April 27, 2017
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(lapatinib) Tablets



Hepatotoxicity has been observed in clinical trials and postmarketing experience. The hepatotoxicity may be severe and deaths have been reported. Causality of the deaths is uncertain [see WARNINGS AND PRECAUTIONS].


Lapatinib is a small molecule and a member of the 4-anilinoquinazoline class of kinase inhibitors. It is present as the monohydrate of the ditosylate salt, with chemical name N-(3-chloro-4-{[(3fluorophenyl) methyl]oxy}phenyl)-6-[5-({[2-(methylsulfonyl)ethyl]amino}methyl)-2-furanyl]-4quinazolinamine bis(4-methylbenzenesulfonate) monohydrate. It has the molecular formula C29H26ClFN4O4S (C7H8O3S)2 H2O and a molecular weight of 943.5. Lapatinib ditosylate monohydrate has the following chemical structure:

TYKERB® (lapatinib) Structural Formula Illustration

Lapatinib is a yellow solid, and its solubility in water is 0.007 mg/mL and in 0.1N HCl is 0.001 mg/mL at 25°C.

Each 250 mg tablet of TYKERB contains 405 mg of lapatinib ditosylate monohydrate, equivalent to 398 mg of lapatinib ditosylate or 250 mg lapatinib free base.

The inactive ingredients of TYKERB are: Tablet Core: Magnesium stearate, microcrystalline cellulose, povidone, sodium starch glycolate. Coating: Orange film-coat: FD&C yellow No. 6/sunset yellow FCF aluminum lake, hypromellose, macrogol/PEG 400, polysorbate 80, titanium dioxide.

What are the possible side effects of lapatinib (Tykerb)?

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,...

Read All Potential Side Effects and See Pictures of Tykerb »

What are the precautions when taking lapatinib (Tykerb)?

Before taking lapatinib, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart disease (e.g., irregular heartbeat), liver disease.

Lapatinib may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can infrequently result in serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are...

Read All Potential Precautions of Tykerb »

Last reviewed on RxList: 4/25/2017
This monograph has been modified to include the generic and brand name in many instances.

Tykerb - User Reviews

Tykerb User Reviews

Now you can gain knowledge and insight about a drug treatment with Patient Discussions.

Here is a collection of user reviews for the medication Tykerb sorted by most helpful. Patient Discussions FAQs

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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