Kobayashi H, Kobayashi S, Inoue A, Oka T, Nakamizo N
Pharmaceutical Research Laboratories, Kyowa Hakko Kogyo Co., Ltd., Shizuoka, Japan.
Arzneimittelforschung. 1988 Nov;38(11A):1730-3.
A gas chromatographic assay procedure was developed for measuring subnanogram order concentrations of (+/-)-(R*)-2,6-dimethyl-4-(m-nitrophenyl)-1,4-dihydropyridine-3,5- dicarboxylic acid (R*)-1-benzyl-3-piperidinyl ester, methyl ester hydrochloride (benidipine hydrochloride, KW-3049) in plasma. KW-3049 yielded the oxidation product partially during gas chromatography. To avoid decomposition, KW-3049 was oxidized in advance by nitrogen dioxide, extracted by diethylether under alkaline condition, chromatographed on the OV-1 column and measured using electron capture detector.
