Sluiter C, Kettenes-van den Bosch JJ, Hop E, van der Houwen OA, Underberg WJ, Bult A. Degradation study of the investigational anticancer drug clanfenur.
Int J Pharm 1999;
185:227-35. [PMID:
10460918 DOI:
10.1016/s0378-5173(99)00160-x]
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Abstract
Clanfenur belongs to a new group of substituted benzoylphenylureas. The drug shows both in vitro and in vivo antitumour activity. To assess its chemical stability, a study was carried out in which the effect of pH, temperature, ionic strength and buffer concentration on the reaction rate constant k(obs) were examined. A stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) system was used. The pH-log k(obs) degradation profile, obtained at 70 degrees C, shows that clanfenur has its maximum stability in the pH region 4-5. At pH 7, half-lives were calculated by extrapolation of the Arrhenius plot; at 4 degrees C the half-life was calculated to be 141 years and at 25 degrees C 9. 5 years. The activation energy was calculated to be 114 kJ/mol. In acidic, neutral, and alkaline media, the ionic strength has no effect on the degradation. The buffer concentration of citrate, phosphate, borate, and carbonate did not affect the value of k(obs). An RP-HPLC chromatogram of degraded clanfenur shows the presence of four degradation products, three of which were identified by LC-ESI-MS as p-chloroaniline, p-chlorophenylurea and 2-fluoro-6-dimethylaminobenzamide.
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