Intravenous glycyrrhizin has been used in Japan for the treatment of chronic hepatitis
for >20 years, although only a few reports of its pharmacokinetic profile after multiple
intravenous doses in small numbers of Japanese patients have been published. The present
study compared these Japanese data against the pharmacokinetic characteristics of
glycyrrhizin after single and multiple intravenous doses in 35 European patients with
chronic hepatitis C infection. We administered 80, 160, or 240 mg glycyrrhizin 3 times/wk
or 200 mg glycyrrhizin 6 times/wk for 4 weeks. Twenty-four-hour pharmacokinetic assessments
were performed on day 1 and on or around day 14. Glycyrrhizin levels were determined
by high-performance liquid chromatography. The mean (+/- SD) volume of distribution
at steady state on day 1 in the 80-, 160-, 200-, and 240-mg groups were 67 +/- 11,
62 +/- 13, 54 +/- 7, and 66 +/- 8 mL/kg, respectively. The respective terminal elimination
half-lives on day 1 were 7.7 +/- 2.8, 10.1 +/- 1.4, 9.0 +/- 2.3, and 8.6 +/- 2.1 hours.
The area under the curve (AUC) increased linearly with doses < or =200 mg (r = 0.67;
P < 0.001). No significant differences between day 1 and day 14 were found in any
dose group, with the exception of AUC in the 200-mg group, which was significantly
higher on day 14 compared with day 1 (P = 0.03). Comparing the European and Japanese
data, the mean (+/- SD) AUC was 289 +/- 244 microg/h per mL for the former and 402
+/- 372 microg/h per mL for the latter; the half-life was 8.2 +/- 2.6 versus 8.8 +/-
9.0 hours; and the total clearance was 7.6 +/- 3.6 versus 8.5 +/- 5.7 mL/h per kg.
Thus our pharmacokinetic data are comparable to those from Japan. Glycyrrhizin's pharmacokinetics
are linear up to 200 mg. Drug accumulation is seen after 2 weeks of treatment with
200 mg administered 6 times/wk.