Abstract: Aim To develop a simple and sensitive high-performance liquid chromatographic method for determination of plasma concentration of cinnamic acid and pharmacokinetic study in rats after a single oral dose of traditional Chinese me-dicinal preparation Zi-Shen pill. Method Plasma samples were acidified with hydrochloric acid and extracted with ethyl ac-etate. Cinnamic acid was determined by HPLC using a C18 column. A mobile phase of methanol-acetonitrile-water-triethyl-amine (7:22:73:0.2, V/V), with the pH adjnsted to 4.0 with phosphoric acid, and with a UV detector set at 340 nm. Results The standard curve was linear over the range of 1.92-192.0 μg·mL^-1. The LLOQ was 1.92 μg·mL^-1. The RSDs of within-day and between-day precision were <8%. The mean recovery was 82.0%. Concusion After valida-tion, the method has been used to investigate the pharmacokinetic profilies of the traditional Chinese medicinal preparation Zi-Shen pill.

Key words: cinnamic acid, cinnamic acid, Zi-Shen pill, Zi-Shen pill, pharmacokinetics, pharmacokinetics, HPLC, HPLC