Disposition study of a new potential antineoplastic agent dimefluron in rats using high-performance liquid chromatography with ultraviolet and mass spectrometric detection.

摘要

The disposition of a new potential antineoplastic drug dimefluron after an oral administration to rats was investigated. Dimefluron, 3,9-dimethoxy-5-(2-dimethylaminoethoxy)-7H-benzo[c]fluoren-7-one hydrochloride, was administered in a single oral dose (250mgkg(-1) of body weight) in the form of an aqueous solution via a gastric probe. Dimefluron metabolites were being searched for in rat faeces. Synthetic standards of the expected phase I metabolites (the products of O- and N-desmethylation, N-oxidation and carbonyl reduction of dimefluron) were prepared and used together with dimefluron and internal standard in the development of two HPLC bioanalytical methods based on different separation principles. The first separation of dimefluron and the phase I metabolites was tested on a 250mmx4mm chromatographic column with LiChrospher 60 RP-selectB 5mum (Merck) using an isocratic mobile phase containing 0.01M nonylamine buffer (pH 7.4) and acetonitrile in the 1:2 ratio (v/v). The second separation was performed on a 250mmx4mm chromatographic column Discovery HS F5, 5mum (Supelco) using a linear gradient mode with the mobile phase containing acetonitrile and phosphate buffer (0.05M KH(2)PO(4), pH 3). The flow rate was 1mlmin(-1) in both cases. UV detection was performed in the dual wavelength mode, with 317nm having been used for dimefluron and all 7H-benzo[c]fluoren-7-one metabolites, 367nm for 7H-benzo[c]fluoren-7-ol metabolites. A higher homologue of dimefluron served as an internal standard. The identity of the dimefluron metabolites in biological samples was confirmed using HPLC-MS experiments. The elimination study showed that the concentration maximum for dimefluron and its metabolites in rat faeces was reached 48h after the administration of the parent drug. O-Desmethylated derivatives of dimefluron prevailed among the phase I metabolites.