Study On Oral Nano - Drug Delivery System Of 9 - Nitro - Camptothecin Phospholipid Complex

20(S)-Camptothecin (CPT), a pentacyclic alkaloid, firstly extracted from the wood, bark, leaves and fruits of Camptotheca acuminate in the1960s.Camptothecin and its analogues has been received considerable attention. The anti-tumor mechanism of CPT and its analogues were based on inhibition of DNA synthesis by specifically targeting and inhibiting the nuclear enzyme of DNA topoisomerase I (topo I).9-Nitrocamptothecin (9-NC) is a new camptothecin derivative and was currently in Phase III trials. Basic and clinical researches suggested that9-NC had a high antitumor activity such as pancreatic cancer, ovarian epithelial cancer and leukemia and pharmacological studies disclosed that the antitumor activity of9-NC was superior to that of CPT. Unfortunately, despite the promising biological effects of9-NC, its defects of poor water-soluble (lower than5μg/mL in distilled water,25℃) and fat-soluble has restricted its application in the management of human ailments. Some researchers tried to overcome these defects using novel drug delivery systems, such as self-microemulsion, liposome, nanoparticles and polymeric micelles and so on. The results of reseaech indicated that they could improve the effects of the drug indeed, while the preparation of these systems were so complicated, the security of excipients used should be assessed and so restricted application in future. These years, phoshpolipid complex (PC) has been attracted more and more attentions, it could improve the degration of drugs and lower the side effects of drugs in the gastrointestinal tract, so this paper prepared9-NC-PC and its lipid drug delivery system for research.In our study, firstly, efforts have been given to prepare phospholipids complex of9-NC, and an orthogonal design was used for optimization of preparation process. And then, the physical and chemical properties of9-NC-PC were evaluated, XRD and DSC were used to structural confirmatory. In order to improve dispersibility of9-NC-PC, Two kinds of nanoparticles were studyed. For evaluating the improved of bioavailability of9-NC-PC, animal study was carried out to evaluate pharmacokinetics and intestinal absorption, which verified the rationality of the design.1. The preparation of9-NC-PC and the study of characteristicsIn this section, complification efficacy was used as assessment criteria. The effect of such factors as the solvent of reaction, the ratio of reactants, the reactive temperature, the reactive time and the concentration of reactants was studied by the single factor tests and orthogonal design. The optimal conditions obtained were as follows:9-NC and phospholipids were put in tetrahydrofuran (the ratio of9-NC to phospholipids was1:2) and the concentration of9-NCwas1mg/mL, after the agitation at temperature of55℃, solvent was evaporated, then put in vacuum drying oven for12h and obtain phospholipid complex. The results of DSC and XRD indicated that9-NC-PC exhibited different phase compared with physical mixture. Moreover,there was a great improvement in the solubility of9-NC-PC both in water and n-Octanol.2. The preparation of9-NC-PC-NPs and the study of its physicochemical characteristicsFirstly, we established accurate high performance method. GM and Migloyl812were employed as carriers,9-NC-PC-SLN was prepared by emulsification-ultrasonication. Using phospholipids as carrier to preparate9-NC-PC-NPs by high pressure homogenization, and then in vitro release、size distribution and zeta potential were studied.When using GM and Miglyol812as carrier its in vitro release displayed a slow-release characterictics, and9-NC-PC-NPs sudden release features. The particle diameters of9-NC-PC-NPs prepared by ultrasonication or high pressure homogenization were184.7±7.9nm and146.0±5.lnm separately The zeta potentials were9.11±1.03mv and11.39±1.25mv. The entrapment efficiency was90.04%+1.76%and89.90%±1.37%respectively. The drug loading was9.34%±0.27%and9.83%±0.55%respectively.3.The preliminary studies of single pass intestinal perfusion of9-NC and9-NC-PC-NPsFirst of all, we established accurate high performance method to determine the concentration of9-NC.In this section, Single pass intestinal perfusion was used to study of absorption characteristics of9-NC、9-NC-PC and9-NC-PC-NPs. The results showed that9-NC-PC could improve its absorption rate constant(Ka) in duodenum, jejunum, ileum and colon. The improved times were3.81,2.25,2.84and3.01.9-NC-PC-NPs also improved Ka compared to9-NC in duodenum, jejunum, ileum and colon. The improved times were4.02,2.10,2.99and3.04.9-NC-PC could improve its apparent permeability coefficients (papp) in duodenum, jejunum, ileum and colon. The improved times were4.35,2.46,3.20and3.25.9-NC-PC-NPs also improved Papp compared to9-NC in duodenum, jejunum, ileum and colon. The improved times were4.64,2.25,3.47and3.19. The results showed that9-NC-PC and9-NC-PC-NPs could improve Ka and Papp significantly.4.The study of pharmacology of9-NC、9-NC-PC and9-NC-PC-NPs in ratsA HPLC method for the determination of9-NC in plasma was established to study pharmacokinetics and relative bioavailability of9-NC,9-NC-PC,9-NC-PC-NPs and9-NC-PC-SLN after oral administration. When using GM and Miglyol812as carrier to preparate9-NC-PC-SLN, the Ke of9-NC-PC-SLN group was reduced significantly compared to the group of9-NC and9-NC-PC, Tmax was delayed over1h; The AUC of9-NC-PC-SLN and9-NC-PC was greater than9-NC-PC(<0.05), its relative bioavailability(compare to9-NC) was inproved512%and640%. When using phospholipids as carrier to prepare9-NC-PC-NPs, its relative bioavailability (compare to9-NC) was inproved542%and708%.