Tykerb (Lapatinib) belongs to the class of medications called antineoplastics (anticancer medications). It is used in combination with another anticancer medication, Capecitabine, to treat advanced or metastatic (cancer that has spread to other parts of the body) Breast Cancer that is HER2-receptor positive and has progressed despite treatment with other anticancer medications, including Trastuzumab. Tykerb (Lapatinib) is also used in combination with the medication Letrozole, when suitable, for the treatment of metastatic post-menopausal breast cancer in women whose cancer is HER2-receptor positive.

Tykerb (Lapatinib) delays the progression of breast cancer but does not reduce its symptoms or improve survival. It works by interfering with the growth of certain cancer cells. Your doctor may have suggested Tykerb (Lapatinib) for conditions other than those listed in these drug information articles. As well, some forms of Tykerb (Lapatinib) may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking Tykerb (Lapatinib), speak to your doctor. Do not stop taking Tykerb (Lapatinib) without consulting your doctor.

Do not give Tykerb (Lapatinib) to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take Tykerb (Lapatinib) if their doctor has not prescribed it.

Lapatinib/capecitabine combination: The usual dose of Tykerb (Lapatinib) is 1,250 mg (5 tablets) once daily. It should be taken at least 1 hour before or at least 1 hour after a low-fat meal. The tablets should be swallowed whole with water. Do not drink grapefruit juice while you are taking Tykerb (Lapatinib).

Lapatinib/letrozole combination: The usual dose of Tykerb (Lapatinib) is 1,500 mg (6 tablets) once daily. It should be taken at least 1 hour before or at least 1 hour after a low-fat meal. The tablets should be swallowed whole with water. Do not drink grapefruit juice while you are taking Tykerb (Lapatinib).

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take Tykerb (Lapatinib) exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store Tykerb (Lapatinib) at room temperature (but not above 30°C) and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Tykerb (Lapatinib). If you are concerned about side effects, discuss the risks and benefits of Tykerb (Lapatinib) with your doctor.

The following side effects have been reported by at least 1% of people taking Tykerb (Lapatinib). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• back pain
• Constipation
• difficulty sleeping
• dry skin
• Fever
• hair loss or thinning
• headache
• indigestion
• joint pain
• loss of appetite
• mouth sores or sore mouth
• nail tenderness, infection, or swelling
• nausea
• nosebleeds
• pain in the arms or legs
• skin rash
• stomach pain
• sun sensitivity
• tingling, numbness, pain, swelling, or redness of the palms of the hands or soles of the feet
• tiredness
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Diarrhea
• symptoms of heart problems (e.g., shortness of breath, swelling of the ankles or feet, chest pain, irregular heartbeat)
• symptoms of irregular heartbeat (e.g., chest pain, dizziness, rapid, pounding heartbeat, shortness of breath)
• symptoms of liver problems (e.g., nausea, vomiting, abdominal pain, yellowing of the skin and eyes, itchy skin, dark urine)
• symptoms of lung problems (e.g., shortness of breath or difficulty breathing, chest pain, cough)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• symptoms of a Anaphylaxis (severe allergic reaction) (e.g., Hives; difficulty breathing; swelling of the face, mouth, tongue, or throat)
• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Tykerb (Lapatinib).

Each yellow, oval, biconvex, film-coated tablet, with one side plain and the opposite side debossed with "GS XJG", contains Tykerb (Lapatinib) ditosylate 250 mg. Nonmedicinal ingredients: tablet core: magnesium stearate, microcrystalline cellulose, povidone, and sodium starch glycolate; coating: hypromellose, iron oxide red, iron oxide yellow, macrogol/PEG 400, polysorbate 80, and titanium dioxide.

Do not take Tykerb (Lapatinib) if you are allergic to Tykerb (Lapatinib) or any ingredients of the medication or the container.

There may be an interaction between Tykerb (Lapatinib) and any of the following:

• Aliskiren
• Amiodarone
• other anticancer medications (e.g., Docetaxel, Doxorubicin, Paclitaxel, Teniposide, Topotecan, Venetoclax, Vincristine)
• antipsychotics (e.g., Chlorpromazine, Clozapine, Haloperidol, Olanzapine, Quetiapine, Risperidone)
• Apixaban
• Aprepitant
• "azole" antifungals (e.g., ketoconazole, itraconazole, Voriconazole)
• bilastine
• Bosentan
• calcium channel blockers (e.g., Amlodipine, Diltiazem, Nifedipine, Verapamil)
• Carbamazepine
• Carvedilol
• cetirizine
• chloroquine
• Cobicistat
• Colchicine
• conivaptan
• corticosteroids (e.g., Hydrocortisone, Prednisone, Dexamethasone)
• Cyclosporine
• dabigatran
• Deferasirox
• Degarelix
• Digoxin
• Dipyridamole
• Disopyramide
• dofetilide
• Domperidone
• Dronedarone
• Edoxaban
• estrogens (e.g., conjugated estrogen, Estradiol, ethinyl estradiol)
• Fentanyl
• "gliptin" diabetes medications (e.g., Linagliptin, Saxagliptin, Sitagliptin)
• grapefruit juice
• Hepatitis C antivirals (e.g., daclatasvir, ledipasvir, sofosbuvir, velpatasvir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delavirdine, efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• Lomitapide
• Loperamide
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• Methadone
• Methotrexate
• mifepristone
• Modafinil
• Nadolol
• Phenobarbital
• Phenytoin
• primidone
• procainamide
• other protein kinase inhibitors (e.g., Pazopanib, Sunitinib)
• Prucalopride
• quinidine
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, Norfloxacin, Ofloxacin)
• Ranitidine
• rifabutin
• rifampin
• Riociguat
• Romidepsin
• St. John's wort
• selective serotonin reuptake inhibitors (SSRIs; e.g., Citalopram, Fluoxetine, Paroxetine, Sertraline)
• serotonin antagonists (anti-emetics; e.g., Granisetron, Ondansetron)
• Silodosin
• Sirolimus
• Sotalol
• "statin" anticholesterol medications (e.g., Atorvastatin, Lovastatin, Simvastatin)
• Stiripentol
• Tacrolimus
• Tocilizumab
• Tolvaptan

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Tykerb (Lapatinib). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.