Determination of Tanshinone Ⅱ_A in the Self-Microemulsifying Preparation in Rat Plasma

OBJECTIVE To establish a method for the determination of tanshinone Ⅱ_A in rat plasma and investigate pharmcokinetic characteristics of tanshinone Ⅱ_A self-microemulsifying preparation (TSP). METHODS Protein precipitation method with acetonitrile was applied to purify plasma samples before analysis. The concentration of tanshinone Ⅱ_A in rat plasma was detected by HPLC using Kromasil C₁₈ column(250 mm×4.6 mm, 5.0 mm). The mobile phase was consisted of acetonitrile and 0.01 mol·L^-1 citric acid solution(80∶20). The flow rate was 1 mL·min^-1 and the column temperature was 25 ℃. The detection wavelength was 270 nm. The pharmacokinetic profiles of tanshinone Ⅱ_A between self-emusifying and suspension were compared by oral administration. RESULTS The standard curve was linear over the range of 0.102-8.2 mg·L^-1 (r=0.998 6). The absolute recovery was 77.5% to 85.6%, and the assay recovery was 88.3% to 96.8%. The intra- and inter-day precision RSD were less than 15%. The AUC after TSP administration was approximately 2.5-fold compared with that of the suspension. CONCLUSION The method is accurate and sensitive for the determination of tanshinone Ⅱ_A in rat plasma. Bioavailability of tanshinone Ⅱ_A was improved by self-microemulfying.