Lapatinib Newbury
Dual Tyrosine Kinase Inhibitor for HER2-Positive Breast Cancer
Quick Facts
Key Takeaways
- Lapatinib Newbury is a dual HER1/HER2 tyrosine kinase inhibitor used for HER2-positive metastatic breast cancer that has progressed after prior treatment.
- It is always used in combination with capecitabine, trastuzumab, or an aromatase inhibitor – never as monotherapy.
- Tablets must be taken on an empty stomach (at least 1 hour before or after meals) at the same time each day.
- Regular cardiac and liver function monitoring is essential throughout the treatment period.
- Diarrhoea is the most clinically significant side effect and should be reported to your doctor immediately at first onset for early management.
What Is Lapatinib Newbury and What Is It Used For?
Lapatinib Newbury belongs to a class of medications known as tyrosine kinase inhibitors (TKIs). It works by blocking the intracellular signalling pathways of two specific receptor proteins: HER1 (also known as EGFR or ErbB1) and HER2 (also known as ErbB2). In approximately 15–20% of all breast cancers, the HER2 protein is overexpressed on the surface of tumour cells, driving aggressive growth and proliferation. By inhibiting both HER1 and HER2, lapatinib can slow or stop the growth of cancer cells and potentially induce cell death.
Unlike monoclonal antibody therapies such as trastuzumab that target the extracellular domain of HER2, lapatinib acts on the intracellular tyrosine kinase domain, offering a complementary mechanism of action. This distinction is clinically significant because lapatinib may retain activity against certain forms of HER2-positive disease that have become resistant to trastuzumab, including some cases where the truncated p95HER2 receptor is present.
Lapatinib Newbury is not used as a standalone treatment. It is prescribed as part of combination regimens in three distinct clinical settings:
In combination with capecitabine
This combination is indicated for patients with HER2-positive advanced or metastatic breast cancer who have previously received treatment that included trastuzumab. The landmark EGF100151 trial demonstrated that adding lapatinib to capecitabine significantly improved time to progression compared with capecitabine alone in patients whose disease had progressed on trastuzumab-based therapy. This combination is particularly important for patients who have exhausted trastuzumab-containing regimens and require further systemic therapy.
In combination with trastuzumab
This regimen is indicated for patients with hormone receptor-negative metastatic breast cancer who have received prior treatments for advanced disease. The dual HER2 blockade approach – combining the intracellular kinase inhibitor lapatinib with the extracellular antibody trastuzumab – has shown improved outcomes compared with single-agent HER2 therapy. The EGF104900 trial provided evidence that this combination prolonged overall survival in patients with heavily pretreated HER2-positive metastatic breast cancer.
In combination with an aromatase inhibitor
This combination is used for postmenopausal women with hormone-sensitive (hormone receptor-positive), HER2-positive metastatic breast cancer who are not currently intended to receive chemotherapy. By blocking both the HER2 growth signalling pathway and oestrogen-driven tumour growth simultaneously, this dual inhibition strategy addresses cross-talk between hormone receptor and HER2 pathways that can drive resistance to endocrine therapy alone. The EGF30008 trial demonstrated significant improvement in progression-free survival with this combination.
What Should You Know Before Taking Lapatinib Newbury?
Contraindications
You must not take Lapatinib Newbury if you have a known allergy (hypersensitivity) to lapatinib or any of the other ingredients listed in the composition section of this page. Allergic reactions to lapatinib, while rare, can be serious and may include skin rash, hives, difficulty breathing, or swelling of the face, lips, tongue, or throat. If you have previously experienced an allergic reaction to lapatinib in any formulation, you should not take Lapatinib Newbury.
Warnings and Precautions
Before starting Lapatinib Newbury, your doctor will conduct a thorough assessment of your health and discuss any potential risks. It is essential that your doctor is aware of the following conditions:
Cardiac effects: Lapatinib can affect how your heart functions. Your doctor will perform cardiac assessments (including echocardiography or MUGA scan to measure left ventricular ejection fraction) before and at regular intervals during treatment. Decreases in left ventricular ejection fraction (LVEF) have been reported during lapatinib therapy. In clinical trials, approximately 1–2% of patients experienced symptomatic cardiac events. If you have pre-existing heart conditions, including congestive heart failure, coronary artery disease, or uncontrolled hypertension, discuss this with your doctor as the risks and benefits of treatment will need careful evaluation.
Liver function: Hepatotoxicity has been reported with lapatinib, ranging from asymptomatic elevations in liver enzymes to severe cases including hepatic failure. Your doctor will perform liver function tests before starting treatment and at regular intervals throughout. In rare cases, liver injury associated with lapatinib can be serious. Report any symptoms of liver problems immediately, including yellowing of the skin or eyes (jaundice), dark urine, nausea, vomiting, loss of appetite, or pain in the upper right abdomen.
Lung disease: Cases of interstitial lung disease and pneumonitis have been reported with lapatinib. If you have a history of lung disease or lung inflammation, inform your doctor before starting treatment. Seek immediate medical attention if you develop new or worsening shortness of breath, cough, or fever during treatment.
Kidney function: If you have kidney problems, your doctor may need to monitor you more closely during treatment, although no specific dose adjustment is required for mild to moderate renal impairment.
Diarrhoea: Diarrhoea is one of the most common and potentially serious side effects of lapatinib. Proactive management at the very first sign of loose stools is critical to prevent dehydration and more severe complications. Your doctor will advise you on preventive measures and when to start antidiarrhoeal medication.
Pregnancy and Breastfeeding
The effects of Lapatinib Newbury during pregnancy have not been established in humans. Based on its mechanism of action and findings from animal studies, lapatinib may cause harm to an unborn baby. You should not use Lapatinib Newbury if you are pregnant unless your doctor specifically recommends it after careful consideration of the risks and benefits.
If you are of childbearing potential, you must use reliable contraception during treatment and for at least 5 days after the last dose. If you become pregnant while taking Lapatinib Newbury, inform your doctor immediately.
It is not known whether lapatinib passes into breast milk. Due to the potential for serious adverse effects in a nursing infant, you must not breastfeed during treatment with Lapatinib Newbury and for at least 5 days after the last dose.
Driving and Operating Machinery
Lapatinib Newbury may cause side effects that could impair your ability to drive or operate machinery, including fatigue, dizziness, and visual disturbances. You are responsible for assessing your fitness to drive. If you experience any symptoms that affect your concentration or reaction time, do not drive or operate machinery and consult your doctor.
How Does Lapatinib Newbury Interact with Other Drugs?
Lapatinib is extensively metabolised in the liver by the cytochrome P450 enzyme system, particularly CYP3A4 and CYP3A5. It is also a substrate of the P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) transporters. Medications that affect these pathways can significantly change the concentration of lapatinib in your blood, potentially reducing its effectiveness or increasing the risk of side effects.
Additionally, lapatinib itself can inhibit certain enzymes and transporters, potentially affecting the blood levels of other medications you are taking. It is critical that your doctor reviews all your medications before starting Lapatinib Newbury.
Major Interactions
The following medications have clinically significant interactions with lapatinib and their concurrent use requires careful medical evaluation:
| Drug / Class | Effect on Lapatinib | Clinical Significance |
|---|---|---|
| Ketoconazole, Itraconazole, Posaconazole, Voriconazole (azole antifungals) | Increased lapatinib levels (CYP3A4 inhibition) | Higher risk of toxicity; dose adjustment may be needed |
| Rifampicin, Rifabutin (anti-tuberculosis agents) | Decreased lapatinib levels (CYP3A4 induction) | Reduced efficacy; avoid concurrent use |
| Ritonavir, Saquinavir (HIV protease inhibitors) | Increased lapatinib levels (CYP3A4 inhibition) | Higher risk of side effects; careful monitoring required |
| Phenytoin, Carbamazepine (anti-epileptics) | Decreased lapatinib levels (CYP3A4 induction) | Reduced efficacy; alternative anti-epileptic may be needed |
| St. John’s wort (herbal supplement) | Decreased lapatinib levels (CYP3A4 induction) | Avoid during treatment; may significantly reduce efficacy |
| Erythromycin, Telithromycin (macrolide antibiotics) | Increased lapatinib levels (CYP3A4 inhibition) | Higher risk of toxicity; use alternative antibiotic if possible |
Other Notable Interactions
Lapatinib can also affect the blood levels of certain other medications through its inhibition of CYP3A4, CYP2C8, P-gp, and BCRP transporters. The following require monitoring:
| Drug | Interaction Type | Recommendation |
|---|---|---|
| Digoxin | Lapatinib may increase digoxin levels (P-gp inhibition) | Monitor digoxin levels closely |
| Ciclosporin | Mutual P-gp interaction | Avoid concurrent use; discuss alternatives |
| Repaglinide | Lapatinib may increase repaglinide levels (CYP2C8 inhibition) | Monitor blood glucose; dose adjustment may be needed |
| Paclitaxel, Docetaxel, Irinotecan, Topotecan | Lapatinib may alter levels of these chemotherapy agents | Close monitoring required; dose adjustment possible |
| Rosuvastatin | Lapatinib may increase rosuvastatin levels (BCRP inhibition) | Monitor for statin-related side effects |
| Verapamil | May increase lapatinib levels | Use with caution; monitor for increased side effects |
| Acid-reducing agents (PPIs, H2 blockers, antacids) | May reduce lapatinib absorption | Separate dosing; discuss with your oncologist |
What Is the Correct Dosage of Lapatinib Newbury?
Always take Lapatinib Newbury exactly as prescribed by your oncologist. The dose varies depending on which combination therapy has been selected for your treatment. Your doctor will determine the appropriate dose based on the type of breast cancer being treated and your overall health status.
Adults
The following dosing regimens apply to adult patients. Lapatinib Newbury has not been studied in paediatric populations for breast cancer indications.
With Capecitabine
Dose: 1,250 mg (5 tablets of 250 mg) once daily, taken as a single dose.
Continue treatment daily for as long as your doctor recommends. Capecitabine is taken according to its own prescribing instructions (typically in 21-day cycles).
With Trastuzumab
Dose: 1,000 mg (4 tablets of 250 mg) once daily, taken as a single dose.
Trastuzumab is administered intravenously according to its own schedule, typically once every three weeks.
With an Aromatase Inhibitor
Dose: 1,500 mg (6 tablets of 250 mg) once daily, taken as a single dose.
The aromatase inhibitor (such as letrozole) is taken according to its own prescribing instructions.
How to Take the Tablets
Proper administration of Lapatinib Newbury is essential for consistent drug exposure and optimal efficacy:
- Swallow tablets whole with water, one at a time. Do not crush, chew, or break the tablets.
- Take on an empty stomach – either at least one hour before or at least one hour after a meal. Food significantly increases lapatinib absorption, which can lead to variable drug levels.
- Same time each day – take your dose at the same time in relation to meals every day. For example, if you consistently take it one hour before breakfast, maintain this schedule.
- Do not take a double dose if you miss a dose. Simply take the next dose at the usual scheduled time.
Dose Adjustments
Your doctor may reduce your dose or temporarily stop treatment depending on the side effects you experience. Common reasons for dose modification include cardiac events (decreased LVEF), hepatotoxicity, severe diarrhoea, or other grade 3–4 adverse events. Do not adjust your dose on your own – always follow your doctor’s instructions.
Missed Dose
If you forget to take a dose of Lapatinib Newbury, do not take a double dose to make up for the missed one. Skip the missed dose and take your next scheduled dose at the usual time. Taking extra tablets to compensate can increase the risk of serious side effects.
Overdose
If you take more Lapatinib Newbury than prescribed, or if someone accidentally ingests the medication, seek immediate medical attention. Contact your local poison control centre or go to the nearest emergency department. Bring the medication packaging with you if possible. There is no specific antidote for lapatinib overdose; treatment is supportive and symptomatic.
What Are the Side Effects of Lapatinib Newbury?
Like all medications, Lapatinib Newbury can cause side effects, although not everyone experiences them. The frequency and severity of side effects can vary between individuals and may also depend on which combination therapy is being used. Your oncology team will monitor you for side effects throughout treatment and can provide guidance on managing them.
Very Common
- Diarrhoea (can be severe; report to doctor immediately at first sign)
- Skin rash, dry skin, itching
- Loss of appetite
- Nausea and vomiting
- Fatigue and weakness
- Indigestion and constipation
- Mouth sores or soreness
- Abdominal pain
- Insomnia
- Back pain, joint pain, pain in hands and feet
- Hand-foot syndrome (tingling, numbness, pain, swelling, or redness of palms or soles)
- Cough and shortness of breath
- Headache
- Nosebleeds
- Hot flushes
- Unusual hair loss or thinning
Common
- Effects on heart function (usually asymptomatic; detected by monitoring tests; may cause irregular heartbeat or breathlessness)
- Liver problems (may cause itching, jaundice, dark urine, or upper right abdominal pain)
- Nail disorders (painful infection and swelling around the nail bed)
- Skin fissures (deep cracks or chapped skin)
Uncommon
- Interstitial lung disease / pneumonitis (may cause breathlessness or cough; seek immediate medical attention)
- Abnormal liver blood test values (usually mild and reversible)
Rare
- Severe allergic reactions (anaphylaxis)
Not Known
- Irregular heart rhythm (QT prolongation; changes in the electrical activity of the heart)
- Severe skin reactions including Stevens-Johnson syndrome (rash, skin redness, blistering of the lips, eyes, or mouth, peeling skin, fever)
- Pulmonary arterial hypertension (elevated blood pressure in the arteries of the lungs)
Managing Diarrhoea
Diarrhoea is one of the most significant side effects of Lapatinib Newbury and requires proactive management. If you experience diarrhoea during treatment:
- Stay hydrated: Drink 8 to 10 glasses of clear fluids per day (water, electrolyte drinks, or clear broth)
- Dietary adjustments: Choose low-fat, high-protein foods over fatty or spicy foods
- Eat cooked vegetables instead of raw vegetables, and peel fruit before eating
- Avoid dairy products (including ice cream) during episodes of diarrhoea
- Avoid herbal supplements as some may worsen diarrhoea
- Contact your doctor if diarrhoea persists or worsens
Managing Skin Rash
Skin reactions are common with lapatinib. To care for sensitive skin during treatment:
- Use gentle, soap-free cleansers
- Apply fragrance-free, hypoallergenic moisturisers regularly
- Use sunscreen with SPF 30 or higher when outdoors
- Report any rash to your doctor, particularly if it is severe, blistering, or accompanied by fever
How Should You Store Lapatinib Newbury?
Keep Lapatinib Newbury in its original packaging until ready for use. Store the tablets out of the sight and reach of children at all times. There are no special temperature or humidity requirements for storage of this medication.
Check the expiry date on the blister pack or bottle and the outer carton before each use. The expiry date refers to the last day of the stated month. Do not use any tablets after this date has passed.
Do not dispose of unused or expired medications via household waste or by flushing them down the drain. Return any unused medication to your pharmacist for safe disposal. These measures help to protect the environment and prevent accidental exposure.
What Does Lapatinib Newbury Contain?
Active Substance
The active ingredient is lapatinib. Each film-coated tablet contains lapatinib ditosylate monohydrate, equivalent to 250 mg of lapatinib. Lapatinib ditosylate is the salt form used to improve the stability and bioavailability of the drug.
Excipients (Inactive Ingredients)
The other ingredients are:
- Tablet core: Microcrystalline cellulose (E460), povidone (E1201), sodium starch glycolate, magnesium stearate (E470b)
- Film coating: Hypromellose (E464), titanium dioxide (E171), macrogol (E1521), polysorbate (E433), yellow iron oxide (E172)
Appearance and Pack Sizes
Lapatinib Newbury tablets are oval, biconvex, yellow film-coated tablets debossed with “250” on one side. They are available in the following pack sizes:
- Blister packs: 70, 84, or 105 tablets (aluminium blisters with 7 tablets per blister strip)
- Multi-pack: 140 tablets (2 packs of 70 tablets)
- Plastic bottles: 70, 84, 105, or 140 tablets
Not all pack sizes may be marketed in all countries.
Manufacturer: PharOS MT Ltd., HF62X, Hal Far Industrial Estate, Birzebbugia BBG3000, Malta.
Frequently Asked Questions About Lapatinib Newbury
Lapatinib Newbury is used to treat HER2-positive advanced or metastatic breast cancer. It is always used in combination with another cancer medication: capecitabine (for patients previously treated with trastuzumab), trastuzumab (for hormone receptor-negative metastatic disease), or an aromatase inhibitor (for hormone-sensitive disease). Your oncologist will select the most appropriate combination based on your tumour biology and treatment history.
The most common side effects include diarrhoea (which can be severe and should be reported immediately), skin rash, dry skin, itching, loss of appetite, nausea, vomiting, fatigue, insomnia, back and joint pain, hand-foot syndrome, headache, and nosebleeds. Your oncology team will help you manage these side effects throughout treatment.
Swallow the tablets whole with water, one at a time, at the same time each day. Take them on an empty stomach – at least one hour before or one hour after a meal. The number of tablets depends on your combination therapy: 5 tablets with capecitabine, 4 tablets with trastuzumab, or 6 tablets with an aromatase inhibitor. Never crush, chew, or break the tablets.
No, you should avoid grapefruit and grapefruit juice entirely while taking Lapatinib Newbury. Grapefruit inhibits the CYP3A4 enzyme that metabolises lapatinib, which can lead to higher than expected drug levels in your blood. This increases the risk of serious side effects. Other citrus fruits such as oranges and lemons are safe to consume.
The safety of Lapatinib Newbury during pregnancy has not been established. Based on its mechanism of action, it may harm an unborn baby. You should not take it during pregnancy unless your doctor specifically recommends it. Use reliable contraception during treatment and for at least 5 days after the last dose. Breastfeeding is also not recommended during treatment and for at least 5 days after the last dose.
Regular monitoring is essential while taking Lapatinib Newbury. Your doctor will check your heart function (LVEF via echocardiography or MUGA scan) before and during treatment, as lapatinib can affect cardiac function. Liver function tests are performed at baseline and at regular intervals throughout therapy. Blood counts and general health assessments are also carried out at each visit. Report any new symptoms to your oncology team promptly.
References
- Geyer CE, Forster J, Lindquist D, et al. Lapatinib plus capecitabine for HER2-positive advanced breast cancer. N Engl J Med. 2006;355(26):2733-2743. doi:10.1056/NEJMoa064320
- Blackwell KL, Burstein HJ, Storniolo AM, et al. Overall survival benefit with lapatinib in combination with trastuzumab for patients with human epidermal growth factor receptor 2-positive metastatic breast cancer: final results from the EGF104900 study. J Clin Oncol. 2012;30(21):2585-2592. doi:10.1200/JCO.2011.35.6725
- Johnston S, Pippen J Jr, Pivot X, et al. Lapatinib combined with letrozole versus letrozole and placebo as first-line therapy for postmenopausal hormone receptor-positive metastatic breast cancer. J Clin Oncol. 2009;27(33):5538-5546. doi:10.1200/JCO.2009.23.3734
- European Medicines Agency (EMA). Tyverb (lapatinib) – Summary of Product Characteristics. Available at: www.ema.europa.eu
- National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. Version 2.2025.
- Cardoso F, Paluch-Shimon S, Senkus E, et al. 5th ESO-ESMO international consensus guidelines for advanced breast cancer (ABC 5). Ann Oncol. 2020;31(12):1623-1649. doi:10.1016/j.annonc.2020.09.010
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List (2023). Geneva: WHO; 2023.
- British National Formulary (BNF). Lapatinib. National Institute for Health and Care Excellence (NICE). Available at: bnf.nice.org.uk
Medical Editorial Team
This article has been written, reviewed, and approved by iMedic’s medical editorial team, comprising board-certified specialists in oncology and clinical pharmacology.