with chemotherapy called capecitabine or in combination with a type of hormone therapy.
WHAT DOES LAPATINIB LOOK LIKE?
Lapatinb is available as an oval-shaped, yellow tablet measuring 250 mg.
HOW IS LAPATINIB ADMINISTERED?
Lapatinib should be taken with a glass of water an hour before or after meals. It should not be taken with grapefruit or grapefruit juice. It should be taken at the same time each day, so if you start taking it an hour before meals, you should keep taking it at this time.
POSSIBLE SIDE EFFECTS OF LAPATINIB
Each person reacts differently to cancer treatment. Some people have very few side effects, while others may develop more. The side effects described here will not affect everyone who is treated with the drug.
We outline the most commonly side effects, though we have left out the rarer ones. If you notice you develop any side effects that are not listed here, talk to your doctor or specialist nurse.
The side effects of lapatinib are normally mild; however, because it is given with other treatments to fight cancer, there may also be certain side effects associated with these other treatments.
This is the most common side effect of lapatinib, and it develops around a week after the treatment. Normally, this can be easily controlled with drugs, so tell your doctor if your diarrhea is severe or ongoing. It's important to drink lots of fluids if you have diarrhea.
You may develop an acne-like rash on your head, chest, or back. This usually starts in the first 2-3 weeks of treatment and can disappear gradually over the first weeks even if you continue receiving the treatment. Your skin may become dry or sensitive. Tell your doctor if you develop any of the following side effects, as they can prescribe medication to help.
Taking this advice can help reduce the severity of changes to the skin, although they may not prevent them entirely:
- When bathing and washing, use tepid water and gentle, unscented soap.
- Avoid using skin products that contain alcohol.
- Do not use anti-acne products on your skin. Although the rash may look like acne, it is not. Anti-acne products can dry out your skin and make your symptoms worse.
- Apply sunscreen with a minimum SPF of 30 and UVA protection before going outside. Sunlight can worsen skin symptoms.
- Moisturize your skin regularly and after bathing.
Tiredness is a common side effect, especially toward the end of treatment and for a few weeks after the treatment has finished. It is important that you try to pace yourself and rest as much as you need to. Try to balance this with light exercise, such as taking short walks. If you feel drowsy, don't drive or operate heavy machinery.
NAUSEA AND VOMITING
Your doctor can prescribe antiemetic drugs to prevent or greatly reduce your nausea or vomiting. If your nausea remains uncontrolled or continues, tell your doctor.
Some of these drugs can cause constipation. Tell your doctor or nurse if this is a problem.
INDIGESTION AND HEARTBURN
This common side effect can usually be relieved by taking an antacid. You should have your antacid at least an hour before or after taking lapatinib. Tell your doctor or nurse if your indigestion doesn't go away.
STOMACH CRAMPS AND BLOATING
Tell your doctor if you have stomach cramps or bloating, as they can prescribe medication that will help relieve these symptoms.
LOSS OF APPETITE
Some people lose their appetite. This can be mild and last for a few days. If it doesn't get better, request to see a dietitian or specialist nurse at your hospital. They can give you advice on how to improve your appetite and maintain a healthy weight.
SORENESS OF THE MOUTH AND MOUTH ULCERS
Your mouth may become sore or dry or you may develop small ulcers during your treatment. Some find that sucking on ice can help. Drinking lots of fluids and regularly brushing your teeth gently using a soft-bristled toothbrush can help lower the risk of this happening. Tell your doctor or nurse if you have any of these problems, as they can prescribe a mouthwash and drugs to prevent infection in the mouth.
Your may experience constipation, so it could help to drink lots of fluids, eat a more fiber-rich diet, and get some light exercise. You may have to take laxatives to help with this.
MUSCLE AND JOINT PAIN
You may have joint or muscle pain, especially in your back. Tell your doctor if this happens so they can prescribe you some painkillers.
Some people find that lapatinib gives them headaches. Let your doctor or nurse know if this is the case, as they can give you painkillers to relieve this.
Some people have difficulty sleeping while taking lapatinib. Relaxation techniques can help this. If you still have problems sleeping, talk to your doctor about sedatives.
YOUR LIVER MAY BE TEMPORARILY AFFECTED
Rarely, lapatinib can temporarily change the way the liver functions. Though it is unlikely that these changes will cause damage to your liver, your doctor will monitor you closely.
CHANGES IN THE WAY THE HEART FUNCTIONS
Lapatinib may cause changes to the muscle in your heart. These changes can affect the way the heart works. You will have tests done before and during the treatment to see how well your heart is working.
ADDITIONAL INFORMATION ON LAPATINIB
Some drugs, including those bought over the counter in a store or pharmacy, may be harmful to you while you are taking lapatinib. Tell your doctor if you are taking any medicines, including over-the-counter medications, complementary therapies, and herbal medicines.
This treatment may affect your ability to conceive. It is important that you talk to your doctor before beginning treatment.
Little is known about the effects of lapatinib on developing babies. Therefore, it is not recommendable to become pregnant while taking this drug.
It is unknown whether lapatinib is present in semen or vaginal fluid. In order to protect your partner, it is safest to avoid having sex or use a barrier contraceptive device for about 48 hours after the chemotherapy.
There is a potential risk that lapatinib may be present in breast milk, and therefore women are recommended not to breast feed during the treatment and for a few months afterward.
If you are admitted to the hospital for any reason not related to cancer, it is important that you tell your doctors and nurses caring for you that you are receiving treatment with lapatinib.
OTHER ISSUES TO KEEP IN MIND ABOUT LAPATINIB TABLETS
It is important to take the pills as indicated by your doctor, nurse, or pharmacist.
If you are being treated for a non-cancerous condition, always tell your doctor you are taking lapatinib, and that lapatinib treatment should not be stopped or restarted without talking to your cancer specialist first.
Keep the tablets in their original packaging at room temperature. They should be stored away from heat and direct sunlight.
Keep them in a safe place out of the reach of children.
Tell your doctor if you vomit right after taking the pills. You may have to take another dose. Do not take any other pills before consulting with your doctor, nurse, or pharmacist.
If you forget to take a pill, do not take a double dose. Tell your doctor and maintain your normal dose schedule.
If your doctor decides to halt your treatment, return the remaining tablets to the hospital. Do not flush them down the toilet or throw them away.