Determination of serum concentrations of glycyrrhizin in humans by semi-micro high-performance liquid chromatography after administration of a therapeutic dose

A simple and sensitive semi-micro high-performance liquid chromatography (W PLC) was established for determining the serum levels of clycyrrhizin (GL) in humans. Butyl p-hydroxybenzoate was used as the internal standard and se rum was deproteinized by methanol. The samples were separated on a Capcell Pak C18 UG120 column (150 x 1.5 mm i.d.: particle size, 5 mu m). The detect ion limit of GL in serum was 100 ng/ml, which enables determination of seru m levels of GL after administration of a therapeutic dose. The time-course study suggested that the elimination rate of GL differed between subjects f or the same administered dose, although the sample was too small to allow a meaningful comment, In clinical practice, GL is used for its antiviral and anti-inflammatory effects. Excessive administration of GL can induce pseud oaldosteronism; however the optimal GL concentration in serum remains to be determined. The determination method reported here is expected to aid in t he safe and efficient use of the drug in clinical practice.