Methyl cellulose

Tegafur, 5-FU, gimeracil, and potassium oxonate were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). SDT was obtained from Hankook Shinyak Corp. (Nonsan, Chungnam, Korea). Sodium carboxymethyl cellulose (CMC-Na) and methyl cellulose (MC) were obtained from Junsei Chemical (Tokyo, Japan). Acetonitrile and distilled water (all HPLC grades) were purchased from J.T. Baker, Inc. (Phillipsburg, NJ, USA), and formic acid was obtained from Aldrich Chemical Co. (Milwaukee, WI, USA).

Gemcitabine hydrochloride and erlotinib hydrochloride were purchased from LC Laboratories (Woburn, MA, USA). 2′,2′-Difluoro-2′-deoxyuridine (dFdU) was purchased from Toronto Research Chemicals Inc. (North York, ON, Canada). Desmethyl erlotinib was purchased from Santa Cruz Biotechnology Inc. (Santa Cruz, CA, USA). Hyangsayukgunja-tang (HYT) was obtained from Hankook Shinyak Corp. (Nonsan, Chungnam, Korea). Carboxy methyl cellulose sodium (CMC-Na) and methyl cellulose (MC) were obtained from Junsei Chemical (Tokyo, Japan). Acetonitrile and distilled water (all HPLC grades) were purchased from J.T. Baker, Inc. (Phillipsburg, NJ, USA) and formic acid was obtained from Aldrich Chemical Co. (Milwaukee, WI, USA).