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标题：Kinetics of Nikkomycin Z Degradation in Aqueous Solution and in Plasma
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作者：Tadakazu TOKUMURA ; Toru HORIE
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：1997
卷号：20
期号：5
页码：577-580
DOI：10.1248/bpb.20.577
出版社：The Pharmaceutical Society of Japan
摘要：The stability of nikkomycin Z in aqueous solution at various pH values and in the plasma of several kinds of experimental animals was studied. The degradation of nikkomycin Z in aqueous solution at pH 4 to 11.5 and in plasma was an apparent first-order reaction. The degradation rate at 37°C increased with increasing pH, from 4.0 to 7.5, and decreased with increasing pH from 7.5 to 10.2. Above pH 10.2, the degradation rate was constant. The maximal rate of nikkomycin Z degradation was observed in pH 7.5 buffer solution, in which the apparent first-order rate constant (k_obs) was 8.08×10^-2h^-1 (t_1/2=8.6 h). The degradation rate of nikkomycin Z in dog plasma at 37°C was the almost same as that in pH 7.5 buffer. The rates in rat, mouse, and rabbit plasma were much greater than that in pH 7.5 buffer; the k_obs values for rat, mouse, rabbit, and dog plasma at 37°C were 1.74×10^-1min^-1, 3.64×10^-2 min^-1, 5.10×10^-1 h^-1, and 6.14×10^-2 h^-1, respectively. The degradation rate of nikkomycin Z in rat plasma was remarkedly decreased when NaF, an esterase inhibitor, was added to the plasma. The findings of faster degradation rates in rat, mouse, and rabbit plasma compared with that in pH 7.5 buffer were considered to be due to an esterase in the plasma. This notion was supported by results showing the degradation rate of nikkomycin Z in porcine liver esterase solution.
关键词：nikkomycin Z;stability;aqueous solution;plasma;apparent first-order reaction