Rifampicinの酵素誘導と時間依存性

概要

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Pharmacokinetics and enzyme induction effects of rifampicin, an antituberculosis, were studied on 8 female and 2 male patients. Rifampicin (450 mg) was administered orally every morning before breakfast over a period of 8 weeks. On the 1st, 14th, 21st, 28th and 56th days of treatment, venous blood samples were drawn immediately, 2,4 and 8 h after the administration of rifampicin. Rifampicin level in the serum was determined by high-performance liquid chromatography. Determination of rifampicin level was made in duplicate. Data of rifampicin levels in the serum (C_t) were calculated with a personal computer. Biexponential equation, C_t=A (e^<-K_at>-e^<-K_et>), and the pharmacokinetic parameters were non linear least squares regression analysis. The first-pass effect was obtained from calculated by the method of Gibaldi et al. C_<max> and area under blood concentration curve gradually decreased until the 21st day of treatment and, thereafter, reached a steady-state until the 56th day of treatment. Biological half-life fluctuated until the 28th day of treatment and reached steady-state on day 28. V_d, Cl and first-pass effects showed a definite increase until the 21st day of treatment. After that, they reached a steady-state until the 56th day of treatment. In summary, pharmacokinetics of rifampicin was found to be time-dependent and closely related to the enzyme inducibility of the drug.
社団法人日本薬学会の論文
1984-08-25