What is Lapatinib?

Hepatotoxicity, which may be fatal or severe, has been observed in clinical trials and postmarketing experience. Causality of the deaths is uncertain .

Lapatinib is used in combination with capecitabine to treat advanced or metastatic HER2-receptor positive breast cancer (breast cancer that has already spread) after other treatments have failed. It belongs to the group of medicines called antineoplastics (cancer medicines).

Lapatinib is also used together with letrozole to treat postmenopausal women with hormone-receptor positive and HER2-receptor positive metastatic breast cancer.

Lapatinib interferes with the growth of cancer cells, which are eventually destroyed. Since the growth of normal cells may also be affected by the medicine, other unwanted effects will also occur. Some of these may be serious and must be reported to your doctor.

This medicine is available only with your doctor's prescription.

Medicines used to treat cancer are very strong and can have many side effects. Before receiving this medicine, make sure you understand all the risks and benefits. It is important for you to work closely with your doctor during your treatment.

Take this medicine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

This medicine comes with a patient information insert. Read and follow the instructions carefully. Ask your doctor if you have any questions.

This medicine should be taken at least 1 hour before or 1 hour after a meal. All of the tablets are taken together as one dose.

Lapatinib is given together with capecitabine or letrozole. It is important that you take each medicine at the right time. Follow your doctor's instructions on when to take these medicines.

Do not eat grapefruit or drink grapefruit juice while you are using this medicine.

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (tablets):
  • For advanced or metastatic breast cancer with capecitabine:
    • Adults—1250 milligrams (mg) or 5 tablets together as a single dose once a day for 21 days. Your doctor may tell you to repeat the 21-day cycle.
    • Children—Use and dose must be determined by your doctor.
  • For metastatic breast cancer with letrozole:
    • Adults—1500 milligrams (mg) or 6 tablets together as a single dose once a day.
    • Children—Use and dose must be determined by your doctor.

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Appropriate studies have not been performed on the relationship of age to the effects of lapatinib in the pediatric population. Safety and efficacy have not been established.

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of lapatinib in the elderly.

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

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.

• Amifampridine
• Amisulpride
• Bepridil
• Cisapride
• Dronedarone
• Fluconazole
• Mesoridazine
• Nelfinavir
• Pimozide
• Piperaquine
• Posaconazole
• Saquinavir
• Sparfloxacin
• Terfenadine
• Thioridazine
• Ziprasidone

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.

• Alfuzosin
• Amiodarone
• Amitriptyline
• Amoxapine
• Anagrelide
• Apomorphine
• Aripiprazole
• Aripiprazole Lauroxil
• Arsenic Trioxide
• Asenapine
• Astemizole
• Atazanavir
• Azithromycin
• Bedaquiline
• Betrixaban
• Buprenorphine
• Buserelin
• Carbamazepine
• Ceritinib
• Chloroquine
• Chlorpromazine
• Ciprofloxacin
• Citalopram
• Clarithromycin
• Clomipramine
• Clozapine
• Cobicistat
• Conivaptan
• Crizotinib
• Cyclobenzaprine
• Dabrafenib
• Dasabuvir
• Dasatinib
• Degarelix
• Delamanid
• Desipramine
• Deslorelin
• Deutetrabenazine
• Dexamethasone
• Digoxin
• Disopyramide
• Dofetilide
• Dolasetron
• Domperidone
• Donepezil
• Droperidol
• Efavirenz
• Encorafenib
• Erythromycin
• Escitalopram
• Fingolimod
• Flecainide
• Fluoxetine
• Foscarnet
• Fosnetupitant
• Fosphenytoin
• Gatifloxacin
• Gemifloxacin
• Gonadorelin
• Goserelin
• Granisetron
• Halofantrine
• Haloperidol
• Histrelin
• Hydroxychloroquine
• Hydroxyzine
• Ibutilide
• Idelalisib
• Iloperidone
• Imipramine
• Indinavir
• Inotuzumab Ozogamicin
• Itraconazole
• Ivabradine
• Ivosidenib
• Ketoconazole
• Leuprolide
• Levofloxacin
• Lofexidine
• Lopinavir
• Lumefantrine
• Macimorelin
• Mefloquine
• Methadone
• Metronidazole
• Mifepristone
• Moxifloxacin
• Nafarelin
• Nefazodone
• Netupitant
• Nilotinib
• Norfloxacin
• Nortriptyline
• Octreotide
• Ofloxacin
• Ondansetron
• Osimertinib
• Paliperidone
• Panobinostat
• Pasireotide
• Pazopanib
• Phenytoin
• Pimavanserin
• Pitolisant
• Procainamide
• Prochlorperazine
• Promethazine
• Propafenone
• Protriptyline
• Quetiapine
• Quinidine
• Quinine
• Ranolazine
• Ribociclib
• Rifabutin
• Rifampin
• Rifapentine
• Ritonavir
• Salmeterol
• Sertraline
• Sevoflurane
• Simeprevir
• Sodium Phosphate
• Sodium Phosphate, Dibasic
• Sodium Phosphate, Monobasic
• Solifenacin
• Sorafenib
• Sotalol
• St John's Wort
• Sulpiride
• Sunitinib
• Tacrolimus
• Telavancin
• Telithromycin
• Tetrabenazine
• Tizanidine
• Topotecan
• Toremifene
• Trazodone
• Trifluoperazine
• Trimipramine
• Triptorelin
• Vandetanib
• Vardenafil
• Vemurafenib
• Venetoclax
• Vinflunine
• Voriconazole
• Zuclopenthixol

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.

• Paclitaxel

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

• Grapefruit Juice

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Diarrhea or
• Liver disease, or history of or
• Lung disease (eg, interstitial lung disease, pneumonitis), history of—Use with caution. May make these conditions worse.

• Heart disease, history of or
• Heart rhythm problems (eg, congenital long QT syndrome) or
• Hypokalemia (low potassium in the blood), uncorrected or
• Hypomagnesemia (low magnesium in the blood), uncorrected—Use with caution. May cause side effects to become worse.

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away.

Serious heart problems can occur with this medicine. Check with your doctor right away if you are having fast, pounding, or irregular heartbeats, shortness of breath, or unusual tiredness or weakness.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, a loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Check with your doctor right away if diarrhea occurs while taking this medicine. You may need medicines to help manage or prevent the diarrhea.

Check with your doctor right away if you start having breathing problems, shortness of breath, a cough, chest pain, fever, or chills. These could be symptoms of a serious lung problem.

Contact your doctor right away if you have any changes to your heart rhythm. You might feel dizzy or faint, or you might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you or anyone in your family has ever had a heart rhythm problem such as QT prolongation.

Serious skin reactions can occur with this medicine. Check with your doctor right away if you have blistering, peeling, or loose skin, red skin lesions, severe acne or skin rash, sores or ulcers on the skin, or fever or chills while you are using this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John's wort) or vitamin supplements.