lapatinib

What is the most important information I should know about lapatinib?

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

Before you take lapatinib, tell your doctor if you have heart disease, liver disease, an electrolyte imbalance (low potassium or magnesium), or a personal or family history of Long QT syndrome.

To make sure you can safely take lapatinib, your heart function will need to be checked before you start treatment. Your liver function will need to be checked every 4 to 6 weeks during treatment.

Take lapatinib on an empty stomach.

Take this medication for the entire length of time prescribed by your doctor.

What is lapatinib?

Lapatinib is a cancer medication.

Lapatinib is used together with another medicine called capecitabine (Xeloda) or letrozole (Femara) to treat a certain type of advanced breast cancer that has spread to other parts of the body.

Lapatinib is often given after other cancer medications have been tried without successful treatment of symptoms.

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

What should I discuss with my health care provider before taking lapatinib?

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

To make sure you can safely take lapatinib, tell your doctor if you have any of these other conditions:

• heart disease;
• liver disease;
• an electrolyte imbalance (such as low levels of potassium or magnesium in your blood); or
• a personal or family history of "Long QT syndrome."

FDA pregnancy category D. Do not use lapatinib if you are pregnant. It could harm the unborn baby. Use effective birth control, and tell your doctor if you become pregnant during treatment.

It is not known whether lapatinib passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are taking this medication.

How should I take lapatinib?

Take exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.

This medication comes with patient instructions for safe and effective use. Follow these directions carefully. Ask your doctor or pharmacist if you have any questions. Be sure to also read the medication guide or patient instructions for capecitabine (Xeloda) or letrozole (Femara).

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

The usual dose of lapatinib is equal to 5 or 6 tablets given at one time. The number of tablets you take will depend on your condition and whether you are also taking capecitabine (Xeloda) or letrozole (Femara).

Do not crush a lapatinib tablet. Swallow the pill whole. The medicine from a crushed or broken pill can be dangerous if it gets on your skin. If this occurs, wash your skin with soap and water and rinse thoroughly.

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.

Lapatinib is usually taken together with capecitabine (Xeloda) in a 21-day cycle. Lapatinib is given once daily for all 21 days in a row, and capecitabine is given twice daily for only the first 14 days of the cycle. This 21-day cycle is then repeated until your doctor decides that lapatinib is no longer an appropriate treatment for your condition. Follow your doctor's instructions.

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

Lapatinib is usually taken together with letrozole (Femara) daily for as long as you continue to take letrozole.

Take lapatinib for the full prescribed length of time. This medication is usually continued unless your condition gets worse or you have serious side effects.

Your heart function will need to be checked before you start treatment with lapatinib. To be sure this medication is not causing harmful effects, your liver function will need to be checked every 4 to 6 weeks. Visit your doctor regularly.

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

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

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

What should I avoid while taking lapatinib?

Grapefruit and grapefruit juice may interact with lapatinib and lead to potentially dangerous effects. Avoid using these products while taking lapatinib.

What are the possible side effects of lapatinib?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using lapatinib and call your doctor at once if you have a serious side effect such as:

• fast or pounding heartbeats;
• extreme dizziness or tired feeling;
• feeling like you might pass out;
• severe diarrhea;
• dry cough, feeling short of breath;
• white patches or sores inside your mouth or on your lips;
• nosebleeds; or
• nausea, pain in your upper stomach, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Less serious side effects may include:

• mild diarrhea, upset stomach;
• pain or redness on the palms of your hands or the soles of your feet;
• dry skin, mild rash;
• unusual hair loss; or
• problems with your fingernails or toenails.

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.

What other drugs will affect lapatinib?

Many drugs can interact with lapatinib. Below is just a partial list. Tell your doctor if you are using:

• bosentan (Tracleer);
• conivaptan (Vaprisol);
• dexamethasone (Decadron, Hexadrol);
• digoxin (Lanoxin, Lanoxicaps);
• imatinib (Gleevec);
• isoniazid (for treating tuberculosis);
• midazolam (Versed);
• sirolimus (Rapamune) or tacrolimus (Prograf);
• St. John's wort;
• rifabutin (Mycobutin), rifampin (Rifadin, Rifater, Rifamate), or rifapentine (Priftin);
• an antibiotic such as clarithromycin (Biaxin), erythromycin (E.E.S., EryPed, Ery-Tab, Erythrocin), levofloxacin (Levaquin), pentamidine (NebuPent, Pentam), and others;
• an antidepressant such as nefazodone, amitriptylline (Elavil, Vanatrip), citalopram (Celexa), desipramine (Norpramin), fluoxetine (Prozac, Sarafem), and others;
• antifungal medication such as itraconazole (Sporanox) or ketoconazole (Nizoral);
• a barbiturate such as phenobarbital (Solfoton);
• heart or blood pressure medication such as diltiazem (Cartia, Cardizem), felodipine (Plendil), nifedipine (Nifedical, Procardia), or verapamil (Calan, Covera, Isoptin, Verelan);
• heart rhythm medicine such as amiodarone (Cordarone, Pacerone), disopyramide (Norpace), propafenone (Rythmol), quinidine (Quin-G), sotalol (Betapace), and others;
• HIV or AIDS medications;
• medicine to prevent or treat nausea and vomiting, such as dolasetron (Anzemet) or ondansetron (Zofran);
• medicines to treat narcolepsy;
• medicines to treat psychiatric disorders, such as clozapine (FazaClo, Clozaril), haloperidol (Haldol), pimozide (Orap), or ziprasidone (Geodon);
• migraine headache medicine such as sumatriptan (Imitrex);
• narcotic medication such as methadone (Dolophine, Methadose); or
• seizure medication such as carbamazepine (Carbatrol, Tegretol), felbamate (Felbatol), oxcarbazepine (Trileptal), phenytoin (Dilantin), or primidone (Mysoline).

This list is not complete and there are many other drugs that can cause serious or life-threatening medical problems if you take them together with lapatinib. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor. Keep a list of all your medicines and show it to any healthcare provider who treats you.

Where can I get more information?

Your doctor or pharmacist can provide more information about lapatinib.