Erlotinib

All solvents were of analytical grade and used without further purification. KCl, NaCl, HCl, KOH, dimethyl sulfoxide (DMSO), NaH2PO4 and Na2HPO4, warfarin (WF), dansylglycine (DG), HSA containing fatty acids (A8763) and fatty acid free (A1887) were purchased from Sigma Aldrich. Osimertinib (OSI) was purchased from Atomole Scientific, afatinib maleate (AFA-mal) from Chemscene, erlotinib (ERL) hydrochloride, gefitinib (GEF), and afatinib (AFA) free base from LC laboratories all in >98% purity. KP2187 [22] and dansyl sarcosine (DS) [23] were synthesized according to literature. Doubly distilled Milli-Q water was used for sample preparation. Samples for albumin binding studies were prepared in phosphate buffered saline (PBS) at pH 7.40. HSA solution and solutions of WF and DG were prepared as described previously [24, 25] . Stock solution of DS was prepared on a weight-involume basis and its molar absorbance was determined (328nm = 4397 M -1 cm -1 ).This value was used to estimate the concentration of subsequent stock solutions. Slightly acidic stock solutions (c = 0.2-1 mM; pH ~3) of the inhibitors were prepared and their concentrations and molar absorptivities were determined based on a weight-in-volume basis (see details in Section S1/Table S1). In HSA binding experiments these stocks were diluted with PBS to get our working solutions (c = 50-200 μM, pH = 7.40).