A simple, reliable and efficient assay for quantitative analysis of a novel Kv7/KCNQ/M-channel opener QO58-lysin in rat plasma was developed using high-performance liquid chromatography（HPLC） with UV detection. Separation of compound QO58-lysin from plasma was achieved using a reverse-phase C18 column with a mobile phase of 0.2 M ammonium acetate in H2O–acetonitrile（40：60, v/v） with nitrendipine used as an internal standard（IS）. The retention times of QO58-lysin and the IS in rat plasma were 3.8 and 5.4 min, respectively. Calibration curve was linear ranging from 0.1 to 120 μg/mL with correlation coefficient（r2） of 0.9996. The lower limit of quantification was 0.1 μg/mL. Accuracy, precision, recovery as well as stability were all within acceptable criteria according to Food and Drug Administration（FDA） guidelines. This validated assay was successfully applied to determine the pharmacokinetics of QO58-lysin administered intravenously（10 mg/kg） in SD rats. The distribution and elimination half-life of QO58-lysin in plasma was（0.25±0.16） h and（2.15±0.12） h, respectively.
