Pharmacokinetic comparisons of schizandrin after oral administration of schizandrin monomer, Fructus Schisandrae aqueous extract and Sheng-Mai-San to rats

Sheng-Mai-San (SMS) is a famous traditional Chinese medicine (TCM) recipe, containing Radix Ginseng (Panax ginseng C.A. Mey., Araliaceae), Radix Ophiopogonis (Ophiopogon japonicus (Thunb.) Ker-Gawl., Liliaceae) and Fructus Schisandrae (Schisandra chinensis (Turcz.) Baill., Magnoliaceae), and has been used more than one thousand years. In this research, pharmacokinetics of one component of this TCM recipe was studied. Schizandrin is the main absorbed effective ingredient of Fructus Schisandrae and its pharmacokinetics were studied following oral administration of pure schizandrin, Fructus Schisandrae aqueous extract, and SMS decoction in rats with approximately the same dose of 5 mg/kg. At different time points (0, 0.083, 0.25, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10 and 12 h) after administration, the concentrations of schizandrin in rat plasma were determined by LC-MS, and main pharmacokinetic parameters were estimated. It was found that both AUC_0-tn and T_1/2 of schizandrin in Fructus Schisandrae aqueous extract and in SMS decoction were increased significantly (p < 0.05) comparing with that in monomer. The content assay also revealed that the concentrations of lignans would increase when SMS decocting, comparing with Fructus Schisandrae. These results indicate that some ingredients in SMS may increase the dissolution of schizandrin when decocting in vitro, and delay its elimination and enhance its bioavailability in rat.