LAPANIX (LAPATINIB) 250MG Tabs 150`S

Lapatinib is an oral dual tyrosine kinase inhibitor that blocks both EGFR (HER1) and HER2 receptor tyrosine kinases simultaneously. HER2 overexpression drives tumour growth in approximately 20–25% of breast cancers; lapatinib blocks the intracellular signalling downstream of both receptors, inhibiting cancer cell proliferation and survival.

It is used in combination (never as monotherapy) for: HER2-positive advanced or metastatic breast cancer — in combination with capecitabine (after prior treatment with anthracycline, taxane, and trastuzumab); or in combination with letrozole in post-menopausal women with HER2-positive, hormone receptor-positive metastatic breast cancer.

The usual dose is 1250 mg (5 tablets of 250 mg) once daily when combined with capecitabine, OR 1500 mg (6 tablets) once daily when combined with letrozole. Take on an EMPTY STOMACH — at least 1 hour before or 1 hour after a meal. Take all tablets at the same time each day. Do not crush or chew.

Lapatinib must not be used in: known hypersensitivity; severe hepatic impairment (Child-Pugh C) — contraindicated; known QT prolongation; and with strong CYP3A4 inhibitors or inducers without dose adjustment.

•       Strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, clarithromycin): markedly increase lapatinib — avoid or reduce lapatinib dose to 500 mg/day.

•       Strong CYP3A4 inducers (rifampicin, carbamazepine, dexamethasone, St John's Wort): markedly reduce lapatinib levels — avoid; if unavoidable, increase lapatinib dose gradually.

•       QT-prolonging agents: additive risk — avoid or monitor ECG.

•       Substrates of CYP3A4, CYP2C8 and P-glycoprotein (digoxin, warfarin, ciclosporin): lapatinib inhibits these — monitor levels.

Store below 30°C. Original packaging, protect from moisture. Keep out of reach of children.

Lapatinib must always be taken on an empty stomach — this is one of the most important instructions. Food dramatically increases drug absorption and worsens side effects. Plan your daily schedule so you take the tablets at least 1 hour before or 1 hour after eating.

Diarrhoea and hand-foot syndrome are the most common reasons for dose reductions. Both are more manageable with early action: start loperamide at the very first loose stool; apply thick emollient cream to hands and feet every day from the start of treatment.

Lapatinib 1250 mg/day (5 × 250 mg) with capecitabine is the EMA-approved combination for trastuzumab-pretreated HER2+ MBC. The 1500 mg/day (6 × 250 mg) dose is used with letrozole in hormone receptor-positive/HER2-positive MBC.

LVEF monitoring is mandatory — discontinue permanently if absolute LVEF decrease ≥ 20% below baseline and below institutional lower limit of normal.

Hepatotoxicity: severe (Grade 3+) in ~2% — monitor LFTs monthly; reduce dose to 750 mg/day in severe hepatic impairment (Child-Pugh C). 150-tablet pack = 30 days at 5 tablets/day. QTc baseline essential — do not start if QTc > 480 ms.

My heart scan showed a change — what does that mean?

Lapatinib can reduce the heart's pumping function (LVEF) in some patients. Your oncologist will discuss whether a dose adjustment or temporary break in treatment is needed based on the degree of change.

Can I take ibuprofen for pain?

Consult your oncologist before taking any over-the-counter medicines. NSAIDs can interact with capecitabine (your combination partner) and should generally be avoided.

Why do I need an ECG before starting?

Lapatinib can prolong the QT interval on ECG — a measure of heart electrical recovery. Prolonged QT can lead to dangerous arrhythmias. Baseline ECG checks ensure it is safe to start.

What do I do if I have very bad diarrhoea?

Start loperamide immediately and drink plenty of oral rehydration fluids. If diarrhoea exceeds 6 loose stools per day, or you develop fever, or are unable to stay hydrated, contact your oncology team immediately or go to hospital.