How should I take lapatinib?
Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.
When used with letrozole, the usual dose of lapatinib is 6 tablets taken once daily every day. Letrozole is also taken every day.
When used with capecitabine, the usual dose of lapatinib 5 tablets taken once daily for 21 days in a row. Capecitabine is also taken twice daily for only the first 14 days. This 21-day cycle is then repeated.
Follow your doctor's dosing instructions very carefully.
Take lapatinib on an empty stomach, at least 1 hour before or 1 hour after a meal.
You may swallow each lapatinib tablet one at a time, but take the entire dose (all 5 or 6 tablets) at the same time each day.
Capecitabine must be taken with food or within 30 minutes of eating.
You will need blood tests every 4 to 6 weeks to check your liver function. Your heart function may also need to be checked using an electrocardiograph or ECG (sometimes called an EKG).
Store lapatinib at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.
Your doctor will determine how long to treat you with lapatinib and capecitabine or letrozole. Take your medications for the full prescribed length of time. Combination chemotherapy is usually continued unless your condition gets worse or you have serious side effects.