Lapatinib is used with capecitabine (Xeloda) to treat a certain type of advanced breast cancer in people who have already been treated with other chemotherapy medications. Lapatinib is in a class of medications called kinase inhibitors. It works by blocking the action of the abnormal protein that signals cancer cells to multiply. This helps stop or slow the spread of cancer cells.Lapatinib comes as a tablet to take by mouth. It is usually taken once a day, at least 1 hour before or 1 hour after a meal. Take all of the tablets for your daily dose at one time each day; do not divide the tablets to take as separate doses. Take lapatinib at around the same time every day.