Pharmacokinetic study on spinosin in rat plasma after oral administration of suanzaoren extract at a single dose.

AIM: To study the pharmacokinetics of spinosin in rat plasma after oral administration of Suanzaoren extract using sulfamethoxazole (SMZ) as internal standard by RP-HPLC method.

METHODS: Plasma samples were deproteined with acetonitrile, followed by evaporation of the acetonitrile to dryness. The residual was then resolved in mobile phase and HPLC separation was achieved on a Hypersil C18 (5 microns, 200 mm x 4.6 mm ID) column at 35 degrees C. The mobile phase consisted of acetonitrile-water-acetic acid (15:85:1) at a flow rate of 0.7 mL.min-1. The UV detection wavelength was set at 334 nm.

RESULTS: The calibration curve was shown to be linear over the range from 18.1 to 903.5 micrograms.L-1 (r2 > or = 0.995). Mean recovery was 94.5%. Within-day and between-day precisions RSD were less than 9.0%. The limit of quantitation was 18.1 micrograms.L-1. The plasma spinosin was stable at -20 degrees C.

CONCLUSION: The simple, sensitive and accurate HPLC method developed has been applied to determine the pharmacokinetics of spinosin in rat plasma after having taken Suanzaoren extract at a single dose.