Indications
Lapatinib is a targeted cancer medicine used for advanced or metastatic breast cancer that is HER2-positive (the cancer cells have too much of a protein called HER2). It is given together with Capecitabine after earlier treatments, or with Letrozole or another aromatase inhibitor in women after menopause whose cancer is also hormone receptor positive.
How It Works
Lapatinib blocks two growth signal proteins on cancer cells, HER2 and EGFR, from inside the cell. This stops the signals that tell the cancer cells to grow and divide, slowing the disease.
Dosage and Administration
Take exactly as prescribed by your cancer specialist. The tablets are taken once a day, all at the same time, either at least 1 hour before or at least 1 hour after food, at the same time each day. Do not split the daily dose. If you miss a dose, skip it and take the next dose at the usual time. Your doctor may pause or lower the dose if side effects occur.
Interactions
Avoid grapefruit and grapefruit juice. Ketoconazole, Itraconazole, Clarithromycin and Ritonavir raise its level; Rifampicin, Carbamazepine, Phenytoin and St John’s Wort lower it. Acid reducers such as Omeprazole may reduce absorption. Avoid other medicines that prolong the QT interval. It can raise levels of Digoxin and some other medicines. Tell your doctor about all medicines you take.
Contraindications
- Allergy to lapatinib or any ingredient
- Use with care or avoid in severe liver disease, heart failure or long QT interval
Side Effects
Very common effects are diarrhoea, nausea, vomiting, rash, dry skin, redness and soreness of the palms and soles, mouth sores, tiredness and loss of appetite. It can reduce the heart’s pumping strength and affect liver function. Rarely, it can cause lung inflammation.
Get urgent medical help for severe or long-lasting diarrhoea (more than 4 loose stools a day above normal, or with fever or dizziness), breathlessness, swelling of the ankles, fast or irregular heartbeat, yellow skin or eyes or dark urine, a new cough, or a severe skin reaction.
Pregnancy and Lactation
Lapatinib may harm an unborn baby. Women should use reliable contraception during treatment and for at least 1 week after the last dose. Do not breastfeed during treatment and for at least 1 week after the last dose.
Precautions and Warnings
Your doctor will check heart function (echo scan), liver tests and ECG before and during treatment. Start anti-diarrhoea treatment and drinking extra fluids early as advised. Tell your doctor about any heart or liver problems.
Overdose
Overdose may cause severe diarrhoea and vomiting. Seek medical help at once.
Therapeutic Class
Antineoplastic; tyrosine kinase inhibitor
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.