Lapatinib (Tykerb) is an oral medication used to treat certain types of breast cancer that has spread to other areas of the body (metastatic). This medication is only taken once a day, but it’s typically used together with another anticancer medication. Lapatinib (Tykerb) commonly causes diarrhea.
HER2-positive metastatic breast cancer
HR-positive, HER2-positive metastatic breast cancer
Lapatinib (Tykerb) is a tyrosine kinase inhibitor (TKI). It works by blocking the action of specific proteins called human epidermal growth factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR). HER2 and EGFR are both found on normal and cancer cells, and they play a role in cell growth.
In certain cancers, the cancer cells have more HER2 and EGFR proteins than normal cells. When these proteins are blocked by lapatinib (Tykerb), cancer cells can’t grow and spread as well.
Source: DailyMed
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
More common
difficult or labored breathing
itching, skin rash
loosening of the fingernails
nosebleed
redness or soreness around the fingernails
redness, swelling, or pain of the skin
scaling of the skin on the hands and feet
tightness in the chest
tingling of the hands and feet ulceration of the skin
unusual tiredness or weakness
Rare
decreased urine output
dilated neck veins
extreme tiredness or weakness
irregular breathing
irregular heartbeat
swelling of the face, fingers, feet, or lower legs
Incidence not known
Blistering, peeling, or loosening of the skin
chest discomfort
chills
clay-colored stools
dark urine
decreased appetite
difficulty with swallowing
dizziness
fainting
fast heartbeat
headache
irregular or slow heart rate
loss of appetite
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
red skin lesions, often with a purple center
red, irritated eyes
sores, ulcers, or white spots in the mouth or on the lips
stomach pain or tenderness
swelling of the feet or lower legs
vomiting
yellow eyes or skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Back pain
belching
cracked lips
diarrhea (mild)
difficulty in moving
discoloration of the fingernails or toenails
indigestion
lack or loss of strength
muscle pain or stiffness
pain in the arms or legs
stomach discomfort or upset
swelling or inflammation of the mouth
thinning of hair or hair loss
trouble sleeping
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Available as pills that are swallowed once a day
Available as a lower-cost generic
A treatment option for some people who’ve tried other medications before that didn’t work
Must take 5 or 6 pills all at once each day
Not used alone to treat your breast cancer; typically taken with another anticancer medication
Requires monitoring of your liver and heart health
Take lapatinib (Tykerb) at the same time every day. Take all the tablets at one time each day; don’t split them up over the course of a day.
Take your lapatinib (Tykerb) dose at least 1 hour before or 1 hour after a meal. Food can affect how much medication gets absorbed into the body, which might affect how well it works or how safe it is for you.
Avoid grapefruit and grapefruit juice while taking lapatinib (Tykerb). Grapefruit can raise the medication levels in your body and lead to a higher risk of side effects from lapatinib (Tykerb).
Make sure to stay hydrated as much as possible to avoid dehydration from possible diarrhea. During treatment, let your provider know if you get dehydrated (e.g., dry mouth, not urinating as much, lightheadedness, dizziness).
Whether you're female or male, if you're taking lapatinib (Tykerb) and you or your partner can get pregnant, use birth control during treatment and for at least 1 week after your last dose. Lapatinib (Tykerb) might cause harm to an unborn baby. Contact your provider if you or your partner becomes pregnant during this time.
It’s important to tell your provider and pharmacist about all the medications you take, including supplements and over-the-counter (OTC) medications. Certain medications can interact with lapatinib (Tykerb). Your provider can adjust your medication doses (including that of lapatinib (Tykerb)) or recommend safer alternatives.
Ask your provider or pharmacist about the best way to handle and throw away lapatinib (Tykerb) safely. Cancer medications can be very harmful to people who handle or come into contact with them.
Lapatinib (Tykerb) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk factors: Severe liver problems
Rarely, some people taking lapatinib (Tykerb) developed liver damage, which can be severe. Liver damage can happen within days or months of starting lapatinib (Tykerb). Your provider will track your liver health through lab work while you’re taking this medication. Let your provider know if you develop any symptoms of liver problems, including yellowing of the skin or whites of your eyes, dark urine, and pain or discomfort in the right upper stomach area.
Risk factors: Low blood magnesium or potassium levels | Heart problems, including those affecting heart rhythm | Taking other medications that can affect your heartbeat or damage your heart
Lapatinib (Tykerb) can cause problems with your heart, such as a change in how well your heart pumps blood through your body or a change in your heartbeat. Your provider will check how well your heart is working while you’re taking this medication. They also might check your heart rhythm regularly if you’re also taking other medications that can affect your heartbeat. Tell your provider if you have trouble breathing or feel your heart pounding or racing, dizzy, lightheaded, or tired. These can be symptoms of heart problems. If they’re severe, you might need a lower dose of lapatinib (Tykerb), or you might need to stop treatment.
Most people taking lapatinib (Tykerb) have diarrhea. Though severe cases aren’t common, some can be deadly. Diarrhea typically happens within the first week of starting lapatinib (Tykerb) and lasts about 5 days. If you start to have diarrhea or any changes in your bowel movement patterns, let your provider know immediately. They can recommend antidiarrheal medications like loperamide (Imodium A-D) if your diarrhea is mild. But if your diarrhea is severe, or if you have stomach cramping, nausea, or vomiting along with diarrhea, your provider will likely pause or stop your treatment.
Some people taking lapatinib (Tykerb) experienced lung problems like inflammation or scarring of the lungs. Contact your provider if you develop any new or worsening breathing problems like a cough that won’t go away or trouble breathing. Your provider might instruct you to stop taking lapatinib (Tykerb) while they figure out what is causing the problem.
Lapatinib (Tykerb) might cause harm to an unborn baby. If you’re a female who can get pregnant and you’re taking lapatinib (Tykerb), your provider might check to see if you’re pregnant before you start treatment. Make sure to use birth control while you’re receiving lapatinib (Tykerb) and for at least 1 week after your last dose. If you’re a male taking lapatinib (Tykerb) and your partner is able to become pregnant, you should also use birth control while you’re taking the medication and for at least 1 week after your last dose. Let your provider know right away if you or your partner becomes pregnant during this time.
Each tablet contains 250 mg of lapatinib.
HER2-positive metastatic breast cancer: The typical dose is 5 tablets (total of 1,250 mg of lapatinib) taken by mouth at one time every day.
HR-positive, HER2-positive metastatic breast cancer: The typical dose is 6 tablets (total of 1,500 mg of lapatinib) taken by mouth at one time every day.
Your dose might be different if you have liver problems.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
HER2-positive metastatic breast cancer
HR-positive, HER2-positive metastatic breast cancer
Advanced HER2-positive breast cancer that can’t be surgically removed
Metastatic HER2-positive breast cancer that’s spread to other parts of the body
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