Comparative pharmacokinetics studies of benzoylhypaconine, benzoylmesaconine, benzoylaconine and hypaconitine in rats by LC-MS method after administration of Radix Aconiti Lateralis Praeparata extract and Dahuang Fuzi Decoction.

A rapid and sensitive high-performance liquid chromatography-mass spectrometric (HPLC-MS) method was developed and validated for simultaneous determination of benzoylhypaconine (BHA), benzoylmesaconine (BMA), benzoylaconine (BAC) and hypaconitine (HA) in rat plasma for the first time. The analytes were separated on a Kromasil C₁₈ column with a total running time of 11 min. The validation data demonstrated a sound feasibility for the newly developed method and it was then applied to the pharmacokinetic study of these analytes in rats. Pharmacokinetic behaviors of BHA, BMA, BAC and HA in rats were studied after oral administration of Radix Aconiti Lateralis Praeparata extract (FZ) and Dahuang Fuzi Decoction (DFD). The main parameters for the two groups of subjects were compared, and significant differences between Radix Aconiti Lateralis Praeparata extract group and Dahuang Fuzi Decoction group in calculated parameters, such as the area under the plasma concentration-time from zero to the last quantifiable time-point (AUC(₀-t)), the area under the plasma concentration-time curve from zero to infinity (AUC(₀-∞)), peak plasma concentration (C(max)), half-life of elimination (T₁/₂), mean retention time (MRT(₀-t)), plasma clearance (CL), volume of distribution (V(d)) and time to reach Cmax (T(max)), were found. After oral administration of DFD, the AUC(₀-t), AUC(₀-∞) and C(max) of BHA, BMA, BAC and HA decreased remarkably (p < 0.05) compared with those of the FZ extract group. Vd and CL values of BHA, BMA, BAC and HA increased, two of which showed significant difference (p < 0.05). T₁/₂ and MRT(₀-t) values of BHA, BMA and BAC in the DFD group were significantly delayed compared with those of FZ extract group. Only the T(max) of HA, the toxic ingredient in FZ, delayed significantly in DFD group compared with the value of FZ group. All these pharmacokinetic parameters were statistically compared, and the rationality of the combination for DFD was clearly demonstrated.