LC analysis and pharmacokinetic study of pachymic acid after intravenous administration to rats

A simple and sensitive high-performance liquid chromatographic method with UV detection was developed and validated to investigate the concentration of pachymic acid (PA) in rat plasma. The sample preparation was a liquid-liquid extraction and chromatographic separation was achieved with a Dikma Diamonsil (TM) C(18) column (250 x 4.6 mm I.D.) with a C(18) guard column (8 x 4 mm I.D.) using a mobile phase consisting of MeOH-MeCN-aq. 0.45% H(3)PO(4) (45:40:22) at a flow rate of 1.0 mL min(-1). The UV detection was at 210 nm. Standard curves were linear (r = 0.9998) in plasma over the concentration range of 0.5-50 mu g mL(-1) and had acceptable accuracy and precision. Intra- and inter-day precisions expressed as the relative standard deviation (RSD) were 0.26-1.60% and 1.24-2.31%. The lower limit of quantification and lower limit of detection were 0.45 and 0.17 mu g mL(-1). The method has been used successfully to study the pharmacokinetics of PA. After a dose of 30 mg kg(-1) by intravenous administration, the main pharmacokinetic parameters t(1/2), AUC(0-infinity), CL, V(ss) and MRT(0-infinity) were 8.79 +/- 6.80 h, 18.90 +/- 9.39 mu g h mL(-1), 0.53 +/- 0.28 L h(-1), 5.60 +/- 4.60 L and 12.58 +/- 9.95 h, respectively.