Determination of glycyrrhizin and 18 alpha-, 18 beta-glycyrrhetinic acid in rat plasma by high-performance thin-layer chromatography.

An HPTLC method is described for the simultaneous determination of glycyrrhizinic acid tripotassium salt (3K-G), 18 alpha- and 18 beta-glycyrrhetinic acid (18 alpha-GA, 18 beta-GA) in rat plasma, after oral administration of 3K-G (30 mg/kg once a day for 30 days). Systolic pressure and the volume of urine excreted in 24 hours were recorded during this period to observe any drug-induced effects.