Content Determination Of Three Major Components From Extracts Of Cortex Daphnes And Relevant Topical Delivery

Cortex Daphnes is the stem cortex and root bark of Daphne giraldii Nitsche,Daphne retusa Hemsl or Daphne tangutica Maxim, a folk herb used in west ofChinese,which often used for the treatment of active rheumatoid arthritis. In order toincrease the concentration of drug and enhance its anti-inflammatory effect,meanwhile reduce its adverse reactions by oral administration and reduce skin toxicity,we developed the extract from Cortex Daphnes and studied its penetration in vitro andpharmacokinetics in vivo.In order to determine the main components in vitro or in vivo, a highperformance liquid chromatography （HPLC） method was established. The HPLCcondition of three major components （daphnin, daphnetin-8-glucoside and daphnetin）in vitro is as follows: Prodigy ODS（3） as solid phase, methanol-0.05%phosphoricacid aqueous solutions （18:82）, and327nm as detective wavelength with flow rate1.0mL/min. The concentration is in good line relationship with peak area, thus aqualifie linear curve of leflunomide was obtained. The HPLC condition of three majorconponents in vivo rabbit plasma and phase, gradient eluted with methanol and0.05%phosphoric acid aqueous solutions, ferulic acid as inner standard and327nm asdetective wavelength. The concentration is in good line relationship with ratio of peakarea, thus a qualifie linear curve of leflunomide was obtained.Normal saline was used as receptor solution in vitro percutaneous penetrationexperiments because the solubility and stability of three major components in thesolution were suitable for these experiments. Franz vertical diffusion cells wereadopted as apparatus for in vitro skin permeation to study the effects of percutaneousabsorption enhancer like azone on the transdermal characters of three majorcomponents through rabbit excised skin in this paper. The three major components incataplasm was permeated at zero rate. Total acumulative permeation amount was543.72μg·cm^-2by physical method depilation in24hours and the penetration rate was14.93μg·cm^-2·h^-1with lag time4.06hours （n=3）. Total acumulative permeationamount was1541.21μg·cm^-2by chemical method depilation in24hours and thepenetration rate was38.28μg·cm^-2·h^-1with lag time0.30hours （n=3）.The plasma concentration-time profiles of three major components were fitted tothe two-compartment model with first order absorption.Taken blood at different time points after single administration, drawn concentration-time curve. Thepharmacokinetic parameters were assessed by two compartment model using DAS2.1.1. The main pharmacokinetic parameters of daphnin were: t_1/2（ka）:0.156h; t_1/2α:0.308h; t_1/2β:14.675h; Tmax:0.75h; Cmax:23.02μg mL^-1; AUC:123.533μg h mL^-1.The main pharmacokinetic parameters of daphnetin-8-glucoside were: t_1/2（ka）:0.147h; t_1/2α:0.243h; t_1/2β:7.542h Tmax:0.75h; Cmax:15.80μg mL^-1; AUC:58.21μg h mL^-1.The main pharmacokinetic parameters of daphnetin were: t_1/2（ka）:0.462h; t_1/2α:0.975h; t_1/2β:4.926h; Tmax:0.75h; Cmax:5.66μg mL^-1; AUC:18.144μg h mL^-1.Results shown that the extracts from Cortex Daphnes have fair transdermaldelivery and the absorption is rapid in vivo. It also lays a foundation for subsequentdevelop of Cortex Daphnes cataplasm.