Lapatinib

Lapatinib is used to treat advanced hormone-related breast cancer that has gotten worse or spread after other cancer treatments.

Lapatinib is used for this condition only if your tumor tests positive for a protein called human epidermal growth factor receptor 2 (HER2). HER2 protein can make cancer cells grow faster.

In postmenopausal women, lapatinib is given along with a hormonal medicine called letrozole (Femara). In others, lapatinib is given together with a cancer medicine called capecitabine (Xeloda).

Lapatinib may also be used for reasons not listed in this medication guide.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

When used with letrozole, the usual dose of lapatinib is 6 tablets taken once daily every day. Letrozole is also taken every day.

When used with capecitabine, the usual dose of lapatinib is 5 tablets taken once daily for 21 days in a row. Capecitabine is also taken twice daily for only the first 14 days. This 21-day cycle is then repeated.

Follow your doctor's dosing instructions very carefully.

Take lapatinib on an empty stomach, at least 1 hour before or 1 hour after a meal.

You may swallow each lapatinib tablet one at a time, but take the entire dose (all 5 or 6 tablets) at the same time each day.

Capecitabine must be taken with food or within 30 minutes of eating.

You will need blood tests every 4 to 6 weeks to check your liver function. Your heart function may also need to be checked using an electrocardiograph or ECG (sometimes called an EKG).

Store lapatinib at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

Your doctor will determine how long to treat you with lapatinib and capecitabine or letrozole. Take your medications for the full prescribed length of time. Combination chemotherapy is usually continued unless your condition gets worse or you have serious side effects.

Do not use lapatinib if you are pregnant. It could harm the unborn baby.

Lapatinib can cause serious or life-threatening liver issues. Call your doctor immediately if you experience: upper stomach pain, itching, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

You should not use lapatinib if you are allergic to it.

Tell your doctor if you have ever had:

• heart disease;
• liver disease (lapatinib can cause severe or fatal liver problems);
• an electrolyte imbalance (such as low levels of potassium or magnesium in your blood); or
• long QT syndrome (in you or a family member).

You may need to have a negative pregnancy test before starting this treatment.

Both men and women using lapatinib should use effective birth control to prevent pregnancy. Lapatinib can harm an unborn baby or cause birth defects if the mother or father is using this medicine. Keep using birth control for at least 1 week after your last dose.

Tell your doctor right away if a pregnancy occurs while either the mother or the father is using lapatinib.

Do not breast-feed while using this medicine, and for at least 1 week after your last dose.

Get emergency medical help if you have signs of an allergic reaction (hives, difficulty breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Lapatinib can cause severe or fatal liver problems. Call your doctor immediately if you have: upper stomach pain, itching, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Also call your doctor right away if you have:

• fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might faint);
• severe or ongoing diarrhea; or
• new or worsening cough, wheezing, chest pain, feeling short of breath.

Common side effects of lapatinib may include:

• indigestion, loss of appetite;
• nausea, vomiting, diarrhea;
• rash, itching, dry skin, acne;
• pain or redness on the palms of your hands or the soles of your feet;
• problems with your fingernails or toenails;
• feeling weak or tired;
• nosebleeds, mouth sores;
• thinning hair; or
• headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Usual Adult Dose for Breast Cancer:

HER2-Positive Metastatic Breast Cancer (in combination with capecitabine): 1250 mg orally once a day on Days 1 to 21 continuously in repeating 21-day cycles in combination with capecitabine 2000 mg/m2/day (administered orally in 2 doses approximately 12 hours apart) on Days 1 to 14 in a repeating 21-day cycleHormone Receptor-Positive, HER2-Positive Metastatic Breast Cancer (in combination with letrozole): 1500 mg orally once a day continuously in combination with letrozole 2.5 mg orally once a dayComments:-The dose of this drug should be once daily (5 tablets administered all at once); do not divide the daily dose. is not recommended [see Clinical Pharmacology (12.3)]. Capecitabine should be taken with food or within 30 minutes after food. If a day's dose is missed, the patient should not double the dose the next day. Treatment should be continued until disease progression or unacceptable toxicity occurs.-HER2-positive metastatic breast cancer patients should have disease progression on trastuzumab prior to initiation of therapy with this drug in combination with capecitabine.Uses: -In combination with capecitabine for treatment of patients with advanced or metastatic breast cancer whose tumors overexpress HER2 and who have received prior therapy including an anthracycline, a taxane, and trastuzumab.-In combination with letrozole for treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer that overexpresses the HER2 receptor for whom hormonal therapy is indicated.

Take the medicine as soon as possible, but skip the missed dose if it is nearly time for your next dose. Do not take two doses at once.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

• Grapefruit may interact with lapatinib and lead to unwanted side effects. Avoid the use of grapefruit products.

Sometimes, it is not safe to use certain medications together. Some drugs can change how much of another drug is in your blood, which may increase side effects or reduce the effectiveness of the medications.

Many drugs can affect lapatinib. This includes prescription medicines, over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are mentioned here. Inform your doctor about all the medicines you are currently taking and any medicine you start or stop using.