Structural formula of Lapatinib

Lapatinib (Lapatinib) is a small molecule drug that is a 4-aniline quinazoline kinase inhibitor. It exists as the xylene sulfonate monohydrate with the chemical name N-(3-chloro-4-{[(3-fluorophenyl)methyl]oxy}phenyl)-6-[5-({[2-(methylsulfonyl)ethyl]amino}methyl)-2-furyl]-4-quinazolinamine bis(4-methylbenzenesulfonate) monohydrate. Its molecular formula is C29H26ClFN4O4S (C7H8O3S)2 H2O, and its molecular weight is 943.5g/mol. Each 250 mg lapatinib tosylate tablet contains 405 mg of lapatinib xylene sulfonate monohydrate, equivalent to 398 mg of lapatinib xylene sulfonate or 250 mg of lapatinib free base.