HPLC Method Determination of Isoliquiritin Apioside and Isoliquiritin in Rat Plasma for Application in Pharmacokinetic Study after an Oral Administration of Zhigancao Extract

Table 3

Pharmacokinetic parameters of ILA and IL in following an oral administration of Zhigancao extract. The 𝐶_max was the measured maximal concentration of ILA and IL, and the 𝑡_max was the time to reach maximal concentration of ILA and IL, obtained directly from the observed value. Plasma concentrations in the terminal phase for each subject were fit to a log-linear regression by the method of least squares to obtain the elimination rate constant (𝑘_𝑒). The 𝑡_1/2𝑧 value was calculated with the following formula: 𝑡_1/2 = ln(2)/𝑘_𝑒. The AUC_0−𝑡 value was the area under the concentration-time curve from 0 to 36 h (calculated using the linear trapezoidal rule), and AUC_0−∞ value was calculated using the formula: AUC_0−∞=AUC_0−𝑡 + 𝐶_last/𝑘_𝑒, where 𝐶_last was the last measurable concentration. The mean residence time (MRT) was obtained from the formula AUMC/AUC (AUMC-area under the concentration × time curve), and MRT_0−∞ was calculated using the formula: MRT_0−∞=AUMC_0−∞/AUC_0−∞.

Parameter	ILA	IL
𝐶max (μg/mL)	0.88 ± 0.34	1.45 ± 0.47
𝑇max (h)	2.08 ± 2.11	1.92 ± 2.06
𝑡1/2𝑧 (h)	8.12 ± 1.72	8.56 ± 1.17
AUC0−𝑡 (μg/mL * h)	8.93 ± 3.06	15.39 ± 3.91
AUC0−∞ (μg/mL * h)	9.49 ± 3.35	16.20 ± 4.23
MRT0−𝑇 (h)	11.17 ± 2.72	11.53 ± 1.66
MRT0−∞ (h)	12.27 ± 4.35	13.20 ± 2.34