Abstract: OBJECTIVE:To elucidate the interaction between hydrophilic lithospermic acid B and lipophilic tanshinone Ⅱ A in rats.METHODS:A reliable high-performance liquid chromatography method was adopted for simultaneous determination of lithospermic acid B and tanshinone Ⅱ A in rat plasma,through which the pharmacokinetic interaction between lithospermic acid B and tanshinone Ⅱ A by intravenous injection was investigated.RESULTS:The simultaneous intravenous injection of tanshinone Ⅱ A and lithospermic acid B significantly altered the pharmacokinetic parameters of both compounds when compared with the individual intravenous administration of each compound.The area under the concentration-time curve of tanshinone Ⅱ A and lithospermic acid B increased by 18.35 and 59.31%,respectively.The mean retention time of tanshinone Ⅱ A and lithospermic acid B increased,respectively,from 9.3 to 32.8 h and20.2 to 49.1 h.The concomitant use of tanshinoneⅡ A magnified the volume of distribution at steady state(V_(ss)) and time for the drug in the plasma to reduce the highest concentration by half(t_(1/2)) of lithospermic acid B,while at the same time the V_(ss) and t_(1/2)of tanshinone Ⅱ A changed significantly in the presence of lithospermic acid B.CONCLUSION:Lithospermic acid B and tanshinone D A interact with each other following simultaneous intravenous injection in rats and this observation may expand the clinical use of Danshen(Radix Salviae Miltiorrhizae).

Key words: Tanshinone, Lithospermic acid B, Pharmacokinetics, Drug interactions