Abstract: A new pre-column derivation HPLC method with solid-phase extraction to determine captopril in human plasma was established. Derivation products were extracted by a solid-phase extraction method after the reagent, p-α-dibromoacetophenone (p-BPB), was added in the plasma samples. The samples were analyzed in a VP-ODS column with UV-detector. The calibration curve of captopril was linear within the range of 5~1000 g·mL^-1 with r = 0.9987, the recovery of this method was 98.65±2.04%, within day and between day RSD were no more than 3.4% and 8.4% respectively. To study the pharmacokinetics and the relative bioavailability of captopril tablets, two formulations of captopril tablets were given to 18 healthy male volunteers according to a randomized 2-way cross-over design with a 1-week washout period. The respective AUC0~6, Cmax and Tmax values of the two formulations were 424.5±125.7 and 439.4±113.3 μg·h·L^-1; 505.9±244.6 and 504.8±172.2 μg·L^-1; 0.662±0.181 and 0.528±0.176 h. Results from statistics analysis showed that there were no significant difference between the AUC0~6, Cmax and Tmax values of the two formulations, The relative bioavailability of tablets I with respect to II was 96.1±14.6% from AUC0~6 measurement. Bioequivalance was observed between the two tablets.

Key words: Captopril, Solid-Phase Extraction, HPLC, Pharmacokinetics, Bioavailability