Lapatinib (Oral)

Lapatinib is an antineoplastic chemotherapy treatment that is used for the treatment of advanced breast cancers.


Lapatinib is an oral medication taken in conjunction with capecitabine in the treatment of advanced or metastatic HER2-receptor positive cancer of the breast. This medication is an aggressive antineoplastic chemotherapy treatment that is used once the breast cancer has spread and only where other medications have already failed.

In postmenopausal women Lapatinib is used instead with letrozole in the treatment of HER2-receptor positive metastatic breast cancer.

Lapatinib works by interfering with the growth of the cancer cells, which will eventually allow the cancer to be destroyed. The growth of normal cells may also be affected by Lapatinib, which means that certain side effects will occur from use. Some side effects can be very serious and will need to be reported to the doctor immediately.

Lapatinib is available as Tykerb tablets only when prescribed by a doctor.

The medication will often make patients sick and nauseous. In this case it is vital that you continue use of the treatment so that it may have full effect.

Condition treated

  • Advanced or metastatic HER2-receptor positive breast cancers

Type Of Medicine

  • Antineoplastic
  • Chemotherapy

Side Effects

In addition to the needed effects of Lapatinib, other unwanted side effects can also occur. While not all of the following side effects may occur, in some cases when they do you will need to seek urgent medical attention.

You should check with your doctor immediately if you experience any of the following side effects:

Occurring less commonly:

  • Difficult breathing
  • Fainting or faintness
  • Increased heartbeat
  • Irregularity of heartbeat
  • Labored breathing
  • Severe diarrhea
  • Tightness across the chest
  • Unusual tiredness
  • Unusual weakness

Occurring only rarely:

  • Abdominal pain
  • Darkened urine
  • Decrease in appetite
  • Feverishness
  • Headaches
  • Itching
  • Lost appetite
  • Nausea
  • Skin rash
  • Stomach pain or tenderness
  • Stools with a clay-like coloration
  • Swelling of the feet or lower legs
  • Vomiting
  • Yellowing of the eyes
  • Yellowing of the skin

Frequency of occurrence not known:

  • Blistering of the skin
  • Chest pains
  • Chills
  • Coughing
  • Diarrhea
  • Difficulty with swallowing
  • Dizziness
  • General feeling of discomfort
  • General feeling of illness
  • Hives
  • Irritated eyes
  • Joint pains
  • Loosening of the skin
  • Muscle pain
  • Peeling of the skin
  • Puffy or swollen around the eyes, face, lips or tongue
  • Red eyes
  • Skin lesions that sometimes have a purple center
  • Soreness of the throat
  • Sores or ulcers appearing in the mouth
  • Thickening of bronchial secretions
  • White spots on the mouth or lips

Lapatinib may also cause other side effects that are less serious and do not necessitate that you seek medical attention. These side effects will usually abate over time and do not normally indicate the occurrence of wider medical conditions that need to be treated. If these side effects are ongoing or become bothersome, however, then you should consult your healthcare professional for advice on how you can alleviate the symptoms.

Occurring commonly:

  • Acid stomach
  • Sour stomach
  • Back pains
  • Belching
  • Cracking of the lips
  • Mild diarrhea
  • Dryness of the skin
  • Heartburn
  • Indigestion
  • Pain in the arms or legs without cause
  • Red, swollen or painful skin
  • Scaling of the skin on the hands and/or feet
  • Sores, ulcerations or white spots appearing on lips, tongue or inner mouth
  • Stomach discomfort
  • Stomach upset
  • Stomach pain
  • Swollen or inflamed mouth
  • Tingling of the hands and/or feet
  • Trouble with sleeping

Frequency of incidence not known:

  • Loosening of the fingernails
  • Reddening or soreness of the fingernails

In some patients Lapatinib may also cause other side effects to occur that have not been listed herein. If you experience any other side effects then you should contact your doctor for advice on how best to alleviate the symptoms and whether or not to seek further medical attention.


Before you begin use of this medication it is important that you understand the risks and benefits of doing so. Lapatinib is a very serious medication that will have a lasting impact on your body. You must work closely with your doctor during treatment to achieve the best outcome for your health.

Lapatinib must be taken only as directed by your doctor. You should not in any way adjust the schedule, dose or frequency of use and must take it only for the period ordered by your doctor.

This medication will be prescribed with a patient information guide. Before you begin treatment it is vital that you read this thoroughly and ensure that you understand it. If you have any questions after reading then you should consult your doctor for advice.

Lapatinib will always be given with either capecitabine or letrozole. You must take these medications as prescribed and at the correct time too. Failure to do so will limit the effective use of this treatment and expose you to greater risks of side effects.

You should not eat or drink any grapefruit or grapefruit products during treatment with this medication.

The dose of this medication given will vary from patient to patient. The dose you are given will depend on a range of factors including your wider health, age and the progression of the condition being treated. You should not ever make changes to your dose and should always follow the advice of your doctor exactly. The following information should be used as a guideline only and should not be used to make adjustments to your medication or dosing:

When taking Lapatinib in conjunction with capecitabine:

  • An adult will be treated with 1250mg once daily for 21 days. This 21-day cycle may be repeated depending on the results.
  • The doctor must determine the use of this medication in children.

When taking Lapatinib in conjunction with letrozole:

  • An adult will be treated with 1500mg once daily.
  • The prescribing doctor must determine the use and dose of this medication for children.

If a dose of medication is missed then you should take the dose as soon as possible. If you are close to your next dose being due, however, then you should skip the dose and return to your normal dosing schedule. Do not ever take a double dose to make up for missing a dose. You must inform your doctor if you have missed a dose of this medication.


Lapatinib can interact with other medication in the body. You should not take any other medications with this treatment unless you have been directed to by your doctor or healthcare professional. Certain medications can react violently in the body with severe medical complications. In other cases certain treatments may prevent others from working. To avoid interactions between medications you must inform your doctor of all other medications you are taking whether they were prescribed or otherwise obtained. This is especially important in the following cases:

The use of Lapatinib in conjunction with the following medications is not recommended. Your doctor may decide not to use this treatment if you are taking the following:

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

The use of Lapatinib is not normally recommended in conjunction with the following medication. In some cases, however, both treatments may be required and you may take both with adjusted doses or frequency of use:

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

Using Lapatinib with the following medication can increase the risk of side effects occurring. Both treatments may be used in some cases but the frequency of use and dose may be adjusted:

  • Paclitaxel

This list has been compiled due to the severity of the interactions that occur, but it is not necessarily all-inclusive. You must inform your doctor of all other medications you are taking too so that interactions can be prevented.

Lapatinib can also interact with certain foodstuffs. You should not consume the following in conjunction with Lapatinib:

  • Grapefruit Juice
  • Grapefruit

Other medical conditions from which you suffer can also impact on the use of Lapatinib. Some other conditions may be worsened by the use of this treatment and may prohibit its use. You must inform your doctor of all other medical conditions from which you suffer before beginning treatment. This is especially important in the following cases:

The following conditions may be worsened by treatment with Lapatinib:

The following conditions may cause more severe side effects to occur:

  • History of heart disease
  • Heart rhythm problems
  • Hypokalemia
  • Hypomagnesemia

Other medical problems not listed here could also impact on the use of Lapatinib. You must inform your doctor of your full medical history before use.


Before beginning use of this medication it is essential that you read the medication guide and understand it fully. You should ask your doctor for advice on anything that you do not understand and should ensure that all of the following has been taken into account:

Allergies ' You must inform your doctor of all allergies that you have suffered. This is particularly important if you have ever suffered a bad or unusual reaction to any medications in the past. You should also inform your doctor of any allergies to dyes, preservatives and other substances.

Pediatric ' Studies have not been carried out on the use of Lapatinib in children and safety has not been established.

Geriatric' There are no known limitations to the use of Lapatinib in the elderly. Caution should be used, however, as there is an increased likelihood of other medical conditions being present that may impact on its use.

Pregnancy' Using this medication when you are pregnant can cause harm to your baby. It is important that you use effective birth control to prevent pregnancy during use and for a period afterwards. If you believe that you have become pregnant during use then you must inform your doctor straight away.

Breastfeeding ' No specific tests have been carried out and the risks are unknown. Discuss this with your doctor. It is likely that you will be advised not to breastfeed during use as chemotherapy treatments can be passed on through breastmilk.

Your doctor will need to make regular checks on your health during treatment. This will confirm that the medication is working properly and blood tests may be taken to check for unwanted side effects

You may develop serious heart conditions with the use of this treatment. You must report any unusual heart rhythms or changes to your doctor immediately for examination.

You may develop a serious condition of the liver or liver failure with use of Lapatinib. You must report any of the following symptoms to your doctor straight away:

  • Pain or tenderness in the abdomen or stomach
  • Nausea
  • Sickness
  • Unusual tiredness
  • Unusual weakness
  • Yellowing of the eyes
  • Yellowing of the skin
  • Darkened urine
  • Paleness of stools

If severe diarrhea occurs then you must inform your doctor. Do not take over the counter diarrhea treatments as these may make it worse. Your doctor may prescribe you with further medication to help manage or prevent your diarrhea.

Serious lung problems can develop from the use of Lapatinib. If you are struggling with your breathing or develop a cough or other lung irritation then you should inform your doctor straight away.

Heart rhythm problems may develop with use. You should inform your doctor if you feel dizzy or faint. You should inform your doctor before treatment if any family members have suffered from heart rhythm problems in the past.

Serious skin problems can develop from the use of this medication. You must inform your doctor if you develop any rashes, loosening of the skin or scaling.

Do not take any other medications in conjunction with Lapatinib that have not been prescribed. To do so can put you at serious risk. All medications should be approved by your doctor before use.


This medication should be stored in the original packaging until you are ready to take it. Store it in a cool, dry place out of direct light.

Always keep this medication out of the reach of children.

You should not keep unwanted or unused medication for longer than necessary. Ask your healthcare professional how best to dispose of the medication that you have not used.


Lapatinib is an oral medication used in the treatment of certain advanced breast cancers. It is used in conjunction with either capecitabine or letrozole and is used only when other medications have failed to have the desired effects.

Lapatinib is an aggressive antineoplastic chemotherapy treatment that works by interfering with the growth of cancer cells. The medication will also interfere with the growth of normal cells, however, and as such will cause unwanted side effects to occur.

Lapatinib is provided with a medication guide that patients should read and understand. It is important that the risks are fully understood before use begins so that the patient knows what to expect and is prepared for the potential outcomes.

Lapatinib is usually taken in cycles of 21 days, although this cycle may be repeated if the cancer is still present in the patient after this time. The different combinations of treatment will have different cycles of dosing and different doses taken daily too.

This medication should not be used on pregnant women and females receiving this treatment will need to use effective birth control during treatment to prevent pregnancy from occurring. The use of Lapatinib when pregnant will cause harm to the unborn baby and must be avoided.

Lapatinib can cause certain side effects including nausea and the loss of fingernails to occur that may be bothersome to the patient. It is important that the course of treatment is completed, however, so that the treatment can have full effect and the cancer cells can be completely eliminated.