Lapatinib Ditosylate, which is sold under the brand name “Tykerb”, is indicated for the treatment of “advanced hormone-related breast cancer that has progressed or spread after treatment with other cancer medicines” (drugs.com). It is also used in combination with a chemotherapy medication called Capecitabine in patients whose cancer has not gotten better with other anticancer drugs. This medication basically works by hindering the growth of cancer cells. According to Wikipedia, there was a randomized clinical trial on female breast cancer which demonstrated that administrating Lapatinib Ditosylate in combination with Capecitabine “delayed the time of further cancer growth compared to regimens that use Capecitabine alone”. Even though Lapatinib Ditosylate is generally regarded as well tolerated, it can cause nausea, diarrhea, fatigue, and rash. And when used with Capecitabine, reversible decreased left ventricular function is quite common as well. Bear in mind that Lapatinib Ditosylate can harm an unborn baby, or even cause birth defects. Therefore, using effective birth control to prevent pregnancy is highly recommended.