Design And Evaluation Of Multiple Unit Type Colon-targeted Drug Delivery System Of Pulsatilla

The traditional Chinese herb Pulsatilla has been reported to be effective in clearing away heat, detoxicating, removing heat from the blood and arresting dysentery, and especially in clearing large intestine damp-heat and noxious heat in blood system, so as being a common drug for clinical treatment of Ulcerative Colities(UC). Accoring to the low patient compliance of enema administration and large individual difference of oral colon-targeted preparations, this paper explored research of multiple unit type colon-targeted drug delivery system of Pulsatilla based on coated pellets and particle design technology, and evaluated the system in vitro and in vivo relatively. The dissertation is summarized as follows:1. Primary screen for anti-UC action of Pulsatilla extract and its mechanismThe pharmacodynamic test of Pulsatilla extract(PE) was conducted using DSS-induced UC mice model. The results showed that Pulsatilla from Heilongjiang had the strongest anti-UC effect in the three kinds of different producing areas, and the effect of alcohol extrat was stronger than water extrat. Thus, Pulsatilla from Heilongjiang was extracted by ethanol, then separated and purified by macroporous resins to prepare PE. The anti-UC effect of PE was confirmed and the optimum dose was screened by pharmacodynamic test. Meanwhile, according to the results of biochemical indexes in the pharmacodynamic test, the mechanism of anti-UC action of PE might be related to the inhibition of inflammatory factor, the reduction of oxygen free radicals production, and the increase of oxygen free radicals clearance.2. Pharmaceutical pre-formulation studyThis paper researched the micromentic property, solubility and bio-pharmaceutical characteristics of PE. The results indicated that it had low bulk density, poor fluidity, low water content, and weak hygroscopicity; Precipitation method, index component dissolvability, and particle diameter measurement were used to evaluate the solubility and gived the similar result that its solibility in water was poor; The rat intestinal valgus test showed that the index component hederagenin3-0-a-L-rhamnopyranosyl(1â†'2)-[β-D-glucopyranosyl(1â†'4)]-a-L-arabinopyranoside could reflect the general absorption of the extract, while the absorption of the index component in different intestinal segments had no significant difference, and there was not a special absorption window. 3. Preparation of Pulsatilla inclusion complex pelletsIn order to solove the dissolution problem, the paper used solid dispersion technology and inclusion technique respectively. The research showed that it significantly increased the dissolution after preparing PE-hydroxypropyl-β-cyclodextrin inclusion complex(PE-HP-β-CD). The optimum formulation and preparation of pellets were:granulation-spheronization process for preparation of pellets, PE-HP-β-CD as raw material,50%MCC as excipient,30%mannitol as bulking agent, and30%ethanol as wetting agent. The pellets were coated by Glatt fluid bed. When the flowing pressure was0.45bar, pressure of spray was1.0bar, intake flow velocity was2.0mL·min-1, material temperature was30℃, and aging3-4h at40℃, it had high coating efficiency and no bonding. The optimum formula of coating was:Eudragit S100as coating material, TEC as plasticizer(15%of the polymer), talc powder as antiadherent(50%of the polymer), with coating weight of12%.4. Preparation of Pulsatilla particle design powderThis paper prepared Pulsatilla particle design powder(PPDP) by grinding method in the particle design technology. The PPDP was characterized by description of appearance characters, in vitro release, particle size, SEM, X-RD and surface contact angle etc. The research showed that the optimum formulation and preparation of PPDP were:mass ratio of PE to S100of3:17, grinding time of20min, and we find that comminution degree of PE had no significant effect on PPDP. The PE particles were coated by S100in PPDP, so PPDP had the same characteristic diffraction peaks and surface wettability with S100.5. Quality evaluation of Pulsatilla colon-targeted preparation in vitroThe three batches PE-HP-β-CD coated pellets and PPDP were prepared according to the optimized formulation and preparation,and the character, content, in vitro release and preliminary stability were studied. The results showed that these two kinds of colon-targeted preparations had even appearance, small differences among different batches, in vitro release accorded with requirement of colon-targeted preparation, and good stability.6. Quality evaluation of Pulsatilla colon-targeted preparation in vivoThe content of durgs in rat gastrointestinal contents and gastrointestinal tract tissues at different time after oral administration was determined by HPLC. The results showed that compared with the general suspension of extract, more drugs reached terminal ileum and colon in coated pellets and PPDP, and drugs in the colon tissues also significantly increased.The paper established a method for determination of index component of Pulsatilla in rat plasma by LC-MS, and studied pharmacokinetics of Pulsatilla extrat, PE-HP-β-CD coated pellets and PPDP in rats by oral administration. The results indicated that the Tmax, MRT and Cmax of PE-HP-β-CD coated pellets were1.9,3.4and0.4times of PE extract respectively, while the Tmax, MRT and Cmax of PPDP were4,2.4and0.3times of PE extract respectively. PE-HP-β-CD coated pellets and PPDP had longer peak time and mean residence time, and lower maximum plasma concentration, so as to show colon-specific-drug-released characteristics.PPDP was more superior than PE-HP-β-CD coated pellets no matter in colon-specific-drug-released characteristics or in individual differences. The pharmacodynamic test showed that PPDP of a quarter dose had equivalent effect of anti-UC action with Pulsatilla extract.