Abstract: AIM: To establish LC-MS method in the determination of matrine in plasma of Beagle dogs and to investigate its absolute bioavailability.METHODS: Lichrospher C18 column was used as the analytical column and maintained at 25 ℃, 250 mm×4.6 mm (ID), and 5 μm.The mobile phase was consisted of 10 mmol·L^-1ammonium acetate and methanol (25 ∶75, v ∶v).Flow rate was 1 ml·min^-1.Electrospray ionization (ESI) was carried out.The ESI ion source was set in positive ion polarity mode.The selective ion monitoring (SIM) was set at m z 249.2 for matrine.RESULTS: The linearity of matrine ranged from 2 to 5 000 μg·L^-1(r=0.9975) and the detection limits of it was 0.3 μg·L^-1.The RSD of within day and between day was less than 4.5 %.The recovery of this method was more than 96.6 %.The disposition was conformed to a two-compartment model.The C_max, T_max, T_1/2β, AUC_0→∞ and absolute bioavailability of matrine were 3821±705 μg·L^-1, 0.4±0.1 h, 11.2±2.1 h, 7446±1456 μg·L^-1·h and (60.1±19.0) %, respectively.CONCLUSION: This study provides a highly sensitive, rapid, simple and special method for determining concentrations of matrine in plasma of Beagle dogs.Matrine shows higher absolute bioavailability in Beagle dogs.

Key words: matrine, pharmacokinetics, absolute bioavailability, LC-MS, Beagle dogs