Purity ≥99%. ATP-competitive EGFR & ErbB-2 dual tyrosine kinase inhibitor. Lapatinib is an ATP-competitive epidermal growth factor receptor (EGFR) and HER2/neu (ErbB-2) dual tyrosine kinase inhibitor, with IC(50) values of 10.8 and 9.2nm respectively. It is an orally active drug for treatment of breast cancer and other solid tumors. A free base form of Lapatinib Ditosylate. Lapatinib (as the di-p-toluenesulfonate salt) is the active ingredient in the drug sold under the trade names Tykerb in the US and Tyverb in Europe. This drug has been approved in at least one country to treat advanced metastatic breast cancer in conjunction with the chemotherapy drug Xeloda (generic name, capecitabine). Solubility: Soluble in DMSO at 200mg/ml; very poorly soluble in ethanol; very poorly soluble in water; maximum solubility in plain water is estimated to be about 1-10uM; buffers, serum, or other additives may increase or decrease the aqueous solubility.