Lapatinib acts as a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR/ErbB1) and human epidermal growth factor receptor 2(HER2/ErbB2). It competes for its binding site on the tyrosine kinase domain with adenosine triphosphate (ATP). Lapatinib mediates has been studied in vitro in the inhibition of cell growth as well as and apoptosis induction in several human cancer cells such as breast, lung, vulva, gastric, and head and neck cancer.