The Effects of Rheum palmatum L. on the Pharmacokinetic of Major Diterpene Alkaloids of Aconitum carmichaelii Debx. in Rats.

BACKGROUND AND OBJECTIVES: Aconitum carmichaelii Debx. (Fuzi) is usually compatible with Rheum palmatum L. (Dahuang) in clinic. The study is conducted to investigate the influence of Dahuang on the pharmacokinetics of Fuzi.

METHODS: Twelve rats were randomly divided into two groups. Fuzi group was orally administered a single dose of 38.4 mg/kg total alkaloids from Fuzi, and Fuzi-Dahuang group was given 38.4 mg/kg total alkaloids from Fuzi and 76.8 mg/kg Dahuang anthraquinones at the same time. The plasma concentrations of aconitine (AC), mesaconitine (MC), and hypaconitine (HC), benzoylaconine (BAC), benzoylmesaconine (BMC), benzoylhypaconine (BHC), and aconine (ACN) were determined by ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry method. The pharmacokinetic parameters were calculated including maximum plasma concentration (C max ), area under the plasma concentration-time curve in all time-points (AUClast ), apparent volume of distribution (V z /F), apparent plasma clearance (CL/F), elimination half-life (T 1/2 ), and time to achieve maximum concentration (T max ).

RESULTS: AUClast of diester diterpene alkaloids (DDAs) were 58.20, 169.78, 278.48 ng·h/mL for AC, MC, and HC in Fuzi-Dahuang group which were remarkably lower than that in Fuzi group (71.62, 183.13, 410.59 ng·h/mL for AC, MC, HC). CL/F was significantly increased from 173.88 to 218.85 mL/h for AC, 433.22 to 800.21 mL/h for MC, 1150.61 to 1307.30 mL/h for HC after combination. However, with the significantly increased C max , AUClast of monoester diterpene alkaloids (MDAs) and amine diterpenoid alkaloids (ADAs) were 152.42, 1238.95, 287.96, 123.33 ng·h/mL for BAC, BHC, BMC, ACN in Fuzi-Dahuang group which were remarkably higher than that in Fuzi group (54.47, 1105.48, 200.75, 86.48 ng·h/mL for BAC, BHC, BMC, ACN). At the same time, CL/F was significantly decreased from 1030.15 to 607.09, 3594.06 to 1437.54, 1441.23 to 1310.14, and 391.30 to 239.50 mL/h for each one after combination.

CONCLUSIONS: Fuzi diterpene alkaloids pharmacokinetics was greatly influenced by Dahuang which may account for the compatibility mechanism of effect-enhancing and toxicity-reducing.